Certified Flight Registered Nurse (CFRN) 2025 – 400 Free Practice Questions to Pass the Exam

Question: 1 / 400

Which statement about pulse oximetry in the context of mechanical ventilation is TRUE?

It is useful in carbon monoxide poisoning.

It can be used in patients suffering from hypotension.

It may be unreliable in hypothermic patients.

The statement that pulse oximetry may be unreliable in hypothermic patients is true because low body temperature can cause peripheral vasoconstriction, which may lead to decreased blood flow to the extremities where the pulse oximeter is typically placed. This reduced perfusion can result in inaccurate readings or a failure to obtain a reading altogether.

In hypothermic patients, the physiological response can interfere not only with the sensor's ability to detect oxygen saturation but also with the waveform needed for accurate measurement. Thus, clinicians should be cautious in interpreting pulse oximetry data for these patients and consider additional assessment methods for more accurate oxygen saturation levels.

The other statements do not hold true in the context of mechanical ventilation and pulse oximetry. For example, while pulse oximeters can detect hypoxemia, they are not effective for detecting carbon monoxide poisoning, as both oxygen and carbon monoxide can bind to hemoglobin, leading to falsely normal readings. Similarly, while patients suffering from hypotension can still have pulse oximetry applied, it may not provide a complete picture of their oxygen status due to potential shunting or poor perfusion. Lastly, peripheral vascular disease can adversely affect pulse oximetry readings due to compromised blood flow, resulting in unreliable

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Readings are unaffected by peripheral vascular disease.

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