Carbon Monoxide Facts 2018-01-13T20:52:05+00:00

Carbon Monoxide Facts

 What is Carbon Monoxide Poisoning ?

Carbon monoxide poisoning typically occurs from breathing in too much carbon monoxide (CO). Symptoms are often described as “flu-like” and commonly include headachedizziness, weakness, vomiting, chest pain, and confusion. Large exposures can result in loss of consciousnessarrhythmiasseizures, or death. The classically described “cherry red skin” rarely occurs. Long term complications may include feeling tired, trouble with memory, and movement problems.[

CO is a colorless and odorless gas that is always part of exhaust from gasoline and diesel motor vehicles. When CO is absorbed into tissues via your lungs, skin, eyes, ears, nose and mouth, it can cause a wide range of adverse effects that may persist for weeks, months or years after your CO exposure stops. As a rule of thumb, the more total CO exposure you’ve had (which you can judge from the miles on your Explorer), the longer it may take to excrete all the CO you
have accumulated. [Note that the CO in blood bound to hemoglobin as carboxyhemoglobin (HbCO) is relatively harmless and does not impair oxygen delivery to your tissues unless the gap between arterial and venous is greater than 3%, or if either is over 50%].

What is the normal level of carbon monoxide in the blood?

CO can be measured in both arterial and venous blood as carboxyhemoglobin (COHb), but these tests are expensive, painful, inaccurate, unnecessary and unhelpful, especially if only one or the other is done. Both are needed to determine if CO is still being absorbed (when arterial is greater than venous COHb) or excreted (when venous is greater, which is abnormal and unhealthy unless you are pregnant or in premenstrual phase of your period). Healthy individuals, in contrast, are in healthy arterial-venous equilibrium, with COHb less than 1% in non-smokers and 3-10% in smokers. It is faster, less painful, less expensive and more accurate to measure CO in arteries, veins and tissues via exhaled breath, simply by holding your breath before blowing the last of your exhalation into a clear plastic bag.

 Can a blood test detect carbon monoxide poisoning?

 Yes, but both arterial and venous blood tests for carboxyhemoglobin (COHb) can only measure the amount of CO that is bound to hemoglobin, not the far more dangerous level of unbound (or free) CO that remains in tissues and organs. This can be measured only via exhaled breath which offers additional advantages of being non-invasive, faster, less expensive and more accurate than blood testing.

Contributed by Albert Donnay, MC, MHS,

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