Zero ventilation: a transient episode.

: A 65-year-old man with known ischemic heart disease and previous coronary artery bypass grafts was admitted having been found collapsed in the street. He was a smoker with a history of alcohol abuse. On clinical examination he was unkempt, febrile, hemodynamically stable, and had no systemic deficits. The O2 saturation on air was 99%, with a po2 of 9.2, and pco2 of 4.0. Ventilation perfusion (VQ) scan was performed to rule out a pulmonary embolism. While in the department he was noted to be dyspneic and generally unwell. The perfusion images showed reduced perfusion to both lower zones more marked on the right. The ventilation study was markedly abnormal on the initial views with no ventilation to the right lung. However, the patient had recurrent episodes of cough with expectoration of sputum before the anterior view was imaged, which subsequently demonstrated ventilation defects in the right mid and lower zones. A repeat ventilation sequence was performed which confirmed these findings in all views. Chest x-ray performed prior to the lung scan was normal.