Adult SPO2 values
Range: 35-99%
Resolution: + -1%
Accuracy: 75% -99 &: + -2%
50% -75%: + -3%
0% -50%: unspecified

SPO2 values in children aged 5 to 12 years
Range: 35-99%
Resolution: + -1%
Accuracy: 75% -99 &: + -3.2%
50% -75%: + -3.8%
0% -50%: unspecified

Pulse rate
Range: 30-240 bpm
Resolution: + - 1bpm
Accuracy: + - 2bpm

Batteries
Type: 2 AAA alkaline batteries or rechargeable batteries
Power consumption: less than 30 hours on
Voltage: 2.6-3.6V

The principle of pulse oximetry is based on the red and infrared light absorption characteristics of oxygenated and deoxygenated hemoglobin. Oxygenated hemoglobin absorbs more infrared light and allows more red light to pass through. Deoxygenated (or reduced) hemoglobin absorbs more red light and allows more infrared light to pass through. Red light is in the 660 nm wavelength light band. Infrared light is in the 940 nm wavelength light band.

Pulse oximetry uses a light emitter with red and infrared LEDs that shines through a reasonably translucent site with good blood flow.

After the transmitted red (R) and infrared (IR) signals pass through the measuring site and are received at the photodetector, the R/IR ratio is calculated. The R/IR is compared to a "look-up" table (made up of empirical formulas) that convert the ratio to an SpO2 value. Most manufacturers have their own look-up tables based on calibration curves derived from healthy subjects at various SpO2 levels. Typically a R/IR ratio of 0.5 equates to approximately 100% SpO2, a ratio of 1.0 to approximately 82% SpO2, while a ratio of 2.0 equates to 0% SpO2.

Pulse oximeters may be used in a variety of situations but are of particular value for monitoring oxygenation and pulse rates throughout anaesthesia. They are also widely used during the recovery phase. The oxygen saturation should always be above 95%. In patients with long standing respiratory disease or those with cyanotic congenital heart disease readings may be lower and reflect the severity of the underlying disease.

Indications in Primary Care:

Rapid initial assessment of patients with respiratory disease in both normal and emergency consultation.
Continuous monitoring during transport to hospital in patients with unstable respiratory status.
In home care for patients with respiratory disorders.
It is useful, along with clinical data to assess the severity of asthma attacks allowing continuous monitoring.
It has been suggested pulse oximetry as the fifth vital sign, along with BP, heart rate, respiratory rate and temperature.

Do not use on children under 5 years old. For use on children please use a pediatric model.