Respiratory and haemodynamic effects of volume-controlled vs pressure-controlled ventilation during laparoscopy: a...

The effects of pressure-controlled (PC) ventilation on the ventilatory and haemodynamic parameters during laparoscopy procedures had not been carefully assessed. This prospective cross-over study was undertaken to compare how volume-controlled (VC) and PC modes could affect pulmonary mechanics, gas exchange, and cardiac function in patients undergoing laparoscopy.

Twenty-one patients undergoing laparoscopic urological procedures had their lungs ventilated at the beginning with VC ventilation. PC ventilation was instituted at the end of the VC sequence. Ventilator settings were adjusted to keep tidal volume, respiratory rate, and Fi(o(2)) constant in every mode. A complete set of ventilatory, haemodynamic, and gas exchange parameters was obtained under VC after 40 min of pneumoperitoneum and 20 min after switching for PC. Transoesophageal echocardiography was performed in order to evaluate systolic and diastolic function of the heart.

When VC was switched to PC, peak airway pressure decreased [mean (sd) 32 (6) vs 27 (6) cm H(2)O; P < 0.0001], peak inspiratory flow increased [17 (3) vs 48 (8) litre min(-1); P < 0.0001), and dynamic compliance improved [+15 (8)%]. No difference was noted for static airway pressure, static compliance, and arterial oxygenation. No significant change could be demonstrated in the systolic [left ventricular end-systolic wall stress 66 (16) vs 63 (14) x 10(3) dyn cm(-2) m(-2)] or diastolic function [early diastolic velocity 10.3 (2.5) vs 10.5 (2.7) cm s(-1)].

In this study, no short-term beneficial effect of PC ventilation could be demonstrated over conventional VC ventilation in patients with pneumoperitoneum.