PREDICTION OF CARBOXYHEMOGLOBIN FORMATION DUE TO TRANSIENT EXPOSURE TO CARBON-MONOXIDE

Fifteen men were exposed to 6,683 ppm (CO)-O-18 for 3.09-6.65 min. Art erial and antecubital vein blood samples were drawn at 1-min intervals beginning at the start of (CO)-O-18 inhalation and ending 10 min late r. Simultaneously, alveolar ventilation was calculated from the measur ed values of minute ventilation and dead space. All other parameters o f the Coburn-Forster-Kane equation (CFKE), except the Haldane affinity ratio, were measured separately in each subject. Means of CFKE predic tions of increases in venous HbCO (Delta HbCO) in samples collected si milar to 2 min after cessation of exposure were accurate, but the rang e in errors of prediction for individual subjects was +/- 3.8% HbCO, d epending on the time after exposure cessation. Increases in venous and arterial HbCO were inaccurately predicted during and immediately afte r HbCO formation, however. Venous blood was overestimated during CO up take because of a delayed appearance of HbCO. Individual subjects diff ered markedly in the degree of delay of HbCO appearance in venous bloo d. Arterial Delta HbCO was consistently underestimated either by the C FKE or by predictions based on venous blood samples. Thus, exposure of such organs as brain or heart to HbCO may be substantially higher tha n expected during transient high-level CO exposure.