Fit for surgery? The impact of muscular and cardiopulmonary function on surgical outcomes after major abdominal surgery

Ocaña, Pablo Duro (2024) Fit for surgery? The impact of muscular and cardiopulmonary function on surgical outcomes after major abdominal surgery. Doctoral thesis (PhD), Manchester Metropolitan University.

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Abstract

Background: Poor physical function predicts outcomes after major abdominal surgery. The aim of this thesis is to assess the ability of perioperative patients’ function to prognose adverse surgical outcome and the efficacy of supervised pre-operative exercise programs to reduce adverse surgical outcomes. Methods: Reliability of ultrasound to measure Vastus Lateralis (VL) size, architecture and quality was assessed. Differences in VL size and quality between hepatobiliary surgery patients, old healthy adults and master athletes (MAs) were assessed. Ability of preoperative cardiopulmonary exercise testing, VL size, architecture and quality assessment, body composition using abdominal computed tomography scans, maximum isometric knee extension, rate of force development during maximum voluntary contraction (MVC) and changes in VL size and architecture during in-hospital recovery to prognose surgical outcome were assessed. Effectiveness of supervised pre-operative exercise programs to improve patient fitness and surgical outcome was assessed with a systematic review and meta-analysis. Results: Ultrasound images showed varying degrees of intra-rater (Intraclass correlation coefficient [ICC]≥0.824), inter-rater (ICC≥0.520) and inter machine (against magnetic resonance imaging) (ICC≥0.892) reliability. Pre-operative VL quality was lower in hepatobiliary surgery patients compared to healthy older adults and MAs (18.9±6.0, 26.7±4.9 and 28.3±7.0, respectively, p<0.001). Pre-operative low Psoas muscle index and high equivalents of carbon dioxide increased the risk of 3-years mortality (Hazard ratio [95% confidence interval]: 2.372 [1.246-4.515], p=0.009). Patients who performed two supervised exercise sessions per week before surgery showed higher six-minute walk distance (mean difference between groups [95%CI]: +47 [20-75] m., p<0.001) and lower relative risk (RR) of post-operative complications (RR [95%CI]: 0.59 [0.46-0.75], p<0.001) compared to patients following usual care (UC). Patients undergoing abdominal aortic aneurysms repair that performed a prehabilitation program showed similar peak oxygen uptake compared to UC group (mean difference between groups [95%CI]: 1.42 [0.51-2.34] ml·kg-1·min-1, p<0.001). Conclusion: Cardiopulmonary fitness and psoas muscle mass can predict long-term mortality. Two or more weekly supervised sessions are needed to improve fitness and surgical outcome.