Flow-controlled ventilation: general settings and compliance-guided positive end-expiratory pressure and driving pressure titrations.

Flow-controlled ventilation (FCV) is an emerging ventilation mode that is increasingly used during general anaesthesia for surgery. In FCV, both inspiration and expiration occur with a constant, controlled flow, resulting in gradual, predictable changes in pressure throughout the respiratory cycle. This contrasts with conventional modes of ventilation, in which either pressure or volume is controlled only during inspiration. With pressure-controlled and volume-controlled ventilation, tidal volume, pressure and rate are set, whereas with FCV, flow determines minute ventilation. Another important difference from conventional modes is that gradual pressure changes, together with controlled rather than passive expiration, promote lung recruitment. This requires a different approach to setting positive end-expiratory pressure (PEEP) and driving pressure, which can be adjusted according to dynamic compliance. We propose practical guidance for the systematic configuration and adjustment of flow and other key aspects of FCV, alongside a pragmatic framework for the titration of PEEP and driving pressure. We aim to help readers understand how the use of FCV differs from conventional ventilation modes, and how to apply it safely and effectively during general anaesthesia for surgery.