Effects of pressure versus volume controlled ventilation on postoperative pulmonary complications during elderly trendelenburg laparoscopic surgery.

The impact of different mechanical ventilation modes on pulmonary outcomes following laparoscopic surgery in the Trendelenburg position remains unclear. This study aimed to compare the effects of two common ventilation modes on postoperative pulmonary complications (PPCs) in elderly patients undergoing such procedures. Elderly patients scheduled for laparoscopic surgery in the Trendelenburg position were randomly allocated to receive either pressure-controlled ventilation (PCV) or volume-controlled ventilation (VCV). Both groups were managed with a lung-protective ventilation strategy. The primary outcome was the incidence of PPCs within the first three postoperative days. Airway pressures, details enabling the calculation of respiratory system dynamic compliance (Cdyn) and arterial blood gas levels were also recorded at predetermined intraoperative time points: before anesthesia induction (T0); 10 min after tracheal intubation in the supine position without pneumoperitoneum (T1); 30 min (T2) and 60 min (T3) after establishing pneumoperitoneum and the Trendelenburg position; and at the end of surgery after returning to the supine position (T4). Compared with the VCV group (32.1%), the PCV group exhibited a significantly lower incidence of PPCs (13.0%; χ2 = 5.758, P = 0.016) (RR = 0.403, 95% CI: 0.183-0.888). Furthermore, patients managed with PCV exhibited significantly lower intraoperative airway pressures-including peak airway pressure (Ppeak), plateau pressure (Pplat), and driving pressure (ΔP)-as well as reduced dead space fraction (VD/VT) and arterial partial pressure of carbon dioxide (PaCO₂). Cdyn was higher in the PCV group. In elderly patients undergoing laparoscopic surgery in the Trendelenburg position, pressure-controlled ventilation was shown to improve Cdyn and was associated with a lower composite rate of postoperative pulmonary complications than volume-controlled ventilation. Whether these physiological advantages translate into clinically meaningful benefit requires confirmation in larger studies.