Non-invasive Haemoglobin Monitoring in Preterm Neonates: Agreement with Laboratory Haemoglobin and Implications for Phlebotomy Reduction and Transfusion Guidance

Background Preterm neonates are disproportionately affected by iatrogenic anaemia from frequent phlebotomy for laboratory monitoring. In high-volume neonatal units managing critically ill preterm neonates, minimising blood loss without compromising clinical monitoring is an important goal. Non-invasive haemoglobin (SpHb) monitoring using pulse CO-oximetry offers a potential strategy to reduce unnecessary invasive sampling. Methods A prospective observational study was conducted in 300 preterm neonates (<37 weeks gestational age) admitted to a tertiary care neonatal intensive care unit in India over 4 months. SpHb was measured using the Masimo Rad-67 and paired with laboratory haemoglobin values (1,435 paired measurements). Agreement was assessed by Bland–Altman analysis; secondary outcomes included trending ability, anaemia detection, measurement accuracy and blood sampling burden. Results Mean bias was −0.002 g/dL (95% CI: −0.040 to +0.036 g/dL), the limits of agreement were −1.438 to +1.434 g/dL, the percentage error was 9.51%, and the intraclass correlation coefficient (2,1) was 0.939 (excellent agreement). Four-quadrant concordance was 91.2% (961 evaluable pairs). The receiver operating characteristic area under the curve was 0.975 (95% CI: 0.950-0.999); at SpHb <13.3 g/dL, sensitivity was 98.7% and negative predictive value was 99.9%. Clinical sepsis was the only independent predictor of significant measurement error (adjusted OR 7.07, 95% CI: 4.62-10.80, P < .001). The median blood volume drawn was 8.2 mL (7.9% of estimated blood volume). Conclusions SpHb demonstrated clinically acceptable agreement with laboratory haemoglobin across a large prospective cohort of preterm neonates. Trending ability and anaemia detection performance were robust. SpHb may serve as a useful adjunct to help reduce unnecessary invasive sampling in clinically stable neonates, with caution advised in the presence of sepsis or haemodynamic instability.