Pneumothorax During Positive-Pressure Mechanical Ventilation

Abstract

The hemodynamic and respiratory effects of unilateral pneumothorax were studied during positive-pressure mechanical ventilation in five sheep. The sheep were anesthetized, intubated, and placed on mechanical ventilation with positive end-expiratory pressure (5 cm H2O). After baseline studies, including chest roentgenograms, were taken, increments of air were injected into the right pleural cavity. Measurements were repeated at pneumothoraces of 500, 1,000, and 1,500 ml. There was a steady fall in cardiac output (p