Monitoring of PCO2 by skin surface sensors.

The methodology of cutaneous PCO2 measurement and the results of the first clinical studies performed with a newly developed sensor are reported. The in vitro data of the sensor are: sensitivity 55 mV/decade; response time tau 90% = 50 s; drift less than 10% per 24 h; no measurable interference by oxygen and anesthetic gases. At a sensor temperature of 44 degrees C, the correlation between arterial PCO2 and cutaneous PCO2 is significant, with correlation coefficients above 0.

Electrochemical sensors for invasive and non-invasive monitoring of blood gases.

The need for continuous monitoring of blood gases in critically ill patients has become more and more evident during the past years. Electrochemical sensors appear to be most appropriate for such measurements because of their simplicity, ease of use and low cost. Intravascular sensors and skin surface sensors for pO2 and pCO2 are available today in different degrees of technical maturity.

Interference of anesthetic gases at skin surface sensors for oxygen and carbon dioxide.

Several variables may account for the response of electrochemical skin surface PO2 sensors to anesthetic gases: cathode material and size, pH of the electrolyte and membrane material. These variables cannot be chosen arbitrarily and their influence has been tested with two types of sensors. In one type (LSC), a large size cathode (mm range) and a membrane with low permeability for oxygen such as mono-axially oriented polyethylene is used.