Carbon Monoxide Poisoning Musings…
*** You CANNOT measure how much carbon monoxide is in the blood using a non-invasive pulse oxymeter or a standard arterial blood gas measurement! You must have a special blood gas machine called a co-oxymeter to make this measurement!.***
I am a lung/critical care specialist in my real job. I appreciate Steve’s warnings about carbon monoxide. Carbon monoxide(CO) is an odorless, colorless gas that binds to hemoglobin, the protein molecule in blood that binds and carries oxygen from the lungs to the tissues of the body. The CO binds to hemoglobin with an affinity 100 times greater than that of oxygen. This means that if there is one CO molecule for every 100 oxygen molecules, 50% of the hemoglobin will bind with CO and the remaining hemoglobin will bind with oxygen. This means that even very small quantities CO in the air that are breathed into the lungs preferentially bind to hemoglobin in a nearly irreversible fashion effectively poisoning that molecule so it is no longer able to participate in meaningful oxygen delivery to the body tissues. As the CO exposure continues, the poisoning is cumulative and the body becomes increasingly oxygen starved. Oxygen delivery to the body by hemoglobin is not linear. If the oxygen saturation in your blood is 88%, you qualify for home oxygen by Medicare criteria! A normal oxygen saturation in the blood for someone with normal lungs at low altitude is 92% or above (meaning that 92% of the hemoglobin is bound to oxygen). Most normal people have an oxygen saturation of about 96%. If you are exposed to CO that binds up between 4 to 8% of your hemoglobin, your body is being starved for oxygen.
Most cigarette smokers have a CO level in their blood (called carbocyhemoglobin level) of about 4 to 6%.
1/2 of 1 percent of carbon monoxide mixed in room air (with 21% oxygen) will bind 50% of your hemoglobin at steady state. Permanent neuralgic damage occurs with a CO level of 17%.and above. The antidote for CO poisoning is high oxygen concentration. This therapy attempts to recapture some of the hemoglobin that was bound by the CO by direct competition. This is a slow process and irreversible neurological damage or death frequently occurs. The gold standard treatment for CO poisoning is immediate placement in a hyperbaric oxygen chamber.