Reduction of carboxyhaemoglobin levels in the venous blood of cigarette smokers following the administration of carbogen

Cigarette smokers have high carboxyhaemoglobin levels which can promote tumour radioresistance. Inhalation of carbogen gas shortens the half-life of carboxyhaemoglobin, increasing tumour radiosensitivity in animal models. Breathing 2.5% carbogen for 30 min results in a Greater reduction in venous blood COHb levels than breathing 5% carbogen for 7 min. (C) 2004 Elsevier Ireland Ltd. All rights reserved.