A 44-year-old man is admitted to the hospital due to severe abdominal pain and vomiting. The patient reports drinking about 10 shots of whiskey daily for the past 6 months. He has no other medical conditions. The patient is diagnosed with acute pancreatitis and receives intravenous fluids, pain control, and NPO. On the second day, he reports a sensation that he "can't get enough air." The patient is afebrile. Physical examination demonstrates bilateral crackles. Chest x-ray reveals bilateral, diffuse alveolar opacities. Echocardiography shows normal left and right ventricular function without major valvular disease. He undergoes endotracheal intubation and mechanical ventilation due to progressive hypoxemia. Which of the following treatment strategies is most likely to decrease this patient's risk of in-hospital mortality?

Question

A 44-year-old man is admitted to the hospital due to severe abdominal pain and vomiting.  The patient reports drinking about 10 shots of whiskey daily for the past 6 months.  He has no other medical conditions.  The patient is diagnosed with acute pancreatitis and receives intravenous fluids, pain control, and NPO.  On the second day, he reports a sensation that he "can't get enough air."  The patient is afebrile.  Physical examination demonstrates bilateral crackles.  Chest x-ray reveals bilateral, diffuse alveolar opacities.  Echocardiography shows normal left and right ventricular function without major valvular disease.  He undergoes endotracheal intubation and mechanical ventilation due to progressive hypoxemia.  Which of the following treatment strategies is most likely to decrease this patient's risk of in-hospital mortality?

Quizplus · Accepted Answer

11ec25c8_d4a1_4b6f_bc81_11ebc88a6b65_MD0003_00 This patient likely has acute respiratory distress syndrome (ARDS) due to acute pancreatitis. ARDS presents clinically as dyspnea, tachypnea, significant hypoxemia, and bilateral alveolar infiltrates on chest x-ray, all developing within a week of a clinical insult (eg, pancreatitis). Mechanical ventilation is often required to support patients' lungs. The goal of mechanical ventilation in ARDS is to provide adequate oxygenation and ventilation without causing further injury to the lungs. This is accomplished by using lung-protective strategies such as low-tidal-volume ventilation (LTVV) (ideal tidal volume = 4-6 mL/kg of ideal body weight). In ARDS, a significant number of the alveoli remain collapsed despite positive airway pressure, and any tidal volume delivered by the ventilator is distributed to those remaining open (functional "baby lung"). LTVV prevents overdistension of these alveoli. Compared to use of higher tidal volumes (≥8 mL/kg), LTVV improves mortality in patients with ARDS (number needed to treat = 11). Higher tidal volumes cause excessive stretching of damaged and delicate alveoli to further compound the lung injury. (Choice A) Low tidal volumes induce hypoventilation; therefore, LTVV commonly causes mild hypercapnic respiratory acidosis. This permissive hypercapnia is well tolerated and is correlated with improved survival, likely because it reflects adherence to LTVV, protecting the lungs from further trauma. (Choice B) Neuromuscular blocking agents (eg, cisatracurium) are useful in promoting patient-ventilator synchrony to improve gas exchange and reduce barotrauma, as well as in minimizing oxygen consumption by skeletal muscle. Neither an adverse effect nor a benefit of these agents has been established regarding patient mortality. (Choice C) In ARDS, positive end-expiratory pressure is needed to recruit and aerate collapsed alveoli. Decreasing alveolar recruitment is associated with higher lung stiffness, poor oxygenation, and likely poorer outcomes. (Choice D) In the normal supine position, ventilation is already high in the ventral lung regions, and a further increase causes alveolar overdistension. Prone positioning distributes the ventilation from the ventral to the dorsal (dependent) lung regions, where the majority of alveoli are located. This improves the homogeneity of ventilation throughout the lungs and decreases mortality in patients with ARDS (number needed to treat = 6). Prone positioning Educational objective: Management of acute respiratory distress syndrome (ARDS) involves mechanical ventilation to provide adequate oxygenation and ventilation without causing further injury to the lungs. Low-tidal-volume ventilation is a lung-protective strategy that reduces alveolar overdistension to decrease mortality in patients with ARDS. Prone positioning also decreases mortality, likely by homogenizing ventilation throughout the lungs. References: Effects of interventions on survival in acute respiratory distress syndrome: an umbrella review of 159 published randomized trials and 29 meta-analyses. (http://www.ncbi.nlm.nih.gov/pubmed/24667919) Mechanical ventilation of acute respiratory distress syndrome. (http://www.ncbi.nlm.nih.gov/pubmed/26045965) Approach to the patient with the acute respiratory distress syndrome. (http://www.ncbi.nlm.nih.gov/pubmed/25453418)

A 44-Year-Old Man Is Admitted to the Hospital Due to Severe