Case3 What to do when SpO2 cannot be measured accurately

There are some cases where it is difficult to measure SpO2, such as with restless patients due to body movement. In order to obtain accurate and stable SpO2 measurements, the probes should be attached in the correct position.

Read More

If accurate or stable SpO2 cannot be obtained, try the following measures;

Attach the Probe Correctly

(1) Make sure that the light emitter and the photo detector face each other as in the image below.

Good attachmentBad attachment

Good attachment (left)

  • The light penetrating the center of the finger is detected.
  • Large pulse waves can be detected.

Bad attachment (right)

  • The light penetrating the edge of the finger is also detected. (The light passing by the finger may also be detected.)
  • Pulse wave decreases.

(2) When the probe is used on a finger, place the LED on the root of the finger nail.
The following illustration shows a good example and a bad example of attaching a disposable probe.

When the LED is on the root of the nailWhen the LED is on the joint

When the LED is on the root of the nail (left)
Pulse wave is strong thus suitable for SpO2 measurement
When the LED is on the joint (right)
Pulse wave is weak thus not suitable for SpO2 measurement

Use Surgical Tape

Pay attention to the tightness of the tape when attaching adhesive-type SpO2 probes or probes that are attached using surgical tape.

Use Surgical Tape

Even if the tape is not too tight when it is applied, some types of surgical tape contract after application, resulting in excessive pressure after a period of time. On the other hand, as the light emitter and photo detector parts must be in close contact to the measurement site in the measurement using a pulse oximeter, looseness also causes problems.

  • Loose probe attachment;
    ・May cause probe displacement and detachment due to body movement.
    ・Increases the influence of body movement.
    ・Increases sensitivity to the effect of venous pulses.
  • Tight probe attachment;
    ・Prevents stable measurement due to weakness of pulse caused by pressure on blood vessels.
    ・Increases the possibility of low temperature burn, pressure necrosis, and other skin damage due to the pressure on tissues.

Accordingly, tape-type probes should not be attached tightly. Instead, apply the tape gently along the skin.
Use genuine Nihon Kohden disposable probes!

Ideas for Securing the Probes

For restless patients, precise measurement is often prevented by the displacement and detachment of the probes. Although securing the probe is important, the use of additional surgical tape over the probe not only increases the pressure on the probe attachment site but also hinders the dissipation of heat from the LED.
The following simple ideas can ensure stable measurement while preventing pressure.

  • If the probe is detached due to body movement, secure the cable at a position near the probe.
    ・ Give some slack to the cable so that bending and stretching motions do not cause stress on the probe.
    ・ Use Ω-shaped taping* so that the fixing tape will not be peeled off by the movement of the cable.
  • If the skin is dirty or oily, clean with an alcohol cotton swab before attaching the probe.
    ==> This is particularly important when an adhesive-type probe is used.
  • Use our option items (probe fastener, BluPRO attachment tape, earlobe clip, etc.) to support probe attachment.
    ==> BluPRO attachment tape is made of the same tape that is used in SpO2 probes and ECG electrodes.

*The following illustration shows how to do Ω (Omega)-Shaped Taping:
The tape is wrapped around the cable using a pinching action so only the ends of the tape are attached to the skin.
(The movement of the cable is not directly transmitted to the probe attachment site.)

Ω (Omega)-Shaped Taping

Avoid the use of elastic tapes and elastic bandages as much as possible.
Although these surgical tapes and bandages are convenient for the purpose of covering and fixing the probe, they gradually tighten after attachment and they will cause skin problems. If they are used out of necessity, check the condition of the probe and surrounding areas at shorter intervals.