[Hemodynamic effects of lung inflation during bilateral and single lung ventilation--a clinical investigation]

Hemodynamic changes during positive airway pressure ventilation is well known. To compare changes of hemodynamic variables during one-lung inflation with those during two-lung inflation, we studied the effects of lung inflation on hemodynamic changes in 15 anesthetized patients who were intubated endobronchially. When the airway pressure was increased from 0 cmH2O to 10, 20, 30 cmH2O, systolic pressure decreased gradually and central venous pressure increased during both two-lung and one-lung inflations (P less than 0.05). During one-lung inflation, the decrease in arterial pressure relative to apneic arterial pressure was significantly less than those during two-lung inflation at each level of airway pressure (P less than 0.05). During one-lung inflation, central venous pressure which was higher relative to apneic central venous pressure, and was less than that during two-lung inflation at 30 cmH2O (P less than 0.05). Heart rate was unchanged during both two and one-lung inflations compared with apneic heart rate. We conclude that during one-lung inflation, systolic pressure and central venous pressure are influenced less by the increased airway pressure than during two-lung inflation. The results indicate that during one lung ventilation, lungs inflated with clinically accepted levels of airway pressure do not depress the systemic circulation, but when the airway pressure during one-lung inflation (like a leak test) exceeded over 30 cmH2O, a significant depression of the systemic circulation occurs.