SOME CHARACTERISTICS OF TRANSCUTANEOUSLY MONITORED OXYGEN PARTIAL PRESSURE IN NORMAL NEWBORNS

The transcutaneous oxygen partial pressure (Ptc_O2) was monitored in 50 healthy, normally and spontaneously delivered newborns. Measurements were performed during the first to fourth day of life. The electrode temperature was 44.5°C. The mean Ptc_O2 level recorded during about 45 min was 9.2 kPa (S.D. 1.4) recorded from the minute-to-minute values. The Ptc_O2 level normally oscillated to a certain extent and the oscillations were closely related to the breathing pattern of the patient. When the patient fell asleep during measurement, the normal oscillating pattern was replaced by a “silent pattern”. During crying, the Ptc_O2 level showed four main reaction patterns. A decrease in the Ptc_O2 level could be observed during breast-feeding. One child, recently fed, vomited a small amount of breast milk after a short period of crying and apparently had a laryngospasm, shown by a sudden drop in the Ptc_O2 level without any other signs of discomfort. The study shows that Ptc_O2(and thus also Pa_O2 very sensitively reacts to changes in activity. This implies that earlier used methods for determination of Pa_O2 might give values that are not representative for the steady state as the sampling method per se might influence the recorded P_O2value.