Question

A 62-year-old man undergoes a partial pancreatectomy for exocrine pancreatic cancer. The surgery is complicated by excessive peripancreatic bleeding requiring careful surgical hemostasis. The patient receives packed red blood cell transfusion during the surgery as well as intravenous normal saline. He is transferred to the surgical intensive care unit for close monitoring and is successfully extubated. Twelve hours later, the nurse reports decreased oxygen saturation. The patient has received multiple doses of morphine for pain control since the surgery. Temperature is 37.5 C (99.5 F), blood pressure is 80/40 mm Hg, pulse is 112/min, and respirations are 28/min. The patient's pulse oximetry shows 87% or 4 L nasal cannula oxygen. Examination reveals bilateral basal crackles. The abdomen is mildly distended and tender, and bowel sounds are decreased. There is no rebound tenderness or rigidity. Pulmonary artery catheter readings show a cardiac index of 2 L/min/m² (normal, 2.8-4.2) and a pulmonary capillary wedge pressure of 20 mm Hg (normal, 6-15). Which of the following is the most likely etiology of this patient's current condition?

A. Acute pancreatitis

B. Adrenal crisis

C. Myocardial infarction

D. Pulmonary embolism

E. Retroperitoneal hemorrhage

F. Transfusion-related acute lung injury

Correct Answer: C. Myocardial Infarction

This patient's presentation of shock, hypoxia, and hemodynamic instability with an elevated PCWP and low cardiac index is most consistent with cardiogenic shock due to acute myocardial infarction, especially in the postoperative period.

Surgical Procedure
🧠 Partial pancreatectomy with blood loss → Packed RBC transfusions + IV fluids
⬇
Volume Overload
⬆ Pulmonary capillary wedge pressure (PCWP)
⬆ Hydrostatic pressure in pulmonary capillaries
⬇
Pulmonary Congestion
🧠 Basal crackles + Hypoxemia (O₂ saturation 87%)
⬇
⬆ Respiratory Rate (28/min)
⬇
Initial compensation: Tachypnea

Perioperative Stress (Surgery)
⬆ Catecholamine release + Risk of thrombosis in coronary arteries
⬇
🧠 Predisposition to Myocardial Ischemia
⬇
⬆ Oxygen demand + Decreased myocardial perfusion
⬇
Acute Myocardial Infarction (MI)
🧠 Key insight: Reduced myocardial contractility
⬇
⬇ Cardiac Output (Cardiac Index: 2 L/min/m²)
⬇
⬆ Pulmonary venous pressure
⬇
Pulmonary Edema
🧠 Key insight: Worsens hypoxemia and crackles on examination

Systemic Hypoperfusion
⬇ Systolic BP (80/40 mm Hg)
⬆ Heart rate (112/min) → Reflex tachycardia
⬇
Reduced oxygen delivery to tissues
⬇
Lactic Acidosis
⬇
Fatigue + Decreased organ perfusion

Final Diagnosis: Acute Myocardial Infarction with Cardiogenic Shock
🧠 Supported by:
⬆ PCWP (20 mm Hg, left heart failure)
⬇ Cardiac index (pump failure)
Correct Answer: C. Myocardial Infarction

Explanation of Other Answers

A. Acute Pancreatitis
Pancreatic inflammation → Systemic cytokine release
⬇
🧠 Expect fever, severe abdominal pain, and systemic inflammatory response syndrome (SIRS)
⬇
Why Incorrect: No fever or significant abdominal pain

B. Adrenal Crisis
Inadequate corticosteroid production → Hypotension + Shock
⬇
🧠 Key Insight: Typically with electrolyte abnormalities (⬇ Na⁺, ⬆ K⁺)
⬇
Why Incorrect: No lab findings suggest adrenal insufficiency

D. Pulmonary Embolism (PE)
Thrombus in pulmonary vasculature → ⬆ Pulmonary vascular resistance
⬇
🧠 Key Insight: Normal or low PCWP with hypoxemia, but no crackles
⬇
Why Incorrect: Elevated PCWP and crackles are not consistent with PE

E. Retroperitoneal Hemorrhage
Bleeding → Hypovolemia → Hypotension
⬇
🧠 Key Insight: Does not explain crackles or hypoxemia
⬇
Why Incorrect: No evidence of active bleeding or anemia

F. Transfusion-Related Acute Lung Injury (TRALI)
Immune reaction to transfused plasma → Non-cardiogenic pulmonary edema
⬇
🧠 Key Insight: Normal PCWP (non-cardiogenic)
⬇
Why Incorrect: Elevated PCWP indicates cardiogenic cause

Flashcards

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