6.10 : Pulse Oximetry

Pulse oximetry, or SpO₂, is a non-invasive method for continuously monitoring arterial oxygen saturation (SaO₂). This procedure involves attaching a probe or sensor to the patient's fingertip, forehead, earlobe, or nose bridge. The sensor works by detecting changes in oxygen saturation levels through light signals generated by the oximeter and reflected by the pulsing blood under the probe.

Purpose

Average SpO₂ values are greater than 95%. If the readings fall below 90%, it indicates that tissues are not receiving enough oxygen, necessitating further evaluation. Pulse oximetry is particularly valuable in perioperative and critical care situations where anesthesia, sedation, or decreased consciousness may mask signs of hypoxia. It allows nurses to detect changes in SpO₂ swiftly and administer appropriate treatment.

Procedure

To ensure accurate readings, the nurse should verify the correct placement of the probe and minimize or eliminate excess motion, such as shivering or movement of the extremity. It's noteworthy that pulse oximetry readings become less accurate when the SpO₂ falls below 70%.

Nursing Responsibilities

Nurses should be aware of factors that can alter the accuracy of pulse oximetry, including motion, anemia, cold extremities, bright fluorescent lights, intravascular dyes, acrylic nails, and dark skin color. In cases where the accuracy of SpO₂ reading is doubtful, an arterial blood gas (ABG) analysis should be obtained to verify the values.