Transcutaneous carbon dioxide for short-term monitoring of neonates

We studied transcutaneous pCO2 monitoring in 70 neonates, most of them premature with respiratory distress syndrome. Measurements were at 44 degrees C. Calibration drift was large in some instances. Least squares linear regression analyses of transcutaneous pCO2 (y) vs arterial pCO2 (x) in kilopascals showed, for all observations (n = 516), for one observation randomly selected from each patient (n = 70), and for the first observation from each patient (n = 70): y = -0.28 + 1.80x, y = 0.01 + 1.74x, and y = 0.73 + 1.63x, respectively. Regression lines for individual patients with 14 or more observations each were not coincident (F = 2.80, p less than 0.002). Transcutaneous pCO2 monitoring was most useful clinically as a means of following short-term trends in arterial pCO2 continuously during extubation and afterward when avoiding re-intubation. In view of the potential for error associated with drift, we recommend that intervals between calibrations be limited to about 3 h.