PURPOSE: -
The aim of this scientific study is to evaluate the use of Oxygen Concentrators during Covid and non-Covid times, over the last 6 years, in Nepal. These machines provided almost pure oxygen and were supplemented with compressed air to drive a ventilator, as it is difficult to provide oxygen cylinders due to the bad network of roads in rural areas of Nepal. Oxygen cylinders were first used in 1985, but early concentrators were not very reliable delivering a very low percentage of oxygen. In 1993, during a trial, we used an oxygen concentrator called PM MULTICUT VENTILATOR (PMMV), a machine which could deliver oxygen and then supplement it with compressed air to be sent to the ventilator for use in anaesthesia. This machine is very reliable and has been used in various surgeries in neurology and heart cases, not only in cities, but also in remote camps with good results.
This machine is still working and delivering almost 85 percent oxygen at very good pressure and can be used in wards, operation theaters, etc.
METHOD: -
This study was done from 1999 till 2019 in two hospitals in Kathmandu. Oxygen from this machine was combined with air and given to the patients, including children. An oxygen cylinder was kept as a backup. All parameters such as oxygen levels, blood pressure, ECG were carefully monitored.
RESULTS: -
Out of 378 patients, 175 underwent nerve related surgeries, and rest other types of operations; and age of patients varied from 6 months to 78 years. The oxygen concentrator was used fully during the operation and recovery period. There was no case of breathing difficulty or death or any other complications.
DISCUSSION: -
Oxygen is essential for anaesthesia and recovery, however looking at the land topography of Nepal, oxygen cylinders are not only bulky. but difficult to carry to remote parts of the country. Absence of oxygen can be very risky for patients, and may even lead to death. Therefore, a portable oxygen concentrator is the solution for Nepal.
But due to erratic maintenance, most of the old machines have stopped working and hence Doctors and Nurses have lost faith in these machines.
Oxygen concentrators like the PMMV machine are very reliable and we have used it in over 4000 casse with success. Now a days, post covid many manufacturers world over have come out with oxygen concentrator which deliver variable amount of oxygen depending on the patients need, from 2 L - 5 L to 10 L. The cost varies from 40,000 Indian rupees to 80,000. The imported ones from China are relatively cheap for short term use.
HOW DOES THE OXYGEN CONCENTRATOR WORK: -
Normal air consists of around 79 percent of Nitrogen and 21 percent of Oxygen; however, the latest technology machines can now purify oxygen to the tune of 95 percent.
Room air is sucked into the machine, filtered and then it is sent through a can having a chemical, which absorbs Nitrogen from the air, providing almost pure oxygen for use.
The air is pumped by a motor through two such cans which work alternately to give continuous supply of oxygen.
The chemical in the can can give up to 20,000 hours of pure oxygen, after which it needs to be replaced. These machines are very easy to use and hardly require any maintenance. If oxygen falls below 85 percent, then an alarm sounds and shuts down automatically.
CONCLUSION: -
We have used this oxygen concentrator regularly during anaesthesia in city hospitals and camps and found it to be quite reliable and cost effective.
We strongly recommend the use of such a machine in places where cylinders are difficult to get.