Cardiopulmonary Exercise Testing in Preoperative Assessment: From Exercise Physiology to Personalized Perioperative Care

Major surgery imposes physiological stress requiring coordinated adaptation of the cardiovascular, respiratory, hematological, and musculoskeletal systems. Conventional preoperative assessment remains essential but may underestimate heterogeneity in physiological reserve because resting measurements incompletely capture the response to increasing metabolic demand. Cardiopulmonary exercise testing (CPET) provides an integrated assessment of oxygen transport and utilization, linking pulmonary ventilation and gas exchange to cardiovascular performance and peripheral oxygen extraction. This narrative review examines the role of CPET in preoperative assessment, from prognostic testing to physiological phenotyping and personalized perioperative care. We summarize the physiological basis of key variables, including peak oxygen uptake, anaerobic threshold, oxygen pulse, ventilatory efficiency, end-tidal carbon dioxide, breathing reserve, and exercise kinetics, and discuss how integrated interpretation can identify patterns suggestive of haemodynamic, ventilatory, pulmonary vascular, or peripheral limitations. Evidence across major surgical populations is critically appraised, with attention to isolated thresholds and the distinction between prognostic association and clinical effectiveness. The current data support selective rather than universal use of CPET, particularly when functional capacity is uncertain or physiological information may alter management. We propose a phenotype-oriented framework in which CPET findings identify potentially modifiable impairments and inform cardiovascular optimization, respiratory treatment, nutritional support, exercise training, and prehabilitation. Emerging approaches combining complex CPET, non-invasive haemodynamic assessment, wearable technologies, and artificial intelligence may enable personalized profiling, although prospective validation remains necessary. CPET should therefore be considered not simply a risk-prediction tool, but an in vivo interrogation of physiological reserve that can contribute to mechanism-oriented perioperative assessment.