Estimation of red blood cell lifespan from alveolar carbon monoxide measurements

Krishnan, Sheeja M and Dixit, Narendra M (2009) Estimation of red blood cell lifespan from alveolar carbon monoxide measurements. In: Translational Research, 154 (1). pp. 15-17.

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Abstract

Measurement of alveolar carbon monoxide (CO) presents a facile technique to estimate the lifespan, L, of red blood cells (RBCs) in vivo. Several recent studies employ this technique and calculate L (in days) using the expression, L = 13.8 (Hb)/P-CO(end), where (Hb) is the concentration (in g/dL) of hemoglobin in blood, and P-CO(end) is the endogenous production of CO (in ppm). Implicit in this calculation is the assumption that the fraction, f, of endogenous CO production due to RBC turnover is a constant equal to 0.7, which yields the expected RBC lifespan, L approximate to 120 days, in normal controls. In anemic patients, however, enhanced RBC turnover may increase f substantially above 0.7. The above expression then overestimates L. Here, we deriv an alternative tive expression, L = 3390[Hb]/322P(CO (end)-110, that accounts explicitly for the dependence of f on the rate of RBC turnover and thereby provides more accurate estimates of L without requiring additional measurements. Using the latter expression, we recalculate L from recent measurements on hepatitis C virus infected patients undergoing treatment with ribavirin. We find that our estimates of L in these patients (39 +/- 13 days) are significantly lower than current estimates (46 +/- 14 days), indicating that ribavirin affects RBC survival more severely than expected from current studies. Our expression for L is simple to employ in a clinical setting and would render the broadly applicable technique of alveolar CO measurement for the estimation of RBC lifespan more accurate.

Item Type:	Journal Article
Publication:	Translational Research
Publisher:	Elsevier Science
Additional Information:	Coopyright of this article belongs to Elsevier Science.
Department/Centre:	Division of Mechanical Sciences > Chemical Engineering
Date Deposited:	22 Jul 2009 07:24
Last Modified:	19 Sep 2010 05:38
URI:	http://eprints.iisc.ac.in/id/eprint/21626

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