Certified Pulmonary Function Technologist (CPFT) Practice Exam

What is considered a normal level of carboxyhemoglobin (COHb)?

1. 0-1%

2. 2-5%

3. 5-10%

4. 10-15%

The correct answer is: 0-1%

A normal level of carboxyhemoglobin (COHb) is typically recognized to be in the range of 0-1%. This measurement reflects the percentage of hemoglobin in the blood that is bound to carbon monoxide, which is a hazardous gas that can interfere with the blood's ability to carry oxygen. In healthy individuals who are not exposed to significant levels of carbon monoxide, such as those living in well-ventilated environments without exposure to smoke or exhaust gases, the COHb levels are usually very low, typically within that 0-1% range. This level indicates a normal state of functioning without any abnormal exposure to carbon monoxide. As COHb levels rise, even slightly above this normal range, there is an increasing risk of oxygen transport issues, which could lead to symptoms of carbon monoxide poisoning. Therefore, the 0-1% range serves as an important benchmark in assessing potential carbon monoxide exposure and toxicity in patients.