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Perioperative cardiopulmonary exercise testing in the elderly

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The elderly constitute an increasingly large segment of the population and of the patients requiring medical attention. Major surgery is associated with a substantial burden of postoperative morbidity and mortality. Advancing age is a particular risk factor for these outcomes. This article reviews the current literature on the value and practical applications of cardiopulmonary exercise testing (CPET) as a tool to evaluate risk and thereby improve the management of the elderly patient undergoing major surgery. There is a consistent association between CPET-derived variables and outcome following major surgery. Furthermore, CPET-derived variables have utility in perioperative risk prediction and identification of patients at high risk of adverse outcome following major surgery. This optimal predictor appears to differ between various surgery types and the incremental benefit of combining CPET with alternative methods of perioperative risk prediction remains poorly defined.

Introduction

The elderly constitute an increasingly large segment of the population and of the patients we treat. Between 2009 and 2010, more than 7.4 million individuals aged 60 years and older required some form of hospital in-patient treatment in the UK, a rise of 37% since 1999–2000. Of these, 4.5 million individuals required some form of procedure or intervention.1 A recent study of more than 4 million patients in the UK found hospital mortality after surgery to be 1.9% (0.44% in elective procedures and 5.4% in emergency procedures). In patients with a mean age of 75 years, in-hospital mortality rose to 12.3%. This patient cohort accounted for 83.8% of deaths but only 12.5% of hospital admissions, 88.5% of whom presented as an emergency.2 Almost two decades ago, Older et al. identified an association between low functional capacity (low fitness levels), as determined by cardiopulmonary exercise testing (CPET), and poor patient outcome following non-cardiopulmonary surgery.3 Based on this, and subsequent published literature, CPET-derived variables have been increasingly adopted as objective measures of fitness prior to surgery, particularly within the National Health Service (NHS) in the UK. This information is used to inform operative decisions, choice of perioperative management and to discuss risk with patients.5 The aim of this article is to review the current literature on the values and practical applications of CPET as a tool to improve the management of the elderly patient in the perioperative setting. Specifically, we aim to assess its use as a risk-stratification tool for major surgery and its value in predicting surgical outcome in the elderly population.

Section snippets

Understanding the basics of CPET

CPET involves the measurement of physiological variables during incremental exercise, to assess a patient’s functional capacity. CPET provides a global assessment of the integrated response to increasing aerobic work involving the cardiovascular, respiratory, neuropsychological and skeletal muscle systems, all of which are activated during the neurohumoral stress response to surgery.5 CPET allows evaluation of the integrated oxygen delivery system when the demand for oxygen is high and the

CPET versus other methods of estimating exercise tolerance

The advantage of CPET over other methods of preoperative assessment is that it provides an integrated assessment of oxygen use under conditions of dynamic stress (exercise). It is recognised that dynamic tests, in comparison with static tests, are a more effective means of evaluating human physiology. Moreover, patients have an intuitive understanding of the concept of being “Fit for Surgery” and therefore the test has good face validity. The concept underlying CPET is that the physiological

Age, fitness and preoperative risk

An age-related decline in VO2Peak and AT has been observed in both longitudinal46, 47 and cross-sectional studies.48, 49 The decline in VO2Peak and AT with age is multifactorial, with alterations in both central and peripheral factors. Changes in body composition and physical activity can also contribute to this decline. The reduction in VO2Peak in older patients has been associated with a greater risk of mortality, primarily because of an increased cardiovascular risk.50 VO2Peak has been shown

Current applications and evidence-based value of CPET

In their seminal early study, Older and colleagues showed that cardiovascular mortality was virtually restricted to patients with an AT of <11 ml kg−1 min−1 in the patients they studied.3 Since the publication in the early 1990s, a large number of studies have addressed the association between CPET-derived variables and perioperative outcome in a variety of clinical contexts. Several of these have also evaluated the predictive utility of CPET-derived variables as a means of describing

Thoracic surgery

The incidence of postoperative pulmonary complications after thoracotomy and lung resection is about 30% and is related not only to the removal of lung tissue but also to alterations in chest-wall mechanics.53 Gerson et al.54 performed supine exercise ergometry in 177 patients, aged 65 years and over, undergoing elective major abdominal and non-cardiac thoracic surgery. Results showed that patient inability to perform 2 min of supine bicycle exercise raising the heart rate above 99 beats min−1

Major intra-abdominal surgery

Older et al.3 recorded the pre-surgical AT of 187 elderly patients undergoing major intra-abdominal surgery. They found that an AT <11 ml kg−1 min−1 was associated with increased cardiovascular mortality. In patients with a low AT and preoperative ischaemia, the mortality rate rose from 4% to 42%. This established the idea of preoperative risk stratification and increased postoperative care. In a later study, 11 Older et al. investigated the impact of triaging patients on the basis of the above

Vascular surgery

Nugent et al.61 highlighted the potential use of CPET for identifying high-risk individuals prior to undergoing an abdominal aortic aneurysm (AAA) repair in an elderly population (mean age 72 years). Albeit in a small study (30 patients), the authors advocate that a V˙O2 peak <20 ml kg−1 min−1 be proposed as a marker to identify patients at increased perioperative risk, despite no differences in V˙O2 peak being present between patients with or without postoperative complications. Following this,

Upper gastrointestinal (GI) surgery

Nagamatsu et al.62 investigated the association between CPET-derived variables and outcome following upper gastrointestinal (GI) surgery. They analysed data from 52 patients who had a right thoraco-laparotomy for thoracic oesophageal cancer and observed significant differences in V˙O2max and AT (both normalised to body surface area) between patients with and without postoperative cardiopulmonary complications. In a follow-up study, they retrospectively analysed data from 91 patients (mean age

Discussion

In the literature reviewed above, we have shown that CPET variables are reliably associated with outcome following major surgery. CPET also has utility in identifying the high-risk surgical patient. However, the optimal predictor of high risk appears to differ between surgery types, with AT shown to be the best indicator of higher risk patients for major intra-abdominal surgery and VE/VCO2 for AAA repair surgery.*6, *7, *12 Furthermore, it appears that the role of CPET is of less clear value in

Review limitations

The strengths of this review are that it includes data from a fairly large number of patients (n = 3449) taken from 14 studies. We endeavoured to make use of all systematic reviews and randomised controlled trials, available in the published literature. Limitations of this review include the preponderance of small studies and limitations of primary study design. Due to the limited number of available articles, we included studies that did not have an ‘a priori’ power calculation and were

Conclusion/summary

This review literature supports the notion that patients with reduced objectively measured fitness are more likely to suffer postoperative morbidity or mortality after major surgery. CPET has been shown to be a useful predictor of perioperative complications in major surgery, although the predictive utility varies between procedure types. AT and VO2Peak provide a means of risk stratification in an elderly population prior to major surgery. The only systematic review67 on this subject (reviewing

Conflict of interest

None.

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