Preoperative cardiopulmonary exercise testing
Reading, UK
* E-mail: c.danbury{at}reading.ac.uk
Editor—We were interested to read the article by Murray and colleagues1 which demonstrated the value of a shuttle walk test in predicting outcome after oesophagectomy. It would appear that an inability to walk 350 m during a test is of similar predictive value to an anaerobic threshold of <11 ml kg–1 min–1 obtained from formal cardiopulmonary exercise (CPX) testing.
CPX testing is, however, much more than anaerobic threshold measurement.2 This technique has powerful diagnostic utility and prognostic value. A well-conducted CPX test gives an immense amount of physiological data and a measurement of actual work done by the patient. The data, when mapped out in a typical Wasserman 9 panel plot,3 indicate concurrent pathophysiology, such as cardiac ischaemia, COPD, or pulmonary hypertension.
Since the incorporation of CPX testing into the oesophageal cancer management programme in our hospital, we have tested 23 consecutive patients with oesophagogastric tumours. One patient did not proceed to surgery after their CPX test. No patient tested on the programme died within 30 days of surgery and none remained on intensive care for more than 7 days after operation.
Murray and colleagues question the use of CPX on cost grounds. We believe that in addition to the prediction of relative perioperative risk, the value of CPX testing is that it enables better diagnosis of underlying co-morbidities, and therefore more precise peroperative (or non-operative) management.
Sheffield, UK
* E-mail: paul.murray{at}sth.nhs.uk
Editor—We are grateful to Dr Danbury and colleagues for their interest in our paper.1 It is apparent that preoperative exercise testing is becoming more widely employed in UK practice. I would draw attention to the recently published study by Forshaw and colleagues4 which concluded that CPX was of limited value in predicting morbidity after oesophagectomy. However, the in-hospital mortality was only 1.3% in this group of patients, which may not be representative of wider practice, and I would be interested to see further data from Dr Danbury's group.
References
1 Murray P, Whiting P, Hutchinson SP, Ackroyd R, Stoddard CJ, Billings C. Preoperative shuttle walking testing and outcome after oesophagogastrectomy. Br J Anaesth (2007) 99:809–11.
2 Nagamatsu Y, Shima I, Yamana H, Fujita H, Shirouzu K, Ishitake H. Preoperative evaluation of cardiopulmonary reserve with the use of expired gas analysis during exercise testing in patients with squamous cell carcinoma of the thoracic esophagus. J Thorac Cardiovasc Surg (2001) 121:1064–8.
3 Wasserman K, Hansen JE, Sue DY, Stringer WW, Whipp BJ. Lippincott Williams and Wilkins. Principles of Exercise Testing and Interpretation (2005) 4th Edn.
4 Forshaw MJ, Strauss DC, Davies AR, et al. Is CPX a useful test before oesophagectomy? Ann Thorac Surg (2008) 85:294–9.
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