JBL EMT Practice Exam

You are evaluating a patient who has been exposed to cyanide. What should you expect to find in terms of oxygen saturation?

1. Decreased because of inhibited cellular usage of oxygen

2. Decreased due to impaired ventilation

3. Increased as a result of oxidative stress on cells

4. Normal because cyanide affects cellular respiration

The correct answer is: Normal because cyanide affects cellular respiration

When a patient is exposed to cyanide, the expected outcome in terms of oxygen saturation is that it will remain normal because cyanide affects cellular respiration. Cyanide works by inhibiting the utilization of oxygen at the cellular level, specifically by interfering with the enzyme cytochrome c oxidase in the electron transport chain. This disruption prevents cells from using oxygen effectively, leading to cellular hypoxia and ultimately tissue damage. Despite this inhibition of cellular oxygen usage, the overall oxygen saturation level in the blood may remain relatively normal as measured by pulse oximetry, as oxygen is still present in the bloodstream but is not being effectively utilized at the cellular level due to the cyanide exposure. Option A is incorrect because inhibited cellular oxygen usage would lead to decreased oxygen saturation, not normal levels. Option B is incorrect as impaired ventilation would affect the amount of oxygen reaching the bloodstream, resulting in decreased oxygen saturation. Option C is incorrect because oxidative stress on cells would not lead to increased oxygen saturation; instead, it would likely contribute to cellular damage and dysfunction, further exacerbating the effects of cyanide poisoning.