Effects of Tidal Volume on Physiology and Clinical Outcomes of Surgery Patients Undergoing One-lung Ventilation: A Meta-analysis of Randomized Controlled Trials
Abstract Objective: It is unclear how tidal volume (Vt) impacts patients during one-lung ventilation (OLV). A meta-analysis was performed to assess the effect of Vt on physiology and clinical outcomes in OLV patients. Methods: PubMed, Cochrane library, and Web of Science were retrieved until February 2020. Randomized controlled trials comparing the application of low and high Vt ventilation in adults with OLV were included. Demographic variables, Vt, physiology, and clinical outcomes were retrieved. Summary odds ratios (ORs) with 95% confidence intervals (CIs) and mean difference with standard deviation were calculated using a random-effects model.Results: 12 studies involving a total of 876 participants met inclusion criteria. Significant difference in blood interleukin-6 (IL-6) was observed between low Vt ventilation and high Vt ventilation (MD -35.51 pg/ml, 95% CI [-66.47, -4.54 pg/ml], p = 0.02). Low Vt ventilation decreased driving pressure (ΔP) (MD -6.02 cmH2O, 95% CI [-8.32, -3.72 cmH2O], p < 0.0001), Peak pressure (Ppeak) (MD -2.88 cmH2O, 95% CI [-4.60, -1.16 cmH2O], p = 0.001), and improved PaO2/FiO2 (MD 32.27 mmHg, 95% CI [19.54, 45.01 mmHg], p <0.00001). Risk of atelectasis was the same between the two groups. Furthermore, the study suggested that low Vt ventilation was associated with decreases in the risk of acute lung injury (OR 0.05, 95% CI [0.28, 0.88], p = 0.02). Decreased hospital length of stay in the low Vt group occurred when Vt was set 4-5 ml/kg (MD -0.78 d, 95% CI [-1.45, -0.11 d], p = 0.02).Conclusions: In OLV patients, low Vt ventilation improved PaO2/FiO2, and it was also associated with decreased blood IL-6, ΔP, Ppeak, and risk of acute lung injury, when the low Vt was set 4-5 ml/kg hospital length of stay was decreased .
