FETAL AND NEONATAL MEDICINE

Arterial oxygen saturation in preterm infants at discharge from the hospital and six weeks later Christian F. Poets, MD,* V a l e r i e A. S t e b b e n s , BSc, John R. A l e x a n d e r , MSc, FSS,FIS, William A. Arrowsmith, FRCP, DCH, S t e p h e n A. W. Salfield, MB,BS,MRCP, DCH, a n d D a v i d P. Southall, MD, FRCP From the National Heart and Lung Institute, Brompton Hospital, London, Syntex Research Maidenhead, Doncaster Royal Infirmary, Doncaster, and Rotherham District General Hospital, Rotherham, England To obtain normal data on arterial o x y g e n saturation (SaO2) in preterm infants and to study early d e v e l o p m e n t a l c h a n g e s in SaO2, we o b t a i n e d overnight t a p e recordings of $a02 and breathing movements in 160 preterm infants at their disc h a r g e from three special care b a b y units (mean gestational a g e at birth 33 weeks; at time of study, 37 weeks). One hundred ten infants (69%) underwent a s e c o n d recording 6 weeks later. Median baseline SaO2 during regular breathing was 99.5% (range 88.7% to 100%) at discharge, and 100% (range 95.3% to 100%) at follow-up (p __37 weeks of gestational age), had a significantly lower baseline SaO2 and a higher frequency and duration of episodic falls in SaO2 than did the infants born at term. Data comparability was limited, however, because the preterm infants were of lower GA at recording. In addition, these studies did not address (1) how baseline SaO2 and the frequency of desaturation change with age, (2) whether premature birth is an independent risk factor for a low baseline SaO2 or frequent desaturation, and (3) how long an outlying result will persist in an infant. To answer these questions and to provide data representative for most preterm infants at discharge from the hospital, the previously described study2 was enlarged by including (1) recordings from infants who had not reached term at the time of the study, (2) recordings from those who had been studied within 3 days after discharge, and (3) follow-up recordings, which were obtained from two thirds of the infants at about 6 weeks after discharge. METHODS Patients. During a 1-year period (August 1986 to July 1987), the parents of all preterm infants born at three maternity hospitals and admitted to special-care baby units immediately after birth were approached for permission to obtain an overnight tape recording of physiologic variables on their baby at discharge. Parents were approached only if the infant had a good prognosis for survival. A total of 305 infants were available, and in 261 cases (86%) parental consent was given for this investigation. For reasons of homogeneity, only those 175 infants (67%) from whom recordings were obtained within the 3 days before or after discharge were included in this study. After parental permission was given, 113 of the 175 infants also had a follow-up recording at home. Eighteen recordings (15 discharge, 3 follow-up) were of poor signal quality throughout and were removed from the study. Thus the study involved analysis of 160 recordings obtained at discharge from hos-

pital and 110 follow-up recordings obtained at home about 6 weeks later. In addition, a comparison was made between those 53 of the 110 follow-up recordings obtained at a GA of 42 to 47 weeks and the recordings from 67 term infants of similar GA studied with the same method.1 The project, including the decision not to use the data collected to influence the treatment of the infants, was approved by the hospitals' ethics committees. Clinical data were obtained from the discharge summaries. Mean GAs and birth weights of all 160 infants studied at discharge were virtually identical to those of the 110 from whom a follow-up recording was obtained (Table I). The 160 infants studied at discharge, however, had lower GAs at birth and birth weights than did those (n = 145) who were not enrolled in the study (mean GA 32.8 _+ 2.5 weeks vs 33.1 _+ 2.4 weeks, p = 0 . 0 4 ; mean birth weight 1844 + 481 gm vs 1930 _+ 544 gm, p 20 seconds], bradycardia [heart rate

Arterial oxygen saturation in preterm infants at discharge from the hospital and six weeks later.

To obtain normal data on arterial oxygen saturation (SaO2) in preterm infants and to study early developmental changes in SaO2, we obtained overnight ...
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