Cardiopulmonary exercise testing as a risk assessment method in non cardio‐pulmonary surgery: a systematic review

Abstract

SummaryThis study reviews the predictive value of maximum oxygen consumption ( _ VO 2 max ) and anaerobic threshold, obtained through cardiopulmonary exercise testing, in calculating peri-operative morbidity and mortality in non-cardiopulmonary thoraco-abdominal surgery. A literature review provided nine studies that investigated either one or both of these two variables across a wide range of surgical procedures. Six of the seven studies that reported sufficiently detailed results on peak oxygen consumption and four of the six studies that reported sufficiently detailed results on anaerobic threshold found them to be significant predictors. We conclude that peak oxygen consumption and possibly anaerobic threshold are valid predictors of peri-operative morbidity and mortality in non-cardiopulmonary thoraco-abdominal surgery. These indicators could potentially provide a means of allocating increased care to high-risk patients. Cardiopulmonary exercise testing (CPET or CPX) is a non-invasive, integrated assessment of cardiovascular and pulmonary function both at rest and under stress. Among the purported benefits is its ability to determine the ability of the subject's physiological capacity to cope with the metabolic demands created by the trauma of major surgery. During the test subjects are exposed to incremental physical exercise up to their maximally tolerated level, dictated either by exhaustion or symptom related cessation (e.g., breathlessness or angina). Several physiological variables are recorded including ventilatory parameters, inspiratory and expiratory gases, blood pressure (BP) and electrocardiogram (ECG). From these are derived two key indicators: the body's maximum oxygen uptake ( _ VO 2 max ) and the point at which anaerobic metabolism exceeds aerobic metabolism (Ventilatory Anaerobic Threshold or VAT). Together, these broadly indicate the ability of the cardiovascular system to deliver oxygen to the peripheral tissues and the ability of the tissues to utilise that oxygen. It has already been demonstrated that measures such as _ VO 2 max are useful predictors of postoperative complications of pulmonary resection surgery [1][2][3] and assessing the timing of cardiac transplant surgery [4], while the VAT is a predictor of postoperative cardiac complications in abdominal surgery [5]. Physiology of the anaerobic thresholdLactate accumulation in exercising muscle occurs when the muscle O 2 demand exceeds the supply. At this point the venous lactate concentration will begin to rise. This point is called the Lactate Anaerobic Threshold (LAT). The muscle lactate ⁄ pyruvate ratio increases at the LAT which supports the concept that the lactic acidosis results from relative muscle hypoxia [6][7][8].As an individual commences an incremental exercise test, their expired minute volume ( _ V E ), oxygen consumption per minute ( _ VO 2 ) and CO 2 production per minute ( _ VCO 2 ) all increase linearly with respect to variables such as work rate or time. However a point is reached when _ VCO 2 increases out of ...

Summary of Consensus Report on Preoperative Evaluation

“…If needed, coagulation tests, blood gases, and an echocardiographic examination should be considered. Signs of active infection in the preoperative period necessitate hospitalization and preoperative intensive pulmonary treatment [77].…”

2014 ESC/ESA Guidelines on Non-cardiac Surgery: Cardiovascular Assessment and Management

“…177 Two review papers have assessed the role of CPX as a pre-operative evaluation tool. 178,179 Meta-analyses are difficult, due to heterogeneity in methodology and outcome measures. There are no 'blinded' studies and the CPX results may influence the decision on whether to operate on a patient with a potentially serious disease and prognosis.…”

“…One of the above papers concludes that paucity of robust data precludes routine adoption of CPX in risk-stratifying patients undergoing major vascular surgery, 178 while the other reports that peak oxygen consumption-and possibly anaerobic threshold-are valid predictors of perioperative morbidity and mortality in patients undergoing non-cardiopulmonary thoraco-abdominal surgery. 179 The current ESC Guidelines on acute and chronic heart failure give a strong recommendation for the use of optimal tolerated doses of ACE inhibitors (or ARBs in the case of ACE intolerance), beta-blockers, and aldosterone antagonists as primary treatment strategies in patients with HF-REF, to reduce morbidity and mortality. 159 Digitalis is a third-level drug to be considered in patients treated optimally with recommended drugs.…”

Quality assessment in surgery: where do we stand now and where should we be heading?

“…The benefit of preoperative assessment of the surgical patient has been recognized since long and aims at reducing over-all perioperative risks [6]. It is essential to consider patient related factors, social related factors, and the duration and extent of the surgery.…”