Ventilatory effects of laparoscopic cholecystectomy

Area of Science:

• Anesthesiology
• Respiratory Physiology
• Surgical Monitoring

Background:

• The arterial-end-tidal CO2 gradient (Fa-ETCO2) during laparoscopic cholecystectomy shows variable results in literature.
• Understanding factors influencing Fa-ETCO2 is crucial for patient safety during insufflation.

Purpose of the Study:

• To evaluate the Fa-ETCO2 during laparoscopic cholecystectomy.
• To determine the contribution of CO2 elimination (VECO2) and alveolar ventilation (VA) to changes in end-tidal CO2 (FETCO2).

Main Methods:

• Studied 15 patients undergoing laparoscopic cholecystectomy under general anesthesia with controlled ventilation.
• Measured FaCO2, FETCO2, temperature, dead space ventilation, and expired volumes before, during, and after pneumoperitoneum.
• Calculated VA based on expired tidal volume and respiratory frequency.

Main Results:

• Fa-ETCO2 decreased or remained unchanged, never increasing during pneumoperitoneum (P < 0.01).
• CO2 elimination (VECO2) increased significantly (peak +22.6%) (P < 0.01).
• Alveolar ventilation (VA) and dead space ventilation remained unchanged.

Conclusions:

• Increased FETCO2 and FaCO2 during laparoscopic cholecystectomy are primarily due to exogenous CO2 loading.
• Alveolar ventilation (VA) does not significantly contribute to increased FETCO2 under these conditions.
• Findings are specific to limited CO2 insufflation pressure in ASA 1-2 patients.