Intermittent or continuous carbon monoxide oximetry can be performed noninvasively with a lightweight, portable display unit. The unit is connected to a sensor probe that’s placed on the adult patient’s fingertip or an infant’s foot. The sensor probe collects
data about the patient’s carboxyhemoglobin saturation and sends that information to the oximeter, which then displays the calculated data in the form of a percentage. A carboxyhemoglobin saturation level greater than 2% for nonsmokers and greater than 9% for smokers indicates exposure to exogenous carbon monoxide.

A patient can have increased carbon monoxide levels from chronic exposure to cigarette smoke or from an acute episode, such as from exposure to a combustion heater without adequate ventilation of natural gas, fire, or vehicle exhaust. However, carbon monoxide poisoning is commonly misdiagnosed because the initial signs and symptoms—fatigue, shortness of breath, mild headache, and nausea—are similar to those of a viral-related illness. Severe symptoms include dizziness, increasingly acute headaches, weakness, drowsiness, and nausea accompanied by vomiting. Carbon monoxide poisoning can result in long-term neurologic damage, psychiatric and cardiovascular disorders, and death.