VEP and Hypoglycemia in Premature Infants

Abstract

Cerebral lesions in premature infants are usually found in the periventricular area, closely related to the optic tracts. Therefore, we have developed a simple set-up which allows repetive measurements of visual evoked potentials (VEP) during the first hours of life leaving the infants undisturbed in the incubator. Stimulation by single flashes during periods of quiet spontaneous EEG activity results in distinct VEPs. In 20 “healthy” newborns (27-34 gw) the latency decreased over a few hours coinciding with the increase in core temperature and with the recovery from slight respiratory- and/or metabolic acidosis. No changes in VEPs were observed in 4 infants with arterial hypotension (m-BP down to 20 mmHg) nor in 5 infants with hypocarbia (pCO2 down to 1.3 KPa). However, in 4 hypoxic infants (a-pO2 down to 2.5 KPa) the latency increased and the amplitude decreased markedly. Finally, in 9 premature infants with asymptomatic hypoglycemia (0.0-1.3; median 0.7 mmol/1) no effects on VEPs were detectable.Conclusion: Repetitive investigations of VEPs immediately after birth appear to be a reliable method of monitoring the cerebral function. Only hypoxia was observed to induce marked changes in VEP and thereby in cerebral metabolism. Asymptomatic hypoglyoemia, however, even when severe, did surprisingly not affect VEP.