A 32-year-old man is hospitalized due to nausea, vomiting, and severe abdominal pain. He has a history of heavy alcohol use and was admitted to the hospital for acute pancreatitis a year ago. He has continued to drink alcohol since his last hospitalization and had a party last weekend, during which he consumed an entire 750-mL bottle of liquor. Temperature is 38.3 C (100.9 F), blood pressure is 110/80 mm Hg, pulse is 104/min, and respirations are 20/min. Abdominal examination is notable for marked tenderness in the epigastric region. Serum lipase is 2,392 U/L. The patient is admitted and started on intravenous fluids, analgesics, and antiemetics with subsequent improvement in his symptoms. His vital signs remain stable with adequate urine output. However, on the second day of hospitalization, the patient develops progressive shortness of breath and hypoxemia. Chest x-ray reveals new bilateral opacities. Which of the following parameters is most likely to be normal in this patient?

Question

A 32-year-old man is hospitalized due to nausea, vomiting, and severe abdominal pain.  He has a history of heavy alcohol use and was admitted to the hospital for acute pancreatitis a year ago.  He has continued to drink alcohol since his last hospitalization and had a party last weekend, during which he consumed an entire 750-mL bottle of liquor.  Temperature is 38.3 C (100.9 F), blood pressure is 110/80 mm Hg, pulse is 104/min, and respirations are 20/min.  Abdominal examination is notable for marked tenderness in the epigastric region.  Serum lipase is 2,392 U/L.  The patient is admitted and started on intravenous fluids, analgesics, and antiemetics with subsequent improvement in his symptoms.  His vital signs remain stable with adequate urine output.  However, on the second day of hospitalization, the patient develops progressive shortness of breath and hypoxemia.  Chest x-ray reveals new bilateral opacities.  Which of the following parameters is most likely to be normal in this patient?

Quizplus · Accepted Answer

11ec160b_3a04_62f9_9249_a15366930d54_MD0001_00 This patient with pancreatitis (abdominal pain, elevated lipase, recent heavy alcohol intake) has developed hypoxic respiratory failure with bilateral pulmonary infiltrates. In a young patient without a history of cardiac disease, this is highly suggestive of acute respiratory distress syndrome (ARDS). Direct (eg, irritant chemicals, trauma, gastric aspiration) or indirect (eg, pancreatitis, sepsis) pulmonary insults cause excessive cytokine release, leading to endothelial activation, neutrophilic migration to the lungs, and degranulation with release of toxic mediators. This process worsens the pulmonary alveolar and endothelial injury, leading to increased pulmonary capillary permeability, leakage of fluid into the alveoli, and pulmonary edema (Choice A). ARDS-associated interstitial edema and hyaline membrane formation along with fluid-filled alveoli collapse and atelectasis result in decreased lung compliance and increased work of breathing (Choices B and E). The fluid-filled, collapsed alveoli are unable to deliver oxygen despite continuing to receive adequate blood flow, resulting in ventilation/perfusion mismatch (ie, physiologic shunting) and hypoxia (Choice D). Noncardiogenic pulmonary edema (eg, ARDS, high-altitude pulmonary edema) can be distinguished from cardiogenic pulmonary edema (eg, decompensated left ventricular failure, volume overload) by a normal pulmonary capillary wedge pressure (6-12 mm Hg). Other distinguishing features include the clinical history (pneumonia/sepsis or pancreatitis suggests ARDS) and physical exam (peripheral edema and jugular venous distension suggest a cardiogenic source). Educational objective: Acute respiratory distress syndrome is characterized by hypoxia and bilateral pulmonary infiltrates and is associated with pneumonia, sepsis, trauma, and pancreatitis. The associated pulmonary edema is noncardiogenic in nature, so the pulmonary capillary wedge pressure will be within the normal range (6-12 mm Hg).

A 32-Year-Old Man Is Hospitalized Due to Nausea, Vomiting, and Severe