1273 THE PULMONARY EXCRETION RATE OF CARBON MONOXIDE (VeCO) AND THE BLOOD CARBOXYHEMOGLOBIN LEVEL (COHb) IN PREMATURES AND NORMAL TERMS

Abstract

Using a flow-through collection system and a highly sensitive (1 ppb CO per 2.5 ml sample) reduction gas detector, we measured VeCO and COHb (1-2 λ whole blood) in 20 normal terms (38-42 wks) and 23 prematures (28-36 wks) breathing room air in the first week of life. The mean VeCO (16.7±5.0 μl/kg/hr) of the prematures was greater than that (13.9±3.5 μ1/kg/hr) of the normal terms (p < .05). VeCO varied among the prematures (range 5.6 to 28.1 μ1/kg/hr) and was not related simply to gestational age. Based on a linear relationship between room air CO (RACO) and COHb (p < .0005), each infant's COHb was corrected (COHbc) for RACO (.36 - 3.10 ppm). The mean COHbc (.58±.18% sat.) of prematures (range .29-1.19%) was greater than that (.45±.11% sat.; n=15) of normal terms (p < .025). The 8 prematures who required phototherapy had higher VeCO (19.5±5.5 vs 15.1±4.1 μ1/kg/hr; p < .05) and higher COHbc (.71±.21 vs.51±.12% sat.; p < .01) means compared to those of the prematures who did not. These data suggest that 1) prematures have a wide range of CO production rates, 2) this range is not the result of known hemolytic disease or related simply to gestational age, and 3) other factors associated with prematurity but variable among individual prematures may be contributing to increased CO production rates in certain infants.