Hemodynamic Effects of Mechanical Ventilation Strategies During Laparoscopic Nephrectomy

Overview

Purpose: To compare hemodynamic effects of two different modes of ventilation (volume-controlled and pressure-controlled volume guaranteed) in patients undergoing laparoscopic gynecology surgeries with exaggerated Trendelenburg position. Methods: Thirty patients undergoing laparoscopic gynecology operations were ventilated using either volume-controlled (Group VC) or pressure-controlled volume guaranteed mode (Group PCVG) (n = 15 for both groups). Hemodynamic variables were measured using Pressure Recording Analytical Method by radial artery cannulation in addition to peak and mean airway pressures and expired tidal volume.

Laparoscopic nephrectomy requires the creation of pneumoperitoneum and lateral positioning, both of which may significantly affect respiratory mechanics and cardiovascular function. Increased intra-abdominal pressure and elevated intrathoracic pressure during pneumoperitoneum may reduce venous return, alter ventricular loading conditions, and impair cardiac output. Therefore, intraoperative ventilatory strategy may play a critical role not only in pulmonary protection but also in maintaining hemodynamic stability. Lung-protective ventilation (LPV), characterized by low tidal volume, moderate positive end-expiratory pressure (PEEP), and periodic recruitment maneuvers, has been shown to reduce ventilator-induced lung injury and postoperative pulmonary complications. However, its hemodynamic consequences during laparoscopic surgery under pneumoperitoneum remain controversial. This prospective, randomized, controlled study was designed to compare the effects of lung-protective ventilation and standard ventilation strategies on advanced hemodynamic parameters in patients undergoing elective laparoscopic nephrectomy. Thirty ASA I-III patients aged 18-70 years were randomized into two groups: Group A (Lung-Protective Ventilation): Tidal volume 6 mL/kg, PEEP 5-8 cmH₂O, periodic recruitment maneuvers. Group B (Standard Ventilation): Tidal volume 8-10 mL/kg, PEEP 0-2 cmH₂O. Advanced hemodynamic monitoring was performed using the PRAM (Pressure Recording Analytical Method) system via radial arterial catheterization. Parameters including cardiac index (CI), cardiac output (CO), stroke volume (SV), stroke volume variation (SVV), pulse pressure variation (PPV), systemic vascular resistance (SVR), arterial elastance (Ea), cardiac cycle efficiency (CCE), and cardiac power output (CPO) were recorded at seven predefined perioperative time points: before induction, after induction, after lateral positioning, 10 minutes after pneumoperitoneum, 1 hour after pneumoperitoneum, after desufflation, and post-extubation. The primary outcome was the comparison of advanced hemodynamic parameters between ventilation strategies. Secondary outcomes included evaluation of hemodynamic responses to positional changes and pneumoperitoneum. This study aims to clarify whether lung-protective ventilation provides hemodynamic advantages in addition to pulmonary protection during laparoscopic nephrectomy.