West Coast EMT Block One Exam

A patient exposed to cyanide is likely to have which of the following observations?

1. An abnormally slow pulse rate.

2. Skin that is cherry red and hot.

3. An abnormally slow respiratory rate.

4. A normal pulse oximetry reading.

The correct answer is: A normal pulse oximetry reading.

When a patient is exposed to cyanide, the body's ability to utilize oxygen is severely impaired, leading to tissue hypoxia even in the presence of adequate oxygen levels in the blood. This can result in a situation where a pulse oximeter, which measures oxygen saturation in the blood, may show a normal reading. Although there is plenty of oxygen in the bloodstream, the tissues cannot utilize it properly because of the cyanide's interference with cellular respiration. In cases of cyanide poisoning, the normal appearance of the skin may also be misleading. While some may expect a typical reaction such as a flushed appearance or central cyanosis (blue discoloration), the actual manifestation might lead to a cherry-red discoloration due to the binding of cyanide to hemoglobin, which also exacerbates the misinterpretation of pulse oximetry readings. A normal pulse oximetry reading, therefore, is consistent with cyanide exposure because of this unique physiological impact, despite the life-threatening hypoxic condition the patient is experiencing. Understanding this response is crucial for EMTs and healthcare providers for effective diagnosis and management in emergency situations involving cyanide toxicity.