Corrected end-tidal carbon monoxide closely correlates with the corrected reticulocyte count in coombs' test-positive term neonates.
OBJECTIVE
To evaluate clinical usefulness of corrected end-tidal carbon monoxide (ETCOc) measurements in healthy, term, Coombs' test-positive neonates and correlate it to the corrected reticulocyte count (RC).


METHODS
ETCOc and RC were determined (at 36 +/- 12 hours of age) in 50 Coombs' test-positive neonates and compared with the ETCOc values of 50 Coombs' test-negative neonates.


RESULTS
Fifty percent of Coombs' test-positive infants had RCs <5% (within a normal range for a healthy newborn) and ETCOc = 1.8 +/- 0.34 parts per million (ppm) and likely did not exhibit hemolysis. Among infants with elevated RCs, 72% had RCs between 5% and 8% and ETCOc = 2.77 +/- 0.68 ppm, and 28% had RCs >8% and ETCOc = 4.52 +/- 0.83 ppm. There was an almost linear correlation (r = 0.86) between the RC and the ETCOc among Coombs' test-positive infants. The 50 Coombs' test-negative infants had ETCOc = 1.6 +/- 0.45 ppm. Serial ETCOc measurements were performed in 14 Coombs' test-positive infants: in all but 1 infant ETCOc values declined over time.


CONCLUSIONS
There is a good correlation between ETCOc and RC in Coombs' test-positive infants. ETCOc >2.5 ppm predicts a significant elevation of RC in 90% of Coombs' test-positive infants.
Javier
Maria Cristina
MC
Division of Neonatology, Department of Pediatrics, Weill Medical College of Cornell University, New York, New York 10021, USA.
Krauss
Alfred
A
Nesin
Mirjana
M
D001787:Blood Group Incompatibility; D001944:Breath Tests; D002248:Carbon Monoxide / Q000378:metabolism; D003298:Coombs Test; D006461:Hemolysis; D006801:Humans; D007231:Infant, Newborn; D015997:Neonatal Screening; D011446:Prospective Studies; D017701:Reticulocyte Count; D013990:Tidal Volume
D002248:Carbon Monoxide