How to measure oxygen saturation with a pulse oximeter
Other platforms explain it with text and video. In VMS you practice it on the patient.
A pulse oximeter is quick and painless, but it can be wrong. Knowing its limits is part of the skill.
Step by step
Prepare
Clean your hands, introduce yourself and explain that the clip does not hurt. [1]
Choose the site
A warm finger with good blood flow. Remove dark nail polish or artificial nails, or use the earlobe. [1]
Place the probe
Light source and sensor face each other across the nail bed. [1]
Wait for a good signal
A steady waveform or bar, and a pulse on the screen that matches the patient's real pulse. [1]
Read and compare
Usual adult range is 95 to 100%. Some patients with chronic lung disease have a lower target set by the prescriber, often 88 to 92%. [1]
Look at the patient too
Check breathing rate, effort, color and confusion. Treat the patient, not the number. [1]
Record
Write the value with the oxygen device and flow (for example 94% on 2 L/min nasal cannula). [1]
Common errors
- Trusting the number with a weak or jumpy signal.
- Cold hands, movement or nail polish giving a false low reading.
- Carbon monoxide poisoning giving a falsely normal reading.
- Readings can be falsely high in people with darker skin: look at the whole patient.
Practice it in VMS
In VMS you do this on the patient, not on paper: every step goes on the checklist with a score, and in Teach mode Blocky tells you what comes next.
VMS cases that train this skill
Sources
Steps adapted from Open RN, Nursing Skills 2e (Chippewa Valley Technical College), licensed under CC BY 4.0. VMS is not affiliated with these organizations. Updated: 2026-10-11.