Tension pneumothorax complicating small-caliber chest tube insertion.

We report two patients who developed tension pneumothorax as a result of improper attachment of a Heimlich valve to a chest tube.

How accurate are ventilation-perfusion scans for pulmonary embolism?

To evaluate the accuracy of ventilation-perfusion scanning in the diagnosis of pulmonary embolism, the pulmonary arteriograms of 55 patients suspected of pulmonary embolism were compared with their ventilation-perfusion scans. The clinical presentation was consistent for the diagnosis of pulmonary emboli in all 55 patients. The scans were divided into the following four categories according to standard guidelines: normal, low, intermediate, and high probability.