[Cardiopulmonary exercise tests -- proposals for standardization and interpretation]

Abstract

I give some recommendations concerning methodology and interpretation of cardiopulmonary exercise tests. The recommendations are based on our comprehensive data bank of exercise tests (282 tests and about 200 single parameters assessed during each test). When I expect an exercise capacity lower than 100 W I perform a ramp test; concerning expected higher exercise capacity steps of 25 W every 2 min are preferred. In order to achieve an optimal assessment of exercise capacity an exhaustion or symptom limited test should be performed. The achieved maximum oxygen consumption does not allow differing between cardiac or pulmonary causes of exercise limitation. It is only a marker of cardiopulmonary exercise capacity. A lot of algorithms to assess the maximum oxygen consumption are available, yet the results of calculating oxygen consumption with these algorithms differ considerably. Therefore it is mandatory to mention the used algorithm when referring to a calculated predicted oxygen consumption value. There are also several methods to assess the ventilatory and metabolic anaerobic threshold. For clinical purposes assessing lactate values is not necessary. The so called 4 mmol x l(-1) threshold accords primarily to the threshold assessed with the V-slope method. The Hf-slope may be used as an index for classification of heart failure stages analogous to the NYHA classification. Changes in dead space ventilation are mainly an expression of changed ventilation perfusion relationships and do not give evidence for any specific cardiac or pulmonary disorder. The slope of the equivalent for CO(2) is a relevant parameter of prognosis in cardiac failure. The value of the breathing reserve is not indicative of pathologic ventilatory limitation of exercise. You may find a reduced breathing reserve of about 0 also in healthy volunteers who are driven to exhaustion limited exercise. The value of the breathing reserve depends strongly on the kind of calculation or measuring mode and depending on the mode you can get normal or extremely reduced values in the same test person. The analysis of the flow volume curve during exercise provides some criteria of ventilatory exercise limitation. Pulse oxymetry is relevant only as a safety parameter. Because of its inaccuracy it should not be used to prove desaturation during exercise. The assessment of the alveolar-arterial pO (2) difference is of diagnostic relevance. The Borg scale, the course of the oxygen equivalent of O(2), the respiratory exchange ratio, and the aerobic capacity are of no major relevance for differential diagnosis.