Tikuisis P, Kane D M, McLellan T M, Buick F, Fairburn S M
Defence and Civil Institute of Environmental Medicine, North York, Ontario, Canada.
J Appl Physiol (1985). 1992 Apr;72(4):1311-9. doi: 10.1152/jappl.1992.72.4.1311.
The purpose of this study was to test the CFK equation for its prediction of the rate of formation of carboxyhemoglobin (HbCO) in exercising humans by use of measured values of the respiratory variables and to characterize the rate of appearance of HbCO with frequent blood sampling. Ten nonsmoking male subjects were exposed to carbon monoxide (CO) on two separate occasions distinguished by the level of activity. Steady-state exercise was conducted on a cycle ergometer at either a low (approximately 45 W) or moderate (approximately 90 W) power output. Each experiment began with an exposure of 3,000 ppm CO for 3 min during a rest period followed by three intermittent exposures ranging from 3,000 ppm CO for 1 min at low exercise to 667 ppm CO for 3 min at moderate exercise. Increases in HbCO were normalized against predicted values to account for individual differences in the variables that govern CO uptake. No difference in the normalized uptake of CO was found between the low- and moderate-exercise trials. However, the CFK equation underpredicted the increase in HbCO for the exposures at rest and the first exposure at exercise, whereas it overpredicted for the latter two exposures at exercise. The net increase in HbCO after all exposures (approximately 10% HbCO) deviated by less than 1% HbCO between the measured and predicted values. The rate of appearance of HbCO fits a sigmoidal shape with considerable overshoot at the end of exposure. This can be explained by delays in the delivery of CO to the blood sampling point (dorsal hand vein) and by a relatively small blood circulation time compared with other regions of the body. A simple circulation model is used to demonstrate the overshoot phenomenon.
本研究的目的是通过使用呼吸变量的测量值来检验CFK方程对运动人群中碳氧血红蛋白（HbCO）形成速率的预测，并通过频繁采血来表征HbCO的出现速率。10名不吸烟男性受试者在两个不同的活动水平下暴露于一氧化碳（CO）中。在功率输出较低（约45瓦）或中等（约90瓦）的自行车测力计上进行稳态运动。每次实验开始时，在休息期间让受试者暴露于3000 ppm的CO中3分钟，然后进行三次间歇性暴露，从低强度运动时3000 ppm的CO暴露1分钟到中等强度运动时667 ppm的CO暴露3分钟。将HbCO的增加量相对于预测值进行标准化，以考虑控制CO摄取的变量的个体差异。在低强度和中等强度运动试验之间，未发现CO标准化摄取量有差异。然而，CFK方程低估了休息时暴露和运动时首次暴露的HbCO增加量，而高估了运动时后两次暴露的HbCO增加量。所有暴露后HbCO的净增加量（约10% HbCO）在测量值和预测值之间的偏差小于1% HbCO。HbCO的出现速率呈S形，在暴露结束时有相当大的超调。这可以通过CO输送到采血点（手背静脉）的延迟以及与身体其他部位相比相对较短的血液循环时间来解释。使用一个简单的循环模型来演示超调现象。
