‘Fit for surgery’: the relationship between cardiorespiratory fitness and postoperative outcomes

Abstract

Surgery accounts for 7.7% of all deaths globally and the number of procedures is increasing annually. A patient's 'fitness for surgery' describes the ability to tolerate a physiological insult, fundamental to risk assessment and care planning. We have evolved as obligate aerobes that rely on oxygen (O 2 ). Systemic O 2 consumption can be measured via cardiopulmonary exercise testing (CPET) providing objective metrics of cardiorespiratory fitness (CRF). Impaired CRF is an independent risk factor for mortality and morbidity. The perioperative period is associated with increased O 2 demand, which if not met leads to O 2 deficit, the magnitude and duration of which dictates organ failure and ultimately death. CRF is by far the greatest modifiable risk factor, and optimal exercise interventions are currently under investigation in patient prehabilitation programmes. However, current practice demonstrates potential for up to 60% of patients, who undergo preoperative CPET, to have their fitness incorrectly stratified. To optimise this work we must improve the detection of CRF and reduce potential for interpretive error that may misinform risk classification and subsequent patient care, better quantify risk by expressing the power of CRF to predict mortality and morbidity compared to traditional cardiovascular risk factors, and improve patient interventions with the capacity to further enhance vascular adaptation. Thus, a better understanding of CRF, used to determine fitness for surgery, will enable both clinicians and exercise physiologists to further refine patient care and management to improve survival.

Temporary hypoxemia at high altitude in an intensive care unit physician

“…Individuals with higher cardiorespiratory fitness levels may have lower postoperative morbidity and mortality, indicating that cardiorespiratory reserve in patients with high levels of fitness may attenuate associated cardiorespiratory burdens of surgery. 13 Obese individuals are considered less fit and respond poorly to hypoxic exposure and hypoxic exercise, experiencing increased autonomic nervous system response with higher heart rate and blood pressure, and subsequently, acute mountain sickness. 14 The hypoxic hyperventilatory response at high altitudes is a protective mechanism to improve arterial oxygen levels (Table 1).…”

Myths and methodologies: Cardiopulmonary exercise testing for surgical risk stratification in patients with an abdominal aortic aneurysm; balancing risk over benefit

“…More recently, concerns have been extended to patients diagnosed with an abdominal aortic aneurysm (AAA), inspired more by intuitive speculation than empirical evidence, owing to the perceived increased risk of blood pressure (BP)‐induced expansion leading to dissection or rupture, which typically proves catastrophic (Myers et al., 2012 ). This is especially relevant when AAA patients undergo cardiopulmonary exercise testing (CPET), which, by design, involves incremental exercise to symptom‐limited exhaustion for determination of CRF, a rapidly evolving ‘vital sign’ (Ross et al., 2016 ) that can inform perioperative risk (Rose et al., 2022 ).…”

“…Regardless, it is now estimated that >30,000 CPET tests are conducted annually in the UK alone (Reeves et al., 2018 ), with ∼83% of all AAA patients undergoing CPET as part of their integrated preoperative risk assessment (Waton et al., 2022 ). Clinicians have become increasingly reliant on CRF metrics to inform and guide the decision to proceed to surgery, triage to the appropriate level of care, optimize anaesthetic techniques, diagnose unexpected comorbidities and, increasingly, to tailor individualized preoperative exercise programmes as part of prehabilitation (Perissiou et al., 2022 ; Rose et al., 2022 ).…”

Assessing cardiorespiratory fitness relative to sex improves surgical risk stratification

“…The routine determination of cardiorespiratory fitness (CRF) employing cardiopulmonary exercise testing (CPET) is increasingly accepted in patient populations undergoing major surgery, given its capacity to improve risk prediction. [1][2][3] Indeed, CRF is considered a vital clinical sign presenting health professionals with unique opportunities to improve patient management and care. 4 Preoperative CPET is used to identify patients with low CRF which is an established predictor of survival following major intra-abdominal surgery.…”