Thoracoscopy: influence of the procedure on some respiratory and cardiac values.

In eight patients with pleural effusion arterial oxygen and carbon dioxide tensions (PaO2 and PaCO2), pH, respiratory frequency, and cardiac rhythm and frequency were measured before, during, and after thoracoscopy. Four of the patients had a PaO2 below 70 mm Hg (9.3 kPa) before the procedure. During and after the procedure respiratory frequency increased and PaCO2 fell, indicating hyperventilation, while the other indices remained unchanged. It is concluded that respiration and the circulation readily adapt to the changes produced by the pneumothorax and the manipulation during thoracoscopy.