Critical Care Medicine-Neurologic Disorders>>>>>Respiratory Failure
Question 3#

A 53-year-old man with a history of mild asthma and alcoholic cirrhosis complicated by ascites (controlled with diuretics) presents to the ED with shoulder pain after a mechanical fall. Musculoskeletal examination and plain films yield a diagnosis of an acute acromioclavicular joint injury. Vitals obtained in the ED are notable for SpO2 of 91% on RA. He uses albuterol MDI about once a week, denies dyspnea, and has no new pulmonary symptom. His lung examination is notable for subtle prolongation of the expiratory phase without wheezes and chest X-ray is clear.

Which is true of the likely etiology for hypoxemia?

A. Spider nevi are infrequently seen
B. SpO2 tends to drop further in the supine position
C. Contrast echocardiography is the test of choice
D. Asthma is a major contributor
E. It is never an indication for liver transplantation

Correct Answer is C

Comment:

Correct Answer: C

This patient has a history of mild asthma and no active wheezing— hypoxemia is typically seen only in very severe life-threatening asthma attacks or with superimposed respiratory disease such as pneumonia. This patient likely has hepatopulmonary syndrome, defined as arterial hypoxemia in the setting of intrapulmonary vascular dilatations associated with liver disease and portal hypertension. Hepatopulmonary syndrome tends to be progressive, and when very severe can be an indication for liver transplantation. Diagnosis involves confirming arterial hypoxemia with an ABG and venous contrast-enhanced transthoracic echocardiography (“bubble study”), which visualizes contrast in the left side of the heart within 3 to 8 heart beats (more rapidly than normal, but less rapidly than with intracardiac shunting). Spider nevi are predictive of higher A-a oxygen gradients in patients with cirrhosis. Orthodeoxia (a decrease in PaO2 or SpO2 when the patient moves from supine to upright) is common in hepatopulmonary syndrome and is due to the redistribution of blood flow to lung zones with more intrapulmonary vascular dilatations. 

References:

  1. Rodriguez-Roisin R, Roca J, Agusti AG, et al. Gas exchange and pulmonary vascular reactivity in patients with liver cirrhosis. Am Rev Respir Dis. 1987;135:1085-1092.
  2. Gómez FP, Martínez-Pallí G, Barberà JA, et al. Gas exchange mechanism of orthodeoxia in hepatopulmonary syndrome. Hepatology. 2004;40:660- 666.