Wandering O2 pleth wave

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Hello, I'm new to ICU nursing. Last night I took care of a patient with an O2 pleth wave that corresponded well with the ECG/HR leads but "wandered" up and down with the patients inspirations/expirations. The patient was on pressure control ventilation. Would this cause a "wandering" pleth wave? What would?

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Specializes in ICU.

Where was the O2 sensor located? Usually they are on a finger. If the patients hand is moving alot, that can cause interference. Also, if the patient has poor circulation...low bp, cold, blood pressure cuff on the same arm, generally poor circulation...the sensor may not pick up right. You can try putting the sensor on another finger, or on the ear and see if that helps. Usually, but not always, if the heart rate from the O2 monitor matched the EKG, it is accurate.

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The patient was not moving. The O2 sensor was on the patients forehead, then I moved it to the patient's ear. It was recieving an accurate reading but I was wondering why the difference in amplitude with inspiration/expiration.

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Specializes in Nurse Anesthesia, ICU, ED.

just a guess, but could the pressure from the vent affect his CO, therefore pulse, and cause the wandering of the pleth?

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Could be caused by hypovolemia. This wandering waveform is best seen when the patient is on mech ventilation.

Br J Anaesth. 1999 Feb;82(2):178-81.

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