Flow-controlled versus pressure-controlled ventilation in thoracic surgery with one-lung ventilation - A randomized controlled trial

Study objective: Comparison of flow-controlled ventilation (FCV) to standard of pressure-controlled ventilation (PCV) in thoracic surgery procedures requiring one-lung ventilation. Design: Prospective, non-blinded, randomized, controlled trial. Setting: Operating theater at a university hospital, Austria. Patients: Patients scheduled for elective, thoracic surgery. Interventions: Participants received ventilation randomly either with FCV or PCV per-protocol for the duration of anesthesia. Measurements: The primary endpoint was oxygenation assessed by paO(2) / FiO(2) ratio 30 min after the start of OLV. Secondary endpoints included the required minute volume for CO2 removal, applied mechanical power and incidence of postoperative pulmonary complications. Main results: A total of 46 patients were enrolled and 43 included in the primary analysis. The primary endpoint paO(2) / FiO(2) ratio was significantly higher in the FCV group (n = 21) compared to the control group (PCV n = 22) (187 vs 136 mmHg, MD 39 (95 % CI 1 to 75); p = 0.047). The required respiratory minute volume to obtain comparable mild hypercapnia during OLV was significantly lower in FCV (3.0 vs 4.5 l/min, MD -1.3 (95 % CI -1.9 to -0.8); p < 0.001). The applied mechanical power was also significantly lower (3.5 versus 7.6 J/min, MD -3.8 (95 % CI -5.3 to -2.7); p < 0.001). Conclusions: In this single-center randomized controlled trial, flow-controlled ventilation improved gas exchange parameters in terms of oxygenation and carbon dioxide removal during one-lung ventilation in patients undergoing thoracic surgery and reduced the mechanical impact of artificial ventilation.