Room Air Exchange Research Articles

Elevated carbon monoxide levels from smoking in blood donors.

The greater affinity of hemoglobin for carbon monoxide than for oxygen can lead to increased carboxyhemoglobin in blood donors who smoke. The presence of carboxyhemoglobin has an adverse effect on the oxygen dissociation curve resulting in a decreased release of oxygen to the tissues. When this is present, along with the progressive decrease in oxygen‐carrying capacity resulting from storage, bank blood will have an even greater loss in ability to provide oxygen to the tissues of a recipient. Carbon monoxide can be displaced from hemoglobin by oxygen when there is room air exchange by donor respiration. The rate of this exchange can be accelerated by taking advantage of the natural gas laws and using a higher concentration of oxygen for respiration or by increasing ventilatory exchange. Volunteers in the present study raised their carboxyhemoglobin levels by heavy smoking and had the rate of decrease in carboxyhemoglobin tested either after breathing pure oxygen or after exercise‐induced hyperventilation. The decreases in carboxyhemoglobin levels were accelerated by either method. Donors who had not smoked showed low carboxyhemoglobin levels which did not decrease after exercise. Thus, blood banks could minimize carboxyhemoglobin levels in collected blood by restricting the smoking of donors, by not collecting blood for at least 2 to 4 hours after smoking, or by using oxygen breathing or exercise‐induced hyperventilation to accelerate the donors excretion of carbon monoxide.