The utility of blood oxygenation as an indicator of postnatal condition

Abstract

Summary In the present study we have attempted to relate level of blood oxygen to the state of the infant at or near the time of birth. Oxygen levels were correlated to clinical ratings of anoxia and to performance on the Behavior-Tests for the Newborn. A low but significant relationship between cord oxygen and clinically observed anoxia was found. There was, however, no relationship between immediate postnatal anoxia and oxygen level at one hour. There was essentially no relationship between oxygen and performance on behavioral tests made when the infants were from 24 to 48 hours of age, although we have found previously that there is a relationship between these tests and the seriousness of the clinical condition. Also, there was no difference in performance on Behavior Tests between extreme groups selected on the basis of oxygen levels. Groups selected because of low cord oxygen or low oxygen throughout the first hour of life did not perform in a manner that was significantly different from groups whose oxygen readings were exceptionally high. The one exception to this was in the reverse direction from what would have been predicted; i.e., the low oxygen group performed better than the high oxygen group. The patterning of early and late oxygen readings was examined. No correlation was found between the cord sample and the 60-minute sample, and the correlation between the 10-and 60-minute samples was low, although statistically significant. In the total group of both uncomplicated and complicated deliveries, infants having cord oxygen above the 50 per cent level showed no greater tendency to be above 90 per cent at one hour than did infants with cord readings below 50 per cent. In complicated deliveries only, those infants with cord readings below 50 per cent were significantly less well oxygenated at one hour than were those whose cord readings were above 50 per cent. It was concluded that the measure of oxygen saturation, while having high face validity and objectivity, does not provide an entirely satisfactory measure of what is clinically regarded as anoxia. The cord sample, which should be the most revealing of the oxygen economy of the infant at the moment of birth, appears likely to be influenced by events of the moment and is unreliable as a predictor of later oxygen status. It was suggested that one of the difficulties with the oxygen measure is the fact that it is too sensitive to transitory states to be serviceable in predicting long-term effects upon the organism.