Peri‐operative rehabilitation bundles and postoperative pulmonary complications in elective cardiac valve surgery: a reply

We thank Ruan for their comments [1] on our randomised controlled trial evaluating a peri-operative rehabilitation bundle in patients undergoing elective cardiac valve surgery [2]. We appreciate the opportunity to respond to the points raised and clarify how our study limitations align with the suggestions offered. The absence of pre- and post-intervention lung function and diaphragm-specific assessments was already stated as a limitation. We agree entirely that incorporating objective measures using ultrasound such as diaphragmatic excursion, thickness and thickening fraction would provide mechanistic insights into how inspiratory muscle training confers clinical benefit. The physiological pathway from respiratory muscle conditioning to a reduced incidence of postoperative pulmonary complications remains an important area of inquiry. Our team is designing a follow-up study that will integrate serial diaphragm ultrasonography and spirometry to elucidate these mechanisms more precisely, building on the clinical foundation established by our initial trial. We acknowledged that adherence and qualitative feedback for self-directed training in the usual care group were unrecorded. The suggestion from Ruan to utilise electronic activity logs, wearable sensors or compliance checklists is highly pertinent. We concur that quantifying the dose of rehabilitation objectively in both intervention and usual care groups is critical for interpreting comparative effectiveness, especially as basic respiratory exercises become more standardised. In future implementation, we plan to employ digital technologies to monitor adherence objectively and to capture patient-reported experiences, thereby distinguishing the effects of supervised intensity escalation from simple engagement. The proposal to measure inflammatory biomarkers, such as high-sensitivity C-reactive protein, interleukin-6 and tumour necrosis factor-α is compelling [2]. While our study was not designed to explore this pathway, we recognise that cardiopulmonary bypass-triggered systemic inflammation is a significant contributor to postoperative pulmonary complications [3]. Investigating whether peri-operative rehabilitation modulates the postoperative inflammatory trajectory represents a logical and exciting next step. Establishing a potential link between training intensity and inflammatory suppression could indeed clarify whether the benefits are purely functional or also immunomodulatory, with substantial implications for higher risk patients and potential adjuvant therapies. Despite these methodological considerations for future research, we designed our trial with a pragmatic focus on feasibility and safety in a real-world clinical setting. As Ruan rightly notes, this makes the intervention particularly relevant for resource-constrained environments. The significant reduction in pneumonia we observed shows that a structured, supervised rehabilitation programme, even with a modest frequency, can deliver meaningful clinical outcomes. We believe that this provides strong justification for its integration into standard peri-operative pathways for patients with valvular heart disease. Our initial trial was a necessary first step in establishing clinical efficacy. We are enthusiastic about advancing this work by incorporating the sophisticated mechanistic and adherence-monitoring approaches highlighted and we hope our ongoing research will continue to enrich the pathophysiological framework supporting peri-operative rehabilitation.