Knowledge of carbon monoxide poisoning has its origins to the days of ancient Greece and Rome. Once it was better understood, carbon monoxide poisoning was at times selected as a more “humane way” of execution in ancient Rome, as opposed to more brutal methods.
There have not been any significant advances in the treatment of carbon monoxide poisoning until 1950 when hyperbaric oxygen therapy (HBO) was first demonstrated to confer a benefit in accelerating the elimination of CO from healthy volunteers.
It is therefore worthwhile to review the current algorithm on the stepwise approach in the treatment of CO poisoning, which is based on both the severity of the exposure and the clinical manifestations exhibited by the patient or victim.
First recall that room air is 21% oxygen, and this is what we are all breathing right now.
The treatment of CO poisoning consists of three “levels” of care.
The first level of care is “first aid” which is to remove the victim from the source of CO and get the individual breathing “fresh air”.
As a measure of the “effectiveness” of treatment, it is often useful to speak in terms of the “half-life elimination” of carboxyhemoglobin. On breathing room air, the half-life elimination of carboxyhemoglobin is about four to five hours. Based on a five half-life endpoint, it would take about twenty-four hours, or one day to eliminate almost all of the CO from the body.
Of course, after about eight to ten hours, or two half-life eliminations, about 75% would be eliminated. (The first half-life would get us from 100% to 50% and the second half-life would get us from 50% to 25%.)
NOTE: This is a significantly over-simplified explanation, and there are several important modifiers which depend on the concentration of the inhaled CO gas and the duration of the CO exposure. Moreover, these aspects correlate with the clinical presentation of a patient with CO poisoning along with the clinical manifestations during subsequent medical management. Furthermore, addressing all of this is well beyond the scope of this webpage. This having been said, we will proceed based on this “simplified model”.
Beyond “first aid”, the second level of care is for the victim to breath 100% oxygen through a tight-fitting non-rebreather mask. This approach would reduce the half-life elimination of carboxyhemoglobin to between one to two hours. With a five half-life endpoint in mind, it would take between seven to ten hours to reach this endpoint.
The third level of care is hyperbaric oxygen (HBO) therapy. This is 100% oxygen delivered at between 2.4 to 3.0 atmospheres pressure occurring inside a hyperbaric chamber. In this situation, the half-life elimination reduces to between twenty to thirty minutes. Once again, and based on a five half-life endpoint, it would take between 1.5 and 2.5 hours, or about ninety to one hundred fifty minutes, to reach this endpoint.