When a patient gets admitted into a ward for care following a COVID-19 infection, besides specific medicines that need to be administered, providing oxygen depending on its saturation level and the need to respond to the level of breathing difficulty is the major medical intervention.
When a patient is inside an ICU, relatives outside often do not know how to interpret the oxygen support that is being provided to the patients. This blog is an attempt to explain the different devices through which oxygen is administered.
There are four broad methods or devices by which oxygen is administered to a patient admitted for COVID treatment. The following are the common oxygen delivery devices.
1. Nasal cannula, adult and paediatric (single use).
They are connected to a lip support and a fully adjustable harness (one tube right/left side). It is a cannula with twin nasal prongs designed for easy administration of medicinal oxygen through the patient’s nostrils
This is the first level of providing oxygen to COIVID-19 patients who need oxygen support. It can deliver 1–6 Litres of oxygen per minute and deliver about 24–44% of oxygen. Humidification may be necessary especially for children. It is easy to use and the patient can eat and talk.
2. Mask with a reservoir bag; adult type.
This is a non-rebreather mask with a reservoir bag. It is used to deliver medical oxygen directly to the upper airway of the patient. It includes two unidirectional valves, one that closes during inspiration to prevent room air mixing with oxygen in a reservoir bag; and one that closes during exhalation to prevent exhaled respiratory gases from entering the reservoir bag.
This is the next level of providing oxygen support. It delivers > 10 Litres per minute and delivers 80–95% oxygen at a higher level of concentration. To be effective the flow should be maintained at > 10 L/min as lesser concentration can cause the bag to collapse during inspiration.
3. Venturi mask; adult and paediatric types.
It is also known as pressure mask or an air-entrainment mask. It delivers oxygen, with a specific concentration from 24–60% minimum. It has an adjustable nose clip.
This is third and highest level of oxygen support without connecting to a ventilator. It can deliver from 2–15 Litres per minute/min and meet 24–60% oxygen need according to the type of mask. It allows precisely measured amount of oxygen to be delivered. It comes in different colours to indicate the flow rate. It confines some patients and it interferes with talking and eating.
Today, many patients are managed with the above three different levels of masks without taking the patient on to a ventilator. If a patient is taken from the first level to the second or third level, it indicates that the patient is not doing well. On the reverse if a patient moves from level three to level two or one it indicates that the patient is improving. This is called non-invasive intervention.
4. Ventilator
A ventilator is a bedside machine with tubes that are inserted inside your airways. The air flows through a tube that goes in your mouth and down your windpipe. It mechanically helps pump oxygen into your body. The ventilator also may breathe out for you, if you can’t do it on your own. The breathing tube may be uncomfortable. While it’s hooked up, the patient can’t eat or talk. This is called invasive intervention.
The following are the indicators for starting a patient on ventilators, rapid progression over hours, lack of improvement with noninvasive methods, hypercapnia or when there is retention or too much carbon dioxide (CO2) in the blood, normally caused by reduced air flow into the lungs, haemo-dynamic changes indicated by low blood pressure and or signs of heart failure, or multi-organ dysfunction indicated by failure of different organs, and altered neutrophil-lymphocyte ratio among white blood cells.
There is a fear in the minds of people that when patients are put on ventilators, that many will die. While in the early days of COVID-19, many who were put on ventilators died, as we did not have proper medicines. Today, many patients who are connected to a ventilator survive, because we know more about the disease and how to manage it.
I hope to cover and share other information about COVID-19 in other areas where we have a better understanding of the disease and how to treat such patients. But prevention is the best and safest as we do not know who will die.
Don’t take chances with the COVID virus. If you give it a chance it will attack you. Wearing mask, keeping safe distance and frequent washing of hands with soap and water or sanitizing is the surest way of preventing the disease.
If you are interested in knowing the full COVID story, you can access the book on the disease available in the following link.
COVID-19
Global eBook http://tiny.cc/gb01tz
Indian eBook http://tiny.cc/bb01tz
Rajaratnam Abel
Rajaratnam Abel 