Fundamental Parameters Influencing the Accumulation and Elimination of Carbon Monoxide by Adult Human Beings

Th, Allen; Rw, Allard

doi:10.21236/ad0265519

Cited by 2 publications

(1 citation statement)

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“…These workers, however, seem not to have considered that [COHb] [COHb]. Previous studies (1)(2)(3)(4) have been concerned with the relationships of exogenous CO and blood [COHb) but did not consider endogenous CO production and, therefore, these approaches have large errors when exposure to exogenous CO is relatively small. In the present study we have made measurements of the variation of exposure to exogenous CO in our hospital population and have used these data to estimate variation of [COHbex] is not a precise index of Vco since it is markedly influenced by other parameters.…”

Section: Methodsmentioning

confidence: 99%

Considerations of the physiological variables that determine the blood carboxyhemoglobin concentration in man.

Coburn¹,

Forster²,

Kane³

1965

J. Clin. Invest.

409

207

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Numerous publications have considered the effects of inspiring high concentrations of CO on the venous blood carboxyhemoglobin concentration [COHb] in man (14). It appears, however, that no previous study has considered the physiological variables that determine [COHb] under conditions where inspired air CO concentrations are in the normal range. It has become apparent in recent years that CO is endogenously produced in normal man as a by-product of hemoglobin catabolism (and probably other hemoproteins as well) and therefore that the body CO stores are influenced by endogenous as well as exogenous CO (5,6). The development of a method of measuring the rate of endogenous CO production (Vco) in man (6) has made it possible to study the relationship of Vco and other variables to [COHb]. This is of particular interest since the latter has been used as an index of hemolysis (7). The Vco has been shown to reflect quantitatively the rate of circulating erythrocyte hemoglobin destruction in normal subjects (8) and in patients with hemolytic anemia (9), and the accuracy of this index would depend on how closely [COHb] reflects Vco.In this paper we have developed equations that appear to describe the major physiological variables that determine blood [COHb] have applied these equations to data obtained from a) normal subjects, b) male volunteers who breathed 100% oxygen for extended periods of time, and c) patients with elevated rates of endogenous CO production. MethodsAir CO measurements. Samples of air taken from the "wards" of the Hospital of the University of Pennsylvania were analyzed for CO concentrations with an infrared CO meter. This instrument has an error (SD) of 4-0.00004% CO and requires a 200-ml sample. These samples were collected during the summer of 1964. Smoking is prohibited in the areas where these samples were collected. We also measured the CO concentrations in air samples taken from smoke-filled conference rooms, a small nonventilated room that we purposely filled with smoke by burning cigarettes, and a rural area well away from automobile combustion. Diurnal changes in blood [COHb] were measured in one subject and compared with the changes in percentage of CO in his environment. Blood [COHb] was determined by a method in which gas extracted from a 2-ml blood sample is measured in the infrared CO meter. This method has an error (SD) of 40.03% [COHb]( 10).Washout experiments. Three normal young male subjects breathed 100% oxygen for 4 to 8 hours. The subjects were seated, wore a noseclip, and breathed the oxygen through a mouthpiece using an open circuit equipped with two one-way valves that directed the expired gas into a 100-L bag in a box, which was in turn connected to a Tissot spirometer. The inspired oxygen contained less than 0.00001% CO. At hourly intervals minute ventilation was measured, expired gas samples were collected and analyzed for CO, and venous blood was drawn and analyzed for [COHb]. The rate of CO excretion (VEco) was calculated from the minute ventilation and CO concen...

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Section: Methodsmentioning

confidence: 99%