USMLE_Emergency I

28-year-old, G2 P1 woman presented to the hospital at 34-weeks gestation because of midepigastric and right upper quadrant pain associated with nausea and vomiting. She has been closely followed for mild hypertension and mild proteinuria (300 mg/24hr) on an outpatient basis since the 28th week of gestation. Her previous pregnancy was without incident. Her temperature is 37.2 C (98.9 F), blood pressure is 160/94 mmHg and pulse is 80/min. Physical examination shows epigastric and right upper quadrant tenderness; her bowel sounds are slightly reduced. The extremities have 2+ edema. Fetal heart sounds are audible on Doppler. Laboratory studies show: Hb: 8.2g/dl, Platelets: 96,000/mm3, Prothrombin time: 12.4 sec, Partial thromboplastin time: 23.6 sec, Serum creatinine: 1.1 mg/dl, Total bilirubin: 2.6 mg/dl, Direct bilirubin: 0.8 mg/dl, Alkaline phosphatase: 120 U/L, Aspartate aminotransferase: 308 U/L, Alanine aminotransferase: 265 U/L, Lipase: 53 U/L. Peripheral blood smear shows numerous red blood cell fragments. Which of the following is the most likely diagnosis?

A 1-month-old female infant presents with persistent jaundice. A serum direct bilirubin is 4.0 mg/dL and an ultrasound of the abdomen shows a shrunken gallbladder and inability to visualize the extrahepatic bile ducts. Which of the following is the most appropriate initial management of this patient?

A 10-year-old girl is the unrestrained backseat passenger in a high-speed motor vehicle collision. She is intubated in the field for unresponsiveness and on presentation to the ER, her heart rate is 160 beats per minute, and her blood pressure is 60/35 mm Hg. She weighs 30 kg. Which of the following is the most appropriate recommendation for her fluid resuscitation?

A 12-year-old boy presents to his pediatrician with frequent episodes of headache, nausea, blurry vision, and sweating. On physical examination, his temperature is 37.4 C (99.3 F), blood pressure is 148/94 mm Hg, pulse is 92/min, and respirations are 18/min. The rest of his examination is unremarkable. His 24-hour urinary vanillylmandelic acid (VMA) and metanephrines are increased. An abdominal CT reveals an extrarenal mass above the left kidney. Which of the following is the most appropriate pharmacotherapy?

A 12-year-old girl presents to the ED for left eye pain and swelling for 2 days. The patient has had cough, congestion, and rhinorrhea for the last week that is improving. On examination, her temperature is 100.8°F, HR 115 beats per minute, RR 12 breaths per minute, and BP 110/70 mm Hg. On eye examination, there is purple-red swelling of both upper and lower eyelids with injection of the conjunctiva. Pupils are equal and reactive to light. There is restricted lateral gaze. Visual acuity is 20/70 in the left eye and 20/25 in the right eye. The rest of the physical examination is normal. What is the most appropriate next step in management?

A 12-year-old girl with mild asthma comes to the office for a health maintenance visit. Her mother states that she is using her albuterol inhaler 2-3 times a week and that she has a cough that wakes her up at night about 3 times a month. On physical examination, she has diffuse inspiratory and expiratory wheezes. She has no accessory muscle use. Pulse oximetry shows 95% oxygen saturation on room air. Which of the following is the most appropriate treatment for her at this time?

A 13-year-old boy is brought to the emergency department at midnight with a 4-hour history of right scrotal pain that was sudden in onset and associated with nausea and one episode of vomiting. On examination, he is in obvious distress. He has mild right lower abdominal tenderness, and high-riding, tender right testes. CBC and urinalysis are normal. Which of the following is the most appropriate next step in management?

A 13-year-old boy is brought to the pediatrician by his mother because of increasing body hair. Several months earlier he had been diagnosed with 17α-hydroxylase deficiency and treated with hydrocortisone. Physical examination reveals an overweight boy with a moderate amount of both chest and genital hair, and some facial hair growth. His physical examination is otherwise unremarkable. Which of the following is the best treatment for this patient?

A 14-year-old boy dives into the shallow end of a swimming pool and hits his head against the bottom. When he is rescued, he shows a complete lack of neurologic function below the neck. He is still breathing on his own, but he cannot move or feel his arms and legs. The paramedics carefully immobilize his neck for transportation to the hospital, and they alert the emergency department to his impending arrival. Once there, which of the following would most likely have an immediate benefit for this patient?

A 14-year-old boy presents in the emergency department with very severe pain of sudden onset in his right testicle. There is no history of either trauma or recent mumps. He is afebrile, and a urinalysis shows no pyuria. The testis is swollen, exquisitely painful, high in the scrotum, and riding in a horizontal position. The cord above the testis is not tender. Which of the following is the most appropriate next step in management?

A 14-year-old girl, angry at her mother for taking away her MP3 player, takes an unknown quantity of a friend’s pills. Within the first hour she is sleepy, but in the emergency center she develops a widened QRS complex on her electrocardiogram (ECG), hypotension, and right bundle branch block. The therapy you would initiate for this ingestion is which of the following?

A 15-year-old boy with Duchenne muscular dystrophy is brought to the emergency department with increasing respiratory distress and cyanosis. On examination, he is diaphoretic, with gasping respirations, poor air entry, and diminished responsiveness. He is tachycardic at 160 beats/min. His chest x-ray film shows a lingular pneumonia, and he is intubated. He improves over the next 10 days with antibiotics but is not extubated secondary to hypoventilation on weaning because of muscle weakness. Which of the following modalities will most likely help wean him off the ventilator?

A 15-year-old Caucasian male is brought to the office by his mother for the evaluation of a six-month history of unstable gait and speech difficulty which are getting worse over time. His past medical history is insignificant. He is not taking any medications, and denies smoking or alcohol consumption. His blood pressure is 120/70 mmHg and pulse is 80/min. Musculoskeletal examination showed scoliosis and feet deformity with 'hammer toes.' The neurologic examination showed dysarthria, dysmetria, nystagmus, and absence of deep plantar reflexes on lower extremities. What is the most common cause of death in this patient population?

A 15-year-old is participating in high school football practice in August in Texas. He had complained of headache and nausea earlier in practice, but kept playing after a cup of water. He is now confused and combative. He is dizzy and sweating profusely. His temperature is 41°C (105.8°F). Therapy should consist of which of the following?

A 16-year-old adolescent boy with a history of severe hemophilia A is undergoing an elective inguinal hernia repair. Which of the following is the best option for preventing or treating a bleeding complication in the setting of this disease?

A 16-year-old girl with a history of ulcerative colitis managed with steroid therapy presents to the emergency department with a 36-hour history of nausea, crampy abdominal pain, and severe bloody diarrhea. On examination, the patient is febrile and pale, with a blood pressure of 90/60 mmHg and heart rate of 130 beats/min. Her abdomen is distended and diffusely tender. A complete blood count (CBC) demonstrates a leukocytosis with a left shift. The patient receives IV fluid resuscitation and nasogastric (NG) tube decompression. Further therapeutic interventions should include which one of the following?

A 17-year-old girl is found unconscious in a bathroom after ingesting a large amount of unknown sleeping pills. On arriving at the emergency department, she is somnolent; her temperature is 37.2 C (98.9 F), blood pressure is 120/74 mm Hg, pulse is 68/min, and respirations are 12/min. She responds to painful stimuli and to hearing her name loudly by opening her eyes briefly. However, she returns to the somnolent state immediately afterward. Which of the following is the most appropriate initial intervention?

A 17-year-old man presents to the ED after getting hit in the right eye with a tennis ball during a tennis match. On arrival to the ED, you note periorbital swelling and ecchymosis. The patient’s visual acuity is 20/20. When you are testing his extraocular muscles, you note that his right eye cannot look superiorly but his left eye can. He also describes pain in his right eye when attempting to look upward. Which of the following is the most likely diagnosis?

A 19-year-old man is brought into the trauma room by EMS after a head-on cycling accident. The patient was not wearing a helmet. Upon presentation his BP is 125/75 mmHg, HR is 105 beats per minute, RR is 19 breaths per minute, and oxygen saturation is 100% on mask. His eyes are closed but open to command. He can move his arms and legs on command. When you ask him questions, he is disoriented but able to converse. What is this patient’s GCS score?

A 19-year-old man is brought to the ED by EMS after he was found lying on the floor at a dance club. EMS states that the patient seemed unconscious at the dance club, but as soon as they transferred him onto the gurney, he became combative. Upon arrival in the ED, his BP is 120/65 mmHg, HR is 75 beats per minute, temperature is 98.9°F, RR is 12 breaths per minute, and oxygen saturation is 98% on room air. On physical examination, his pupils are midsized, equal, and reactive to light. His skin is warm and dry. Lung, cardiac, and abdominal examinations are unremarkable. As you walk away from the bedside, you hear the monitor alarm signaling zero respirations and the oxygen saturation starts to drop. You perform a sternal rub and the patient sits up in bed and starts yelling at you. As you leave him for the second time, you hear the monitor alarm again signal zero respirations. You administer naloxone, but there is no change in his condition. Which of the following is most likely the substance ingested by this patient?

A 19-year-old man receives un-cross-matched blood during resuscitation after a gunshot wound to the abdomen. He develops fever, tachycardia, and oliguria during the transfusion and is diagnosed as having a hemolytic reaction. Which of the following is the most appropriate next step in the management of this patient?

A 19-year-old woman presents to the ED with 1 hour of acute-onset progressively worsening pain in her RLQ. She developed nausea shortly after the pain and vomited twice over the last hour. She had similar but less severe pain 2 weeks ago that resolved spontaneously. Her BP is 123/78 mm Hg, HR is 99 beats per minute, temperature is 99.1°F, and her RR is 16 breaths per minute. On physical examination, the patient appears uncomfortable, not moving on the gurney. Her abdomen is nondistended, diffusely tender, worst in the RLQ. Pelvic examination reveals a normal-sized uterus and moderate right-sided adnexal tenderness. Laboratory results reveal WBC 10,000/μL, hematocrit 38%, and a negative urinalysis and β-hCG. Pelvic ultrasound reveals an enlarged right ovary with decreased flow. Which of the following is the most appropriate management for this patient?

A 19-year-old woman presents to the ED with abdominal pain, nausea, vomiting, diarrhea, and hematemesis after ingesting an unknown substance in a suicide attempt. Which of the following antidotes are correctly paired?

A 19-year-old woman presents with 4 days of bilateral lower abdominal pain right greater than left. She also complains of a fever, nausea, vomiting, and general malaise. Her last menstrual period was 5 days ago. Vitals are HR 98 beats per minute, BP 110/65 mmHg, RR 18 breaths per minute, and temperature of 102.7°F. Pelvic examination demonstrates exquisite cervical motion tenderness and right adnexal tenderness. Laboratory reports are notable for a WBC 15,000/μL, an ESR of 95 mm/h, and a negative urine β-human chorionic gonadotropin (β-hCG). Transvaginal ultrasound demonstrates a right complex mass with cystic and solid components. Which of the following is the most appropriate next step in management?

A 19-year-old woman was attacked while coming home from a party and is brought to the emergency department. She recalls being punched in the side of the head and stabbed in the left flank. Her speech is slow and she complains of a bad headache. Her pulse is 110/min, blood pressure is 90/50 mmHg, and respiratory rate is 25/min. On examination she has a stab wound at the left costal margin in the midaxillary line. Two large-bore intravenous lines are inserted, and after infusion of 2 L of lactated Ringer’s solution her blood pressure rises to 95/55 mmHg. What is the most appropriate next step in management?

A 2 week post mature baby is born and immediately exhibits severe respiratory distress. Previously, green-tinged meconium was noted in the amniotic fluid. Which of the following is the most appropriate next step?

A 2-week postmature neonate exhibits severe respiratory distress immediately after birth. Previously, greentinged meconium was noted in the amniotic fluid. Which of the following is the most appropriate next step in management?

A 2-year-old arrives in the emergency center after having swallowed a button battery from one of her toys. She is breathing comfortably, without stridor. Radiographs show the battery to be lodged in the esophagus. Which of the following is the correct next step?

A 2-year-old boy presents to the emergency department (ED) with severe wheezing. His symptoms have not improved even after three treatments with nebulizers. This is his third trip to the ED in the past two weeks. In the ED, he is given a dose of intravenous steroids, but continues to wheeze. On auscultation, there is no air entry bilaterally. His chest x-ray result is normal. His oxygen saturation is 91% on 6 liters of oxygen. What is the next best step in the management of this patient?

A 20-month-old child is brought to the ED because of fever and irritability and refusal to move his right lower extremity. Physical examination reveals a swollen and tender right knee that resists passive motion. Which of the following is the most likely to yield the diagnosis in this patient?

A 20-year-old female is brought to the emergency room after getting struck by a motor vehicle. She appears confused. According to her parents, she has no other medical problems and does not take any prescription medications. However, they have noticed her increase in appetite recently. She occasionally drinks alcohol and smokes half a pack of cigarettes daily. Her temperature is 37.2°C (99°F), blood pressure is 150/90mmHg, pulse is 110/min, and respirations are 22/min. Examination reveals dry mouth and conjunctival injection. Pupils are equal, reactive to light and accommodation. She has impaired time orientation and shortterm memory. Which of the following is the most likely explanation for this patient's symptoms?

A 20-year-old G1 at 32 weeks presents for her routine obstetric (OB) visit. She has no medical problems. She is noted to have a blood pressure of 150/96 mm Hg, and her urine dip shows 1+ protein. She complains of a constant headache and vision changes that are not relieved with rest or a pain reliever. The patient is sent to the hospital for further management. At the hospital, her blood pressure is 158/98 mm Hg and she is noted to have tonic- clonic seizure. Which of the following is indicated in the management of this patient?

A 20-year-old G1 at 36 weeks is being monitored for preeclampsia; she rings the bell for the nurse because she is developing a headache and feels funny. As you and the nurse enter the room, you witness the patient undergoing tonic-clonic seizure. You secure the patient’s airway, and within a few minutes the seizure is over. The patient’s blood pressure monitor indicates a pressure of 160/110 mm Hg. Which of the following medications is recommended for the prevention of a recurrent eclamptic seizure?

A 20-year-old man presents after being punched in the right eye and assaulted to the head. On a facial CT scan, he is noted to have a blowout fracture of the right orbital floor. Which of the following findings mandates immediate surgical intervention?

A 20-year-old man presents to the ED with multiple stab wounds to his chest. His BP is 85/50 mmHg and HR is 123 beats per minute. Two large-bore IVs (intravenous) are established and running wide open. On examination, the patient is mumbling incomprehensibly, has good air entry on lung examination, and you notice jugular venous distension (JVD). As you are listening to his heart, the nurse calls out that the patient has lost his pulse and that she cannot get a BP reading. Which of the following is the most appropriate next step in management?

A 20-year-old primigravid woman at 32 weeks gestation comes to the physician because of swelling in her hands and ankles. She has no headache, visual disturbances or epigastric pain. She has no previous medical problems. She does not use tobacco, alcohol or illicit drugs. Her previous prenatal check-up at 28-weeks gestation was normal. Her medical records show no preexisting hypertension or proteinuria. Her blood pressure is 156/100 mmHg, and after 15 minutes of lateral rest, a repeat reading is 154/98mmHg. Physical examination shows 2+ pitting edema in both legs and hands. Deep tendon reflexes are normal. Fundoscopic examination shows no abnormalities. FetaI heart tones are audible by Doppler. Laboratory studies show: Hb: 13.0 g/dl; Hct: 50%; Platelets: 300,000/mm3; Creatinine: 1.1 mg/dl; Urinalysis shows 1+ proteinuria, which is new. Which of the following is the most likely diagnosis?

A 20-year-old woman arrives at the emergency department actively seizing with QRS prolongation on ECG per paramedics. The patient’s roommate called emergency medical services after the patient collapsed, was not responsive to questioning, and began having clonic jerks bilaterally in her upper extremities. The patient’s roommate denies any knowledge of the patient consuming alcohol or illicit drugs. She does not believe the patient had any plan of harming herself, but does acknowledge that the patient has seemed “down” lately and was recently prescribed medication for generalized anhedonia. Which of the following is the most appropriate first-line treatment?

A 21-year-old gravida 1, para 0 woman comes to the office for a routine prenatal visit at 26 weeks gestation. She has no complaints. She has no significant past medical history. She does not use tobacco, alcohol, or drugs. She takes prenatal vitamins regularly, and has no known drug allergies. Her vital signs are within normal limits. Examination shows a uterine size appropriate for gestational age, and fetal heart tones are heard. One hour 50gram oral glucose tolerance test shows a blood glucose level of 120 mg/dl. Urine culture grew 105 colony forming units/mL of E coli. This patient is at greatest risk for which of the following complications?

A 21-year-old man comes to the ER with palpitations and dizziness that began suddenly one hour ago. He notes having similar past episodes provoked by fatigue or strong emotions. He says he can usually stop the episodes by putting his head into cold water or squatting and taking a deep breath. However, these techniques are not working this time. Presently, his blood pressure is 60/30 mmHg and his heart rate is 240/min. He is diaphoretic with cold extremities. An EKG rhythm strip shows a regular, narrow complex tachycardia. Which of the following is the best next step in managing his condition?

A 21-year-old man presents to the ED. He has a known history of type 1 diabetes. He is hypotensive with BP of 95/65 mmHg, tachycardic at 120 beats per minute, and tachypneic at 30 breaths per minute. Laboratory results reveal a WBC 20,000/μL, hematocrit 45%, platelets 225/μL, sodium 131 mEq/L, potassium 5.3 mEq/L, chloride 95 mEq/L, bicarbonate 5 mEq/L, BUN 20 mg/dL, creatinine 0.9 mg/dL, and glucose 425 mg/dL. Arterial blood gas reveals a pH of 7.2. Urinalysis reveals glucosuria and ketosis. There is a fruity odor to his breath. Which of the following provides the strongest evidence for the diagnosis?

A 21-year-old man presents with symptoms of headache, fever, chills, and discomfort in both sides of his jaw. He has also noticed discomfort in his testes, but no dysuria or urethral discharge. Physical examination reveals bilateral enlargement of the parotid glands, as well as bilateral testicular enlargement and tenderness on palpation. His temperature is 38.5°C pulse rate of 92/min, and the remaining examination is normal. Laboratory data show hemoglobin 15 g/dL; hematocrit 40%; WBC 12000/mL, with 30% segmented neutrophils, 8% monocytes, and 62% lymphocytes. Which of the following statements concerning this dis- ease is true?

A 21-year-old woman at 36 weeks gestation is admitted for delivery. She has severe preeclampsia. Her blood pressure is 190/110 mmHg, pulse is 80/min and respirations are 16/min. Physical examination shows 3+ pitting edema of the legs and brisk deep tendon reflexes. Fundoscopic examination shows no abnormalities. Laboratory studies show elevated BUN, serum creatinine and serum transaminases. Urinalysis shows 4+ proteinuria. Intravenous hydralazine and magnesium sulfate was initiated on admission. After stabilization, intravenous oxytocin and artificial rupture of membranes (AROM) was administered for induction of labor. Two hours later, her blood pressure is 150/90 mmHg, pulse is 78/min and respirations are 9/min. Repeat examination shows hyporeflexia and a completely effaced cervix that is 5cm dilated. Which of the following is the most appropriate next step in management?

A 21-year-old woman sustains a stab wound to the middle of the chest. Upon arrival to the ER she has equal breath sounds, blood pressure of 85/46 mm Hg, distended neck veins, and pulsus paradoxus. Which of the following is the most appropriate management of this patient?

A 22-year-old African American male suffering from sickle cell anemia presents in the emergency department with a sustained painful penile erection for the last 4 hours. Previously, he had one episode of acute chest syndrome that was treated with oxygenation, hydration and blood transfusion. His pulse is 76/min, respirations are 16/min, blood pressure is 115/76 mm Hg, and temperature is 37°C (98.6°F). Examination of all his systems is unrevealing. What is the best next step in the management of this patient?

A 22-year-old G1P0 has just undergone a spontaneous vaginal delivery. As the placenta is being delivered, a red fleshy mass is noted to be protruding out from behind the placenta. Which of the following is the best next step in management of this patient?

A 22-year-old gang member arrives in the emergency department with multiple gunshot wounds to the chest and abdomen. He has labored breathing and is cyanotic, diaphoretic, cold, and shivering. He is wide awake, and in a normal tone of voice he tells everyone that he is going to die. An initial survey reveals a blood pressure of 60/40 mm Hg. His pulse is 150/min and barely perceptible. He is in obvious respiratory distress and has big distended veins in his neck and forehead. His trachea is deviated to the left, and the right side of his chest is hyperresonant to percussion, with no breath sounds. Which of the following is the most appropriate initial step in management?

A 22-year-old man calls the ED from a local bar stating that he was punched in the face 10 minutes ago and is holding his front incisor tooth in his hand. He wants to know what the best way is to preserve the tooth. Which of the following is the most appropriate advice to give the caller?

A 22-year-old man involved in a motor vehicle collision undergoes a prolonged operation to repair a left femur fracture and femoral artery injury. During the first night after surgery he has pain in the left leg. Despite adequate narcotics, his pain is unremitting; the pain is worse with passive leg movement. Examination shows a pale and swollen leg that is tender to the touch; pulses are palpable. Which of the following is the most appropriate next step in management?

A 22-year-old man is brought to the ED 20 minutes after a head-on motor vehicle collision in which he was the unrestrained driver. On arrival, he is alert and coherent but appears short of breath. His HR is 117 beats per minute, BP is 80/60 mmHg, and oxygen saturation is 97% on a nonrebreather. Examination reveals bruising over the central portion of his chest. His neck veins are not distended. Breath sounds are present on the left but absent on the right. Following administration of 2 L of lactated Ringer solution, his systolic BP remains at 80 mmHg. Which of the following is the most appropriate next step in management?

A 22-year-old man presents to the ED after being ejected from his vehicle following a high-speed motor vehicle collision. Upon arrival, his BP is 85/55 mmHg and HR is 141 beats per minute. Two large-bore IVs are placed in the antecubital veins and lactated Ringer solution is being administered. After 3 L of crystalloid fluid, the patient’s BP is 83/57 mmHg. Which of the following statements is most appropriate regarding management of a hypotensive trauma patient who fails to respond to initial volume resuscitation?

A 22-year-old man presents to the emergency department complaining of fever, nausea, vomiting, and right lower quadrant pain. He has no significant medical history and does not take any medications. He is a senior in college and denies cigarette smoking or drug use. He drinks alcohol occasionally. Physical examination reveals a temperature of 38.6°C, with all other vital signs within normal limits. ACT scan of his abdomen confirms acute appendicitis. Laboratory analyses reveal a leukocytosis but no electrolyte abnormalities. He is taken to the operating room and undergoes a successful laparoscopic appendectomy. Following the procedure, he is given intravenous fluids containing 5% dextrose in a 0.45% (1❄2normal) saline solution at a rate of 150 ml/hr. The next morning the patient feels well but he then becomes progressively confused throughout the afternoon. You are called to his bedside after he has two grand mal seizures lasting 30 seconds apiece. Serum chemistries drawn at that time reveal a sodium concentration of 115mEq/L. What is the most appropriate therapy for this patient?

A 22-year-old man sustains severe blunt trauma to the back. He notes that he cannot move his lower extremities. He is hypotensive and bradycardic. Which of the following is the best initial management of the patient?

A 22-year-old man without medical complaints presents to the ED with a 3-day history of fever, malaise, and myalgias. He denies chest pain, shortness of breath, nausea or vomiting, abdominal pain, cough, sore throat, genitourinary symptoms, or respiratory tract complaints. On examination, the patient’s BP is 100/60 mmHg, HR is 110 beats per minute, RR is 20 breaths per minute, and temperature is 102°F. He appears awake, alert, and comfortable. His physical examination is normal. Which of the following is the most appropriate next step in management?

A 22-year-old primigravid woman at 32 weeks' gestation comes to the emergency department because of heavy vaginal bleeding and abdominal pain. Her prenatal course was unremarkable, including a normal 20- week ultrasound. Physical examination demonstrates a contracted uterus with hypertonus. A large "gush" of blood occurs during the cervical examination, which demonstrates a long and closed cervix. The fetal heart rate tracing shows severe late decelerations. Which of the following is the most appropriate next step in management?

A 22-year-old woman is brought to the ED by ambulance complaining of sudden onset of severe abdominal pain for 1 hour. The pain is in the RLQ and is not associated with nausea, vomiting, fever, or diarrhea. On the pelvic examination you palpate a tender right adnexal mass. The patient’s last menstrual period was 6 weeks ago. Her BP is 95/65 mm Hg, HR is 124 beats per minute, temperature is 99.8°F, and RR is 20 breaths per minute. Which of the following are the most appropriate next steps in management?

A 22-year-old woman is brought to the ED by paramedics who state that they found the patient hunched over on a park bench barely breathing. The patient is rousable only to painful stimuli. Her initial vitals include an HR of 78 beats per minute, a BP of 125/58 mmHg, and a respiratory rate of 6 breaths per minute with an oxygen saturation of 94% on 2-L nasal cannula. Upon physical examination, the patient has clear breath sounds bilaterally and no signs of trauma. Her pupils are 2 mm bilaterally and reactive to light. Which of the following agents may be used to restore this patient’s respirations?

A 22-year-old woman is brought to the emergency department after a motorcycle accident in which she sustained severe crush injuries of her lower extremities. In the field, her Glasgow Coma Score was 14. She is awake and alert on arrival after having been given morphine for pain control. Any details of her past medical history are unknown. Initial examination shows a blood pressure of 140/80 mm Hg and pulse of 100/min. Her oxygen saturation on room air is 95% by pulse oximeter. An ECG is obtained and shows very large, peaked T-waves in leads V1-V6. Which of the following is the most appropriate initial step in patient care?

A 22-year-old woman is involved in a major motor vehicle accident and receives a tracheostomy during her hospitalization. Five days after placement of the tracheostomy she has some minor bleeding around the tracheostomy site. Which of the following is the most appropriate immediate therapy?

A 22-year-old woman is seen in the emergency room after a suicide attempt. She swallowed 10 aspirin in the presence of her mother, with whom she had just had an argument. The patient has a long history of cutting herself superficially with razor blades, which her psychiatrist of the last 5 years confirms by telephone. The patient currently lives in a stable environment (a halfway house) where she has been for 3 years. Which of the following option is the best course of action for the physician in the emergency room?

A 22-year-old woman presents to the ED by ambulance from a dance club. The paramedics report that the patient was agitated in the club and had a generalized seizure. Her BP is 165/100 mmHg, HR is 119 beats per minute, temperature is 101.9°F, RR is 17 breaths per minute, oxygen saturation is 98% on room air, and fingerstick glucose is 92 mg/dL. On examination, the patient is hyperactive and appears to be hallucinating. Her pupils are dilated to 6 mm bilaterally and reactive. Her neck is supple. Examination of the heart is unremarkable except for tachycardia. Her lungs are clear and abdomen is soft and nontender. The patient moves all four extremities. Laboratory results are as follows: Sodium 109 mEq/L, WBC 12,000/mm3, Potassium 3.5 mEq/L, Hct 49%, Chloride 83 mEq/L, Platelets 350/μL, Bicarbonate 20 mEq/L, BUN 10 mg/dL, Creatinine 1 mg/dL, Glucose 103 mg/dL. Which of the following substances did this patient most likely consume?

A 23-year-old male with a history of drug abuse is brought to the emergency department (ED) by an ambulance while having a tonic-clonic seizure. His mother soon arrives at the ED and says that she found him on the floor, where "he must have fallen." She says his seizure has lasted for more than 30 minutes now, and that he never regained consciousness since she found him. In the ED, he is unresponsive and cyanotic. He is biting his tongue and is incontinent. Despite resuscitation and administration of intravenous lorazepam, phenytoin, and glucose, the seizures continue. What is the best next step in the management of this patient?

A 23-year-old man is brought to the emergency department after being involved in a motor vehicle collision. He has multiple organ injuries and is listed in critical condition. Physical examination shows an open wound in the right lower extremity and significant blood loss. He is in hypovolemic shock. Which of the following is the first parameter to change in hypovolemic shock?

A 23-year-old man is brought to the emergency room because of confusion and hallucinations. While in ER, he has an episode of generalized tonic-clonic seizures. His past medical history is significant for illicit drug use. His temperature is 40.0°C (104.0°F), pulse is 95/min, and blood pressure is 120/80 mm Hg. He is confused and disoriented. Fundoscopy is with in normal limits. There is no neck stiffness. The neurological examination shows upgoing plantar reflexes bilaterally. Lumbar puncture is performed and CSF analysis shows the following: Glucose 35mg/dl, Protein 80mg/dl, WBC count 150/cm3, Neutrophils 10%, Lymphocytes 90%, Gram stain Negative. CT scan of the brain without contrast is normal. Which of the following is the most appropriate next step in the management of this patient?

A 23-year-old man presents to the ED with left lower abdominal pain and left testicular pain that started 1 to 2 weeks ago and has gradually worsened. He has some nausea and vomiting. His HR is 98 beats per minute, BP is 125/65 mmHg, temperature is 100.9°F, and RR is 18 breaths per minute. Physical examination reveals a tender left testicle with a firm nodularity on the posterolateral aspect of the testicle. Pain is relieved slightly with elevation of the testicle and the cremasteric reflex in normal. You make the presumptive diagnosis of epididymitis. Which of the following is the next best step?

A 23-year-old woman presents to the ED complaining of abdominal pain, nausea, and vomiting. She has a history of depression but is not currently taking any antidepressant medications. Upon further questioning, the patient states that she ingested a bottle of pills in her medicine cabinet approximately 3 hours ago. Her BP is 115/65 mmHg, HR is 101 beats per minute, temperature is 100.1°F, RR is 29 breaths per minute, and oxygen saturation is 100% on room air. Physical examination is unremarkable except for mild diffuse abdominal tenderness. Laboratory results reveal a white blood cell (WBC) count of 10,300/μL, hematocrit 46%, platelets 275/μL, aspartate transaminase (AST) 70 U/L, alanine transaminase (ALT) 85 U/L, alkaline phosphatase 75 U/L, sodium 143 mEq/L, potassium 3.7 mEq/L, chloride 98 mEq/L, bicarbonate 8 mEq/L, blood urea nitrogen (BUN) 22 mg/dL, creatinine 0.9 mg/dL, and glucose 85 mg/dL. Arterial blood gas values on room air are pH 7.51, PCO2 11 mm Hg, and PO2 134 mm Hg. Which of the following substances did this patient most likely ingest?

A 23-year-old woman undergoes total thyroidectomy for carcinoma of the thyroid gland. On the second postoperative day, she begins to complain of a tingling sensation in her hands. She appears quite anxious and later complains of muscle cramps. Which of the following is the most appropriate initial management strategy?

A 24-year-old firefighter sustains 30% total body surface area (TBSA) burns to his torso, face, and extremities. His wounds are treated topically with silver nitrate. Which of the following complications is associated with use of this agent?

A 24-year-old male is brought to the emergency room after he fainted while practicing football on a bright sunny day. He complained of dizziness and headache before he collapsed. He was in his usual state of health until today and has no medical problems. He takes no medication. On arrival to the emergency room, his temperature is 41°C (105.8°F), blood pressure is 90/60 mm Hg, pulse is 140/min, and respirations are 22/min. He is not oriented. Skin is dry and hot. Neck is supple. Auscultation of the chest is unremarkable. Abdomen is soft and non-tender. Muscle tone and reflexes are within normal limits. Intravenous hydration is started. Which of the following is the most appropriate next step in management?

A 24-year-old man complains of fatigue, malaise, fever, and a sore throat. He was previously well, but now feels tired all the time and has to rest multiple times a day. Physical examination shows enlarged tonsils and palpable anterior and posterior cervical, axillary, and inguinal lymph nodes. There is also tenderness in the right upper quadrant with a liver span of 10 cm. Laboratory data is significant for a heterophil antibody (sheep cell agglutination) test that is positive. Which of the following rare complications can be associated with this condition?

A 24-year-old man is brought into the ED by paramedics after being run over by a car. His systolic BP is 90 mmHg by palpation, HR is 121 beats per minute, RR is 28 breaths per minute, and oxygen saturation is 100% on non-rebreather. The airway is patent and breath sounds are equal bilaterally. You establish large-bore access and fluids are running wide open. Secondary survey reveals an unstable pelvis upon movement with lateral to medial force. Bedside focused abdominal sonography for trauma (FAST) is negative for intraperitoneal fluid. Which of the following is the most appropriate immediate next step in management?

A 24-year-old man is brought to the ED after being shot once in the abdomen. On arrival, his BP is 100/60 mmHg, HR is 115 beats per minute, and RR is 22 breaths per minute. His airway is patent and you hear breath sounds bilaterally. On abdominal examination, you note a single bullet entry wound approximately 1 cm to the right of the umbilicus. During the log roll, you see a single bullet exit wound approximately 3 cm to the right of the lumbar spine. His GCS score is 15. The patient’s BP is now 85/65 mmHg and HR is 125 beats per minute after 2L of fluid. Which of the following is the most appropriate next step in management?

A 24-year-old man presents in septic shock from an empyema. He is febrile to 103°F, tachycardic in the 120s, and hypotensive to the 90s. His oxygen saturation is 98% on 2-L oxygen. His white blood cell count is 25,000/mL and creatinine is 0.8 mg/dL. His blood pressure does not respond to fluid administration despite a CVP of 15. Which of the following therapies is indicated in managing this patient?

A 24-year-old man with a history of depression is brought to the emergency room because of a drug overdose. He is experiencing some nausea and vomiting, but no other symptoms. Physical examination and vital signs are normal. Six hours prior to presentation, he intentionally took 40 tablets of acetaminophen (500mg/tablet). Which of the following is the most appropriate next step in management?

A 24-year-old presents at 30 weeks with a fundal height of 50 cm. Which of the following statements concerning polyhydramnios is true?

A 24-year-old primigravid woman at 28 weeks gestation comes to the physician because she has not felt her baby's movements for the past two weeks. Fetal heart tones are not heard by Doppler. Ultrasonogram shows absence of fetal cardiac activity. Fetal demise is diagnosed. Laboratory studies show:Serum fibrinogen level: 250 mg/dl (normal is 150 - 450 mg/dl ), Platelets: 130,000/mm3, Prothrombin time: 15 sec, Partial thromboplastin time: 33sec. There are no signs of active bleeding. Which of the following is the most appropriate next step in management?

A 24-year-old woman comes into the emergency department with recurrent episodes of palpitations, headache, and tremor. Her blood pressure is 155/95 mmHg, heart rate is 135/min, temperature is 37.9°C (100.2°F), and respiratory rate is 12/min. A CT of the abdomen shows a suprarenal mass. After confirming the diagnosis with a laboratory test, the physician informs the patient that she will require immediate therapy and surgical resection of the mass within the next few weeks. In order to achieve short-term control of her blood pressure, which of the following agents is most appropriate?

A 24-year-old woman is brought to the ED after being found on a nearby street hunched over and in mild respiratory distress. Upon arrival, she is tachypneic at 24 breaths per minute with an oxygen saturation of 97% on face mask oxygen administration. Upon physical examination, the patient appears to be in mild distress with supraclavicular retractions. Scattered wheezing is heard throughout bilateral lung fields. Which of the following medications should be administered first?

A 24-year-old woman is brought to the emergency room after ingesting 14 acetaminophen tablets, 500 mg each, two hours ago. She does not smoke but drinks alcohol on the weekends. She is alert and oriented. Her temperature is 37.2°C (99°F), blood pressure is 110/60mmHg, pulse is 90/min and respirations are 18/min. Examination shows no abnormalities. Laboratory studies show: Hct 40%, WBC 6,000/mm3, Platelet 390,000/mm3. Which of the following is the most appropriate next step in management?

A 24-year-old woman presents to the ED at 4 AM with severe left eye pain that woke her up from sleep. She wears soft contact lenses and does not routinely take them out to sleep. She is in severe pain and wearing sunglasses in the examination room. You give her a drop of proparacaine to treat her pain prior to your examination. On examination, her vision is at baseline and she has no afferent pupillary defect. There is some perilimbic conjunctival erythema. On fluorescein examination, a linear area on the left side of the cornea is highlighted when cobalt blue light is applied. No underlying white infiltrate is visualized. No white cells or flare are visualized in the anterior chamber. What is the most appropriate treatment for this condition?

A 24-year-old woman presents to the emergency department (ED) complaining of right eye pain and blurry vision since waking up this morning. She states that the pain began after taking out contact lenses that were in her eyes for over 1 week. Her blood pressure (BP) is 120/75 mm Hg, heart rate (HR) is 75 beats per minute, temperature is 99.1°F, and respiratory rate (RR) is 16 breaths per minute. Her right and left eye visual acuity is 20/60 and 20/20, respectively. Her conjunctivae are injected. The slitlamp examination reveals a large area of fluorescein uptake over the visual axis. Which of the following is the most appropriate therapy?

A 25-year-old Caucasian woman presents as a new patient after having recently moved to the neighborhood. She says that she was diagnosed with anorexia nervosa two years ago, and that her disorder resolved after intensive psychotherapy. Although her eating pattern is normal now, she is still underweight. Her menstrual cycles have been regular for the past year. She recently married and is now interested in starting a family with her husband. She asks whether her history of anorexia nervosa will affect her ability to conceive or carry a healthy child to term. Given this clinical presentation, which of the following complications is most likely?

A 25-year-old female presents to the office for a prenatal visit. She is gravida 3, para 0, ab 2. Her first abortion was an elective abortion at 18 weeks gestation. Her second abortion was a spontaneous abortion at 17 weeks gestation. She has had a cervical loop electrosurgical excision(LEEP) procedure, 8 months ago, for severe cervical dysplasia. Her LMP was 16 weeks ago. She does not use tobacco, alcohol or illicit drugs. She has had an uneventful pregnancy thus far and denies any concerns at this visit. Her temperature is 98.6 F (37 C), blood pressure is 100/64, heart rate is 72/minute and respirations are 17/minute. Her uterine fundus measures 14.5 cm and is consistent with a 15-16 weeks gestation. The fetal heart rate is 140/minute. This patient is at greatest risk for which of the following complications?

A 25-year-old G1 PO woman at 39 weeks gestation by last menstrual period confirmed by first trimester ultrasound presents to the hospital with complaints of vulvar pain and a "bump" on her vulva. On examination you see clear vesicles and inguinal adenopathy. No cervical or vaginal lesions are present. She is 2 cm dilated, 50% effaced and at -2 station. Fetal heart rate and contraction monitoring is started. She is contracting regularly. No abnormalities are seen. Which of the following is the most effective intervention to reduce neonatal morbidity in this patient?

A 25-year-old G1P0 patient at 41 weeks presents to labor and delivery complaining of gross rupture of membranes and painful uterine contractions every 2 to 3 minutes. On digital examination, her cervix is 3 cm dilated and completely effaced with fetal feet palpable through the cervix. The estimated weight of the fetus is about 6 lb, and the fetal heart rate tracing is reactive. Which of the following is the best method to achieve delivery?

A 25-year-old man is brought into the ED by two police officers because of suspected drug use. The patient is extremely agitated and is fighting the police officers. It takes three hospital staff members and the two police officers to keep him on the stretcher. His vital signs are BP 150/80 mmHg, HR 107 beats per minute, temperature 99.7°F, RR 18 breaths per minute, and oxygen saturation 99% on room air. Physical examination is unremarkable except for cool, diaphoretic skin, persistent vertical and horizontal nystagmus, and occasional myoclonic jerks. Which of the following is the most likely diagnosis?

A 25-year-old man is brought into the trauma resuscitation room after his motorcycle is struck by another vehicle. EMS reports that the patient was found 20 ft away from his motorcycle, which was badly damaged. His vital signs include a BP of 90/60 mmHg, HR 115 beats per minute, RR 22 breaths per minute, and pulse oxygenation of 100% on facemask. Which of the following is the smallest amount of blood loss that produces a decrease in the systolic BP in adults?

A 25-year-old man is brought to the emergency department after falling 12m (40ft) from a ladder. He is unconscious. Examination shows obvious head and neck injuries, and a fractured forearm. He is totally apneic. Which of the following would be the best method to establish an immediate definitive airway in this patient?

A 25-year-old man is brought to the emergency department by ambulance after falling from a ladder for 12 m (40 ft). He was placed on a backboard for spinal stabilization. Intravenous access was obtained en route, and infusion of crystalloids was initiated. The patient is comatose on arrival to the emergency department. Examination shows facial lacerations, a depressed skull fracture, and a forearm fracture. In the emergency department, his blood pressure is 92/45 mm Hg, pulse is 127/min, and respirations are 6/min. His pulse oximetry shows 86% on 40% facemask oxygen. Which of the following is the most appropriate next step in management?

A 25-year-old man is carried into the ED by two of his friends who state that he is not breathing. The patient has a history of heroin abuse. His vital signs are BP 115/70 mmHg, HR 99 beats per minute, temperature 98.9°F, RR 3 breaths per minute, and oxygen saturation 87% on room air. You notice fresh needle marks and miotic pupils. You begin bag-valvemask ventilation and his oxygen saturation increases to 99%. Which of the following is the most appropriate next step in management?

A 25-year-old woman arrives in the ER following an automobile accident. She is acutely dyspneic with a respiratory rate of 60 breaths per minute. Breath sounds are markedly diminished on the right side. Which of the following is the best first step in the management of this patient?

A 25-year-old woman being evaluated for infertility is found to have an abnormal ridge of red, moist granules located in the upper third of her vagina. Pertinent medical history is that her mother was treated with diethylstilbestrol (DES) during her pregnancy. A biopsy from the abnormal vaginal ridge reveals the presence of benign glands underneath stratified squamous epithelium. Which of the following is the most serious long-term complication of this abnormality?

A 25-year-old woman was involved in a motor vehicle crash and sustained a significant closed-head injury, a pulmonary contusion, and a pelvic fracture. She is unresponsive and is ventilated in the intensive care unit (ICU). Which of the following is the best initial approach to the management of this patient’s nutritional needs?

A 25-year-old woman, gravida 2, para 1, at 32 weeks gestation is brought to the emergency department because of acute onset severe uterine contractions and moderate vaginal bleeding. Her first pregnancy was uncomplicated. She has a history of cocaine addiction. Ultrasonogram performed at the 16th week showed no abnormalities and an intrauterine gestation consistent with dates. Her temperature is 37.0 C (98.7 F), blood pressure is 130/80 mmHg, pulse is 90/min and respirations are 15/min. Physical examination shows uterine tenderness, hyperactivity, and increased uterine tone. Fetal heart tracing shows 140/min with good long-term and beat-to-beat variability. Which of the following is the most likely diagnosis?

A 26-year-old bar employee is brought to the emergency room because of agitated, combative behavior in which three people had to restrain her. She has also been hallucinating during this entire period. Her temperature is 37.7°C (100°F), blood pressure is 160/90 mmHg, pulse is 126/min, and respirations are 18/min. She is confused and agitated during the examination. Pupils are 6 mm in diameter and respond to light; prominent nystagmus is present. The remainder of her examination is unremarkable. Which of the following is the most likely diagnosis?

A 26-year-old G1 at 37 weeks presents to the hospital in active labor. She has no medical problems and has a normal prenatal course except for fetal growth restriction. She undergoes an uncomplicated vaginal delivery of a female infant weighing 1950 g. The infant is at risk for which of the following complications?

A 26-year-old man is brought to the emergency room after an attempted suicide by medication overdose. For the past hour, he has suffered two seizures. His temperature is 38.8°C (102°F), blood pressure is 110/85 mmHg, pulse is 90/min, and respirations are 22/min. He is not oriented to time, place, and person. Pupils are dilated, but reactive to light and accommodation; skin is flushed and dry. Abdominal examination shows reduced bowel sounds. EKG shows prolonged QRS complexes (0.19 sec). Toxicology studies are pending. Which of the following is the most appropriate indicator of severity of intoxication?

A 26-year-old man is brought to the emergency room by police with depressed mental status. Out of fear of arrest, he swallowed a handful of pills as the police officers approached him. On examination, he responds to painful stimuli but is somnolent. His respiratory rate is 8/min and after naloxone bolus infusion increases to 12/min. Lungs are clear to auscultation. Which of the following additional findings is most likely to be present in this patient?

A 26-year-old previously healthy man was pinned under a crane at a construction site. After a prolonged extrication, he was brought to the emergency department, immobilized on a back board and receiving 100% oxygen by mask. He is alert and complaining of chest pain with respiratory effort. On examination, he is found to have an oxygen saturation of 90% by pulse oximetry, shallow respirations at a respiratory rate of 35/min, heart rate of 120 beats/min, and a blood pressure of 85/60 mmHg. The trachea is deviated to the right. There is tenderness and crepitation over the left chest wall, asymmetric chest wall movement, and decreased air entry over the left lung field. Which of the following is the most appropriate next step in the initial evaluation and management of this patient?

A 26-year-old woman presents to the ED with fever, malaise, and an evolving rash in the right axilla that she initially thought was from an insect bite that she received while hiking 1 week earlier. She complains of generalized fatigue, nausea, headache, and joint pain over the past several days. Her vitals are BP of 120/75 mmHg, HR of 75 beats per minute, RR of 16 breaths per minute, and temperature of 101°F. On physical examination, she is awake and alert, with a nonfocal neurologic examination. Her neck is supple, but she is diffusely tender over the shoulder, knee, and hip joints bilaterally without any distinct effusions. Her abdomen is soft and nontender. She has a 9-cm erythematous annular plaque with partial central clearing and a bright red outer border and a target center under her right axilla. Which of the following is the next best step?

A 26-year-old woman with a history of depression is brought into the ED. She was found lying on the floor of her apartment next to an unlabeled empty pill bottle. Her HR is 117 beats per minute, BP is 95/65 mmHg, RR is 14 breaths per minute, and oxygen saturation is 97% on 2-L nasal cannula. On examination, the patient appears obtunded, and her pupils are 3 mm and reactive. Her oropharynx is dry and there is no gag reflex to pharyngeal stimulation. Her neck is supple. The heart is tachycardic without murmurs, the lungs are clear to auscultation, and the abdomen is soft. There is normal rectal tone and brown stool that is heme negative. Her skin is cool and moist with no signs of needle tracks. Neurologically, she is unresponsive but withdraws all extremities to deep palpation. Fingerstick blood glucose is 85 mg/dL. Her ECG reveals sinus tachycardia at 119 with a QRS complex of 140 milliseconds and a terminal R wave in lead aVR. Which of the following is the most appropriate next step in management?

A 27 -year-old white female comes to the office and complains of a headache for the last two weeks. She characterizes the headache as intermittent, "feels like a dull ache", 5/10 in severity, and associated with nausea and vomiting. She is afebrile and never had such a headache before. She has no visual complaints. She is a non-smoker and drinks alcohol only on weekends. Her only drugs are oral contraceptive pills (OCPs). Her menses are regular, and she has never conceived. She has no family history of similar problem. Her pulse is 80/min, temperature is 37.1°C, blood pressure is 120/75mmHg and respirations are 15/min. She is 5 feet 10 inches tall, and her weight is 210 lbs. The neurological examination is non-focal, and there are no signs of meningeal irritation. Funduscopy reveals papilledema. MRI of the brain is normal. Which of the following complications is likely to develop if this patient is left untreated?

A 27-year-old G1P0 at 34 weeks gestation presents to your office complaining of a 2-day history of nausea and emesis. On physical examination, you notice that she is icteric sclera and skin. Her vital signs indicate a temperature of 37.2C (99F), pulse of 102 beats per minute, and blood pressure of 130/84 mm Hg. She is sent to labor and delivery for additional evaluation. In labor and delivery, the fetal heart rate is in the 160s with good variability, but nonreactive. Blood is drawn and the following results are obtained: WBC = 22,000, Hct = 40.0, platelets = 72,000, SGOT/PT = 334/386, glucose = 58, creatinine = 2.2, fibrinogen = 209, PT/PTT = 16/50 s, serum ammonia level = 65 mmol/L (nl = 11-35). Urinalysis is positive for 3+ protein and large ketones. Which of the following is the recommended treatment for this patient?

A 27-year-old man brought to the ED by paramedics after a motor vehicle collision. His RR is 45 breaths per minute, oxygen saturation is 89%, HR is 112 beats per minute, and BP is 115/75 mmHg. You auscultate his chest and hear decreased breath sounds on the left. Which of the following is the most appropriate next step in management?

A 27-year-old man presents to the ED extremely agitated complaining of mild chest pain and dyspnea. He states that he was snorting cocaine all afternoon. You place him on a monitor and get his vital signs. His BP is 215/130 mmHg, HR is 112 beats per minute, temperature is 100.1°F, RR is 17 breaths per minute, and oxygen saturation is 98% on room air. An ECG reveals sinus tachycardia at a rate of 116. Which of the following is the most appropriate medication to administer?

A 27-year-old man presents to the ER after a high-speed motor vehicle collision with chest pain and marked respiratory distress. On physical examination, he is hypotensive with distended neck veins and absence of breath sounds in the left chest. Which of the following is the proper initial treatment?

A 27-year-old man sustains a single gunshot wound to the left thigh. In the ER, he is noted to have a large hematoma of his medial thigh. He complains of paresthesias in his left foot. On examination, there are weak pulses palpable distal to the injury and the patient is unable to move his foot. Which of the following is the most appropriate initial management of this patient?

A 27-year-old primigravid woman at 39 weeks' gestation comes to the labor and delivery ward with a gush of fluid and regular contractions. Examination shows that she is grossly ruptured, contracting every 2 minutes, and that her cervix is dilated to 4 cm. The fetal heart rate tracing is in the 140s and reactive. She is admitted to labor and delivery, and over the following 4 hours she progresses to 9 cm dilation. Over the past hour, the fetal heart rate has increased from a baseline of 140 to a baseline of 160. Furthermore, moderate to severe variable decelerations are seen with each contraction. The fetal heart rate does not respond to scalp stimulation. The decision is made to proceed with cesarean delivery. Which of the following is the reason for the cesarean delivery and the preoperative diagnosis?

A 27-year-old woman presents to the ED 6 hours after the onset of body aches, abdominal cramping, and diarrhea. She is currently visiting relatives and normally lives in another state. She regularly takes six to eight tablets daily of hydrocodone for chronic low-back pain, sumatriptan for migraines, and amitriptyline and paroxetine for bulimia nervosa. Her BP is 130/80 mmHg, HR is 100 beats per minute, temperature is 98.6°F, RR is 16 breaths per minute, and oxygen saturation is 99% on room air. Examination shows diaphoresis, dilated pupils, and piloerection. Neurologically she is moving all four extremities and you do not note tremors. She is alert and cooperative but seems restless. She denies hallucinations or suicidal ideations. She becomes very angry when you ask her for the phone numbers of her regular physicians. Which of the following is the most likely explanation of her symptoms?

A 27-year-old woman presents to the ED complaining of an intensely pruritic rash all-over her body, abdominal cramping, and chest tightness. She states that 1 hour ago she was at dinner and accidentally ate some shrimp. She has a known anaphylactic allergy to shrimp. Her BP is 115/75 mmHg, HR is 95 beats per minute, temperature is 98.9°F, RR is 20 breaths per minute, and oxygen saturation is 97% on room air. She appears anxious, and her skin is flushed with urticarial lesions. Auscultation of her lungs reveals scattered wheezes with decreased air entry. Which of the following is the most appropriate next step in management?

A 28-year-old male is brought to the emergency department after being an unrestrained passenger in a motor vehicle collision. In the ambulance on his way to the hospital, he receives 2 liters of normal saline intravenously and 5 Umin of oxygen by nasal cannula. On physical examination, his blood pressure is 100/70 mmHg, heart rate is 120/min, and respiratory rate is 40/min. He is agitated and moves all four extremities spontaneously. His pupils are symmetric and reactive to light. His neck veins are distended, and his trachea is deviated to the right. Which of the following is the best initial management for this patient?

A 28-year-old man is brought to the emergency department 4 hours after being involved in a motor vehicle collision. His blood pressure is 90/50 mm Hg, pulse is 120/min and respirations are 30/min. Examination shows a stuporous man with bruises over his extremities and upper abdomen. His trachea is midline and his neck veins are flat. His abdomen is moderately distended but non-tender. Immediately after being intubated and placed on mechanical ventilation he goes into cardiac arrest. Which of the following could have prevented cardiac arrest in this patient?

A 28-year-old man presents to ER with fever, chills, and generalized weakness for the past one week. He has no history of pre-existing heart disease, but he was admitted to the hospital six months ago for cellulitis of the right arm. His temperature is 40.0°C (104°F), pulse is 110/min, respirations are 22/min, and blood pressure is 110/65 mmHg. Oropharynx is clear. Lungs are clear to auscultation. A holosystolic murmur is heard at the lower sternum which increases in intensity with inspiration. His blood is drawn and sent for culture. What is the most appropriate initial antibiotic therapy for this patient?

A 28-year-old primigravid woman at 34 weeks gestation is brought to the emergency department following a motor vehicle accident. She had intense abdominal pain and became agitated and restless in the ambulance. She has mild vaginal bleeding and diffuse abdominal pain. She is on continuous fetal heart monitoring. Her prenatal course, prenatal tests and fetal growth have been normal. Prenatal ultrasound at the 16th week showed no abnormalities and an intrauterine gestation consistent with dates. Her blood pressure is 90/60mmHg, pulse is 120/min and respirations are 32/min. Physical examination shows hyperventilation, cold extremities and a distended abdomen with irregular contours. Fetal heart monitoring shows repetitive late decelerations and a long-term variability of 2 cycles/min. Which of the following is the most likely diagnosis?

A 28-year-old woman at 30 weeks gestation comes to the physician because of 2 days of a near absence of fetal movements. This is only her second prenatal visit because she has skipped many appointments. She has a medical history significant for chronic hepatitis C infection and a MRSA skin abscess that was drained. She smokes cigarettes and uses heroin, cocaine and alcohol. She says that she is trying hard to be sober. Her temperature is 37.0C (98.7F), blood pressure is 138/85 mm Hg and pulse is 80/min. Physical examination shows a fundal height of 26cm (10.2in). Fetal heart tones are heard by Doppler. Nonstress test (NST) shows no accelerations. After vibroacoustic stimulation, NST is still not reactive so a biophysical profile is ordered and shows a score of 2. Her lab work showed the following: Complete blood count: Hemoglobin: 8.0 g/L, MCV: 105fl, Platelets: 120,000/mm3, Leukocyte count: 3,500/mm3. Which of the following is the most appropriate next step in management?

A 28-year-old woman, gravida 3, para 2, at 35 weeks gestation is rushed to the emergency department because of vaginal bleeding. She was sleeping when she first noticed the bleeding. She has had no uterine contractions. Her prenatal course, prenatal tests and fetal growth have been normal. Prenatal ultrasound at the 14th week of gestation showed an intrauterine gestation consistent with dates and showed no abnormalities. Her previous pregnancies were uncomplicated. Her temperature is 37.0C (98.7F), blood pressure is 90/60 mmHg, pulse is 11 6/min and respirations are 16/min. Physical examination shows cold extremities and bright red vaginal bleeding. Which of the following is the most appropriate next step in management?

A 29-year-old G3P1011 with an IUP at 37 weeks' gestation presents to the emergency department because ofagush offluid from her vagina. The patient denies any other complaints. States that she was watching TV when shefelt the gush. The fluid appeared clear. Vital sign: BP, 110/80 mm Hg; P, 88 beats/min; R, 12 breaths/min; T, 98.6°F. Fetal movement: Present. Contractions: Absent. Vaginal bleeding: Absent. Leakage of fluid: Present. Physical Examination: CVS: Normal, Lungs: Normal, Abdomen: gravid, nontender, nondistended, +Bowel Sound; Extrimities: No edema bilaterally. What is the next step in the management of this patient?

A 29-year-old male is brought to the emergency room because of sudden onset confusion and fever. He was recently admitted to the hospital for hallucinations and was discharged instable condition. His temperature is 38.6°C (101.6°F), blood pressure is 150/100 mmHg, pulse is 112/min, and respirations are 24/min. Mucus membranes are dry. Profuse diaphoresis is present. Lungs are clear to auscultation. Abdominal muscles are rigid. Muscle tone is increased; "lead pipe rigidity" is noted in all four extremities. Deep tendon reflexes are 2+. Tremor is noted. Which of the following is the most likely diagnosis?

A 29-year-old man is brought to the ED by EMS after being stabbed in the left side of his back. His BP is 120/80 mmHg, HR is 105 beats per minute, RR is 16 breaths per minute, and oxygen saturation is 98% on room air. On the secondary survey, you note motor weakness of his left lower extremity and the loss of pain sensation in the right lower extremity. Which of the following is the most likely diagnosis?

A 29-year-old man presents to the ED after being stabbed in his neck. The patient is speaking in full sentences. His breath sounds are equal bilaterally. His BP is 130/75 mmHg, HR is 95 beats per minute, RR is 16 breaths per minute, and oxygen saturation is 99% on room air. The stab wound is located between the angle of the mandible and the cricoid cartilage and violates the platysma. There is blood oozing from the site although there is no expanding hematoma. Which of the following is the most appropriate next step in management?

A 29-year-old woman presents to the ED for hyperventilation. Her initial vitals include an RR of 28 breaths per minute with an oxygen saturation of 100% on room air. She is able to speak in full sentences and tells you that she cannot breathe and that her hands and feet are cramping up. She denies any trauma, past medical history, or illicit drug use. Chest auscultation reveals clear breath sounds bilaterally. A subsequent chest radiograph is normal. Upon reevaluation, the patient reports that she is breathing better. Her vitals include an RR of 12 breaths per minute with an oxygen saturation of 100% on room air. Which of the following conditions is most likely the etiology of this patient’s symptoms?

A 29-year-old woman, gravida 2, para 1, comes to the labor and delivery ward because of contractions. Her prenatal course was significant for a positive Group B Streptococcus (GBS) perineal culture at 35 weeks’ gestation. She has no medical problems. She had a cholecystectomy at the age of 17. She takes no medications and has no known drug allergies. She is found to be 5 cm dilated with contractions every 2 minutes. She is admitted to the labor and delivery unit in active labor and penicillin is started for GBS prophylaxis. Shortly after admission to labor and delivery the patient complains of warmth and tingling of her face. She notes feeling like her lips and tongue are swollen. Physical examination demonstrates normal vital signs but with generalized urticaria and angioedema. Her abdomen is gravid and there is scant bloody mucous around her genital area. Which of the following is the most likely diagnosis?

A 3-month-old, previously well male infant presents to the emergency department in January with a 2-day history of clear rhinorrhea, low-grade fever, and poor appetite, but no cough. On physical examination, there are mild subcostal retractions, coarse breath sounds heard throughout the lung fields, and scattered expiratory wheezes. The child receives an intravenous fluid bolus in the emergency department and is admitted for observation. Which of the following is the most severe, life-threatening complication of this child's illness?

A 3-year-old boy is brought to the emergency room after spilling bleach onto his lower extremities. He is diagnosed with a chemical burn and all involved clothing are removed. In addition to resuscitation, which of the following is the most appropriate initial management of this patient?

A 3-year-old girl is brought to the emergency department because of fever, chills, vomiting, and abdominal pain. Her temperature is 39.5°C (103.1°F), blood pressure is 70/40 mm Hg, pulse is 110/min, and respirations are 20/min. She is restless and diaphoretic. The abdominal examination shows right costovertebral tenderness. Laboratory studies show: Hemoglobin 15.0 g/L, Platelets 260,000/mm3, Leukocyte count 16,500/mm3, BUN 20 mg/dL, Serum creatinine 1.1 mg/dL. Urinalysis: Blood Negative, Glucose Negative, Ketones Negative, Leukocyte esterase Positive, Nitrites Positive, WBC 40-50/hpf, RBC 5-9/hpf. Blood and urine cultures are taken. Which of the following is the most appropriate next step in management?

A 3-year-old girl is brought to the emergency department because she became partially unconscious, lethargic and febrile. Her mother claims that "she suddenly took a turn for the worse" 24 hours ago after an upper respiratory tract infection. She has no allergies, and was not taking oral antibiotics. Her blood pressure is 60/45mm Hg and pulse is 120/min. On examination, she appears emaciated and lethargic. Despite numerous attempts, it is impossible to start a peripheral intravenous line, and the child's condition continues to deteriorate. What is the best next step to obtain IV access in this patient?

A 30-year-old man is brought to the ED by police officers. The patient is agitated, vomiting, and complaining of body aches. He states that he is withdrawing from his medication. His vital signs are BP 160/85 mmHg, RR 20 breaths per minute, HR 107 beats per minute, and temperature 99.7°F. On examination he is diaphoretic, has rhinorrhea, piloerection, and hyperactive bowel sounds. Which of the following substances is this patient most likely withdrawing from?

A 30-year-old man with type 1 diabetes presents to the emergency department (ED). His blood pressure (BP) is 100/70 mmHg and heart rate (HR) is 140 beats per minute. His blood glucose is 750 mg/dL, potassium level is 5.9 mEq/L, bicarbonate is 5 mEq/L, and arterial pH 7.1. His urine is positive for ketones. Which of the following is the best initial therapy for this patient?

A 30-year-old obese woman with no significant past medical history presents to the ED complaining of shortness of breath and coughing up blood-streaked sputum. The patient states that she traveled to Moscow a month ago. Upon returning to the United States, the patient developed a persistent cough associated with dyspnea. She was seen by a pulmonologist, who diagnosed her with bronchitis and prescribed an inhaler. However, over the following weeks, the patient’s symptoms worsened, and she developed pleuritic chest pain. In the ED, she lets you know that she smokes half a pack per day. Her vitals include a temperature of 99°F, BP of 105/65 mmHg, HR of 124 beats per minute, RR of 22 breaths per minute, and an oxygen saturation of 94% on room air. Physical examination is noncontributory, except for rales at the left-mid lung. Her ECG reveals sinus tachycardia with large R waves in V1 to V3 and inverted T waves. Given this patient’s history and presentation, what is the most likely etiology of her symptoms?

A 30-year-old woman presents to the ED with fever, headache, a “sunburn-like” rash, and confusion. A friend states that the patient has complained of nausea, vomiting, diarrhea, and a sore throat over the past few days. Her last menstrual period began 4 days ago. Vital signs are HR 110 beats per minute, BP 80/45 mmHg, RR of 18 breaths per minute, and temperature of 103°F. On physical examination, you note an ill-appearing woman with a diffuse blanching erythroderma. Her neck is supple without signs of meningeal irritation. On pelvic examination, you remove a tampon. You note a fine desquamation of her skin, especially over the hands and feet, and hyperemia of her oropharyngeal, conjunctival, and vaginal mucous membranes. Laboratory results reveal a creatine phosphokinase (CPK) of 5000, WBC 15,000/μL, platelets of 90,000/μL, BUN 40 mg/dL, creatinine 2 mg/dL, and elevated liver enzymes. You suspect thediagnosis of toxic shock syndrome and initiate IV fluids. You target antibiotics at which of the following causative organism?

A 31 -year-old G2P1001 with an IUP at 39 weeks' gestation present to the labor and delivery unitfor contractions. The patient states that her last pregnancy was delivered via C-section, but she wants to deliver this one vaginally. She states that she knows the risks and is willing to accept them. Vital sign: BP, 115/75 mm Hg; P, 82 beats/min; R, 12 breaths/min; T, 98.6°F. Contractions: Present, Fetal movement: Present, Vaginal bleeding: Absent, Leakage of fluid: Present. Physical examination: Gen: Awake, alert-oriented x3, mild pain distress, CVS: Normal, Lungs: Clear, Abd: Gravid, contraction present, Ext: 1+ edema bilaterally. Cervical examination: 7 cm, 100% effaced, -1 station. Fetal Heart Monitoring: Reassuring, good variability, + accelerations, no decelerations. Which of the following is a complication of vaginal birth after C-section (VBAC)?

A 31-year-old man is brought to the ED by EMS who state that the man was found lying on the floor of his garage. He is rousable in the ED, speaks with slurred speech, and vomits. His BP is 140/85 mmHg, HR is 94 beats per minute, temperature is 98.8°F, RR is 17 breaths per minute, and oxygen saturation is 99% on room air. You place an IV line, draw blood, and start a liter of normal saline running through the line. Laboratory results reveal serum sodium 139 mEq/L, potassium 3.5 mEq/L, chloride 101 mEq/L, bicarbonate 14 mEq/L, BUN 15 mg/dL, creatinine 1 mg/dL, glucose 105 mg/dL, arterial blood pH 7.27, COHb 4%, and lactate 2.8 mEq/L. Urinalysis shows 1+ protein, trace ketones, WBC 4/hpf (high-power field), red blood cell (RBC) 2 to 3/hpf, and multiple envelope-shaped and needle shaped crystals. Which of the following conditions would best explain his metabolic acidosis?

A 31-year-old woman with a known psychiatric history presents to the ED after ingesting an unknown quantity of pills from her medication vial. In the ED, she complains of nausea, abdominal cramping, and feels unsteady on her feet. On physical examination, you observe that she is tachycardic and ataxic. Which of the following substances will best be treated by activated charcoal that could present like this?

A 32-year-old diabetic man presents to the ED with a fever and 1 week of increasing right foot pain. He states he stepped on a nail while running barefoot 2 weeks ago but didn’t think much of it at that time. On physical examination, his heel is mildly erythematous and diffusely tender to palpation, with overlying warmth and edema. There is a small amount of purulent drainage through the puncture hole in his heel. A plain radiograph of his foot demonstrates a slight lucency of the calcaneus. He has decreased range of motion, but you are able to passively dorsiflex and plantarflex his ankle without difficulty. His vital signs include a temperature of 101.4°F, HR of 98 beats per minute, BP of 130/75 mmHg, and RR of 16 breaths per minute. Which of the following is the most common causative organism of this condition?

A 32-year-old firefighter presents to the ED in acute respiratory distress. He was taken to the ED shortly after extinguishing a large fire in a warehouse. His initial vitals include an HR of 90 beats per minute, a BP of 120/55 mmHg, and an RR of 18 breaths per minute with an oxygen saturation of 98% on 2-L nasal cannula. An ECG shows a first-degree heart block. Upon physical examination, there are diffuse rhonchi bilaterally. The patient is covered in soot and the hairs in his nares are singed. Given this clinical presentation, which of the following maybe responsible for this patient’s respiratory distress?

A 32-year-old G3P2 at 39 weeks gestation presented to the hospital with ruptured membranes and 4 cm dilated. She has a history of two prior vaginal deliveries, with her largest child weighing 3800 g at birth. Over the next 2 hours she progresses to 7 cm dilated. Two hours later, she remains 7 cm dilated. The estimated fetal weight by ultrasound is 3200 g. Which of the following labor abnormalities best describes this patient?

A 32-year-old male comes to the hospital complaining of pain, swelling and redness of his right arm. His past medical history is significant for substance abuse. His temperature is 38.9°C (102.0°F), blood pressure is 110/60 mmHg, pulse is 110/min and respirations are 14/min. He is started on intravenous clindamycin. The next day the swelling and pain improve, but he develops nausea, vomiting, abdominal cramps and diarrhea. He is restless and asks for pain medication to treat his aching muscles and joints. His temperature now is 37.3°C (99.1°F), blood pressure is 120/70 mmHg, pulse is 80/min and respirations are 16/min. His laboratory studies at the time of admission and the following day show: Hemoglobin 13.0 g/L (12.8 g/L), Leukocyte count 17,500/mm3 (8,500/mm3), NeutrophiIs 86% (64%), Lymphocytes 14% (26%). Which of the following is the most appropriate next step in management?

A 32-year-old male is admitted to the hospital because of confusion. He was recently diagnosed with schizophrenia His temperature is 38.6°C (101.6°F), blood pressure is 160/100 mmHg, pulse is 116/min, and respirations are 22/min. He is not oriented to time, place or person. Mucus membranes are dry. Profuse diaphoresis is present. Lungs are clear to auscultation. Abdominal, neck and extremity muscles are rigid. Muscle tone is increased. Deep tendon reflexes are 2+. Laboratory studies show a serum CK of 50,000 IU/L. CSF fluid analysis shows a total white blood cell count of 5/microL. Which of the following is the most appropriate next step in management?

A 32-year-old man is brought into the ED by EMS with fever, shortness of breath, and stridor. The patient was treated yesterday in the ED for a viral syndrome. His BP is 90/50 mmHg, HR is 110 beats per minute, temperature is 101.2°F, and his RR is 28 breaths per minute. A chest radiograph reveals a widened mediastinum. The patient is endotracheally intubated, given a 2-L bolus of normal saline, and started on antibiotics. His BP improves to 110/70 mmHg and he is transferred to the intensive care unit (ICU). You see a friend that accompanied the patient to the hospital and ask him some questions. You find out that the patient is a drum maker and works with animal hides. What is the most likely organism that is responsible for the patient’s presentation?

A 32-year-old man is brought to the ED by EMS for confusion. EMS reports that the patient was at a local pharmacy filing his prescriptions when the pharmacist noticed the patient sweating and having difficulty answering questions. In the ED, the patient’s BP is 130/68 mmHg, HR is 120 beats per minute, temperature is 98.9°F, and RR is 12 breaths per minute. The patient is unable to explain what happened. His fingerstick glucose is 410 mg/dL and his urine is positive for ketones. An electrolyte panel reveals Na + 131 mEq/L, K + 4 mEq/L, Cl − 91 mEq/L, and Ca 2+ 11 mEq/L. Which of the following electrolytes are most important to supplement during the management of his medical condition?

A 32-year-old man is brought to the ED by paramedics after a diving accident. The lifeguard on duty accompanies the patient and states that he dove head first into the shallow end of the pool and did not resurface. On examination, the patient is speaking but cannot move his arms or legs and cannot feel pain below his clavicle. He is able to feel light touch and position of his four extremities. A cervical spine radiograph does not reveal a fracture. Which of the following is the most likely diagnosis?

A 32-year-old man is stabbed in the left chest and presents to the emergency department in distress. His pulse is 130/min, blood pressure is 70/50 mmHg, and respiratory rate is 39/min. The stab wound is in the left fifth intercostal space in the midaxillary line. On examination his trachea is deviated to the right, jugular veins are distended bilaterally, and he has absent breath sounds and hyperresonance to percussion on the left side. Subcutaneous emphysema is palpated on the left thoracic wall. What is the best next step in management?

A 32-year-old man presented to the emergency department five hours ago with an acute asthma exacerbation. He has been receiving continuous albuterol nebulizer treatments since that time. He has a 20-year history of asthma but notes that recently the frequency of his attacks has increased. Presently, his blood pressure is 110/70 mmHg and heart rate is 120 and regular. On physical exam, the patient appears drowsy. Breath sounds are diminished bilaterally but there are no wheezes. The most recent ABG reveals: pH 7.32, pO2 65mmHg, pCO2 50mmHg. Which of the following is the best next step in managing this patient?

A 32-year-old man undergoes a distal pancreatectomy, splenectomy, and partial colectomy for a gunshot wound to the left upper quadrant of the abdomen. One week later he develops a shaking chill in conjunction with a temperature spike of 39.4°C (103°F). His blood pressure is 70/40 mm Hg, pulse is 140 beats per minute and respiratory rate is 45 breaths per minute. He is transferred to the intensive care unit (ICU), where he is intubated and a Swan-Ganz catheter is placed. Which of the following is consistent with the expected initial Swan-Ganz catheter readings?

A 32-year-old man with Crohn’s disease presents to the emergency department with acute-onset diffuse abdominal pain and emesis. The patient states these symptoms are different than his usual Crohn’s disease flare-ups. The pain is severe (10/10) and is cramping in nature. He says his abdomen feels larger than usual. His Crohn’s disease has been well managed on 6-mercaptopurine for the past 6 months. The patient denies any recent sick contacts or eating underprepared foods. He states he had a bowel movement and flatus since the abdominal pain began. In addition to Crohn’s disease, the patient had appendicitis for which he underwent an appendectomy 12 years ago. His temperature is 37.1°C (98.7°F), blood pressure is 135/86 mm Hg, pulse is 84/min, and respiratory rate is 14/ min. On physical examination the abdomen is distended and diffusely tender with high-pitched bowel sounds. There is rebound tenderness throughout the abdomen along with guarding. The remainder of the physical examination is noncontributory. An x-ray of the abdomen shows dilated small loops of bowel along with absence of gas in the colon. What is the best next step in management?

A 32-year-old woman is brought to the emergency department by her husband because of slurred speech and difficulty walking. She has also been very drowsy for the past several hours, a non-typical behavior for a very active woman. She has a history of bipolar disorder, insomnia, migraine headaches, seizures and hypothyroidism. Her temperature is 37°C (98.6°F), blood pressure is 110/70 mmHg, pulse is 76/min, and respirations are 16/min. She is lethargic and falls asleep during the interview and physical examination. Pupils are 5 mm in size and reactive to light. Neck is supple. Oropharynx is clear. Chest auscultation is unremarkable. Abdomen is soft and non-tender; bowel sounds are normal. Limited neurologic examination shows 1+ deep tendon reflexes in all four extremities; there is no Babinski sign; strength is 5/5 throughout. There is no nystagmus or hand tremor. Blood sugar is 130 mg/dL. Which of the following is the most likely cause of her symptoms?

A 32-year-old woman presents to the ED with 7 days of vaginal discharge and pelvic pain. She is sexually active and admits to several recent “one night stands.” She denies trauma/injury and does not have any urinary or other abdominal complaints. Her HR is 85 beats per minute, BP is 135/90 mmHg, RR is 18 breaths per minute, and temperature is 101.4°F. On bimanual examination, you note a copious, thin, white discharge with mild diffuse adnexal tenderness with significant cervical motion tenderness. There are no rashes, skin lesions, or adenopathy. Laboratory results are notable for a WBC of 18,000/μL. A urinalysis shows WBCs but is otherwise within normal limits. Which of the following is the most appropriate next step in management?

A 32-year-old woman presents to the ED with a 1-month history of general malaise, mild cough, and subjective fevers. She states that she is human immunodeficiency virus (HIV) positive and her last CD4 count, 6 months ago, was 220. She is not on antiretroviral therapy or any other medications. Initial vitals include an HR of 88 beats per minute, a BP of 130/60 mmHg, and an RR of 12 breaths per minute with an oxygen saturation of 91% on room air. Her chest radiograph shows bilateral diffuse interstitial infiltrates. Subsequent laboratory tests are unremarkable except for an elevated lactate dehydrogenase level. Given this patient’s history and physical examination, which of the following is the most likely organism responsible for her clinical presentation?