Wang et al. showed that electrical impedance tomography-guided individualised positive end-expiratory pressure improved intra-operative oxygenation and reduced driving pressure in older patients undergoing lung cancer surgery but did not reduce the incidence of postoperative pulmonary complications 1. Although the trial was presented as a comparison between individualised vs. fixed positive end-expiratory pressure, the individualised group received substantially higher positive end-expiratory pressure levels (median 11 cmH2O and 9 cmH2O during one- and two-lung ventilation, respectively, vs. 5 cmH2O). The intervention therefore combines two elements: higher positive end-expiratory pressure intensity; and individualised titration. This makes it difficult to determine whether the observed improvements in respiratory mechanics arose from true individualisation or from the use of higher positive end-expiratory pressure alone. The negative clinical outcome does not therefore address fully whether individualised titration adds value beyond a moderate fixed positive end-expiratory pressure strategy. This question of attribution also affects how the primary endpoint should be read. The composite pulmonary complication outcome included events with different biological and clinical determinants, and the most frequent component was prolonged air leak 2. Prolonged air leak in thoracic surgery is influenced mainly by surgical and parenchymal factors rather than alveolar recruitment or ventilatory strategy. In contrast, positive end-expiratory pressure is more likely to affect atelectasis, oxygenation-related deterioration and respiratory failure. As shown in Figure 1, prolonged air leak occurred in 13% of patients in both groups, whereas complications related more directly to ventilatory mechanics were less frequent. This endpoint structure may therefore have reduced the ability of the study to detect benefits that were mechanistically closer to the intervention itself. Wang et al. provide important evidence that better intra-operative respiratory mechanics do not necessarily lead to better postoperative outcomes. The findings suggest several directions for future work, such as separating the effect of individualisation from the effect of higher positive end-expiratory pressure; selecting endpoints that more closely match the mechanism of the intervention; and testing adaptive strategies that reflect the dynamic physiology of thoracic surgery. These steps would strengthen the interpretation of negative trials and improve their clinical relevance.
Song et al. (Wed,) studied this question.