THE VALIDITY OF THE TELEMETRIC SYSTEM CORTEX X1 IN THE VENTILATORY AND GAS-EXCHANGE MEASUREMENT DURING EXERCISE

With the portable spirograph CORTEX X1 both the oxygen consumption and the carbon dioxide output can be determined. Therefore, the aim of th e present study was to determine the accuracy of the CORTEX X1 in meas uring FEO2, FECO2 and V-E when attached to a motor-driven mechanical s yringe and to validate the CORTEX X1 against a standardized breath-by- breath system during a graded bicycle ergometry. Fifteen subjects (8 m ale, 7 female; 26.7+/-3.3 years) performed two graded exercise tests o n a bicycle ergometer (50 W incline every 3 min) until volitional fati gue in randomized order. During rest and during the last 30 s of each step ventilatory and gas exchange parameters were measured with the CO RTEX X1 and the OXYCONgamma. At rest and at each step no significant d ifferences exist for (V) over dot O-2 (F=0.97) and (V) over dot CO2 (F =0.90). The orthogonal regression equation of the (V) over dot O-2-val ues was (V) over dot O-2(X1)=-75.5+1.01 x (V) over dot O-2(Oxy) and th e equation of the (V) over dot CO2-values was (V) over dot CO2(X1) = 2 1.7-1.008 x (V) over dot CO2(Oxy). The (V) over dot O-2-max-values wer e nearly the same: 3569 +/- 924 ml/min (Oxy) and 3497+/-993 ml/min (X1 ). Similar findings were made with regard to (V) over dot VCO2max 4117 +/- 1010 ml/min (Oxy) and 4126 +/- 1090 ml/min. (X1). Maximal values for heart rate were 181 +/- 10 beats/min (X1) and 180 +/- 8 beats/min (Oxy) (F=0.21), for maximal power 256 +/- 64 W (X1) and 257 +/- 63 (Ox y) (F = 0.0001) and for maximal ventilation 118 +/- 31 l/min) and 120 +/- 35 l/min (Oxy) (F=0.03) with no significant difference. When attac hed to the motor-driven syringe (V) over dot (E) was accurately measur ed up to 288 l/min. Over a period of 40 min there was no drift observe d in FEO2 and FECO2. In conclusion, with the CORTEX X1 (V) over dot O- 2 and (V) over dot CO2 can be accurately determined.