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.