Measuring Oxygen Saturations
In a healthcare environment, measuring the concentration of circulating blood O₂ levels (oxygen saturation level) is vital. A pulse oximeter (spectrophotometer) is used to detect the amount of light absorbed by haemoglobin in arterial blood and gives the healthcare worker a measurement of the percentage of oxygen circulating in the blood. Selecting an appropriate site for the placement of the probe is vital as it is important to find a vascular bed to gain an accurate reading, for example a digit probe or a smaller clip-on earlobe probe.
The reason pulse oximeter probes interrogate the finger, nose, ear lobe, and forehead is that the skin in these areas have a much higher vascular density than, for example, the skin of the chest wall. Reusable clip probes (finger, nasal, ear) and single-patient adhesive probes (finger, forehead) are the two main types of pulse oximeter probes.
(Chan, Chan & Chan 2013)
Normal values for oxygen are between 96% and 100% and the spectrophotometer is accurate within 2% and 3%.