Five days after being admitted to the hospital for an open cholecystectomy, a 56-year-old woman develops difficulty breathing. She also has fevers, chills, and malaise. She has a cough productive of minimal amounts of yellowish-white sputum that started two days prior. She has type 2 diabetes mellitus, hypertension, and a history of gallstones. Her current medications include metformin, lisinopril, and atorvastatin. Her temperature is 39.5°C (103.1°F), pulse is 104/minute, blood pressure is 94/68 mm Hg, and respirations are 30/minute. Pulse oximetry on 2 L of oxygen via nasal cannula shows an oxygen saturation of 92%. Examination reveals decreased breath sounds over the right lung base. Abdominal examination shows a well-healing scar without erythema or discharge in the right upper quadrant. The skin is warm and well-perfused. Her hemoglobin concentration is 10.5 g/dL, leukocyte count is 16,000/mm3, platelet count is 345,000/mm3, and creatinine is 1.5 mg/dL. She is admitted to the ICU and started on IV fluids. Blood and urine for cultures are obtained. X-ray of the chest reveals a right sided pleural effusion. Which of the following is the next best step in management?

Intravenous vancomycin and cefepime

Intravenous ceftriaxone and azithromycin

External cooling and intravenous acetaminophen

A previously healthy 35-year-old woman is brought into the emergency department after being found unresponsive by her husband. Her husband finds an empty bottle of diazepam tablets in her pocket. She is stuporous. At the hospital, her blood pressure is 90/40 mm Hg, the pulse is 58/min, and the respirations are 6/min. The examination of the pupils shows normal size and reactivity to light. Deep tendon reflexes are 1+ bilaterally. Babinski sign is absent. All 4 extremities are hypotonic. The patient is intubated and taken to the critical care unit for mechanical ventilation and treatment. Regarding the prevention of pneumonia in this patient, which of the following strategies is most likely to achieve this goal?

Subglottic drainage of secretions

Daily evaluation for ventilator weaning

Oropharynx and gut antibacterial decontamination

Prone positioning during mechanical ventilation

Three days after undergoing coronary artery bypass surgery, a 72-year-old man has severe right upper quadrant pain, fever, nausea, and vomiting. He has type 2 diabetes mellitus, benign prostatic hyperplasia, peripheral vascular disease, and chronic mesenteric ischemia. He had smoked one pack of cigarettes daily for 30 years but quit 10 years ago. He drinks 8 cans of beer a week. His preoperative medications include metformin, aspirin, simvastatin, and finasteride. His temperature is 38.9°C (102°F), pulse is 102/min, respirations are 18/min, and blood pressure is 110/60 mmHg. Auscultation of the lungs shows bilateral inspiratory crackles. Cardiac examination shows no murmurs, rubs or gallops. Abdominal examination shows soft abdomen with tenderness and sudden inspiratory arrest upon palpation in the right upper quadrant. There is no rebound tenderness or guarding. Laboratory studies show the following: Hemoglobin 13.1 g/dL Hematocrit 42% Leukocyte count 15,700/mm3 Segmented neutrophils 65% Bands 10% Lymphocytes 20% Monocytes 3% Eosinophils 1% Basophils 0.5% AST 40 U/L ALT 100 U/L Alkaline phosphatase 85 U/L Total bilirubin 1.5 mg/dL Direct 0.9 mg/dL Amylase 90 U/L Abdominal ultrasonography shows a distended gallbladder, thickened gallbladder wall with pericholecystic fluid, and no stones. Which of the following is the most appropriate next step in management?

Intravenous piperacillin-tazobactam therapy and percutaneous cholecystostomy

Intravenous heparin therapy followed by embolectomy

Careful observation with serial abdominal examinations

Endoscopic retrograde cholangiopancreatography with papillotomy

A 52-year-old man presents to the emergency department with sudden-onset dyspnea, tachypnea, and chest pain. He works as a long-haul truck driver, and he informs you that he recently returned to the west coast from a trip to Tennessee. His medical history is significant for gout, hypertension, hypercholesterolemia, diabetes mellitus type 2, and mild intellectual disability. He currently smokes 2 packs of cigarettes/day, drinks a 6-pack of beer/day, and he endorses a past history of injection drug use but currently denies any illicit drug use. The vital signs include: temperature 36.7°C (98.0°F), blood pressure 126/74 mm Hg, heart rate 87/min, and respiratory rate 23/min. His physical examination shows minimal bibasilar rales, but otherwise clear lungs on auscultation, grade 2/6 holosystolic murmur, and a benign abdominal physical examination. A computed tomography angiography (CTA) demonstrates a segmental pulmonary embolism (PE). Which of the following is the most appropriate treatment plan for this patient?

Initiate heparin with a bridge to warfarin

Consult interventional radiologist (IR) for IVC filter placement

Tissue plasminogen activator (tPA)

Initiate warfarin anticoagulation

A 43-year-old woman presents to her primary care physician with complaints of mild shortness of breath and right-sided chest pain for three days. She reports that lately she has had a nagging nonproductive cough and low-grade fevers. On examination, her vital signs are: temperature 99.1 deg F (37.3 deg C), blood pressure is 115/70 mmHg, pulse is 91/min, respirations are 17/min, and oxygen saturation 97% on room air. She is well-appearing, with normal work of breathing, and no leg swelling. She is otherwise healthy, with no prior medical or surgical history, currently taking no medications. The attending has a low suspicion for the most concerning diagnosis and would like to exclude it with a very sensitive though non-specific test. Which of the following should this physician order?

Obtain spiral CT chest with IV contrast

Order a lower extremity ultrasound

Obtain ventilation-perfusion scan

A 68-year-old woman presents to the hospital for an elective right hemicolectomy. She is independently mobile and does her own shopping. She has had type 2 diabetes mellitus for 20 years, essential hypertension for 15 years, and angina on exertion for 6 years. She has a 30-pack-year history of smoking. The operation was uncomplicated. On post-op day 5, she becomes confused. She has a temperature of 38.5°C (101.3°F), respiratory rate of 28/min, and oxygen saturation of 92% on 2 L of oxygen. She is tachycardic at 118/min and her blood pressure is 110/65 mm Hg. On chest auscultation, she has coarse crackles in the right lung base. Her surgical wound appears to be healing well, and her abdomen is soft and nontender. Which of the following is the most likely diagnosis?

Multiple organ dysfunction syndrome

Non-infectious systemic inflammatory response syndrome (SIRS)

Five minutes after arriving in the postoperative care unit following total knee replacement under general anesthesia, a 55-year-old woman is acutely short of breath. The procedure was uncomplicated. Postoperatively, prophylactic treatment with cefazolin was begun and the patient received morphine and ketorolac for pain management. She has generalized anxiety disorder. Her only other medication is escitalopram. She has smoked one pack of cigarettes daily for 25 years. Her temperature is 37°C (98.6°F), pulse is 108/min, respirations are 26/min, and blood pressure is 95/52 mm Hg. A flow-volume loop obtained via pulmonary function testing is shown. Which of the following is the most likely underlying cause of this patient's symptoms?

Type I hypersensitivity reaction

Decreased central respiratory drive

A 55-year-old man presents to his primary care physician for a wellness checkup. The patient has a past medical history of alcohol abuse and is currently attending alcoholics anonymous with little success. He is currently drinking roughly 1L of hard alcohol every day and does not take his disulfiram anymore. Which of the following findings is most likely to also be found in this patient?

Increased transketolase activity

Pulmonary complications for USMLE Step 2 CK: High-Yield Surgery Lessons

Atelectasis - The Collapsing Lung Blues

Most common post-op pulmonary complication, peaks at 24-48 hours.
Pathophysiology: Alveolar collapse from airway obstruction (mucus plugs) and shallow breathing, leading to a V/Q mismatch.
Findings: ↓ breath sounds, dullness to percussion, hypoxemia.
- CXR shows opacification and volume loss.
Prevention/Treatment: Incentive spirometry, deep breathing exercises, and early mobilization.

⭐ On physical exam, look for tracheal deviation towards the side of collapse, a key distinguishing feature.

📌 Mnemonic (Post-Op Fever): "Wind" (atelectasis) is the primary cause on days 1-2.

Pneumonia - Unwanted Lung Guests

Pathophysiology: Post-op atelectasis impairs secretion clearance, leading to bacterial growth. Aspiration is a key mechanism.
Timeline: Typically develops >48 hours after surgery (Hospital-Acquired Pneumonia - HAP).
Risk Factors: Ventilation >48h, age >65, COPD, smoking, thoracic/abdominal surgery.
Diagnosis:
- New infiltrate on chest X-ray.
- Fever, leukocytosis, purulent sputum, ↓ O₂ sat.
Prevention:
- Pre-op: Smoking cessation.
- Post-op: Early mobilization, incentive spirometry, good analgesia.
Management: Empiric antibiotics covering gram-negatives (Pseudomonas) & S. aureus.

Postoperative pneumonia with lobar consolidation on CXR

⭐ High-Yield: Ventilator-Associated Pneumonia (VAP) is a subtype of HAP developing >48 hours after endotracheal intubation. Key prevention includes semi-recumbent positioning and oral hygiene.

Aspiration & ARDS - The Domino Effect

Aspiration: Inhalation of gastric contents into lungs, a common trigger for severe pulmonary complications.
- Risk Factors: Anesthesia, opioids, GERD, NG tube, emergency surgery.
- Manifests as:
  - Pneumonitis: Chemical injury from gastric acid. Rapid onset (hours) of dyspnea, hypoxia, low-grade fever.
  - Pneumonia: Bacterial infection. Slower onset (days), productive cough, consolidation.
ARDS Progression: Aspiration is a primary cause of ARDS.
- Hallmarks: Refractory hypoxemia and bilateral pulmonary infiltrates on CXR, not due to heart failure.
- Key Metric: PaO₂/FiO₂ ratio <300 mmHg.

Chest X-ray: Bilateral diffuse opacities in ARDS

⭐ High-Yield: The cornerstone of ARDS management is lung-protective ventilation with low tidal volumes (~6 mL/kg ideal body weight) to prevent barotrauma, which has been shown to decrease mortality.

Pulmonary Embolism - Clot on the Move

Pathophysiology: Rooted in Virchow's Triad: stasis (e.g., post-op immobilization), hypercoagulability (e.g., malignancy, OCPs), and endothelial injury (e.g., surgery, trauma). Most PEs arise from lower extremity DVTs.
Clinical Picture: Sudden-onset tachypnea, pleuritic chest pain, dyspnea, and tachycardia. Massive PE can present with syncope, hypotension, and right heart failure.
Diagnosis:
- Use Wells score to stratify risk.
- D-dimer is sensitive for ruling out PE in low-risk patients.
- CT Pulmonary Angiography (CTPA) is the definitive diagnostic standard.
Management:
- Anticoagulation is the mainstay (Heparin, LMWH, DOACs).
- For massive PE causing hemodynamic instability: thrombolysis or surgical embolectomy.

⭐ Exam Favorite: While often tested, the classic ECG finding of S1Q3T3 (deep S wave in lead I, Q wave in lead III, inverted T wave in lead III) has low sensitivity for PE.

High‑Yield Points - ⚡ Biggest Takeaways

Atelectasis is the most common cause of post-op fever within 48 hours; prevent with incentive spirometry.

Postoperative pneumonia typically presents 3-5 days later with productive cough and consolidation.

Pulmonary embolism (PE) causes sudden-onset dyspnea and is a major cause of preventable death.

Aspiration pneumonitis is a chemical lung injury from gastric contents, distinct from aspiration pneumonia.

Major risks: smoking, COPD, obesity, and thoracic/upper abdominal surgery.

Prevention is key: early ambulation, pain control, and deep breathing.

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