An EMT should expect that a patient exposed to cyanide will have which pulse oximetry reading?

An EMT should expect that a patient exposed to cyanide will have which pulse oximetry reading?

• A. Normal pulse oximetry readings.
• B. Elevated pulse oximetry readings.
• C. Decreased pulse oximetry readings.
• D. Inaccurate readings due to perfusion issues.

Answer: (A)

Pulse oximetry measures the amount of oxygen bound to arterial hemoglobin, i.e., arterial oxygen saturation, not how well tissues are using that oxygen. In cyanide exposure, the lungs and blood can be fully oxy­genated, but the cells cannot utilize the oxygen. That cellular incapacity means arterial saturation can stay normal even though tissues are starved of oxygen. So you would expect a normal pulse oximetry reading. An elevated reading isn’t typically seen, and a decreased reading would suggest actual hypoxemia or poor lung gas exchange rather than the cellular-block effect of cyanide. Readings can be unreliable if perfusion is severely compromised, but the common expectation in cyanide poisoning is a normal SpO2.

Pulse oximetry measures the amount of oxygen bound to arterial hemoglobin, i.e., arterial oxygen saturation, not how well tissues are using that oxygen. In cyanide exposure, the lungs and blood can be fully oxy­genated, but the cells cannot utilize the oxygen. That cellular incapacity means arterial saturation can stay normal even though tissues are starved of oxygen. So you would expect a normal pulse oximetry reading. An elevated reading isn’t typically seen, and a decreased reading would suggest actual hypoxemia or poor lung gas exchange rather than the cellular-block effect of cyanide. Readings can be unreliable if perfusion is severely compromised, but the common expectation in cyanide poisoning is a normal SpO2.