Effects of low tidal volume ventilation on circulatory function in patients undergoing laparoscopic liver resection

Objective To compare the effect of low tidal volume (LTV) ventilation versus conventional tidal volume (CTV) ventilation on circulatory function in patients undergoing laparoscopic liver resection (LLR). Methods A total of 22 patients who underwent selective LLR in our hospital from July to December 2017 were enrolled into this study. They were prospectively randomized to CTV group (n=11) and LTV group (n=11). They all received same anesthesia induction and maintenance, and those of the CTV group underwent conventional mechanical ventilation (tidal volume: 10~12 mL/kg) without positive end expiratory pressure (PEEP) or recruitment maneuver, while those of the LTV group were given mechanical ventilation with lower tidal volume (6~8 mL/kg) along with recruitment maneuver (once/30 min) but no PEEP during operation, with the airway pressure being maintained at 30 cmH2O for 30 s at a time for 3 cycles. The intraoperative circulation indexes including stroke volume variance (SVV), central venous pressure (CVP), cardiac index (CI), systemic vascular resistance index (SVRI), mean artery pressure (MAP), heart rate (HR), doses of vasopressor usage, and score of intraoperative anesthesia circulation management made by surgeons postoperatively were compared between the 2 groups. Results ① There were less patients receiving norepinephrine to maintain MAP in the CTV group than the LTV group (1 vs 8 cases, P < 0.05). ②After the establishment of pneumoperitoneum, SVV was significantly elevated in the CTV group (22.6±6.2 vs 13.3±3.6, P < 0.01) and the LTV group (17.2±6.4 vs 13.0±3.9, P < 0.05) when compared with that before establishment. SVV was lower in the LTV group than the CTV group during the phase of establishment, with statistical differences at 15 (17.2±6.4 vs 22.6±6.2, P < 0.05) and 30 min (17.1±4.0 vs 22.1±5.8, P < 0.05) after the establishment of pneumoperitoneum. ③ CVP was decreased in the LTV group than the CTV group (2.7±1.6 vs 5.6±2.0 cmH2O) immediately after the establishment of pneumoperitoneum when compared with baseline, though without significant difference. ④ The score of intraoperative anesthesia circulation management was notably higher in the LTV group than the CTV group (3.7±0.8 vs 3.1±0.5, P < 0.05). Conclusion LTV ventilation reduces the adverse effects of pneumoperitoneum on hemodynamics in the patients undergoing LLR when compared with CTV ventilation, and is facilitated to stabilization of hemodynamics and better operating conditions for surgeons.