Cerebral tolerance of hypoxia in growth-retarded and appropriately grown newborn guinea pigs

Abstract

To elucidate if there is a reduced perinatal tolerance of hypoxia in growth retardation and approach its pathophysiologic background, newborn guinea pigs of different weights were subjected to standardized hypoxia. Intrauterine growth retardation was induced through uter­ine artery ligation. After spontaneous delivery experiments were performed within 2 days. After stabilization, hypoxia of stepwise increased severity was instituted. Blood gases, metabolic, cardiovascular, and neurophysiologic [somato-sensory-evoked potentials (SEP)] parameters were moni­tored. A control series in which equally large blood samples were taken at the same intervals was performed. The animals were grouped according to birth weight: >101 g (n = 10,12), 71-100 g (n = 11, 10), and <70 g (» = 8, 3) (hypoxic and control series, respectively). Basal SEP la­tencies did not differ between the groups. Under hypoxia, both the amplitude of the SEP and the time to complete loss of the SEP was reduced in proportion to the degree of growth retardation. The differences between all groups were significant. The animals in the control series did not change their SEP performance significantly. Slight differ­ences in metabolic and cardiovascular parameters between the groups were found not likely to explain the differences in SEP performance. Therefore, it is concluded that a reduced cerebral tolerance of hypoxia prevails in growth-retarded newborn guinea pigs and that this is related to changes in the brain itself. It is also concluded that a relationship exists between the degree of growth retarda­tion and that of reduced cerebral hypoxia tolerance. © 1988 International Pediatrics Research Foundation, Inc.