The medical field has so many different sides to it that it is impossible to keep track of all the innovations in all the fields which are made on a regular basis. However I recently heard about the advantages of pulse oximetry and the various different machines which are available for use at home as well in medical centres and can make life easier for people. Machines such as the Nonin PalmSAT pulse oximeter 2500A with memory, the Heal Force Prince fingertip pulse oximeter and the ChoiceMed fingertip pulse oximeter all have their good points.

The pulse oximeter is a diagnostic tool that enables the indirect measurement of the percentage of oxygenated haemoglobin in a patient's capillary blood. It has been widely used in secondary care for over two decades, especially in peri-operative, paediatric and intensive care patients. Pulse oximetry is often used in emergency departments, but is less well established in general practice.

How does pulse oximetry work?

Oxygen in the air is breathed into the lungs. The oxygen then passes into the blood where the majority of the oxygen attaches to haemoglobin (a protein located inside the red blood cell) for transport in the bloodstream. The oxygenated blood circulates to the tissues.

Pulse oximetry technology utilizes the light absorptive characteristics of haemoglobin and the pulsating nature of blood flow in the arteries to aid in determining the oxygenation status in the body. First, there is a colour difference between arterial haemoglobin saturated with oxygen, which is bright red, and venous haemoglobin without oxygen, which is darker.

Pulse oximeters work by measuring the light absorption properties of haemoglobin1 using a red–infrared light source. The amount of light absorbed varies according to the proportion of oxygenated haemoglobin in the blood, and this is analysed to generate a numerical saturation reading. Pulse oximetry is commonly used in the assessment of children with asthma and wheezing; not least because of the difficulty in subjecting children to repeated blood gases.

The use of pulse oximetry in primary care is still in its infancy. Its advantages are that it is quick, non-invasive, reproducible, accurate in most circumstances, and minimal training is necessary. Its disadvantages are that it needs maintenance, has accuracy limitations in some patients and may not provide a clinical benefit to patient care if used indiscriminately.

Chronic obstructive pulmonary disease (COPD) has a considerable prevalence within the general practice population, and can cause overnight or exercise hypoxia. Some patients with COPD gain a survival benefit from long-term oxygen therapy (LTOT), usually administered via a home concentrator. Pulse oximetry has been used in general practice to screen COPD patients, identifying those who might benefit from LTOT.

Practices that are planning to use oximetry in daily practice need to consider their reaction to an isolated low reading in an otherwise well patient, and in what circumstances readings should be taken. For use in the home the Pulse Oximeter 2500A with alarms and the Pulse Oximeter 2500A with memory are both good as is the Paediatric Probe Oximeter Sensor.