Changes in the ECG and Somatosensory-Evoked EEG Responses during Intrauterine Asphyxia in the Sheep

Abstract

Progressive changes in the S-T interval of the fetal ECG were studied in 14 mature lamb fetuses, acutely exteriorized and submitted to a graded hypoxia. The degree of hypoxic stress was measured from changes in the somatosensory-evoked EEG responses (SER), blood gas analysis and lactate concentration. The ECG and the SER were found to be affected simultaneously. A close relationship was further obtained between pH of the arterial blood and changes in the S-T interval, the ratio between the T and S waves being used for quantifying these changes. This relationship was further strengthened by the strong correlation obtained between the accumulation of lactate and the T/S ratio. The findings corroborate the hypothesis that the hypoxic changes in the ECG pattern could be regarded as a sign of myocardial glycolysis and early hypoxic stress.