SMOKING AND HYPOXIA

Smoking produces carbon monoxide which is inhaled. Inhaled carbon monoxide passes easily into the bloodstream where it enters the red blood cells and binds to the haemoglobin. Carbon monoxide binds to haemoglobin much more strongly than oxygen, resulting in a stable compound, carboxyhaemoglobin. Consequently, it prevents the carriage of oxygen from the lungs to the tissues, so that the tissues become hypoxic and thus increasing the smoker’s physiological altitude and making him/her more susceptible to hypoxia.

• At sea level, the chronic smoker has a physiological altitude of about 5000 to 8000 ft (5 to 8% of carbon monoxide in the bood). As a result, for instance, a typical cabin altitude of 8000 ft, will put he/she at an altitude of approximately 13 000 ft. Smoking at 10 000 ft MSL produces effects equivalent to those at higher altitude without smoking. This is called self-induced hypoxia.
• At altitude, the effects of a given level of carboxyhaemoglobin will be markedly increased by any hypoxia which exists as a result of the reduced partial pressure of oxygen in the inhaled air. The immediate treatment of a victim of carbon monoxide poisoning consists of restoration of a safe breathing supply, preferably 100% oxygen if available, and rest at room temperature.