Improving generalisability
Walston Reginald Martis, Linda Denehy, Hilmy Ismail, Bernhard Riedel · Anaesthesia · 2023
We read the article by Akowuah et al. on prehabilitation in elective cardiac surgery with interest and commend the authors for successfully conducting a large-scale trial that includes both exercise and inspiratory muscle training [1]. We would like to address several considerations that might improve the generalisability of the study. The authors acknowledged the potential for observer bias in reporting adverse events within the prehabilitation group. Despite randomisation, this group showed a higher risk profile for cardiac events, largely due to a greater proportion of patients undergoing aortic and aortic valve surgeries [2]. Given that severe aortic stenosis often coexists with significant coronary artery disease, this further escalates the risk of cardiac events. Did the reported adverse events lead to any expedited interventions? It may also be worth noting that ‘warm-up’ angina could potentially have cardioprotective effects [3]. Regarding exercise protocol adherence, 70% of patients completed at least one hospital-based session per week over a 4-week period. We question whether this frequency is adequate for improving functional capacity, as measured by the six-minute walk test (6MWT). Patients may hesitate to perform home-based exercises, largely due to fears of adverse cardiac events related to their diagnosis. In contrast, inspiratory muscle training was likely performed more frequently (twice daily) at home, contributing to the observed improvement in inspiratory muscle strength. To address healthcare access (the primary reason for declining participation in the study), patient compliance and safety, especially among high-risk cardiac populations, we suggest considering tele-prehabilitation. A multimodal approach to prehabilitation may be more effective [4]. Akowuah et al. reported a significant improvement in 6MWT in the sarcopenic subgroup of the prehabilitation cohort. Was nutritional support provided to this subgroup? Post-exercise protein supplementation has been shown to maximise skeletal muscle synthesis [5]. Lastly, although high-intensity inspiratory muscle training yielded significant differences in inspiratory muscle strength, it did not correlate with a decrease in postoperative pulmonary complications in the prehabilitation group. While the study was not powered to assess this as an outcome, we wonder if a bundled care approach like I COUGH (incentive spirometry, coughing/deep breathing, oral care, understanding (education), getting out of bed and head of bed elevation) could lead to a significant reduction in pulmonary complications [6].