Flow-controlled ventilation: A systematic review of preclinical and clinical studies.

BACKGROUND: Flow-controlled ventilation (FCV) represents a fundamentally different approach compared to conventional ventilatory modes. It actively regulates both inspiration and expiration using a constant, predefined flow, thereby stabilizing expiratory lung volume. Through this, FCV may influence respiratory mechanics, gas exchange, and intrathoracic pressures in ways that differ from conventional ventilation. However, its physiological effects and potential clinical benefits remain incompletely understood, and existing evidence is fragmented across experimental and clinical settings. METHODS: We conducted a systematic review of preclinical and clinical studies comparing FCV with conventional ventilation. MEDLINE and CENTRAL were searched through May 2026. Key outcomes included ventilatory parameters, respiratory mechanics, measures of gas exchange, and hemodynamic effects. Due to study heterogeneity, results were synthesized qualitatively. RESULTS: Ten preclinical and ten clinical studies were included. Preclinical studies consistently demonstrated lower respiratory rate and minute ventilation with FCV while maintaining or improving oxygenation and carbon dioxide control. Clinical studies were more heterogeneous. Six studies applied compliance-guided titration in FCV, whereas four used fixed or protocolized ventilation targets. Studies using compliance-guided titration in FCV generally reported lower respiratory rate and minute ventilation while maintaining carbon dioxide control, often accompanied by improved oxygenation. In contrast, studies using fixed ventilation targets demonstrated more variable physiological effects. No consistent adverse hemodynamic effects were reported. Overall, the certainty of clinical evidence was low to moderate. CONCLUSIONS: FCV may improve ventilatory efficiency and oxygenation without adverse hemodynamic effects. However, clinical evidence remains limited and heterogeneous, highlighting the need for standardization and larger trials.