Comparison of Pressure-controlled Inverse Ratio Ventilation versus Pressure-controlled Ventilation in Laparoscopic Cholecystectomy with LMA

Aims: In comparison with volume-controlled ventilation (VCV), the pressure controlled ventilation (PCV) improves oxygenation and ventilation. PCV method decreases peak airway pressure in laparoscopic surgery. The aim of this study is comparison of PCIRV with I: E ratio 1.5:1 and PCV with I:E ratio 1:2 in laparoscopic cholecystectomy with LMA.

Study Design: Before-after clinical trial study.

Place and Duration of Study: Departments of Anesthesiology, Shahid Sadoughi University of Medical Sciences, Yazd, Iran, between Jull 2014 and Dec 2015.

Methodology: Forty patients who were candidate of elective laparoscopic cholecystectomy were selected. Preparation and medication for anesthesia were same for all patients. Anesthesia ventilation was started by VCV mode, co2 insufflation was done and ventilation continued by PCV mode. Pulmonary and cardiac parameters were examined at baseline. After 20 min results were recorded and then I: E ratio was changed to 1.5:1 and PEEP of 5 cm of H2O continued. Results were recorded after 10 min of PCIRV.

Results: The mean age of patients was 41±11.8 years old. About of participants 25% were male and the mean of BMI was 25.6±2.57.

The Peak pressure were higher in PCV (p-value: 0.001). Plateau pressure was higher during PCIRV (p-value: 0.762). Our results revealed Etco2 significantly increased in PCV. (p-value: 0.023). Airway pressure significantly increased in PCIRV (p-value: 0.001). Tidal volume significantly increased during PCIRV (p-value: 0.001) too. Also in PCIRV mode spo2, heart rate, complliance and PAW were significantly increased. According to our findings there was a significant association between BMI and changes in plateau pressure (p-value: 0.01) and Etco2 (p-value: 0.03) in PCVIR method.

Conclusion: Our study suggests PCIRV as an effective mode of ventilation that could be used in laparoscopic surgery especially in moderately obese patients.