[Continuous monitoring of blood gases in adults]

Single blood gas analysis offers only a momentary value, whereas with continuous monitoring of blood gases their development can be followed very closely. Cutaneous pO2 monitoring has not proved successful in adults, since the measured values depend very much on the condition of the skin, local perfusion, and cardiac output. On the other hand, continuous intravascular pO2 monitoring does represent a relatively safe and convenient method of supervision. At this institute a cutaneous pCO2-sensor developed by the Bio-Electronics Department of F. Hoffmann-La Roche & Co. Ltd. with sensor temperatures of 41 degrees, 43 degrees, and 44 degrees C has been tested. The coefficients of correlation are 0.95 or even higher for all three sensor temperatures. At a sensor temperature of 41 degrees C the reaction velocity is markedly reduced. Accuracy and reaction velocity for the sensor temperatures of 43 degrees and 44 degrees C are equivalent, but at a temperature of 43 degrees C there are fewer and slighter skin reactions. The authors found a slight drift of 0.2--0.3 mm Hg/h. The dependence of cutaneous pCO2 on local perfusion and cardiac output also appears to be slight.