The elements influence Spo2 reading
Interference of lights
The surrounding light can affect the reading because there are a lot of red lights in it. When the light hits the spo2 probe, it distorts the SpO2 waveform, resulting in inaccurate readings. Sunlight or indoor light can also lead to misreading. Studies have shown that fluorescence and sunlight can cause low SpO2 readings.
Whether the sensor has a proper connection with the tissue
When there is dust or others on the sensor, it can cause misreading or even failure. Long nails and artificial nails will interfere with SpO2 readings. In addition, the depth and direction of the finger inserted into the probe and the excessive movement of the monitoring limbs can cause the movement of the fingertip and cause the SpO2 reading to be low or not displayed.
The influence of tissue blood supply on spo2 reading
The accurate reading of the pulse oximeter depends on good tissue perfusion. Long-term use of a finger for monitoring, the pressure caused by the fingertip spo2 sensor on the fingertips can affect local blood circulation. Once the patient has the blood pressure measurement with the same limb, the infusion of the NIBP cuff will influence the blood flow, which also affects the spo2 reading. In addition, cold skin on the fingertips and poor peripheral circulation can also make SpO2 readings low or not displayed.
The influence of nail polish, thick skin, or skin pigmentation
Partial thick skin can affect the penetration of light for a misreading. And nail polish, especially purple and blue, can make SpO2 readings lower due to excessive absorption of red wavelengths.
Artifacts
Excessive movement of the sensor and cable will cause movement artifacts. For example, the patient's arm moves, or the cable crosses the ventilator tube every time it moves with the breathing cycle. It will cause movement artifacts which can cause SpO2 misreading.
The effect of vasoactive drugs
Long-term application of dopamine, norepinephrine, and other drugs can cause the narrowing of peripheral blood vessels, which initiates the reduction of pulse volume and cause distortion or no display of SpO2 waveform. Dopamine, procaine, prilocaine, lidocaine, and other drugs can cause severe deviations in blood oxygen measurement.
The monitor problems
The poor connection of the spo2 cables with the monitor will affect the accuracy of the spo2 monitoring. So does the damage to the sensor and cables.
How to identify and eliminate these influences
Pretreatment
Before monitoring, it is better to select fingers with thin skin and no pigmentation for monitoring. Also, we have to avoid using the finger with nail polish or other colored dyes. If necessary, manicure the nails and remove the nail polish. Also, we have to check the performance of the probe before spo2 measurement. Before and after each time measurement, we have to wipe the sensor with a slightly damp soft cloth to remove dust and other objects. Follow the instructions provided with the probe to connect the sensor to the patient.
Avoid ambient light
During the SpO2 measurement, keep the light soft. If necessary, use a black cloth or opaque tape to cover the probe. When the sunlight is strong, drawing the curtains to prevent direct sunlight from the sensor.
Improve local blood supply
For long-time spo2 monitoring patients, we have to change the measurement position regularly. Check the skin condition of the finger at the probe every 3 to 4 hours, and pay attention to whether there is redness, swelling, and other skin damage. During the monitoring, we also have to keep the limb warm and keep the temperature indoor at 25~28℃. When necessary, the hands should be covered with quilts or use other tools for warm-keeping. Also, we have to avoid using the oximeter on the same site or limb as the blood pressure cuff or vascular intravenous injection.
Reduce the movement artifacts
Choose a relatively stationary place for the patient to reduce movement artifacts. Explain the precautions to the patient during the monitoring and reduce the activity of the tested limbs. If necessary, we can choose ear lab spo2 probes can or toes probes, and newborns can be placed on the soles of the feet. These measures can help reduce movement artifacts. For a sensor with a cable that directly guides the patient, the cable can be tied to one hand or foot to reduce cable movement and movement artifacts.
0 Comments