Abstract

Blood lactate was measured 4-hourly in 21 newborn babies with respiratory distress syndrome, of whom 13 survived and 8 died. In general, lactate levels were higher in babies who died than in survivors, but there were inconsistencies which were uninterpretable if only a single estimation were made in a baby. Analysis of serial determinations showed that all patients in whom the lactate level never exceeded 35 mg/100 ml survived, and babies with high but falling values also did well. Only those who had rising lactate values, even if initially normal, died.

In most cases a high or normal P_ao₂ was associated with normal or decreasing lactate level; but babies with P_ao₂ below 60 mmHg had often also normal or decreasing lactate levels. Some babies had high and increasing lactate levels despite having normal P_ao₂.

In order to use lactate levels for prognosis in respiratory distress syndrome (RDS) serial determinations are required.

It is concluded that there may be a wide range of hypoxaemia without oxygen deficit in body tissues, so that it is not possible to define a `lower acceptable P_ao₂' which will define adequate tissue oxygenation.