Abstract
We examined the effect of core and skin temperature on the accuracy of two pulse oximeters (Nellcor Symphony and Hewlett Packard saturation module, M1020A) and a transcutaneous PCO 2 monitor (Fastrac Transcutaneous monitor) immediately after cardiac surgery in a group of newborns and infants. Seventy-nine sets of data were collected from 46 patients. Core temperatures ranged from 35.3°C to 39.4°C, skin temperatures ranged from 27.0°C to 37.4°C and core-skin temperature gradients ranged from 0.1°C to 10.1°C. Data analysis consisted of comparing the difference between transcutaneous PCO 2 and arterial PCO 2 and the differences between oxygen haemoglobin saturation measured by both pulse oximeters and oxygen haemoglobin saturation measured by co-oximeter to core temperature, skin temperature and core-skin temperature gradients. The mean differences±standard deviations and limits of agreement for transcutaneous PCO 2 and oxygen haemoglobin saturation measured by the Hewlett Packard and Nellcor pulse oximeters were 0.95±4.10 mmHg (-7.09 mmHg to 8.99 mmHg), -1.07±1.84% (-4.68% to 2.54%) and -1.23±2.23% (-5.60% to 3.14%) respectively. Analysis of correlation coefficients showed that the accuracy of the transcutaneous PCO 2 monitor and the pulse oximeters were not affected by core temperature, skin temperature or core-skin temperature gradient in the ranges encountered. We therefore conclude that these devices are acceptably accurate and suitable for use in infants when core and skin temperatures and core-skin temperature gradient are in the range normally found after cardiac surgery.