Identification of risk for neonatal haemolysis

Aim: To identify neonates at risk of haemolytic hyperbilirubinaemia through near-concurrent measurements of total serum/plasma bilirubin (TB) or transcutaneous bilirubin (TcB) and end-tidal breath carbon monoxide (CO), corrected for ambient CO (ETCOc), an index of bilirubin production and haemolysis. Methods: Paired TB/TcB (mg/dL) and ETCOc (ppm) measurements were obtained in newborns (n = 283) at 20 to < 60 hours of age in five nurseries. TB/TcB values were assigned TB/TcB percentile risk values using the Bhutani hour-specific nomogram. In infants having two serial TB/TcB measurements (n = 76), TB rate of rise (ROR, mg/dL/h) was calculated. Results: For the entire cohort (n = 283), 67.1% and 32.9% had TB/TcB < 75th and >= 75th percentile, respectively. TB/TcB (5.79 +/- 1.84 vs 9.14 +/- 2.25 mg/dL) and ETCOc (1.61 +/- 0.45 vs 2.02 +/- 1.35 ppm, p = 0.0002) were different between the groups. About 36.6% of infants with TB/TcB >= 75th percentile had ETCOc >= 2.0 ppm. In the subcohort of infants with serial TB/TcB measurements (n = 76), 44.7% and 55.3% had TB/TcB < 75th and >= 75th percentile, respectively. TB/TcB (5.28 +/- 1.97 vs 9.53 +/- 2.78 mg/dL), ETCOc (1.72 +/- 0.48 vs 2.38 +/- 1.89 ppm, p = 0.05) and TB ROR (0.01 +/- 0.440 vs 0.172 +/- 0.471 mg/dL/h) were different between the groups. Conclusion: The combined use of TB/TcB percentile risk assessments and ETCOc measurements can identify infants with haemolytic hyperbilirubinaemia. The addition of TB ROR can identify those infants with elimination disorders.