Abstract
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.
Highlights
Optimization of intraoperative mechanical ventilation can decrease the incidence of pulmonary postoperative complication and improve outcome especially in obese patients.[1]
Aydin et al showed that volume controlled ventilation (VCV) mode can provide better alveolar ventilation than pressure controlled ventilation (PCV) mode in patients undergoing laparoscopic cholecystectomy operations.[9,10]
Patients in VCV group needed statistically higher tidal volume and respiratory rate to keep target CO2 on 35 and 55 minutes after initiation of the study (Table-II). This means that patients in VCV group needed higher minute ventilation compared to PCV group on 35 and 55 minutes after initiation of the study
Summary
Optimization of intraoperative mechanical ventilation can decrease the incidence of pulmonary postoperative complication and improve outcome especially in obese patients.[1]. Pressure controlled ventilation (PCV) uses a decelerating flow which reaches the highest possible value at the beginning of inspiration, while having a preset pressure limitation with no minimum level for tidal volume This has been attributed to the decelerating inspiratory flow delivery method, whereby high initial flow rates are delivered to quickly achieve and maintain the set inspiratory pressure followed by rapidly decelerating flow.[6,7] This high initial rate of flow leads to a more rapid alveolar inflation and more homogenous distribution of ventilation to the lung and improving ventilation/perfusion mismatch.[8] patients can receive inappropriate levels (low) of tidal volumes during pneumoperitoneum because of increased pressure. 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
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