Effect of hematocrit on exhaled carbon monoxide in healthy newborn infants.
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.


METHODS
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 1.88 ppm (1.3 to 3.4 ppm). ETCOc correlated significantly with HCT (R 2=10.1%, p=0.015) and with Hb (R 2=11%, p=0.011). Infants with a capillary HCT >65% had significantly higher ETCOc (mean 1.99+/-0.49 ppm) than infants with a capillary HCT <65% (1.74+/-0.39 ppm), 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.
Barak
Mila
M
Lis Maternity Hospital, The Sackler Faculty of Medicine Tel Aviv, Israel.
Oron
Tal
T
Mimouni
Francis B
FB
Dollberg
Shaul
S
Littner
Yoav
Y
D001944:Breath Tests; D002248:Carbon Monoxide / Q000097:blood*; D005260:Female; D006400:Hematocrit / Q000706:statistics & numerical data*; D006452:Hemoglobinometry; D006801:Humans; D007231:Infant, Newborn / Q000097:blood*; D008297:Male; D012016:Reference Values; D013223:Statistics as Topic
D002248:Carbon Monoxide