One‐lung ventilation and positive end‐expiratory pressure titration: a reply

We thank Hung and Cheng for their thoughtful and constructive comments [1] on our trial [2]. We agree that lung mechanics during one-lung ventilation are dynamic and may change substantially during surgery. Repeated reassessment is therefore conceptually attractive. However, in routine clinical practice, lung mechanics can change continuously and unpredictably, and any adjustment is inevitably subject to some degree of delay. As a result, the selected positive end-expiratory pressure (PEEP) may not fully reflect the current physiological state. Additionally, frequent multi-time-point measurements are difficult to implement in routine thoracic anaesthesia. Our study was designed to evaluate a pragmatic and widely applicable approach using electrical impedance tomography before surgical incision, rather than a continuously adaptive strategy. In many thoracic settings, continuous intra-operative use of electrical impedance tomography is limited by practical constraints. Our protocol therefore reflects a balance between physiological optimisation and clinical feasibility, with electrical impedance tomography used to determine an initial patient-specific PEEP that was then maintained during one-lung ventilation. Our findings should be interpreted as highlighting the limitations of a single pre-incision titration strategy, rather than refuting individualised PEEP itself. Electrical impedance tomography-guided titration generally resulted in higher PEEP levels than those used commonly in routine practice. In older patients with relatively preserved lung function, conventional fixed PEEP may remain adequate due to physiological reserve, which may partly explain the lack of additional clinical benefit observed. Within a safe and controlled range increasing ventilatory intervention, including higher levels of positive end-expiratory pressure, may not necessarily improve outcomes. From a clinical perspective, these findings help to better define target populations for future research. Rather than applying individualised PEEP universally, greater benefit may be expected in patients at higher risk of postoperative pulmonary complications or with impaired respiratory reserve. Future studies should therefore focus on such high-risk populations and consider strategies that allow reassessment during surgery.