Comparison of Volume-Guaranteed or -Targeted, Pressure-Controlled Ventilation with Volume-Controlled Ventilation during Elective Surgery: A Systematic Review and Meta-Analysis

For perioperative mechanical ventilation under general anesthesia, modern respirators aim at combining the benefits of pressure-controlled ventilation (PCV) and volume-controlled ventilation (VCV) in modes typically named "volume-guaranteed" or "volume-targeted" pressure-controlled ventilation (PCV-VG). This systematic review and meta-analysis tested the hypothesis that PCV-VG modes of ventilation could be beneficial in terms of improved airway pressures (P-peak, P-plateau, P-mean), dynamic compliance (C-dyn), or arterial blood gases (PaO2, PaCO2) in adults undergoing elective surgery under general anesthesia. Three major medical electronic databases were searched with predefined search strategies and publications were systematically evaluated according to the Cochrane Review Methods. Continuous variables were tested for mean differences using the inverse variance method and 95% confidence intervals (CI) were calculated. Based on the assumption that intervention effects across studies were not identical, a random effects model was chosen. Assessment for heterogeneity was performed with the chi(2) test and the I-2 statistic. As primary endpoints, P-peak, P-plateau, P-mean, C-dyn, PaO2, and PaCO2 were evaluated. Of the 725 publications identified, 17 finally met eligibility criteria, with a total of 929 patients recruited. Under supine two-lung ventilation, PCV-VG resulted in significantly reduced P-peak (15 studies) and P-plateau (9 studies) as well as higher C-dyn (9 studies), compared with VCV [random effects models; P-peak: CI -3.26 to -1.47; p < 0.001; I-2 = 82%; P-plateau: -3.12 to -0.12; p = 0.03; I-2 = 90%; C-dyn: CI 3.42 to 8.65; p < 0.001; I-2 = 90%]. For one-lung ventilation (8 studies), PCV-VG allowed for significantly lower P-peak and higher PaO2 compared with VCV. In Trendelenburg position (5 studies), this effect was significant for P-peak only. This systematic review and meta-analysis demonstrates that volume-targeting, pressure-controlled ventilation modes may provide benefits with respect to the improved airway dynamics in two- and one-lung ventilation, and improved oxygenation in one-lung ventilation in adults undergoing elective surgery.