Pulse oximeters are medical devices which will indirectly measure the oxygen saturation of a patient’s blood. But how do you know if you need to use one?

We all know that our blood consists of many different types of cells, with the red blood cells being the ones which carry oxygen around the body. The ‘red’ blood cells actually turn red only when they encounter oxygen and appear blue when they don’t contain oxygen. The arteries are responsible for carrying oxygenated blood away from your lungs and appear red whereas your veins appear blue as they carry blood cells to your lungs in order to receive oxygen. A patient who isn’t getting sufficient blood in their arteries will appear to have a dark or purple colour.

Your circulatory system is responsible for facilitating the transport of oxygen from when the blood cells receive it in the lungs and then to it’s distribution throughout the rest of the body. The heart, which is also oxygenated by the red blood cells, aids the circulation by pumping blood through the bloodstream. Healthy people will have arteries which have a bright red colour.

Red blood cells contain haemoglobin which is an iron-containing ‘metalloprotein’ and is able to absorb oxygen, thus aiding it’s transport to the other cells of the body. This is what enables pulse oximiters to be used.

Pulse oximiters are a non-invasive way of determining how much oxygen is getting pumped from your heart through to the rest of the circulatory system. Once a pulse oximeter has been placed on the patients fingertip it is able to measure their blood oxygen saturation. The pulse oximeter uses light and a light sensor in order to measure the colour of the patient’s blood, and thus calculate the oxygen saturation level of the blood.

The pulse oximeter calculates the blood saturation with a complex mathematical algorith that relies on the amount of light detected by the light sensor. The amount of light that is detected will be dependant on the amount oxygen in the blood. When the blood is fully saturated the pulse oximeter will give a reading of 99%. In the case of a patient who has some sort of pulmonary condition which causes oxygen saturation to be lower then the readout will be lower. The use of pulse oximetry will only measure the percentage of bound haemoglobin, which referrs to haemoglobin which is bound to other gases (such as carbon monoxide). In order to determine whether the apparatus is returning an accurate measurement, it should return a steady pulse or waveform.

A pulse oximeter is an extremely useful piece of equipment, however it should not be the only apparatus used before adjusting someone’s oxygen supply. It is important to remember that pulse oximetry will only measure blood oxygenation and will give no indication of blood pH, bicarbonate concentration or carbon dioxide levels. The amount of oxygen given to a patient is always under prescription from a doctor and should never be changed without their written approval.

Author Bio: Dave Matthews is writing on behalf of Pure O2, a leading UK pulse oximeter supplier.

Category: Advice
Keywords: pulse oximeter, oxygen, breathing, respiration, heart, pulse oximetry, health