Hemodynamic Effects of Carbon Dioxide Insufflation of the Thoracic Cavity During Thoracoscopic Surgery

Abstract

Purpose:

To quantify the effect of increased intrathoracic pressure (IP) on hemodynamics and to determine the optimal IP for surgery.

Materials and Methods:

Five male piglets weighing 30 to 32 kg were used. Each animal was anesthetized by gas inhalation with endotracheal intubation. A 5-mm laparoscopic valved trocar was inserted through the right fifth intercostal space, and insufflation using carbon dioxide gas was started. An IP of 5 mm Hg was maintained for 5 minutes, followed by a stepwise increase to 10 and 15 mm Hg for 5 minutes each. The heart rate, end-tidal CO₂ (ETCO₂), percutaneous saturation of O₂ (SaO₂), arterial blood pressure, and ECG were monitored during the procedure and measured at each IP.

Results:

The heart rate increased from 99.6 ± 17.5 to 96.4 ± 9.7, 118.9 ± 11.9,* and 155.0 ± 21.2* beats/min at 0, 5, 10, and 15 mm Hg, respectively. The ETCO₂ increased from 44.2 ± 7.0 to 43.2 ± 8.6, 53.4 ± 12.2, and 54.5 ± 7.8* mm Hg, respectively. Arterial blood pressure decreased reciprocally from 86.8 ± 11.7/48.1 ± 11.2 to 80.4 ± 17.1/43.8 ± 11.2, 75.4 ± 26.1/42.7 ± 15.5, and 40.5 ± 7.8/29.0 ± 1.4* mm Hg at 0, 5, 10, and 15 mm Hg, respectively. The SaO₂ was maintained in each condition (Asterisks indicate p < 0.05). The ECG showed inversion of the T wave at an IP of 10 mm Hg.

Conclusion:

These data suggest a problematic alteration in hemodynamics at higher intrathoracic pressures in the pig model, which may imply a similar hemodynamic problem in children.