I85PREP
⌘ K
AOBS Surgery study materials
AOBS Surgery study resources

AOBS Surgery practice questions

One question at a time. Build your AOBS Surgery understanding.

First 50 of 200 questions. Each one lists the choices, the correct answer, and an explanation. The checker at the top of this page saves progress in this browser when it is available.

Continue in the practice tool above to load more questions, 50 at a time.

Question 1Cardiothoracic Surgery

A patient sustains blunt chest trauma and develops a rapidly enlarging hemothorax with hypotension. Which vessel is most commonly the source of a massive hemothorax requiring urgent thoracotomy?

  1. Internal mammary artery
  2. Azygos vein
  3. Pulmonary vein
  4. Intercostal artery Correct answer.

Explanation

In blunt and penetrating chest trauma, intercostal arteries are the most frequent source of hemothorax requiring operative control because they run in the costal groove and are easily lacerated by rib fractures. Internal mammary injury is less common and usually associated with anterior parasternal wounds.

Question 2Cardiothoracic Surgery

Which finding on chest radiography is most characteristic of a tension pneumothorax?

  1. Cavitation in the upper lobe
  2. Mediastinal shift away from the affected side with a depressed hemidiaphragm Correct answer.
  3. Bilateral diffuse alveolar infiltrates
  4. Widened mediastinum with a left pleural effusion

Explanation

Tension pneumothorax raises intrapleural pressure, pushing mediastinal structures to the contralateral side and flattening or depressing the ipsilateral diaphragm. These signs reflect the hemodynamic compromise that requires immediate decompression.

Question 3Cardiothoracic Surgery

A 24-year-old is stabbed in the left fourth intercostal space at the midclavicular line. He is hypotensive, and a chest tube drains 1800 mL of blood immediately. What is the most appropriate next step in management?

  1. Insertion of a second chest tube
  2. Observation with serial hemoglobin checks
  3. Urgent thoracotomy Correct answer.
  4. Repeat chest radiograph in 6 hours

Explanation

Initial chest tube output exceeding 1500 mL, or ongoing output greater than 200 mL per hour for several hours, is an indication for operative exploration in thoracic trauma. This volume suggests a major vascular or cardiac injury that will not resolve with tube drainage alone.

Question 4Cardiothoracic Surgery

Which statement best describes the blood supply of the thoracic esophagus relevant to esophagectomy?

  1. It is supplied by a single direct aortic branch along its entire length
  2. It receives its entire supply from the inferior thyroid artery
  3. It has a segmental supply with a relatively poor intramural collateral network Correct answer.
  4. It is supplied exclusively by the intercostal arteries

Explanation

The thoracic esophagus has a segmental arterial supply from esophageal branches of the aorta and intercostal arteries, with limited intramural collaterals. This anatomy underlies the risk of anastomotic leak and the practice of placing anastomoses in well-perfused regions.

Question 5Cardiothoracic Surgery

A patient with achalasia undergoes a Heller myotomy. Which adjunct is routinely added to reduce postoperative reflux?

  1. Truncal vagotomy
  2. Pyloroplasty
  3. Partial fundoplication Correct answer.
  4. Total Nissen fundoplication

Explanation

Heller myotomy disrupts the lower esophageal sphincter and predisposes to reflux, so a partial (Dor or Toupet) fundoplication is added as an antireflux barrier while preserving bolus transit. A total wrap would recreate obstruction at the myotomized segment.

Question 6Cardiothoracic Surgery

Which of the following is the most common indication for lung volume reduction in patients with severe emphysema?

  1. Upper lobe predominant emphysema with hyperinflation Correct answer.
  2. Diffuse homogeneous emphysema with hypercapnia
  3. Emphysema with severe pulmonary hypertension
  4. Emphysema with active tobacco use

Explanation

Lung volume reduction surgery is most beneficial in patients with upper lobe predominant emphysema and hyperinflation, who demonstrate improved elastic recoil and exercise tolerance. Homogeneous disease, active smoking, and severe pulmonary hypertension are unfavorable selection features.

Question 7Cardiothoracic Surgery

During a right upper lobectomy, which structure lies most anteriorly in the hilum and is typically divided first?

  1. Right upper lobe pulmonary artery
  2. Right superior pulmonary vein Correct answer.
  3. Azygos arch
  4. Right main bronchus

Explanation

In the right hilum the superior pulmonary vein lies anterior to the artery and bronchus, making it the most anterior hilar structure. The bronchus is the most posterior structure in the hilar arrangement.

Question 8Cardiothoracic Surgery

A patient develops a persistent air leak and fever on postoperative day 5 after lobectomy. Imaging shows a fluid collection with an air-fluid level in the pleural space. What is the most likely diagnosis?

  1. Atelectasis
  2. Chylothorax
  3. Pulmonary embolism
  4. Bronchopleural fistula with empyema Correct answer.

Explanation

A persistent air leak combined with a febrile pleural collection containing an air-fluid level suggests a bronchopleural fistula with secondary empyema. Management includes drainage and often surgical repair or bronchoscopic control.

Question 9Cardiothoracic Surgery

Which coronary artery is most commonly involved in the territory supplied by the posterior descending artery in a right-dominant circulation?

  1. Left circumflex artery
  2. Left main coronary artery
  3. Left anterior descending artery
  4. Right coronary artery Correct answer.

Explanation

In right-dominant circulation, the right coronary artery gives rise to the posterior descending artery, supplying the inferior wall and inferior septum. This dominance pattern occurs in the majority of individuals.

Question 10Cardiothoracic Surgery

A patient with critical left main coronary artery stenosis is being evaluated for revascularization. Which factor most strongly favors coronary artery bypass grafting over percutaneous intervention?

  1. Age under 50 years
  2. Normal left ventricular function
  3. Single-vessel disease with focal stenosis
  4. Presence of diabetes with multivessel disease and low surgical risk Correct answer.

Explanation

For left main or complex multivessel disease, particularly with diabetes, CABG confers a survival advantage over stenting by providing more durable and complete revascularization. Low surgical risk further supports operative management.

Question 11Cardiothoracic Surgery

What is the most common cause of cardiogenic shock after acute myocardial infarction?

  1. Acute pericardial tamponade
  2. Ventricular septal rupture
  3. Extensive left ventricular infarction with pump failure Correct answer.
  4. Papillary muscle rupture

Explanation

Most postinfarction cardiogenic shock results from loss of a large mass of contracting myocardium leading to pump failure. Mechanical complications are less frequent but must be excluded because they require urgent surgery.

Question 12Cardiothoracic Surgery

Which valve lesion most commonly requires surgery in a patient with a bicuspid aortic valve who develops symptoms in the fifth decade?

  1. Tricuspid regurgitation
  2. Aortic regurgitation from leaflet prolapse
  3. Mitral stenosis
  4. Aortic stenosis from calcific degeneration Correct answer.

Explanation

Bicuspid aortic valves typically undergo accelerated calcific degeneration, producing symptomatic aortic stenosis earlier than in trileaflet valves. Aortic regurgitation can occur but stenosis is the more frequent indication for replacement.

Question 13Cardiothoracic Surgery

A patient with severe symptomatic aortic stenosis and a porcelain aorta is being considered for valve replacement. Which approach is most appropriate?

  1. Transcatheter aortic valve replacement Correct answer.
  2. Balloon aortic valvuloplasty as definitive therapy
  3. Mechanical valve replacement with cardioplegic arrest
  4. Sutureless valve via median sternotomy with cross-clamp

Explanation

A heavily calcified porcelain aorta makes cross-clamping and aortotomy hazardous, so transcatheter aortic valve replacement avoids aortic manipulation and is preferred. Balloon valvuloplasty is only a temporizing measure.

Question 14Cardiothoracic Surgery

Which feature most strongly suggests acute type A aortic dissection on presentation?

  1. Sudden tearing chest pain with pulse deficit between arms Correct answer.
  2. Pleuritic pain relieved by leaning forward
  3. Gradual exertional dyspnea over weeks
  4. Burning epigastric pain after meals

Explanation

Acute type A dissection classically presents with abrupt severe tearing pain and evidence of malperfusion, such as a blood pressure differential or pulse deficit between limbs. This reflects involvement of the ascending aorta and arch vessels.

Question 15Cardiothoracic Surgery

A patient with a 6.2 cm ascending aortic aneurysm and a bicuspid valve is asymptomatic. What is the most appropriate management?

  1. Strict blood pressure control without surgery
  2. Beta-blocker therapy alone with annual imaging
  3. Elective surgical repair Correct answer.
  4. Serial imaging every 2 years

Explanation

Ascending aortic aneurysms reaching approximately 5.5 cm, or lower thresholds with bicuspid valves, warrant elective repair to prevent dissection or rupture. Asymptomatic status does not justify continued observation at this diameter.

Question 16Cardiothoracic Surgery

Which of the following best describes the physiologic goal of the Fontan circulation?

  1. Right ventricular-to-pulmonary artery conduit with a competent valve
  2. Atrial septectomy to allow mixing of systemic and pulmonary venous blood
  3. Systemic-to-pulmonary artery shunt to increase pulmonary blood flow
  4. Passive pulmonary blood flow driven by systemic venous pressure without a subpulmonary ventricle Correct answer.

Explanation

The Fontan operation routes systemic venous return directly to the pulmonary arteries, relying on passive flow without an intervening ventricular pump. This depends on low pulmonary vascular resistance and adequate ventricular function.

Question 17Cardiothoracic Surgery

A neonate with transposition of the great arteries is cyanotic and ductal-dependent. Which intervention is most appropriate to improve mixing before definitive repair?

  1. Placement of a systemic-to-pulmonary shunt
  2. Initiation of diuretics alone
  3. Balloon atrial septostomy Correct answer.
  4. Ligation of the patent ductus arteriosus

Explanation

In transposition, oxygenated and deoxygenated blood circulate in parallel, so creating an atrial communication by balloon septostomy permits mixing and improves oxygenation. Prostaglandin infusion maintains ductal patency as an adjunct.

Question 18Cardiothoracic Surgery

Which of the following is the most appropriate initial management of a hemodynamically stable patient with a small retained hemothorax after chest tube placement?

  1. Intrapleural thrombolytics or VATS evacuation Correct answer.
  2. Immediate thoracotomy
  3. Observation with discharge in 24 hours
  4. Chest tube removal and outpatient follow-up

Explanation

Retained hemothorax that does not drain adequately is managed with early VATS evacuation or intrapleural thrombolytics to prevent empyema and fibrothorax. Immediate thoracotomy is reserved for massive or ongoing bleeding.

Question 19Cardiothoracic Surgery

Which structure is at greatest risk of injury during a left lower lobectomy when dividing the fissure near the hilum?

  1. Recurrent laryngeal nerve
  2. Thoracic duct Correct answer.
  3. Esophagus
  4. Phrenic nerve

Explanation

The thoracic duct courses in the posterior mediastinum near the left hilum and can be injured during left-sided pulmonary resections, producing a chylothorax. The phrenic nerve is more anterior along the pericardium.

Question 20Cardiothoracic Surgery

A patient with a solitary pulmonary nodule is being evaluated. Which feature most strongly suggests malignancy?

  1. Smooth well-defined borders stable for 5 years
  2. Diffuse calcification in a concentric pattern
  3. Subpleural location with a fat density
  4. Spiculated margins with interval growth Correct answer.

Explanation

Spiculation and documented growth are strong radiologic predictors of malignancy in a solitary pulmonary nodule. Benign patterns include concentric or popcorn calcification, stability over years, and fat density.

Question 21Cardiothoracic Surgery

Which of the following is the principal determinant of early mortality after pulmonary endarterectomy for chronic thromboembolic pulmonary hypertension?

  1. Postoperative atrial fibrillation
  2. Recurrent laryngeal nerve injury
  3. Residual pulmonary hypertension from incomplete endarterectomy Correct answer.
  4. Wound infection

Explanation

Outcomes after pulmonary endarterectomy depend on achieving a complete removal of obstructing material; residual pulmonary hypertension from incomplete clearance drives right heart failure and early mortality. Arrhythmias and wound issues are manageable complications.

Question 22Cardiothoracic Surgery

Which of the following patients with myasthenia gravis is most likely to benefit from thymectomy?

  1. A patient with thymic hyperplasia and no symptoms
  2. A patient with thymoma on imaging Correct answer.
  3. A patient with ocular-only symptoms for 20 years
  4. A patient with drug-controlled disease and normal imaging

Explanation

Thymectomy is indicated for all patients with thymoma because of oncologic risk and associated myasthenia. In nonthymomatous myasthenia, benefit is greatest in generalized disease with positive antibody status and is less clear in ocular-only or long-standing disease.

Question 23Cardiothoracic Surgery

Which of the following best explains why the left internal mammary artery is preferred as a conduit for left anterior descending revascularization?

  1. It has a high long-term patency and resists atherosclerosis Correct answer.
  2. It has the largest caliber among arterial grafts
  3. It is the longest available conduit
  4. It avoids the need for proximal anastomosis

Explanation

The left internal mammary artery has superior long-term patency and resistance to atherosclerosis compared with vein grafts, which translates into improved survival when used for the LAD. Length and caliber are not the primary reasons for its preference.

Question 24General Surgery

A 24-year-old man develops right lower quadrant pain that migrates from the periumbilical region over 12 hours, with low-grade fever and tenderness at McBurney's point. Which diagnosis is most likely?

  1. Acute pancreatitis
  2. Acute appendicitis Correct answer.
  3. Sigmoid diverticulitis
  4. Acute cholecystitis

Explanation

Periumbilical pain that migrates to the right lower quadrant reflects early visceral then parietal peritoneal irritation of the appendix. Localized McBurney's point tenderness with low-grade fever supports this pattern.

Question 25General Surgery

Which finding best supports a diagnosis of acute cholecystitis rather than biliary colic?

  1. Right upper quadrant tenderness persisting for more than 6 hours with fever Correct answer.
  2. Pain radiating to the left shoulder
  3. Postprandial pain relieved by antacids
  4. Pain that resolves completely within 30 minutes

Explanation

Biliary colic produces episodic pain that resolves, whereas cholecystitis involves sustained inflammation with persistent tenderness and systemic features such as fever. Duration beyond several hours with localized signs favors cholecystitis.

Question 26General Surgery

A patient has a small, uncomplicated, well-localized perianal abscess. What is the definitive management?

  1. Incision and drainage Correct answer.
  2. Topical corticosteroid cream
  3. Sitz baths with observation for 2 weeks
  4. Oral antibiotics alone

Explanation

Perianal abscesses require prompt incision and drainage because antibiotics alone do not reliably penetrate the pus-filled cavity. Delay risks extension and sepsis.

Question 27General Surgery

Which is the most common cause of small bowel obstruction in a patient with no prior abdominal surgery?

  1. Gallstone ileus
  2. Malignancy
  3. Hernia Correct answer.
  4. Intussusception

Explanation

In patients without prior laparotomy, external hernias are the leading cause of small bowel obstruction. Adhesions dominate only when there has been previous surgery.

Question 28General Surgery

Which organism is most frequently isolated from community-acquired intra-abdominal infections such as perforated appendicitis?

  1. Escherichia coli Correct answer.
  2. Vibrio cholerae
  3. Clostridium tetani
  4. Staphylococcus aureus

Explanation

Intra-abdominal infections are typically polymicrobial with facultative gram-negative rods and anaerobes, and Escherichia coli is the most commonly isolated aerobe. Empiric therapy therefore targets these organisms.

Question 29General Surgery

Which clinical feature is most characteristic of an inguinal hernia that has become strangulated?

  1. Painless swelling that enlarges with coughing
  2. Soft, reducible swelling that disappears on lying flat
  3. Severe localized pain with erythema and systemic toxicity Correct answer.
  4. Intermittent discomfort relieved by manual reduction

Explanation

Strangulation compromises the blood supply of the herniated contents, producing severe pain, overlying skin changes, and signs of systemic illness. Urgent operative exploration is required.

Question 30General Surgery

A patient sustains blunt abdominal trauma with hypotension and a positive FAST scan. What is the most appropriate next step in an unstable patient?

  1. Diagnostic peritoneal lavage followed by discharge
  2. CT scan of the abdomen with contrast
  3. Urgent exploratory laparotomy Correct answer.
  4. Serial abdominal examinations over 24 hours

Explanation

Hemodynamic instability with a positive FAST indicating free fluid mandates immediate operative exploration. Imaging delays definitive hemorrhage control in an unstable patient.

Question 31General Surgery

A 55-year-old man presents with painless jaundice, a palpable gallbladder, and weight loss. Which diagnosis should be suspected first?

  1. Chronic cholecystitis
  2. Periampullary malignancy Correct answer.
  3. Acute pancreatitis
  4. Choledocholithiasis

Explanation

Painless obstructive jaundice with a palpable, distended gallbladder and weight loss suggests malignant obstruction of the distal biliary tree, as in pancreatic head or periampullary cancer. This contrasts with the painful jaundice typical of stones.

Question 32General Surgery

A patient has a 1.5 cm uncomplicated diverticular abscess confined to the pericolic fat. What is the most appropriate initial management?

  1. Percutaneous drainage under radiology
  2. Intravenous antibiotics and supportive care Correct answer.
  3. Immediate Hartmann procedure
  4. Elective sigmoid colectomy within 48 hours

Explanation

Small pericolic abscesses without systemic instability are managed with intravenous antibiotics and observation. Drainage is reserved for larger collections, and surgery for complications or failure of conservative therapy.

Question 33General Surgery

A 70-year-old with atrial fibrillation presents with severe abdominal pain out of proportion to examination findings and a lactate of 5 mmol/L. What is the most likely diagnosis?

  1. Acute gastritis
  2. Acute hepatitis
  3. Irritable bowel syndrome
  4. Acute mesenteric ischemia Correct answer.

Explanation

Pain out of proportion to examination in a patient with an embolic risk such as atrial fibrillation suggests acute mesenteric ischemia. Elevated lactate reflects bowel ischemia and warrants urgent vascular assessment.

Question 34General Surgery

Which is the most appropriate initial management of a hemodynamically stable patient with a Grade III blunt splenic injury and no active contrast extravasation?

  1. Immediate splenectomy
  2. Discharge home with oral analgesia
  3. Splenic artery embolization in all cases regardless of findings
  4. Nonoperative management with monitoring in a facility capable of rapid intervention Correct answer.

Explanation

Hemodynamically stable blunt splenic injuries without active bleeding are managed nonoperatively with close monitoring and blood product availability. Splenectomy is reserved for instability or failure of observation.

Question 35General Surgery

A patient develops fever, tachycardia, and wound erythema with crepitus on the third postoperative day after colorectal surgery. What is the most important immediate step?

  1. Topical antifungal therapy
  2. Reassurance and dressing change alone
  3. Urgent surgical debridement and broad-spectrum antibiotics Correct answer.
  4. Observation until wound cultures return

Explanation

Crepitus with systemic toxicity after surgery suggests necrotizing soft tissue infection, which requires immediate operative debridement and broad-spectrum antibiotics. Delay increases mortality substantially.

Question 36General Surgery

What is the most reliable clinical indicator of adequate resuscitation in a patient with hypovolemic shock from a gastrointestinal bleed?

  1. Urine output of at least 0.5 mL/kg/h with improving mentation Correct answer.
  2. Normalization of hemoglobin concentration
  3. A single normal blood pressure reading
  4. Resolution of tachycardia alone

Explanation

Adequate resuscitation is assessed by end-organ perfusion, reflected in urine output and mental status, rather than by any single vital sign or hemoglobin value. Hemoglobin may remain normal early because of equilibration.

Question 37General Surgery

A patient with a chronic duodenal ulcer develops sudden severe epigastric pain with board-like rigidity and free air on an upright radiograph. What is the most appropriate management?

  1. Nasogastric decompression and observation
  2. High-dose proton pump inhibitor infusion alone
  3. Endoscopic clipping of the ulcer
  4. Urgent operative repair of the perforation Correct answer.

Explanation

Free perforation with peritonitis requires urgent operative repair, typically with omental patch closure, along with peritoneal lavage. Nonoperative therapy is reserved for selected contained perforations.

Question 38General Surgery

Which feature most strongly suggests that an adnexal mass in a woman is malignant rather than benign?

  1. A multiloculated solid mass with ascites and elevated CA-125 Correct answer.
  2. A simple cyst smaller than 5 cm
  3. A unilocular cyst that resolves on repeat imaging
  4. A hemorrhagic cyst in a premenopausal woman

Explanation

Solid components, multilocular architecture, ascites, and elevated CA-125 raise concern for malignancy. Simple cysts in premenopausal women are usually benign and may resolve.

Question 39General Surgery

A patient with a known abdominal aortic aneurysm presents with sudden back pain, hypotension, and a pulsatile abdominal mass. What is the most appropriate next step?

  1. Outpatient ultrasound in 1 week
  2. Elective endovascular repair scheduled in 1 month
  3. Oral beta-blockade and observation
  4. Immediate transfer to the operating room for repair Correct answer.

Explanation

Ruptured abdominal aortic aneurysm presents with the triad of pain, hypotension, and a pulsatile mass and is a surgical emergency. Immediate operative or endovascular repair offers the only chance of survival.

Question 40General Surgery

What is the most appropriate initial test for suspected acute calculous cholecystitis?

  1. Plain abdominal radiograph
  2. Magnetic resonance cholangiopancreatography
  3. Right upper quadrant ultrasonography Correct answer.
  4. Endoscopic retrograde cholangiopancreatography

Explanation

Ultrasonography is the first-line imaging study for suspected cholecystitis, detecting stones, wall thickening, pericholecystic fluid, and a sonographic Murphy sign. More invasive or advanced studies are reserved for specific indications.

Question 41General Surgery

A patient is admitted with a large incarcerated inguinal hernia and signs of bowel obstruction but no signs of strangulation. What is the most appropriate management?

  1. Attempt gentle manual reduction followed by elective repair Correct answer.
  2. Prolonged observation for 48 hours
  3. Application of an external truss indefinitely
  4. Immediate emergency herniorrhaphy without resuscitation

Explanation

In the absence of strangulation, gentle manual reduction can relieve the obstruction, followed by elective repair of the hernia. Emergency surgery is reserved for strangulation, perforation, or failed reduction.

Question 42General Surgery

Which finding on a contrast-enhanced CT scan is most specific for acute appendicitis?

  1. A normal appendix with surrounding clear fat
  2. Thickening of the sigmoid colon
  3. A fluid-filled cecum
  4. A dilated appendix greater than 6 mm with periappendiceal fat stranding Correct answer.

Explanation

An enlarged appendix with periappendiceal inflammation on CT is highly specific for acute appendicitis. This finding is the radiologic correlate of the clinical diagnosis.

Question 43General Surgery

A patient with severe acute pancreatitis develops fever, tachycardia, and a fluid collection containing gas on CT 3 weeks after onset. What is the most likely diagnosis?

  1. Pseudocyst without infection
  2. Acute interstitial pancreatitis
  3. Pancreatic ascites
  4. Infected pancreatic necrosis Correct answer.

Explanation

Gas within a pancreatic collection after severe pancreatitis strongly suggests infection by gas-forming organisms, which is a life-threatening complication. Management typically involves drainage or debridement.

Question 44General Surgery

A patient undergoes a difficult laparoscopic cholecystectomy and develops jaundice and bilious drain output on postoperative day 1. What is the most appropriate next step?

  1. Discharge with outpatient follow-up
  2. Oral ursodeoxycholic acid
  3. Endoscopic retrograde cholangiopancreatography with stenting Correct answer.
  4. Immediate exploratory laparotomy

Explanation

Bilious drainage with jaundice after cholecystectomy suggests a bile duct injury or leak. ERCP allows diagnosis and stenting of the duct in a stable patient, with surgery reserved for major injuries or instability.

Question 45General Surgery

A patient with a history of a recent myocardial infarction undergoes emergency surgery. Which perioperative strategy best reduces the risk of perioperative cardiac events?

  1. Continuing beta-blockade and optimizing volume and oxygen delivery Correct answer.
  2. Withholding all cardiac medications until discharge
  3. Aggressive diuresis to reduce preload
  4. Routine perioperative transfusion to maintain hemoglobin above 12 g/dL

Explanation

Continuation of beta-blockade and optimization of volume status and oxygen delivery reduce myocardial demand and ischemia. Routine transfusion to a high threshold is not supported and diuresis can compromise preload.

Question 46General Surgery

A patient with a strangulated femoral hernia undergoes reduction and repair. Which feature of femoral hernias most increases the risk of strangulation?

  1. Presence of a sac through the inguinal canal
  2. Lateral relation to the femoral vein
  3. Narrow, rigid femoral ring Correct answer.
  4. Wide, compliant femoral ring

Explanation

The narrow, rigid femoral ring predisposes femoral hernias to early incarceration and strangulation, which is why they are repaired promptly even when asymptomatic.

Question 47Surgical Critical Care

A patient in the surgical ICU has a serum sodium of 118 mEq/L with confusion and a witnessed seizure. Which is the most appropriate initial step in management?

  1. Rapid correction to 140 mEq/L within 6 hours
  2. Isotonic saline infusion at maintenance rate
  3. Hypertonic 3% saline bolus with frequent sodium checks Correct answer.
  4. Free water restriction alone until sodium normalizes

Explanation

Severe symptomatic hyponatremia with seizures is a neurologic emergency requiring hypertonic saline to raise sodium modestly and control symptoms. Correction must be limited (generally 8-10 mEq/L in the first 24 hours) to avoid osmotic demyelination. Free water restriction and isotonic saline are too slow or may worsen the sodium in some settings.

Question 48Surgical Critical Care

Which finding best defines septic shock according to current consensus criteria?

  1. Any two systemic inflammatory response criteria with a suspected infection
  2. Persistent hypotension requiring vasopressors with elevated lactate despite fluid resuscitation Correct answer.
  3. Hypotension that resolves completely after a 500 mL crystalloid bolus
  4. Fever with a positive blood culture and a normal blood pressure

Explanation

Septic shock is defined by circulatory and metabolic abnormalities: vasopressor requirement to maintain MAP and a lactate above 2 mmol/L despite adequate fluid resuscitation. Fever with bacteremia or isolated SIRS criteria describe sepsis or infection, not shock. Transient hypotension that responds to fluids is not shock.

Question 49Surgical Critical Care

A postoperative patient develops acute respiratory distress with bilateral infiltrates and a PaO2/FiO2 ratio of 140 on PEEP 10 cm H2O, with no evidence of cardiac failure. What is the ARDS severity classification?

  1. Not ARDS because the ratio exceeds 100
  2. Severe ARDS
  3. Moderate ARDS Correct answer.
  4. Mild ARDS

Explanation

The Berlin definition stratifies ARDS by PaO2/FiO2 on PEEP of at least 5: mild is 200-300, moderate is 100-200, and severe is below 100. A ratio of 140 falls in the moderate range. The presence of bilateral infiltrates without cardiac cause satisfies the definition.

Question 50Surgical Critical Care

Which ventilator strategy is best supported for a patient with moderate-to-severe ARDS?

  1. Routine high-frequency oscillatory ventilation as first-line therapy
  2. High tidal volumes to fully recruit collapsed alveoli
  3. Low tidal volume ventilation targeting plateau pressure below 30 cm H2O Correct answer.
  4. Permissive hyperoxia with FiO2 maintained at 1.0

Explanation

Lung-protective ventilation with tidal volumes around 6 mL/kg predicted body weight and plateau pressure below 30 cm H2O reduces mortality in ARDS. High tidal volumes cause volutrauma, and routine HFOV has not improved outcomes. High FiO2 should be weaned to avoid oxygen toxicity.