Pulmonary Concepts in Critical Care

Pulse Oximetry

nursebob 12/30/00

Pulse oximetry is a simple noninvasive test that determines the percentage of hemoglobin saturated by oxygen (SpO2). A sensor is placed over any translucent area where there may be arterial pulsation. This can be a finger, toe, ear lobe or even the lips. This test can help you approximate the arterial saturation (SaO2). Whenever readings are obtained from a finger by the use of the finger probe make sure that the patient is not wearing nail polish and the hand is placed above heart level.

Several factors will influence the accuracy of your reading. Among these are excessive movement, dark pigmentation, vasoconstriction and edema, poor arterial circulation, and a low body temperature. Values may also be inaccurate in patients with severe anemia, elevated bilirubin levels, elevated carboxyhemoglobin and methylhemoglobin levels. To ensure the accuracy of the reading check to make sure that the patients pulse rate correlates with the pulse reading of the pulse oximeter.

The actual oxygen level may be overestimated by three to five percent in patients with borderline oxygenation. Because of this, the pulse oximetry reading must be correlated with other factors such as hard right, blood pressure, and hemoglobin level in order to completely assess oxygen delivery.

REFERENCES:

Tate, Judy RN, MSN and Tsota, Frederick RN, MSN “Using Pulse Oximetry”, Nursing 2000, Vol 30, Number 19, 30

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