Cardiopulmonary exercise testing in our practice

When we invested in new gear for the lung function lab last year I was very keen to obtain the appropriate equipment to allow us to do cardiopulmonary exercise testing. Having trained in labs where this test was performed frequently I felt that we were not quite providing a comprehensive respiratory function laboratory facility unless we had this capacity.

In conversation with a local anaesthetist recently I was made aware that there are only four facilities in Melbourne that offer medicare-funded cardiopulmonary exercise testing. There are none in regional Victoria, apart from us. Makes me wonder at what point I should reign in my enthusiasm for developing our practice!

The point of our conversation, however, was that there is a growing interest in the anaesthetic literature surrounding the role of cardiopulmonary exercise testing (CPX) in pre-anaesthetic evaluation. Cardiopulmonary exercise testing has previously been demonstrated to be useful in predicting risk of perioperative complications or death following surgery to resect lung cancers. There is a growing body of evidence - not all of it yet consistent - to suggest that measurements of peak oxygen consumption (VO2 max) or anaerobic threshold may also be relevant when it comes to predicting likelihood of complications following bowel resections. The two parameters require a CPX for their calculation.

I will blog more about this in future. At present, indications for CPX as per The American Thoracic Society/American College of Chest Physicians Statement on Cardiopulmonary Exercise Testing (2003) include:

1. Evaluation of exercise tolerance, where the diagnosis is known, in order to objectively evaluate functional capacity, disability or response to treatment.
2. Evaluation of undiagnosed exercise intolerance where cardiac and respiratory aetiologies may coexist, the symptoms are disproportionate to the results of resting investigations or the investigations are non diagnostic.
3. Evaluation of patients with cardiovascular diseases.
4. Evaluation of patients with respiratory diseases/symptoms.
5. Pre-operative evaluation.
6. Exercise evaluation and prescription for pulmonary rehabilitation.
7. Evaluation of impairment/disability.
8. Evaluation for lung, heart and heart-lung transplantation.
   

Some of these are pretty general. Items 1 and 2 cover most of our CPX patients. For some patients who are young but have a considerable burden of respiratory disease, CPX provides a wholistic baseline measure of fitness against which we can refer back to monitor how well a general program of management is working. In patients with cardiac and respiratory disease it can help tease out which is the exercise limiting problem. And finally, in some patients who are simply unfit ('deconditioned') the the CPX can simply confirm that 'diagnosis', which otherwise is usually based on clinical impression.

Andrew