Serial determinations of blood lactate in respiratory distress syndrome

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 Pao 2 was associated with normal or decreasing lactate level; but babies with Pao2 below 60 mmHg had often also normal or decreasing lactate levels. Some babies had high and increasing lactate levels despite having normal Pao2. 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 Pao2' which will define adequate tissue oxygenation.