Abstract
To capitalize on the equi-molar relation between endogenous carbon monoxide production (VCO) and heme turnover, we have e-valuated 6 alternative sampling methods for detecting increased VCO. The greatest resolution of VCO was achieved when %COHb levels were corrected for ambient CO exposure. This correction was based on the CO content of a diffusion chamber that remained at the bedside for 18 hours prior to obtaining a 0.5 cc sample of the patient's blood. The gas space of the chamber (a 100 ml glass syringe) and the area of the diffusion membrane (a loop of silicone tubing) are adjusted according to the patient's CO space and pulmonary function so that the patient's T1/2 for co equilibration with ambient air is duplicated. Our emperic data confirms the theoretical prediction that the effect of ambient CO on %COHb is described by the following e-quation: Δ%COHb=0.16 × CO in ppm. The relation between VCO and %COHb was derived from the intercept of a plot of %COHb vs ambient CO in normal individuals. Confirmation was obtained with the much more cumbersome tests of in vivo survival of Cr51 tagged erythrocytes and measurements of VCO in a rebreathing apparatus. Serial determinations of VCO on patients with Coombs positive hemolytic anemia permitted rapid adjustments of the optimal dose of immuno-suppressive agents. Successive measurements on jaundiced infants demonstrated no increase in VCO during phototherapy. Infants who developed bacterial septicemia did have a pronounced rise in VCO.
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Engel, R., Modler, S., Norberg, W. et al. ENHANCING THE DIAGNOSTIC VALUE OF CARBOXYHEMOGLOBIN (%COHb) DETERMINATIONS. Pediatr Res 8, 467 (1974). https://doi.org/10.1203/00006450-197404000-00761
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DOI: https://doi.org/10.1203/00006450-197404000-00761