Surgery USMLE (101-200)

101. A 65-year-old man has an enterocutaneous fistula originating in the jejunum secondary to inflammatory bowel disease. Which of the following would be the most appropriate fluid for replacement of his enteric losses?

102. A 45-year-old woman is seen with wasting of the intrinsic muscles of the hand, weakness, and pain in the wrist. Which of the following nerves has most likely been injured?

103. A 68-year-old woman presents with a pigmented lesion on the trunk. Upon further examination the lesion has an irregular border, darkening coloration, and raised surface. An incisional biopsy is performed and confirms a melanoma with a thickness of 0.5 mm. The patient is scheduled for a wide local excision of the melanoma in the operating room. Which of the following is the smallest margin recommended for excision?

104. A 25-year-old woman presents with a benign nevus on the right upper arm. She desires removal and undergoes a clean incision and then closure of the incision without complication. With regard to the healing process, which of the following cell types are the first infiltrating cells to enter the wound site, peaking at 24 to 48 hours?

105. A 63-year-old man with history of poorly controlled diabetes presents with right leg swelling and pain. The patient denies trauma to the leg and reports it was normal yesterday. Examination of the right lower extremity is significant for extreme tenderness to palpation, erythema, and edema extending up to the knee. X ray of the right leg shows tissue swelling without gas or osteomyelitis. The patient’s vital signs are normal and he is started on broad-spectrum IV antibiotics and insulin. An hour later the patient’s heart rate increases to 125 beats per minute and the erythema has progressed to the thigh with new blister formation on the leg. Which of the following is the most appropriate next step in management?

106. A 35-year-old woman undergoes an elective laparoscopic cholecystectomy for symptomatic cholelithiasis. Which of the following wound classes best describes her procedure?

107. A 65-year-old woman presents with a 1-cm lesion with a pearly border on her nose, and punch biopsy is consistent with a basal cell carcinoma. She is scheduled to undergo Mohs surgery. Which of the following is a benefit of Mohs surgery over wide local excision?

109. A 25-year-old man is brought to the emergency room after sustaining burns during a fire in his apartment. He has blistering and erythema of his face, left upper extremity, and chest. He also has circumferential frank charring of his right upper extremity with decreased capillary refill. He is agitated, hypotensive, and tachycardic. Which of the following is the most appropriate initial management of his wounds?

110. 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?

111. A 25-year-old man is shot with a .22 caliber revolver. The entrance wound is in the anteromedial aspect of his upper thigh, 5 cm below the groin crease. The exit wound is in the posterolateral aspect of the thigh, half way between the greater trochanter and the knee. He has palpable pulses in the dorsum of his foot and in the posterior tibial artery behind the malleolus. The popliteal pulse is reported normal by one examiner, but cannot be felt by another. There is no hematoma under the entrance wound, and blood is oozing from both wounds but not at an alarming rate. He is hemodynamically stable. Neurologic examination of the leg is normal. X-ray films show the femur to be intact. In addition to local wound care and the appropriate tetanus prophylaxis, which of the following is the most appropriate next step in management?

112. A 62-year-old man with alcoholic cirrhosis of the Uver and ascites presents with generalized abdominal pain that started 12 hours ago. He now has moderate tenderness over the entire abdomen, with minimal guarding and equivocal rebound. Bowel sounds are diminished but present. He has a temperature of 38.4 C (101.2 F) and a leukocyte count of 11,000/mm3. Although he used to be a heavy drinker, he has not touched a drop of alcohol for the past 7 years. Except for the presence of ascites, upright and flat x-ray films of the abdomen are unremarkable. Which of the following is the most appropriate next step in diagnosis?

113. A 56-year-old man presents with progressive jaundice that he first noted 6 weeks ago. The patient has lost about 20 pounds over the past 2 months and he has persistent, nagging pain deep into his epigastrium and upper back. Except for the obvious jaundice and the signs of weight loss, physical examination is remarkable only for the presence of a vaguely palpable, nontender mass under the liver edge. His hemoglobin is 14 g/dL, and there is no occult blood in the stool. Total bilirubin is 22 mg/dL, with 16 mg/dL direct (conjugated) fraction. The transaminases are minimally elevated, whereas the alkaline phosphatase is about 8 times the upper limit of normal. A sonogram shows dilated intrahepatic ducts, dilated extrahepatic ducts, and a very distended, thinwalled gallbladder without stones. Which of the following is the most appropriate next step in diagnosis?

114. A 31-year-old accounting student presents with a persistent headache that began approximately 4 months ago. The headache has been gradually increasing in intensity, and is worse in the mornings. Thinking that she might need new glasses, she sought help from her optometrist, who discovered that she has bilateral papilledema and sent her in for medical evaluation. On direct questioning, she admits to repeat vomiting for the past 3 weeks, with no heaving, straining, or preceding nausea. "I would just open my mouth, and the stuff would hit the wall," she explains. She denies any other neurological symptoms. Which of the following is the most likely diagnosis?

115. A 55-year-old man presents with worsening cirrhosis. After evaluation by a hepatologist, he presents for evaluation for hepatic transplantation. He is informed that prioritization for transplantation is based on the Model of End-stage Liver Disease (MELD) score, and that patients with higher MELD scores have a greater benefit from transplantation. Which of the following contributes to the MELD score?

116. A young woman who has received a transplant has posttransplant fever and malaise. Graft-versus-host disease (GVHD) is diagnosed. This has occurred most commonly with the transplantation of which of the following?

117. A brain-dead potential donor has become available. You must plan for the dispersal of the thoracic organs. Which of the following will necessitate a heart-lung transplant?

118. A 35-year-old man who has had type 1 diabetes for many years undergoes a pancreas transplant with enteric drainage (connection of the donor duodenum to the recipient jejunum). Postoperatively, he has increased pain near his pancreas transplant. Which of the following should be performed to confirm a diagnosis of rejection?

119. A 55-year-old woman who has end-stage liver disease is referred to a hepatologist for evaluation. Which of the following would prevent her from being a transplantation candidate?

120. A 12-year-old boy with a femur fracture after a motor vehicle collision undergoes operative repair. After induction of anesthesia, he develops a fever of 40°C (104°F), shaking rigors, and blood-tinged urine. Which of the following is the best treatment option?

121. A 24-year-old Jehovah’s Witness who was in a high-speed motorcycle collision undergoes emergent splenectomy. His estimated blood loss was 1500 mL. Which of the following strategy should be employed for his resuscitation?

123. A 63-year-old man with a 40-pack per year smoking history undergoes a low anterior resection for rectal cancer and on postoperative day 5 develops a fever, new infiltrate on chest x- ray, and leukocytosis. He is transferred to the ICU for treatment of his pneumonia because of clinical deterioration. Which of the following is a sign of early sepsis?

124. A 60-year-old woman with no previous medical problems undergoes a total colectomy with diverting ileostomy for a cecal perforation secondary to a sigmoid stricture. Postoperatively, she has 2 L of ileostomy output per day. Her heart rate is 110 beats per minute, her respiratory rate is 24 breaths per minute, and her oxygen saturation is 98% on 2-L nasal cannula (NC). Her hemoglobin levels have been stable postoperatively at 9.0 mg/dL. Her other laboratory values on postoperative day 6 are as follows: Na+: 128 K+: 3.0 Cl−: 102 HCO3-: 20 Which of the following statements is the best strategy for correcting her acid–base disorder?

125. A 39-year-old man is undergoing resuscitation with blood products for an upper GI bleed. He is suspected of having a hemolytic transfusion reaction. Which of the following is appropriate in the management of this patient?

126. A 43-year-old trauma patient develops acute respiratory distress syndrome (ARDS) and has difficulty oxygenating despite increased concentrations of inspired O2. After the positive end-expiratory pressure (PEEP) is increased, the patient’s oxygenation improves. What is the mechanism by which this occurs?

127. A 27-year-old man was assaulted and stabbed on the left side of the chest between the areola and the sternum. He is hemodynamically unstable with jugular venous distention, distant heart sounds, and hypotension. Which of the following findings would be consistent with a diagnosis of hemodynamically significant cardiac tamponade?

128. A 55-year-old woman requires an abdominoperineal operation for rectal cancer. She has a history of stable angina. Which of the following clinical markers is most likely to predict a cardiac event during her noncardiac surgery and should prompt further cardiac workup prior to her operation?

129. A 70-kg woman is to undergo nail removal from her right ring finger in the ambulatory surgery clinic. Which of the following is the most appropriate option for local anesthesia?

130. 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?

131. A 58-year-old woman with multiple comorbidities and previous cardiac surgery is in a high-speed motor vehicle collision. She is intubated for airway protection. Because of hemodynamic instability, a central venous catheter is placed in the right subclavian vein. While the surgeon is securing the catheter, the cap becomes displaced and air enters the catheter. Suddenly, the patient becomes tachycardic and hypotensive. What is the best next maneuver?

132. An 18-year-old man was traveling at a high speed when his car slammed into a wall. He is brought into the emergency department by ambulance. His blood pressure is 60/40 mmHg, pulse is 115/min and weak, respirations are 18/min, and central venous pressure is 2 cmH2O. He is responsive only to painful stimuli. Breath sounds are equal bilaterally, and cardiac auscultation reveals only tachycardia. The abdomen is soft, nondistended, and nontender with active bowel sounds. A chest x-ray film shows a widened mediastinum. Which of the following is the most likely diagnosis?

133. A 22-year-old woman is taken to the emergency department after she injures her foot. She had been standing on a chair changing a light bulb, when she accidentally stepped off the chair backward. She heard a cracking sound when she fell and developed pain and swelling behind the ankle. Her symptoms worsened when she tried to descend the stairs in her house. Physical examination demonstrates marked swelling behind her ankle, and her pain is exacerbated by plantar flexion and dorsiflexion of the hallus. Which of the following is the most likely diagnoses?

134. A 72-year-old chronic smoker with severe chronic obstructive pulmonary disease (COPD) is found to have a central hilar mass on chest x-ray. Bronchoscopy and biopsies establish a diagnosis of squamous cell carcinoma of the lung. Pulmonary function studies show that he has an FEVj of 1100 mL, and a ventilation-perfusion scan indicates that 60% of his pulmonary function comes from the affected lung. Which of the following is the most appropriate next step in management?

135. 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?

136. An 80-year-old man comes to the physician because of a slowly growing ulcerated mass on the glans penis. A biopsy is positive for squamous cell carcinoma. Which of the following conditions is usually present in association with this tumor?

137. An 11-year-old girl presents to your office because of a family history of medullary carcinoma of the thyroid. Physical examination is normal. Which of the following tests should you perform?

138. A 37-year-old woman has developed a 6-cm mass on her anterior thigh over the past 10 months. The mass appears to be fixed to the underlying muscle, but the overlying skin is movable. Which of the following is the most appropriate next step in her management?

139. A 50-year-old man is incidentally discovered to have a low-grade mucosa-associated lymphoid tissue (MALT) lymphoma on biopsy of the stomach during esophagogastroduodenoscopy for dyspepsia. CT scans of the chest, abdomen, and pelvis demonstrate no evidence of enlarged regional lymph nodes or distant metastases. Which of the following is the initial treatment of choice?

140. A 33-year-old woman seeks assistance because of a swelling of her right parotid gland. Biopsy is performed and reveals acinar carcinoma. You consent the patient for resection and inform her that at the very least, she will require superficial parotidectomy. Which of the following intraoperative findings would require sacrifice of the facial nerve?

141. A 29-year-old woman on oral contraceptives presents with abdominal pain. A computed tomography (CT) scan of the abdomen demonstrates a large hematoma of the right liver with the suggestion of an underlying liver lesion. Her hemoglobin is 6, and she is transfused 2 units of packed red blood cells and 2 units of fresh frozen plasma. Two hours after starting the transfusion, she develops respiratory distress and requires intubation. She is not volume overloaded clinically, but her chest x-ray shows bilateral pulmonary infiltrates. Which of the following is the management strategy of choice?

142. A 68-year-old hypertensive man undergoes successful repair of a ruptured abdominal aortic aneurysm. He receives 9 L Ringer lactate solution and 4 units of whole blood during the operation. Two hours after transfer to the surgical intensive care unit, the following hemodynamic parameters are obtained: systemic blood pressure (BP) 90/60 mm Hg, pulse 110 beats per minute, central venous pressure (CVP) 7 mm Hg, pulmonary artery pressure 28/10 mm Hg, pulmonary capillary wedge pressure (PCWP) 8 mm Hg, cardiac output 1.9 L/min, systemic vascular resistance 1400 (dyne·s)/cm5 (normal is 900-1300), PaO2 140 mm Hg (FiO2: 0.45), urine output 15 mL/h (specific gravity: 1.029), and hematocrit 35%. Given this data, which of the following is the most appropriate next step in management?

143. A 59-year-old man with a history of myocardial infarction 2 years ago undergoes an uneventful aortobifemoral bypass graft for aortoiliac occlusive disease. Six hours later he develops ST segment depression, and a 12-lead electrocardiogram (ECG) shows anterolateral ischemia. His hemodynamic parameters are as follows: systemic BP 70/40 mm Hg, pulse 100 beats per minute, CVP 18 mm Hg, PCWP 25 mm Hg, cardiac output 1.5 L/min, and systemic vascular resistance 1000 (dyne·s)/cm5. Which of the following is the single best pharmacologic intervention for this patient?

144. A 56-year-old man undergoes a left upper lobectomy. An epidural catheter is inserted for postoperative pain relief. Ninety minutes after the first dose of epidural morphine, the patient complains of itching and becomes increasingly somnolent. Blood-gas measurement reveals the following: pH 7.24, PaCO2 58, PaO2 100, and HCO3− 28. Which of the following is the most appropriate initial therapy for this patient?

145. A 71-year-old man returns from the operating room (OR) after undergoing a triple coronary bypass. His initial cardiac index is 2.8 L/ (min·m 2). Heart rate is then noted to be 55 beats per minute, BP is 110/80 mm Hg, wedge pressure is 15, and his cardiac index has dropped to 1.6 L/(min·m2). He has a normal left ventricle. Which of the following maneuvers will increase his cardiac output?

146. Eight days after a difficult hemigastrectomy and gastroduodenostomy for gastric ulcer, a patient begins to leak 2-3 L of greenish fluid per day through the right corner of his bilateral subcostal surgical incision. He is afebrile and has no clinical signs of an acute abdomen. At surgery, a feeding catheter jejunostomy was placed, through which the patient has been receiving 3 L/day of elemental diet with a caloric content of 1 cal per mL, and 1 g nitrogen per 100 cal. The nursing staff has rigged a very effective collection device for the fluid that is leaking through the wound, and the skin around the site is well protected. Which of the following is the most appropriate next step in management?

147. A college student is tackled while playing football and develops severe knee pain. When examined shortly thereafter, the knee is swollen and the patient has pain on direct palpation over the lateral aspect of the knee. With the knee flexed 30 degrees, passive adduction elicits pain on the same area, and the leg can be adducted further than in the normal contralateral leg (varus stress test). The anterior drawer test, posterior drawer test, and Lachman test are negative. Which of the following is the most likely site of injury?

148. Six hours after undergoing laparoscopic bilateral inguinal hernia repairs, a 62-year-old man complains of suprapubic discomfort and fullness. He feels the need to void but has not been able to do so since the operation. There is a palpable suprapubic mass that is dull to percussion. Palpation of that mass exacerbates the symptoms. Which of the following is the most appropriate next step in management?

149. A 49-year-old man crashes his car against a bridge abutment at high speed. On arrival at the emergency department, he is breathing well, but he has multiple bruises over the chest, and there is a specific spot at about the middle of the sternum that is exquisitely painful to touch. Gentle palpation of that area elicits a gritty feeling of bone grating on bone. He distinctly recalls hitting the steering wheel with his chest and is certain that he hurt that particular spot in that manner. Anteroposterior and lateral chest x-ray films confirm that he has a sternal fracture. The films do not show any mediastinal widening or mediastinal air, and both lung fields are clear. His vital signs are normal, and he does not have subcutaneous emphysema. Which of the following studies is most likely to show evidence of additional injuries?

150. A 60-year-old man complains of anal itching and discomfort, particularly toward the end of the day. He works as a salesman in a department store, where he has to be on his feet all day. When he goes home in the evening, he finds himself sitting sideways to avoid the discomfort. He has no fever, rectal bleeding, or soiling of his underwear, and he has never had surgery in that area. Which of the following is the most likely diagnosis?

151. An 18-year-old previously healthy man is placed on intravenous heparin after having a pulmonary embolism (PE) after exploratory laparotomy for a small-bowel injury following a motor vehicle collision. Five days later, his platelet count is 90,000/μL and continues to fall over the next several days. The patient’s serum is positive for antibodies to the heparin-platelet factor complexes. Which of the following is the most appropriate next management step?

152. A 62-year-old woman undergoes a pancreaticoduodenectomy for a pancreatic head cancer. A jejunostomy is placed to facilitate nutritional repletion as she is expected to have a prolonged recovery. What is the best method for delivering postoperative nutrition?

153. A 65-year-old woman has a life-threatening pulmonary embolus 5 days following removal of a uterine malignancy. She is immediately heparinized and maintained in good therapeutic range for the next 3 days, then passes gross blood from her vagina and develops tachycardia, hypotension, and oliguria. Following resuscitation, an abdominal CT scan reveals a major retroperitoneal hematoma. Which of the following is the best next step in management?

154. A 71-year-old man develops dysphagia for both solids and liquids and weight loss of 60 lb over the past 6 months. He undergoes endoscopy, demonstrating a distal esophageal lesion, and biopsies are consistent with squamous cell carcinoma. He is scheduled for neoadjuvant chemoradiation followed by an esophagectomy. Preoperatively he is started on total parenteral nutrition, given his severe malnutrition reflected by an albumin of less than 1. Which of the following is most likely to be a concern initially in starting total parenteral nutrition in this patient?

155. A 39-year-old woman presents with generalized malaise and lymphadenopathy. Biopsy of a supraclavicular lymph node reveals non-Hodgkin lymphoma. Fortyeight hours after initiation of chemotherapy, she develops a high-grade fever and her laboratory studies demonstrate hyperkalemia, hyperphosphatemia, and hypocalcemia. Which of the following cells mediate this syndrome?

156. A 33-year-old diabetic man receives a renal allograft. The physicians choose cyclosporine as one of the antirejection medications. Which of the following functions does cyclosporine A primarily inhibit?

157. A 24-year-old woman presents with lethargy, anorexia, tachypnea, and weakness. Laboratory studies reveal a BUN of 150 mg/dL, serum creatinine of 16 mg/dL, and potassium of 6.2 mEq/L. Chest x-ray shows increased pulmonary vascularity and a dilated heart. Which of the following is the most appropriate management of this patient?

158. A hypertensive 47-year-old man is proposed for kidney transplantation. He is anemic but is otherwise functional. Which of the following would preclude renal transplantation?

159. A 56-year-old woman is undergoing a cadaveric renal transplant. After revascularization of the transplanted kidney, the transplanted renal parenchyma becomes swollen and blue. The surgeon suspects hyperacute rejection. What is the treatment of choice for this patient?

160. A 57-year-old man has end-stage heart failure due to atherosclerosis. His cardiologist refers him for evaluation for heart transplantation. Which of the following is an absolute contraindication for heart transplantation?

161. A 38-year-old woman who underwent a cadaveric renal transplant 8 years ago presents with fevers, fatigue, and weight loss. Evaluation included CT scans of the head, neck, chest, abdomen, and pelvis; she is noted to have diffuse lymphadenopathy and pulmonary nodules. A biopsy and histologic examination of a lymph node is performed. Which of the following viruses is most likely to be present in the lymph node?

162. A 41-year-old man underwent a successful living-related kidney transplantation 1 year ago with good results. Preoperatively, he was noted to have an elevated calcium level; post-transplantation, he continues to have elevated calcium levels and associated symptoms. Which of the following is the most appropriate next step in management?

163. A 53-year-old man presents with constipation and a 20-lb weight loss over the course of 6 months. Colonoscopy reveals a fungating mass in the sigmoid colon; biopsy is consistent with adenocarcinoma. His metastatic workup is negative. A CEA level is obtained and is 4-fold greater than normal. Which of the following is the appropriate use of this test?

164. An elderly diabetic woman with chronic steroid-dependent bronchospasm has an ileocolectomy for a perforated cecum. She is taken to the ICU intubated and is maintained on broad-spectrum antibiotics, renal dose dopamine, and a rapid steroid taper. On postoperative day 2, she develops a fever of 39.2°C (102.5°F), hypotension, lethargy, and laboratory values remarkable for hypoglycemia and hyperkalemia. Which of the following is the most likely explanation for her deterioration?

165. A cirrhotic patient with abnormal coagulation studies due to hepatic synthetic dysfunction requires an urgent cholecystectomy. A transfusion of FFP is planned to minimize the risk of bleeding due to surgery. What is the optimal timing of this transfusion?

166. On postoperative day 5, an otherwise healthy 55-year-old man recovering from a partial hepatectomy is noted to have a fever of 38.6°C (101.5°F). Which of the following is the most common nosocomial infection postoperatively?

167. Ten days after an exploratory laparotomy and lysis of adhesions, a patient, who previously underwent a low anterior resection for rectal cancer followed by postoperative chemoradiation, is noted to have succus draining from the wound. She appears to have adequate source control—she is afebrile with a normal white blood count. The output from the fistula is approximately 150 cc per day. Which of the following factors is most likely to prevent closure of the enterocutaneous fistula?

168. A 62-year-old, right-handed man has transient episodes of paralysis of the right arm and inability to express himself. There is no associated headache. The episodes have sudden onset, last about 5-10 minutes, and leave no neurologic sequela. The patient is overweight and sedentary. He smokes one pack of cigarettes per day and has high cholesterol, but he is not hypertensive. The only abnormality in the physical examination is a bruit over the left carotid bifurcation. Which of the following is the most appropriate initial step in diagnosis?

169. Eight hours after undergoing a transnasal, transsphenoidal resection of a prolactinoma, a young lady becomes lethargic, confused, and eventually comatose. Review of the record shows that her urinary output since surgery has averaged 600 mL/hr, while her intake of IV fluids (5% dextrose in 0.45% saline) has been 100 mL/hr. Her blood pressure is 110/75 mm Hg, and her pulse is 88/min. Which of the following would most likely yield the correct diagnosis?

170. A 42-year-old man has had a rocky course for the 3 days following a bowel resection for intestinal perforation due to inflammatory bowel disease. His CVP had been 12 to 14 but is now 6, in the face of diminished blood pressure and oliguria. Which of the following is the most likely etiology of his hypotension?

171. Acute renal failure occurs following aortic angiography in a 72-year-old man. His weight has been rising, his lungs show rales at both bases, and he is dyspneic. His fractional excretion of sodium is greater than 1. He has eosinophilia on his peripheral smear, an elevated erythrocyte sedimentation rate, and proteinuria with microscopic hematuria. Which of the following is the most likely cause of his renal failure?

172. A 55-year-old woman has been hospitalized because of recurrent pancreatitis, ARDS, prolonged ileus, and need for parenteral nutrition. She demonstrates weakness, lassitude, orthostatic hypotension, nausea, and fever. Which of the following abnormalities is most likely to explain these symptoms?

173. A young man is shot in the upper part of the neck with a .22 caliber revolver. Inspection of the entrance and exit wounds indicates that the trajectory of the bullet is all above die level of the angle of the mandible, but below the skull. He is fully conscious and neurologically intact. A steady trickle of blood flows from both wounds, and it does not seem to respond to local pressure. He is hemodynamically stable. Which of the following is the most appropriate next step in diagnosis?

174. A 21-year-old college student undergoes surgery to remove a small cyst in his palm at the base of his third digit. He receives an axillary regional block prior to die procedure but still has discomfort post-operatively. Injection of anesmetic in which of the following sites may be used to treat his pain?

175. A 26-year-old man is resuscitated with packed red blood cells following a motor vehicle collision complicated by a fractured pelvis and resultant hemorrhage. A few hours later the patient becomes hypotensive with a normal central venous pressure (CVP), oliguric, and febrile. Upon examination, the patient is noted to have profuse oozing of blood from his intravenous (IV) sites. Which of the following is the most likely diagnosis?

176. A 62-year-old man is suffering from arrhythmias on the night of his triple coronary bypass. Potassium has been administered. His urine output is 20 to 30 mL/h. Serum potassium level is 6.2. Which of the following medications counteracts the effects of potassium without reducing the serum potassium level?

177. An in-hospital workup of a 78-year-old hypertensive, mildly asthmatic man who is receiving chemotherapy for colon cancer reveals symptomatic gallstones. Preoperative laboratory results are notable for a hematocrit of 24% and urinalysis with 18 to 25 WBCs and gram-negative bacteria. On call to the operating room, the patient receives intravenous penicillin. His abdomen is shaved in the operating room. An open cholecystectomy is performed and, despite a lack of indications, the common bile duct is explored. The wound is closed primarily with a Penrose drain exiting a separate stab wound. On postoperative day 3, the patient develops a wound infection. Which of the following changes in the care of this patient could have decreased the chance of a postoperative wound infection?

178. A 72-year-old man undergoes a subtotal colectomy for a cecal perforation due to a sigmoid colon obstruction. He has had a prolonged recovery and has been on total parenteral nutrition (TPN) for 2 weeks postoperatively. After regaining bowel function, he experienced significant diarrhea. Examination of his abdominal wound demonstrates minimal granulation tissue. He complains that he has lost his taste for food. He also has increased hair loss and a new perioral pustular rash. Which of the following deficiencies does he most likely have?

179. A 45-year-old woman undergoes an uneventful laparoscopic cholecystectomy for which she receives 1 dose of cephalosporin. One week later, she returns to the emergency room with fever, nausea, and copious diarrhea and is suspected of having pseudomembranous colitis. She is afebrile and has no peritoneal signs on abdominal examination. She has a mild leukocytosis with a left shift. Which of the following is the appropriate initial management strategy?

180. An 18-year-old woman develops urticaria and wheezing after an injection of intravenous contrast for an abdominal CT scan. Her blood pressure is 120/60 mm Hg, heart rate is 155 beats per minute, and respiratory rate is 30 breaths per minute. Which of the following is the most appropriate immediate therapy?

181. A patient develops a fever and tachycardia during a blood transfusion after a redo coronary artery bypass procedure. The nurse subsequently discovers that there was a mix-up in the cross-match because of a labeling error. Which of the following is diagnostic in a patient with an immediate hemolytic reaction secondary to a blood transfusion?

182. A 72-year-old man with diabetes, renal insufficiency, and coronary artery disease presents in septic shock from emphysematous cholecystitis. His oxygen saturation is 100% on 6-L nasal cannula and his hemoglobin is 7.2 mg/dL. His mixed venous oxygen saturation is 58%. Which of the following treatment options will improve his oxygen delivery the most?

183. An obese 50-year-old woman undergoes a laparoscopic cholecystectomy. In the recovery room, she is found to be hypotensive and tachycardic. Her arterial blood gases reveal a pH of 7.29, PaO2 of 60 mm Hg, and PaCO2 of 54 mm Hg. Which of the following is the most likely cause of this patient’s problem?

184. A 65-year-old man who had a 25-lb weight loss over the previous 6 months is diagnosed with adenocarcinoma of the distal esophagus. He undergoes a transhiatal esophagectomy complicated by a cervical leak. He is receiving enteral feeds through a jejunostomy tube. After a week, his physicians wish to assess his nutritional resuscitation. Which of the following is the most accurate measure of adequacy of his nutritional support?

185. A 47-year-old man with hypertensive nephropathy develops fever, graft tenderness, and oliguria 4 weeks following cadaveric renal transplantation. Serum creatinine is 3.1 mg/dL. A renal ultrasound reveals mild edema of the renal papillae but normal flow in both the renal artery and the renal vein. Nuclear scan demonstrates sluggish uptake and excretion. Which of the following is the most appropriate next step?

186. Approximately 6 weeks following a kidney transplant, a 59-year-old woman develops fever, malaise, and myalgias and is found to have a cytomegalovirus (CMV) infection. Which of the following is a potential sequela of CMV infection?

187. A kidney transplant recipient presents with severe acute rejection that does not respond to steroid treatment. Administration of which of the following agents is the best step in her management?

188. A 24-year-old woman develops moderate, generalized abdominal pain of sudden onset and shortly thereafter faints. At the time of evaluation in the emergency department, she has regained consciousness, is pale, and has a blood pressure of 95/70 mm Hg and a faint pulse rate of 90/min. The abdomen is mildly distended and tender, with normal bowel sounds. Her hemoglobin is 7 g/dL. There is no history of trauma, but it is suspected that she might be bleeding into her abdomen, and a diagnostic peritoneal lavage is performed. The study shows that there is free blood in the peritoneal cavity. She denies the possibility of pregnancy because she has been on birth control pills since the age of 14 and has never missed taking them. Pelvic examination is normal, and a pregnancy test is negative. At laparotomy, the surgeons are likely to find which of the following?

189. A 56-year-old man presents to his urologist for continued evaluation of hypertension and hematuria. The patient has a 10-year history of hypertension and recent onset of painless hematuria for which he sought the attention of an urologist 3 months ago. On detailed questioning, the man states that he has been having severe headaches that are refractory to narcotic analgesics. Three days ago, a renal ultrasound was obtained that demonstrated bilaterally enlarged kidneys with multiple cysts. Which of the following is the most appropriate next step in diagnosis?

190. A patient involved in a high-speed automobile collision arrives in the emergency department unconscious, with multiple facial fractures; brisk bleeding into his nose, mouth, and throat; and gurgly, irregular, noisy breathing. Which of the following would be the best method to secure an airway in this patient?

191. A 30-year-old man is scheduled for a laparoscopic cholecystectomy for biliary colic. He reports a family history of prolonged paralysis during general anesthesia. Which of the following medications should be avoided during his procedure?191. A 30-year-old man is scheduled for a laparoscopic cholecystectomy for biliary colic. He reports a family history of prolonged paralysis during general anesthesia. Which of the following medications should be avoided during his procedure?

192. A 63-year-old man with multiple rib fractures and a pulmonary contusion requires prolonged intubation. He is unable to be weaned from the ventilator and is on a volume control mode. He has a tracheostomy and a percutaneous gastrotomy in place through which he is being fed. The surgeon orders a respiratory quotient (RQ), which is the ratio of the rate of carbon dioxide production over the rate of oxygen uptake. The RQ is 1. Based on this information, which of the following is the next step in his management?

193. 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?

194. A 42-year-old man is undergoing chemotherapy after resection of a cecal adenocarcinoma with positive lymph nodes. You are asked to see him regarding a potential surgical complication. Which of the following potentially operable complications is a common occurrence among patients receiving systemic chemotherapy?

195. A 28-year-old medical student seeks your attention because of a testicular mass. Biopsy is consistent with pure seminoma. There is no evidence of enlarged retroperitoneal lymph nodes on CT scan. Which of the following is the best treatment strategy for this patient?

196. A 25-year-old woman with end-stage renal disease is exploring the benefits of renal transplantation. Which of the following is an advantage of dialysis over renal transplantation?

197. A 30-year-old previously healthy man presents with refractory hypertension on four medications. Urinalysis is positive for metanephrines. He was adopted as an infant and therefore does not know his family history. Which of the following inherited syndromes is not associated with this disease?

198. A 48-year-old man with alcoholic cirrhosis has several episodes of massive hematemesis. Upper gastrointestinal endoscopy confirms that he is bleeding from esophageal varices. Sclerosing injections fail to control the bleeding. After the patient has been transfused 7 units of packed red cells, he is subjected to an emergency side-to-side portacaval shunt. At the time of surgery he has a serum albumin level of 3.1 g/dL, a total bilirubin of 1,7 mg/dL, and a prothrombin time (PT) 2 seconds above the control After surgery, the bleeding stops, and the patient wakes up briefly from the anesthetic but then lapses into a coma. The reason for his neurologic deterioration would most likely be revealed by a laboratory determination of which of the following?

199. A 57-year-old man is returned to the post-surgical recovery unit after an open cholecystectomy. The patient had an uneventful, but prolonged, operative course in a very cold operating room. His past medical history is unremarkable. The only attempt at patient warming was raising the ambient temperature of the room. His urine output since arrival in the post-anesthesia care unit (PACU) has been 5 mL/hr. Which of the following is most likely to confirm the diagnosis?

200. A 25-year-old man presents to the same day surgical center for repair of an old injury to his lateral collateral ligament. The anesthesiologist wants to perform an axillary block for local pain control. If the posterior wall of the axillary artery is pierced during placement of the block, which of the following nerves will most likely be affected?