Comparison of pressure vs. volume controlled ventilation on oxygenation parameters of obese patients undergoing laparoscopic cholecystectomy

Pak J Med Sci. 2017 Sep-Oct;33(5):1117-1122. doi: 10.12669/pjms.335.13316.


Background & objective: There is no special guideline for the best ventilation mode during laparoscopic anesthesia in obese patients and there are too many studies with different controversial points. The aim of this study was to compare the effect of pressure controlled ventilation (PCV) vs. volume controlled ventilation (VCV) on respiratory and oxygenation parameters in patients undergoing laparoscopic cholecystectomy.

Methods: Seventy patients with 30 <BMI<40 and ASA physical status I-II were studied in this randomized prospective trial. Anesthesia was started with VCV and after creation of pneumoperitoneum; the patients were randomized into PCV or VCV groups. Ventilation parameters were adjusted to a CO2 target of 35-40 mmHg. Hemodynamic and oxygenation parameters and respiratory parameters like plateau, mean airway and peak pressure were recorded for all patients during the study.

Results: Patients in VCV group needed higher tidal volume and respiratory rate to maintain target CO2 in 35 and 55 minutes after the study. Plateau pressure and mean airway pressure in two groups didn't have significant difference between two groups but peak airway pressure in 35 and 55 minutes after pneumoperitoneum was significantly higher in VCV group than PCV group. There were no significant differences between two groups regarding PO2, PCO2 and pH, except 35 and 55 minutes after pneumoperitoneum. In mentioned times, patients in PCV group had significantly higher PO2 levels compared to VCV group.

Conclusion: Despite some beneficial effects regarding plateau, mean airway pressure and oxygenation parameters with PCV, there was no significant clinical difference between PCV and VCV in obese patients undergoing laparoscopic cholecystectomy.

Keywords: Laparoscopy; Obese; Oxygenation; Pressure controlled ventilation; Volume controlled ventilation.