Key result
Volume-controlled equal ratio (1:1) ventilation resulted in similar peak airway pressure (P=0.82) and mean airway pressure (P=0.51) compared to conventional 1:2 ratio ventilation.
Why the study?
Patients undergoing laparoscopic surgery risk hypoxemia and elevated airway pressure, while prolonging inspiratory time can improve oxygenation without increasing peak airway pressure.
Does volume-controlled equal inspiratory-to-expiratory ratio (1:1) ventilation improve respiratory mechanics and hemodynamics compared to conventional ratio (1:2) ventilation in patients undergoing upper abdominal laparoscopic surgeries?
RCT (n=76)
randomly allocated
Does volume-controlled equal inspiratory-to-expiratory ratio (1:1) ventilation improve respiratory mechanics and hemodynamics compared to conventional ratio (1:2) ventilation in patients undergoing upper abdominal laparoscopic surgeries?
p-value: p=0.82 and 0.51
Volume-controlled equal ratio (1:1) ventilation does not significantly alter respiratory mechanics or hemodynamics compared to conventional (1:2) ventilation during upper abdominal laparoscopic surgeries.
Does not support changing to 1:1 ventilation based on airway pressures alone; leaves open effects on outcomes in larger trials.
Background: Patients undergoing laparoscopic surgeries are often at risk of developing hypoxemia, increased airway pressure, and barotrauma due to pneumoperitoneum. Prolongation of inspiratory time in a respiratory cycle has been found to improve oxygenation without any increase in peak airway pressure. Hence, we studied the effect of equal ratio volume-controlled ventilation on the mechanics of respiration and hemodynamics in comparison with conventional ratio volume-controlled ventilation. Materials and Methods: Seventy-six general surgical patients aged 18–70 years of age belonging to the American Society of Anaesthesiologists (ASA) I and II posted for upper abdominal laparoscopic surgeries were randomly allocated to two groups. Group A patients were ventilated with volume-controlled 1:1 ventilation whereas Group B patients were ventilated with 1:2 ratio ventilation. Intraoperatively, parameters of respiratory mechanics that included peak airway pressure, mean airway pressure, end-tidal carbon dioxide, and hemodynamics (MAP and heart rate) were recorded. The parameters measured were compared between the two groups using repeated measures ANOVA. Results: There were no significant differences in peak airway and MAPs recorded between the two groups ( P = 0.82 and P = 0.51, respectively). The hemodynamic parameters, saturation, and end-tidal carbon dioxide measurements also remained similar between the two groups. Conclusion: Volume-controlled equal ratio ventilation was found to be similar to conventional ratio ventilation in terms of parameters of respiratory mechanics and hemodynamics in patients undergoing upper abdominal laparoscopic surgeries.
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Gunasekaran et al. (2024) conducted an RCT in upper abdominal laparoscopic surgeries (n=76). volume-controlled equal inspiratory-to-expiratory ratio (1:1) ventilation vs. conventional ratio (1:2) ventilation was evaluated on peak airway pressure and mean airway pressure (p=0.82 and 0.51). Volume-controlled equal ratio (1:1) ventilation resulted in similar peak airway pressure (P=0.82) and mean airway pressure (P=0.51) compared to conventional 1:2 ratio ventilation.
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