Redefining mechanical ventilation in thoracic anesthesia: flow–controlled ventilation from bench to bedside—a narrative review

One–lung ventilation (OLV) remains a cornerstone of thoracic anesthesia but continues to challenge perioperative respiratory management. Restriction of ventilation to a reduced functional lung volume promotes ventilation–perfusion mismatch, alveolar instability, and exposure of the dependent lung to increased mechanical stress. Although contemporary lung–protective ventilation strategies have evolved considerably, postoperative pulmonary complications remain common, highlighting the need for innovative approaches to respiratory support. Flow–controlled ventilation (FCV) introduces a distinct physiological concept by actively controlling both inspiration and expiration through constant gas flow. Unlike conventional ventilation modes, which rely on passive exhalation, FCV enables linear pressure changes throughout the respiratory cycle and combines active expiratory control with direct intratracheal pressure monitoring and compliance–guided ventilator titration. This approach aims to improve ventilation efficiency while reducing mechanisms implicated in ventilator–induced lung injury. In this narrative review, we examine the physiological principles underlying FCV, discuss the technological innovations enabling its clinical application, and summarize current evidence from bench, preclinical, and clinical investigations. Experimental studies demonstrate improvements in respiratory mechanics, lung aeration, oxygenation, and mechanical power compared with conventional ventilation. Limited clinical data during OLV suggest potential improvements in oxygenation and carbon dioxide elimination at lower minute ventilation requirements; however, these findings are derived from small studies primarily evaluating physiological endpoints. Despite encouraging physiological results, important evidence gaps remain. Current clinical studies are limited by small sample sizes and focus predominantly on surrogate physiological outcomes. It remains unknown whether the observed improvements will translate into reductions in postoperative pulmonary complications or other patient–centered outcomes. By shifting attention from inspiration alone to the entire respiratory cycle, FCV challenges conventional paradigms of perioperative ventilation. Future multicenter outcome–driven trials will determine whether active expiratory control represents a meaningful advance in thoracic anesthesia or primarily a physiological innovation with limited clinical impact.