Guidelines for the use of pulse oximetry in the non-invasive estimation of oxygen saturation in oxygen-dependent newborn infants.

An Ohmeda Biox 3700 oximeter was evaluated during treatment of 12 patients with respiratory distress. The infants were of 27-33 weeks' gestation and between 2 days and 5 months postnatal age. Blood gases were taken from indwelling arterial catheters and were measured on an ABL 30 blood gas analyser. The study tested the accuracy of the oximeter in detecting hypoxia (PaO2 less than 55 mmHg) and hyperoxia (PaO2 greater than 80 mmHg). Results are based on 175 paired observations. Guidelines are suggested for the use of the pulse oximeter under three conditions. In a newborn infant with acute respiratory distress without direct arterial access, the limits should be set at 85% (lower) and 90% (upper). In an older infant with chronic respiratory distress, the upper limit of use should be 95%. In order to avoid oxygen tensions less than 55 mmHg which would increase the risk of pulmonary vasoconstriction, however, the lower limit should be 87%. Infants with indwelling arterial lines during their first few weeks of treatment should have oxygen tension measurements and simultaneous oxygen saturation readings plotted on a graph at the bedside. The graph should be updated every 48 h to take into account changed levels of 2,3-diphosphoglycerate, haemoglobin F, and carboxyhaemoglobin and the recommended limits should be changed accordingly.