The randomised trial by Wang et al. evaluating electrical impedance tomography-guided individualised positive end-expiratory pressure in patients undergoing lung cancer surgery contributes valuable data on whether physiological optimisation translates into improved clinical outcomes 1. While the study shows improvements in intra-operative respiratory mechanics with the individualised positive end-expiratory pressure (PEEP), including reduced driving pressures and improved oxygenation, the lack of a reduction in postoperative pulmonary complications warrants further consideration. Generalisability is uncertain as the study population consisted predominantly of patients graded as ASA physical status 2, and only a small proportion were aged > 75 y. The results may therefore not apply to frail or multimorbid populations, in whom the balance between benefit and harm of different PEEP strategies may differ. By comparison, around 40% of patients in the PROTHOR trial were ASA physical status 3 2. More broadly, patient selection is only one factor in a complex causal pathway towards postoperative pulmonary complications, which are influenced by multiple peri-operative factors such as pre-operative optimisation; postoperative respiratory care; multimodal analgesia; and early mobilisation. The composite nature of postoperative pulmonary complications may have diluted clinically relevant effects. Prolonged air leak, which was the most common postoperative pulmonary complication, is determined largely by surgical technique rather than intra-operative ventilation strategy, potentially limiting the ability of a ventilation-guided intervention to influence the primary outcome. This highlights the challenge of selecting endpoints that are sensitive to the intervention and clinically meaningful. Future studies may benefit from focusing on clinically significant or patient-centred outcomes, such as respiratory failure requiring intervention or prolonged hospitalisation, rather than broader composite endpoints. The intervention was static following initial titration, without readjustment during intra-operative physiological changes, which may not reflect the dynamic nature of thoracic anaesthesia. In addition, the comparator strategy of fixed PEEP at 5 cmH2O without recruitment manoeuvres may represent a suboptimal control, as reflected in similar findings from the PROTHOR trial, raising the possibility that the study compared two non-optimised strategies rather than testing a superior approach 2. The use of electrical impedance tomography-guided PEEP titration, while physiologically appealing, is also unlikely to be practical and scalable in routine clinical practice. If data are available, an analysis of mechanical power, which integrates multiple components of ventilator-induced lung stress, would be of interest 3. Overall, the discordance observed in this trial reinforces a recurring finding in peri-operative and critical care trials – improvements in physiological variables (e.g. blood pressure, oxygenation targets, haemoglobin, fluid administration) do not necessarily translate into improved clinical outcomes. As highlighted recently, bridging clinical ventilation practices with underlying cellular and biological responses may offer an avenue for more precise, mechanism-informed care 4.
Mukherjee et al. (Thu,) studied this question.