Portable oxygen concentrators (POCs) are a fantastic development in the provision of oxygen supplementation. There are a range of units available but all include the following features: they can be plugged in to standard power supply, are supplied with an adaptor so that they can be powered while driving, and include rechargeable batteries. Most units also come with a trolley so that they can be wheeled around by the user increasing the ‘portability’ of the unit. The more compact units look more like a camera bag than a piece of medical equipment!
How do they work?
In order to reduce the size of the machine, POCs usually supply a ‘pulse dose’ of oxygen on inhalation only. This reduces the waste of the continuous oxygen supply method used by other oxygen supply systems. POCs have a range of flow settings varying from 1 to 6, with the pulse dose of about 9mL per setting. As such the settings reflect the oxygen supply at litres per minute (LPM), and are similar to the continuous flow settings.
Normal room air contains about 21% oxygen, 78% nitrogen and small amounts of some other gases. A tiny compressor pressurises air through a system of chemical filters which sieve out the nitrogen whilst concentrating the oxygen. Some of the oxygen goes to the user of the POC with the remainder fed back into the unit to clear the nitrogen out ready for the next pulse. The system can produce oxygen up to 96% concentration.
On inhalation the POC administers a ‘bolus’ or ‘shot’ of oxygen. The size of the bolus is adjusted in relation to the amount of oxygen inhaled if the individual was on continuous flow oxygen.
Battery life can vary up to 4 hours with the better units able to provide 8 hours of oxygen therapy on a medium setting with 2 batteries in place.
With technological advancements, boluses can now be varied in response to breathing rate making the application of more recently developed POC units suitable for use by people suffering from sleep apnoea.
It is very important that you seek the advice of your specialist before purchasing a POC as it is imperative that you select the best machine to meet your oxygen and lifestyle needs.