Supplementary Material for: Measuring End-Tidal Carbon Monoxide of Jaundiced Neonates in the Birth Hospital to Identify Those with Hemolysis

Background: End-tidal breath carbon monoxide (ETCOc) levels correlate with catabolism of heme, but until recently, this measurement was not readily available for application to neonatology practice. Objectives: We performed a prospective, multihospital, test-of-concept study where ETCOc was measured during the birth hospitalization of neonates with a total bilirubin (TB) value >75th percentile on the Bhutani bilirubin nomogram. This was done to test the feasibility and ease of use of this new device. Methods: Neonates with an elevated ETCOc (with a >95th percentile reference interval previously established) were labeled as having ‘hemolytic jaundice'. We recommended a follow-up TB check Results: One hundred and fifteen neonates were eligible for the study, the parents of 103 provided consent, and measurements were obtained for 100. Sixty-three had normal and 37 had elevated ETCOc values. By means of a direct antiglobulin test (DAT; Coombs), 11 of these 37 were found positive for ABO hemolytic disease; the remaining 26 had other etiologies. Thirty-six of the 37 with an elevated ETCOc had repeat TB monitoring 75th percentile (p = 0.079). Conclusion: ETCOc measurement is a feasible means of assessing hemolysis in jaundiced neonates during the birth hospitalization. When hemolysis is identified, parents are likely to comply with instructions to bring the infant for a TB checkup <24 h after discharge home.