Identification of neonatal haemolysis: an approach to predischarge management of neonatal hyperbilirubinemia

Aim Relative contributions of increased production [by end‐tidal carbon monoxide concentrations ( ETCO c)] and decreased elimination of bilirubin to predischarge hour‐specific total bilirubin ( TB ) levels were assessed in healthy late‐preterm and term newborns. Secondly, we report predischarge ETCO c ranges to guide clinical management of hyperbilirubinemia. Methods TB and ETCO c (≤3 timepoints) determinations of newborns aged between six hours and <6 days (n = 79) were stratified by postnatal age epochs. Hyperbilirubinemia risk was assessed by plotting TB values as a function of ETCO c. Results Stratifications of ETCO c (in ppm, mean, median and interquartile ranges) by postnatal age epochs (0–24, 24–48 and 48–72) were as follows: 2.0, 1.9, 1.8–2.2 (n = 11); 1.6, 1.5, 1.1–2.0 (n = 58); and 2.0, 1.8, 1.6–2.3 (n = 9), respectively. Infants with ETCO c ≥ 2.5 were at high risk, between 1.5 and 2.5 at moderate risk and ≤1.5 were at low risk. Risk due to haemolysis alone was not independent (p < 0.01). For infants with TB >75th percentile (n = 31), 23% had ETCO ≤1.5, and 77% had ETCO c > 1.5 (p < 0.00003). Conclusion Near‐simultaneous ETCO c and TB measurements in infants with TB >75th percentile accurately identify haemolytic hyperbilirubinemia.