Bilateral diaphragm paralysis: a challenging diagnosis.

Bilateral diaphragm paralysis is a rare cause of unexplained respiratory failure. Although it is a known complication of cardiothoracic surgery, it is often under-recognized and diagnosis is frequently delayed.1 It should be considered in patients with low lung volumes on imaging, progressive hypercapnia, and pronounced dyspnea in the supine position.2 Pulmonary function tests reveal a restrictive process; the maximum inspiratory pressure (MIP) is reduced. It can be very challenging to definitively diagnose. Fluoroscopic sniff test, which is 90% sensitive for the diagnosis of unilateral diaphragm paralysis, can provide misleading results when bilateral diaphragm paralysis is present. Measurement of transdiaphragmatic pressure with gastric and esophageal balloon placement is the only reliable method to accurately diagnose this disorder.3 We report a case of recurrent hypercapnia, supine dyspnea, and respiratory failure for 2 months prior to diagnosis and treatment of bilateral diaphragm paralysis.