Pulmonary hemodynamics during direct diagnostic laryngoscopy.

Acute changes in systemic and pulmonary hemodynamics, together with blood gas changes, were recorded during diagnostic laryngoscopy for biopsy. Laryngoscopy was performed under general anesthesia, and two groups of patients were studied, one was ventilated intermittently, the other had controlled ventilation through an endotracheal tube. PaCO2 rose in both groups, but only in the intermittently ventilated patients did the PaCO2 values increase above normal levels. No significant difference in cardiovascular response was found between the two groups. Significant changes were: increases in mean arterial pressure, pulmonary arterial mean pressure, pulmonary capillary wedge pressure and central venous pressure. The increases reached a maximum during the laryngoscopic procedure and returned towards control values when the laryngoscope was removed. Systemic and pulmonary vascular resistance remained unchanged. The rises in PaCO2 and sympathetic stimulation are believed to the the man causes for the observed hemodynamic changes.