Effect of hematocrit on exhaled carbon monoxide in healthy newborn infants

Mila Barak*, Tal Oron, Francis B. Mimouni, Shaul Dollberg, Yoav Littner

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review


Objective: We tested the hypothesis that, the red blood cell (RBC) mass, estimated by hematocrit (HCT) or hemoglobin (Hb) level, influences the carbon monoxide (CO) production rate. Study design: The relationship between end tidal CO corrected for ambient carbon monoxide level (ETCOc) and the RBC mass have been studied in 58 full-term infants at the mean age 4.9 hours. Results: Mean ETCOc was 1.88ppm (1.3 to 3.4ppm). ETCOc correlated significantly with HCT (R2 =10.1%, p=0.015) and with Hb (R2 =11%, p=0.011). Infants with a capillary HCT >65% had significantly higher ETCOc (mean 1.99±0.49ppm) than infants with a capillary HCT <65% (1.74±0.39ppm), p=0.035. When CO production was corrected for HCT (ETCOc/HCT), this difference did not longer exist. Conclusions: In newborn infants ETCOc significantly correlates with RBC mass. Comparing different infant's CO generation rate one should take into consideration their initial RBC level. In order to adjust for the existing differences in RBC, we suggest the use of the ETCOc/HCT index.

Original languageEnglish
Pages (from-to)784-787
Number of pages4
JournalJournal of Perinatology
Issue number12
StatePublished - Dec 2005
Externally publishedYes


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