The measurement of TcPO2 and TcPCO2 in newborn infants at 44 degrees C, 42 degrees C and 37 degrees C after initial heating to 44 degrees C.

Prolonged measurement of the transcutaneous O2 and CO2 tension at an electrode temperature of 44 to 45 degrees C often causes a second degree burn of the underlying skin. To avoid this, we compared the readings at 44 degrees C, 42 degrees C and 37 degrees C, after 2 hours pre-heating of the skin by the electrodes at 44 degrees C. In order to eliminate the electrodes' own temperature coefficients, electrodes with a built-in temperature correction were used. The changes observed therefore represent changes in the O2 and CO2 tension in the skin. The obtained values were compared to repeated arterial samples. We found that the TcPO2 and TcPCO2 values obtained at 42 degrees C and 37 degrees C were lower than those obtained at 44 degrees C, but when corrected for the in vivo temperature coefficients previously found by us the TcPO2 values at 42 were quite similar to the 44 degrees C values, whereas the 37 degrees values remained lower. TcPCO2 values at 44, 42 and 37 degrees were all similar. The temperature coefficient of PO2 was calculated to be 0.044 +/- 0.008 and for TcPCO2 as 0.049 +/- 0.007.