Background
Traditionally, assessment of fitness for surgery involves a surgeon’s subjective judgement on whether a patient is sufficiently conditioned to undergo the proposed procedure. Valid and reliable assessment of a person’s functional capacity is thus considered an important component of preoperative evaluation1. The initial clinical evaluation (ICE) can be a useful screening tool to identify frail patients in the pre-operative assessment, despite limited research to validate implementation. ‘Frailty’ identifies those patients with a diminished capacity to compensate adequately for external stressors who are at greater risk of adverse outcomes including a prolonged hospital stay, institutionalisation, worsening disability and even death2, 3. It is important to recognize diminished capacity in patients prior to surgery given that they are less likely to survive or return to functional status following the physiological insult of surgery compared to their fitter, more resilient counterparts4.
ICE almost inextricably requires a clinician to make a rapid decision concerning the fitness for an operation based on little more than external appearances. In contrast, preoperative cardiopulmonary exercise testing (CPET) enhances the integrated risk assessment by providing a more objective measure to establish if a patient has adequate cardiorespiratory fitness (CRF) to tolerate major surgery. In support, CPET has gained popularity as part of the routine preoperative diagnostic assessment and its predictive value in relation to mid- and long-term survival in patients undergoing elective open surgical abdominal aortic aneurysm (AAA) repair is well established including its ability to forecast postoperative morbidity5-7.
This is especially relevant for open thoracoabdominal aortic aneurysm (TAAA) surgery, given that it requires careful selection of patients who will be suitable to undergo extensive surgery and lengthy postoperative recovery (Figure 1). Predictive risk models have shown that multi-system impairment is related to negative operative outcomes predisposing to longer recovery times and increased risk of short- and long-term mortality and morbidity8. Lung disease, older age, female sex, New York Heart Association’s (NYHA) moderate (III) or severe (IV) classifications and reduced left ventricular ejection fraction have been identified as independent risk factors for patients undergoing proximal aortic repair9. However, there is no singular metric with the capacity to accurately predict clinical outcome2.
Thus, it is suspected that patients with poor CRF are especially vulnerable when faced with the enhanced metabolic demands posed by open TAAA repair and have an unmet need to better guide patient evaluation, risk and clearance for surgery. In the coming years when both open and endovascular options for thoracoabdominal aortic repair are widely available, there will no doubt be a need to objectively evaluate each patient to identify the ideal method of surgical repair.
To that end, the present study sought to compare subjective ICE (‘eyeballing’) by experienced clinicians against the more objective validated preoperative assessment using formalised CPET metrics for patients undergoing major elective surgery. We hypothesized that subjective assessment would underestimate a patient’s ‘true’ surgical risk, highlighting the benefits of a more integrated objective approach that has direct relevance for patients scheduled for open TAAA repair.