P2C311: Etcoc Test: An Aid to Identify Neonatal Hemolysis

Background: Per AAP 2004 Clinical Practice Guidelines: Management of Hyperbilirubinemia in infants >35 weeks -
The standard laboratory tests for hemolysis have poor specificity and sensitivity & frequently unhelpful. End-tidal carbon monoxide, corrected for ambient carbon monoxide, End-Tidal Carbon Monoxide (ETCOc), levels can confirm the presence or absence of hemolysis, and ETCOc is the only clinical test that provides a direct measurement of the rates of heme catabolism and bilirubin production.

Methods: In this pilot study, we evaluated whether ETCOc enhances management of Neonatal Hyperbilirubinemia i) reduce the frequency of laboratory draws, ii) reduce the frequency of direct antiglobulin tests (DAT) and iii) reduce cost burden. We also recorded the time to test. The Cedars-Sinai Medical Center IRB evaluated and approved the study.
All Newborns GA>35 weeks and BW> 2000 g, post-natal age 6 hours to < 6 days of age admitted to well-baby nursery at CSMC and any of the following criteria: candidate for early discharge, TsB/ TcB on or > 75th percentile of Bhutani Hyperbilirubinemia Nomogram OR had 2 or more clinical or neurotoxic risk factors for neonatal jaundice. This was a comparative study of “Retrospective” control group versus a “Prospective” group for the indicators listed above.

Results: We resourced a Retrospective cohort of 600 patients was selected by the HERB (Honest Enterprise Research Broker) committee at CSMC to gather data from electronic records who met eligibility criteria. A Prospective Group who consented included 122 patients. Both groups were similar in terms of gender & race distribution and gestational age. i) 84.4% (103/122 lab draws of at least one test compared to 100% (600/600 lab draws) for prospective and retrospective groups, respectively (p=0.0001 by Wilcoxon rank sum test); a reduction of 10.4% in the mean number of Lab tests. ii) 52.5% (64/122) were tested for DAT in the Prospective Group compared to 58% (348/600) in the Retrospective Group, Fisher exact test P = 0.27
iii) mean ETCOc test time was 5.05 + SD 2.43 minutes (range=1 - 14) 71.4% < 5 minutes for the prospective group. We also report that only 2/85 (2.4%) babies with ETCO < 2.0ppm received phototherapy as compared to 13/34 (38.2%) babies with ETCOc > 2.0 ppm received phototherapy (p < 0.0001 by Fisher test).

Conclusion: ETCOc determination enhances routine management of neonatal hyperbilirubinemia in well-baby nursery by decreasing the number of laboratory tests ordered by clinicians to potentially reducing the cost of laboratory and blood testing burden. The time to perform this non-invasive breath test usually averaged 5 minutes at bedside. There was an added advantage of high ETCOc producers to alert the need for likelihood for neonatal phototherapy. Re-interpretation with extrapolation to 2022 Hyperbilirubinemia guidelines and a follow up study is planned.