Accelerated Clearance of Carbon Monoxide by Normocapnic Hyperpnea in Human Subjects

Akinori Takeuchi, A. Vesely, J. Rucker, J. Tesler, L. Sommer, A. Lavene, L. Fedorko, S. Iscoe, J. A. Fisher
1999 Prehospital and Disaster Medicine  
The rate of carbon monoxide (CO) elimination is increased by CO 2 -stimulated ventilation in CO poisoned, unconscious dogs. However, most conscious humans are unlikely to tolerate prolonged breathing of 5-10% CO 2 . We proposed to determine: 1) the effect on the half-time of carboxyhemoglobin (COHb) elimination (Tj/ 2 ) of a voluntary increase in ventilation of approximately 5 times from resting levels with FjO 2 = 100%); 2) whether this level of hyperpnea is sustainable long enough to provide
more » ... herapeutic benefit when the PCO 2 is maintained at control levels; and 3) the effect of minute ventilation on the half time of elimination of carboxyhemoglobin. Methods: After obtaining institutional board approval, seven normal male volunteers were exposed to CO until their venous [COHb] reached 10%. They then breathed 100% O 2 at resting ventilation or approximately 5 times the resting level of ventilation (~96% O 2 , balance CO 2 ) for 1.5 h on separate days. A non-rebreathing circuit (Eur. Respir. J. 1998;12(3):698.) was used to prevent changes in P E^C O 2 during hyperpnea. The Ty 2 was calculated from plots of [HbCO] versus time. Results: 1) The Tjy 2 significantly fell from 78 minutes at resting ventilation to 31 minutes with hyperpnea (p <0.01)( Figure 1) ; 2) All subjects sustained the hyperpnea without difficulty; and 3) There was a hyperbolic relation between minute ventilation (normalized for body weight and a [Hb] of 15 g/L) and the Tjy 2 ( Figure 2) . P E T CO 2 during hyperpnea did not differ from that during resting ventilation.
doi:10.1017/s1049023x00034713 fatcat:u3ghcfjy6bbohfrttnvblyapfe