The role of the Shuttle Walking Test in predicting mortality and morbidity post oesophagogastric surgery

Introduction

The Shuttle Walking Test (SWT) has been previously shown to correlate well with patients' maximal oxygen uptake (VO₂ max) [1–3]. Older and colleagues demonstrated that an anaerobic threshold of 911 ml/min/kg, in patients undergoing major abdominal surgery, was an excellent predictor of mortality from cardio-respiratory causes [4]. Patients undergoing oesophagogastric surgery currently have a 30-day mortality of approximately 9% in our institution and are all admitted to critical care postoperatively. Our aim was to assess the value of a preoperative SWT in trying to identify high-risk patients.

Method

All patients listed for oesophagogastrectomy between April 2002 and September 2004 undertook a SWT as a standard part of their preoperative assessment. Routine anaesthesia, surgery and critical care was provided guided by clinical requirements. Thirty-day mortality was compared retrospectively with shuttle test data.

Results

Thirty-nine patients undertook a SWT, and had surgery. The mean age of the group was 64 years (range 44–81 years). The mean SWT distance was 480 m (range 220–880 m). At the 30th postoperative day, 18 patients had been discharged home (46.2%), 14 patients remained on the wards (35.9%), three still required critical care (7.7%) and four patients had died (10.2%). No patient with a SWT of greater than 350 m died within 30 days of surgery. Patients with a SWT of 350 m and below had a 50% 30-day mortality.

Discussion

This small patient group appears to be representative of the oesophagogastric surgical population within our institution (mortality 10.2% vs 9%). A SWT of 350 m appears to be a sensitive marker of increased postoperative mortality in this particular patient population. This finding is consistent with Lewis and colleagues' [2] data correlating SWT distance with VO₂ max and Older and colleagues' [4] work on the anaerobic threshold and perioperative outcome. Further evaluation is required, but using this simple, cheap and reliable non-invasive preoperative test may help to risk-stratify patients undergoing high-risk surgery. High-risk groups may benefit from appropriately informed consent for surgery but potentially also from preoperative cardiopulmonary training and a focused utilisation of resources.