Biological quality control for exercise testing

Background-A study was undertaken to evaluate the use of a biological quality control programme for a computer controlled, breath-by-breath exercise test system over a 2.5 year period, Methods-One healthy volunteer performed a regular progressive treadmill test with breath-by-breath measurements of oxygen uptake ((V)O-2), carbon dioxide output ((V)over dot CO2), ventilation ((V)over dot E), and the ECG heart rate (HR). Following a familiarisation period, five consecutive tests were performed and the measurements at peak exercise were averaged to give baseline values. All tests were compared with these values. Results-A total of 35 tests were recorded. The within subject standard deviation for measurements at peak exercise were 52 ml/min for (V)over dot O-2, 74 ml/min for (V)over dot CO2, 3.1 1/min for (V)over dot E, and 3 beats/min for HR. The mean (SE) percentage variation in measurements at peak exercise compared with the baseline values was +0.37 (0.30)% for (V)over dot O-2, -0.10 (0.39)% for (V)over dot CO2, -0.88 (0.52)% for (V)over dot E, and +1.2 (0.26)% for HR. The variability present in measurements made during high and moderate intensity exercise (73% (V)over dot O(2)peak) was not significantly different (p > 0.05). During the study period the quality control detected a fault on the oxygen analyser which was not apparent from the automatic calibration. Conclusions-Regular quality control using a healthy volunteer allows all components of the breath-by-breath system to be checked simultaneously and in a manner which is consistent with its clinical use. This practice can highlight faults not detected by automatic calibration.