Emergency Medical Technician (EMT) Intermediate Practice Exam

When using a pulse oximeter, what should be considered to ensure accurate readings?

1. Skin temperature of the patient

2. Presence of nail polish

3. Abnormally bound hemoglobin

4. Pulse rate

The correct answer is: Abnormally bound hemoglobin

Using a pulse oximeter requires consideration of various factors that can influence the accuracy of the readings. Abnormally bound hemoglobin, such as carbon monoxide-bound hemoglobin or methemoglobin, can significantly skew the results provided by a pulse oximeter. These forms of hemoglobin can interfere with the device's ability to detect the correct saturation levels because the technology relies on specific light absorbance properties of normal oxyhemoglobin versus deoxyhemoglobin. In cases where there are abnormal hemoglobin types, the pulse oximeter may misinterpret the light passing through the tissue, resulting in misleading readings. This makes it crucial for healthcare providers to recognize when abnormal hemoglobin might be present and to consider alternative methods of assessing oxygenation, such as blood gas analysis, which may offer more accurate information. Other factors, like skin temperature, presence of nail polish, and pulse rate, can also influence readings to a certain extent, but they do not typically create as profound an impact on the results as the presence of abnormal hemoglobin does.