Pulse oximetry should be avoided where significant amounts of carbon monoxide have been inhaled until levels have fallen. Significant carboxyhemoglobin levels usually occur in patients admitted from a fire. Cigarette smoking can cause over-readings up to four hours after smoking a cigarette. Hypercapnia As well as supplying the body with oxygen, breathing oxygen removes carbon dioxide, a waste product of metabolism. Oximetry measures the saturation of hemoglobin by oxygen, but does not indicate carbon dioxide carriage.
Carbon dioxide is used in the production of carbonic acid, the main intravascular acid.
Hypercapnia contributes significantly to respiratory acidosis. Nurses should observe patients breathing pattern rate and depth. Poor breathing patterns may mean that blood carbon dioxide remains high. Any concerns should be reported to the medical staff so that appropriate drugs, such as respiratory stimulants, may be prescribed. Nurses should continue to monitor closely the patients respiratory pattern, as well as oximetry.