Carboxyhaemoglobin levels and free-radical-related diseases in prematurely born infants

Carboxyhaemoglobin (COHb) levels may reflect the level of early oxidative stress which plays a role in mediating free-radical-related diseases in prematurely born infants.To assess the relationship of COHb levels in the first seven days of after birth to the development of bronchopulmonary dysplasia (BPD) and other free-radical-related diseases.Retrospective analysis of routinely performed COHb via blood gas samples of infants born at less than 30 weeks of gestation admitted to a tertiary neonatal intensive care unit was undertaken.One hundred and four infants were included with a median (range) gestational age of 27.4 (22.4-29.9) weeks and a birthweight of 865 (395-1710) grams.The maximum COHb per infant per day was recorded for the first 28 days and BPD and other free-radical-related diseases including intraventricular haemorrhage (IVH) were noted. The severity of BPD, requirement for home oxygen on discharge and survival to discharge were also recorded.Infants who developed BPD (n = 76) had significantly higher COHb levels in the first seven days [1.7% (0.3-6.8)] compared to those that did not develop BPD [1.6% (0.9-3.8); p = 0.001]. Higher COHb levels in the first seven days after birth were also observed in infants with grade three/four IVH [n = 20; 1.9% (1.0-6.8)] compared to those without [1.6% (0.3-5.6); p < 0.001]. COHb levels, however, were not associated with the duration of ventilation, BPD severity or survival to discharge.Higher COHb levels in prematurely born infants were associated with the development of BPD and IVH.