Randomised crossover study on pulse oximeter readings from different sensors in very preterm infants

Objective In extremely preterm infants, different target ranges for pulse oximeter saturation (SpO(2)) may affect mortality and morbidity. Thus, the impact of technical changes potentially affecting measurements should be assessed. We studied SpO(2) readings from different sensors for systematic deviations.Design Single-centre, randomised, triple crossover study.Setting Tertiary neonatal intensive care unit.Patients: 24 infants, born at <32 weeks' gestation, with current weight <1500 g and without right-to-left shunt via a patent ductus arteriosus.Interventions Simultaneous readings from three SpO(2) sensors (Red Diamond (RD), Photoplethysmography (PPG), Low Noise Cabled Sensors (LNCS)) were logged at 0.5 Hz over 6 hour/infant and compared with LNCS as control using analysis of variance. Sensor position was randomly allocated and rotated every 2 hours. Seven different batches each were used.Outcomes Primary outcome was the difference in SpO(2) readings. Secondary outcomes were differences between sensors in the proportion of time within the SpO(2)-target range (90-95 (100)%).Results Mean gestational age at birth (+/- SD) was 27(4/7) (+/- 2(3/7)) weeks, postnatal age 20 (+/- 20) days. 134 hours of recording were analysed. Mean SpO(2) (+/- SD) was 94.0% (+/- 3.8; LNCS) versus 92.2% (+/- 4.0; RD; p<0.0001) and 94.5% (+/- 3.9; PPG; p<0.0001), respectively. Mean SpO(2) difference (95% CI) was -1.8% (-1.9 to -1.8; RD) and 0.5% (0.4 to 0.5; PPG). Proportion of time in target was significantly lower with RD sensors (84.8% vs 91.7%; p=0.0001) and similar with PPG sensors (91.1% vs 91.7%; p=0.63).Conclusion There were systematic differences in SpO(2) readings between RD sensors versus LNCS. These findings may impact mortality and morbidity of preterm infants, particularly when aiming for higher SpO(2)-target ranges (eg, 90-95%).