Abstract
During the course of measurements of pulmonary function in newborn infants breathing 60–100 % oxygen, we have previously noted frequent, rapid and significant decreases in hematocrit and hemoglobin levels. The present investigation has been designed to confirm and elucidate this finding. 14 newborn infants varying in gestational age from 36–37 weeks, in birth weight from 2.7–4.6 kg and in postnatal age from 1–18 h breathed 60 % O2 by demand valve for periods of 60–70 min. Hematocrit (Hct), hemoglobin (Hb), total protein (TP) and blood gases were followed throughout and blood volume (CO method) was measured in 3 infants. Within 10 min of onset of O2 breathing prompt decreases of Hb, Hct, TP were seen reaching levels of 20 % below control values by 60 min. These changes promptly reversed upon resumption of air breathing. TP changes were seen to be more consistent and marked than changes in Hct or Hb. The response was seen with arterial O2 tensions of as low as 116 mm Hg. Total blood volume increases of 40–60 ml/kg were noted during O2 breathing in 3 infants. These data suggest auto-infusion of tissue fluid from some vascular bed in response to O2 breathing; this may imply an increase in precapillary resistance with consequent decrease in capillary pressure and derangement of the Starling equilibrium. Preliminary investigations indicate that bradycardia and increased peripheral vascular resistance are involved in this phenomenon. (APS)
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Nelson, N., Nourse, C., Priestley, B. et al. 90 Vascular Responses to Oxygen Breathing in the Newborn Infant. Pediatr Res 1, 223 (1967). https://doi.org/10.1203/00006450-196705000-00096
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DOI: https://doi.org/10.1203/00006450-196705000-00096