Noninvasive Detection of Hemolysis with ETCOc Measurement in Neonates at Risk for Significant Hyperbilirubinemia.

BACKGROUND

Hemolytic hyperbilirubinemia due to blood group incompatibility or glucose-6-phosphate dehydrogenase deficiency (G6PD) is a common cause of significant hyperbilirubinemia. Hemolysis in a hyperbilirubinemic infant increases the risk of bilirubin neurotoxicity. A new portable device (CoSense) can rapidly detect breath end-tidal carbon monoxide corrected to ambient carbon monoxide (ETCOc). ETCOc levels are surrogate markers of hemoglobin breakdown and bilirubin production.

OBJECTIVE

The aim was to evaluate the association between ETCOc values and hemolysis and its relevance in neonates at risk for significant hyperbilirubinemia.

METHODS

A prospective study was conducted among newborn infants born at more than 35 weeks and with a birth weight greater than 2,000 g with a G6PD deficiency, blood group incompatibility, or clinical jaundice needing phototherapy during the first 7 days of life. The recruited infants had their breath ETCOc measured twice, first on the day of recruitment and then again on the following day.

RESULTS

Fifty infants completed this study. Their mean ETCOc was 1.61 (±0.56) ppm. There was a linear correlation (r = 0.89) between increasing ETCOc values and reticulocyte counts (RC). Sixteen newborns with ABO incompatibility had a significantly higher mean ETCOc of 1.98 ppm (±0.71) as compared to 1.43 (±0.38) ppm in the nonhemolytic hyperbilirubinemia (NHH) group (n = 25) (p = 0.002). This was suggestive of hemolysis as shown by the significantly higher RC of 6.90% (±3.38) compared to 4.68 (±1.26) in the NHH group (p <0.005). Neonates with an ETCOc level ≥1.8 ppm had a higher RC, a lower hemoglobin level, higher serum bilirubin levels, and a rapid rise in serum bilirubin and needed a longer duration of phototherapy. ETCOc values ≥1.8 ppm were suggestive of hemolysis (RC ≥6%), with a sensitivity of 90% and a specificity of 83%.

CONCLUSION

Higher ETCOc values ≥1.8 ppm are suggestive of hemolysis and they are associated with significant hyperbilirubinemia.