Differences in arteriovenous carboxyhemoglobin in neonates with noninflammatory pulmonary diseases.

Background: To retrospectively examine whether differences in arteriovenous carboxyhemoglobin (a-vCOHb) can be used as a marker for evaluating the severity of neonatal lung disease that develops soon after birth.

Methods: The subjects were 129 newborn neonates who were classified into three groups comprising 48 infants with severe respiratory disorder (group S), 46 with mild-to-moderate respiratory disorder (group M), and 35 in a control group without respiratory disorder (group C). Various parameters including COHb were measured using a blood gas analyzer/oximeter at the time of admission, with sampling of arteries and veins performed at short intervals (within 30 min).

Results: The arterial COHb values were significantly higher in group C than in group S. The a-vCOHb values were significantly higher in groups C and M than in group S. This suggested that a loss of carbon monoxide excretion due to the generation of shunt blood with lung collapse at the alveolar level and a decrease in the total amount of carbon monoxide generated within the lungs resulted in the decrease of a-vCOHb values in group S. Receiver operating characteristic curve analysis of a-vCOHb for predicting the need for respiratory support identified an a-vCOHb cut-off value of 0.3% with a sensitivity of 75% and specificity of 74% (p < 0.001).

Conclusion: An a-vCOHb cut-off value of 0.3% may be useful in determining the severity of lung disease in the early neonatal period.