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Covid Crisis: Clearing the Air about Medical Oxygen​

Representative image

Representative image

Medical oxygen has been used in hospitals, nursing homes and even in homes since long, but Covid-19 has led to a multifold increase in its use.

The ferocity of the second wave of Covid-19 caught us unawares. Spending almost the whole of 2020 as a pandemic year, we declared an early victory over the disease. The policy decisions that had been taken slowed down. The result: many preventable deaths due to undersupply of medical oxygen. Let’s try to understand the situation by answering some common questions.

What is medical oxygen?

From our school days, we know that atmospheric air consists of a mix of 21% oxygen, 78% nitrogen, 0.9% argon and 0.1% other trace gases. Medical oxygen is a more concentrated (over 95%) and contamination-free form of oxygen than air, fit for use by the human body in illnesses leading to a drop in oxygen levels. In a nutshell, if we remove nitrogen from the atmosphere, we get concentrated oxygen.

Who should use medical oxygen?

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Medical oxygen has been used in hospitals, nursing homes and even in homes since long, but Covid-19 has led to a multifold increase in its use. However, not all patients of Covid-19 require oxygen as we have seen. Those who are asymptomatic or mildly symptomatic in home quarantine or any other designated quarantine/isolation do not require oxygen. They only need to monitor their health after isolating. There is no need for preventive hoarding of cylinders or portable oxygen concentrators as it deprives those who really need them. Medical oxygen like any other medicine should be prescribed by a doctor as it is covered by the Drugs and Cosmetics Act of 1940.

Why is medical oxygen falling short?

As the number of Covid-19 cases has surged tremendously in the second wave in India and the number of moderate, and critical cases has proportionately, or disproportionately, increased (as there are pointers towards enhanced virulence, aggressiveness and even immune escape of the mutant strains), demand is far exceeding supply. Oxygen, be it in the form of cylinders, oxygen concentrators and big oxygen plants in hospitals, is falling short. Many countries of the world have witnessed this shortage including the developed world, not to speak of low-income (LIC)and low-middle-income (LMIC) countries like India.

Another factor responsible for the shortage is the maldistribution of oxygen resources. Based upon a triaging of cases into mild, moderate and severe (including critical), the ministry of health and family welfare in June last year issued a clinical management protocol. That protocol needs to be followed in letter and spirit if resources are to be used where most needed. For example, the highest demand for oxygen is where severe and critical cases are housed, where patients are in need of high-flow nasal oxygen, CPAP/BiPAP, non-invasive/invasive ventilation.

Moderate cases requiring lesser flows can be housed in district hospitals, with training and advisory support from tertiary care hospitals.

In what forms does ‘oxygen for medical use’ exist?

On a larger scale for use in bigger hospitals, oxygen for medical use exists in the form of liquid or gas. Oxygen at a patient’s bedside (and other gases) is ensured through a centralised medical gases and manifold system with its storage/generation plant, a distribution pipeline and terminal ports with humidifiers.

Liquid oxygen: It is generated for industrial purposes but under normal circumstances, a small percentage was supplied to hospitals in huge, specialised cryogenic tankers (it requires a temperature of -183℃ to stay liquid). It is stored in the hospitals in open areas in large, special insulated tanks from where it passes through the vaporiser, changing into a gaseous form. It then reaches the patient in gaseous form through a dedicated pipeline system. Liquid oxygen is economical with very little maintenance, manpower requirement, power saving.

In pre-Covid times, hospitals usually required to fill their tanks once a week. Producers of liquid oxygen in India are located either in the Northeast (Linde India in West Bengal; Linde is a company based in France) or in the west (Inox in Mumbai). A tanker coming to north India usually took 6 days or more to reach its destination. However, demand-supply issues rose during Covid-19 and dramatically so during the current second wave surge; this lead time is not acceptable in the current scenario. In Jammu and Kashmir, one liquid oxygen plant has been installed in GMC Jammu. However, it is not feasible in Kashmir at present due to connectivity issues.

Gaseous oxygen: Hospitals can concentrate their own oxygen in the gaseous form with the help of huge oxygen concentrator plants using the PSA (pressure swing adsorption, which has been used since1970) technology from ambient air. An oxygen concentrator consists of an air compressor, two cylinders filled with zeolite pellets sieve, a pressure equalising reservoir, valves and tubes. Oxygen from ambient air is compressed into the first large cylinder (which are actually large tanks) and passed through synthetic zeolite which adsorbs nitrogen. This cycle lasts three seconds. The pressure in the cylinder reaches about 2.5 times the atmospheric pressure. Almost pure oxygen flows into the reservoir following which the valves reverse. The pressure in the tank is reduced to atmospheric level and the zeolite is readied for reuse after purging by oxygen while nitrogen is vented out. Similarly, during the purge phase of the first tank (again three seconds), the same process is repeated using the second cylinder and concentrated oxygen is produced. (Indian Pharmacopeia 2010 requires that oxygen 93% contains not less than 90% and not more than 96% of oxygen, the remainder consisting mostly of argon and nitrogen; however, current technology ensures a higher purity around 95% to 99%).

These plants can produce hundreds to thousands of litres of oxygen per minute. The capacity of the plant is determined by the size and functioning of the hospital. Oxygen thus concentrated is delivered to the patient at required pressures (< 5bar) through a distribution system of copper pipes with a terminal console consisting of oxygen ports and humidifiers. Oxygen concentrators are more economical for a hospital than portable cylinders but require trained manpower and maintenance.

In addition, the hospitals have a manifold system consisting of a centrally placed bank of bulk storage cylinders (one in use and others on standby) connected through a pipeline system to a patient’s bedside delivery ports.

In J&K, the SKIMS hospital has centralised oxygen concentrators in place since its inception. Newer plants have been installed and yet more are being added. The government has also installed a plant in GMC, Srinagar, and many district hospitals.

Portable oxygen concentrators: They are available for domiciliary use and in hospitals. These work on the same principle as big oxygen concentrators in hospitals. Earlier these would supply 5 litres per minute but newer ones claim 10-15 litres per minute of oxygen. These deliver oxygen at about 95% purity.

Both large and portable concentrators consume electricity, require maintenance; hospital-based plants require trained manpower. But still they have many advantages, especially of onsite generation.

Oxygen cylinders: Bulk, medium and small cylinders (around 7,000 L, 1,500 L and 1,300 L capacity respectively) used to store oxygen in compressed form, are made of iron or aluminium. While bulk cylinders are required for manifolds as double-banks, these days we visualise patients getting oxygen by the bedside or during transit from these cylinders.

Medium and small-sized cylinders are required for transportation of oxygen-dependent patients within or outside a hospital. Domiciliary oxygen in the form of portable oxygen concentrators or cylinders has been extensively used during Covid-19; this has even lessened the burden on healthcare facilities, but a doctor should be consulted for advice.

Oxygen cylinders are usually heavy (nowadays aluminium ones are light), require a lot of space for storage, need to be transported for refill, and have potential risk of fire if leaking, but do not consume power and are maintenance free.

Finally, in the case of centralised gases, oxygen after being transported through a colour-coded pipeline system is delivered to the patient from oxygen ports using oxygen accessories. Depending upon the oxygen demand of a patient, these accessories in increasing order range from simple nasal cannulas (if demand is up to 6L), regular oxygen masks (5- 10 L), oxygen masks with reservoir bag (10- 15 L), NIV mask/ venturi mask (10 – 15 L), high flow nasal cannulas (can deliver up to 60 L), invasive ventilator circuits, etc. Enough ventilators, high flow nasal devices, CPAP machines are also to be ensured for oxygen delivery to critical Covid-19 patients.

For domiciliary use, only nasal cannulas or regular oxygen masks are required.

What steps have been taken for meeting the surge in oxygen demand due to Covid-19?

The oxygen crisis was recognised by the world at large in 2020 during the first wave of the pandemic. At the international level, WHO has formed an Access to Covid-19 Tools Accelerator (ACT-A) global partnership, in the therapeutic pillar of which oxygen and dexamethasone have been recommended as the only proven therapeutic agents. However, the biomedical consortium has a fund gap, although efforts have been made for LIC and LMIC countries. We have also seen the international mobilisation of oxygen and related resources for the cause. The government of India has also taken steps like restricting oxygen use for medical purposes and cutting down industrial use, strengthening the transportation system (oxygen trains, pressing defence airplanes for importing oxygen, diverting tanker use for oxygen supply), increasing the number of beds, initiating the setting up of new production units, etc, with international help coming in. The courts have also stepped in to monitor the process. But we must not forget enhanced production or import of small logistic accessories required for delivery such as flowmeters, regulators, tubing, oxygen masks of all types, high flow nasal devices and cannulas, panels with ports, etc. Last, but not the least, hospital beds which may be set up in prefabricated structures like the ones used for conducting Amarnath Yatra.

What more can be done?

The government is already monitoring the oxygen status of healthcare facilities on a daily basis. However, some suggestions are put forward here for consideration. Wiser use of oxygen resources, be it equipment, manpower or any other, is the need of the hour. Manpower is critical in the handling of oxygen and includes technical and nontechnical (unskilled) personnel. When the national dialysis programme was rolled out in the district hospitals of the erstwhile state of J&K, the staff from the existing pool in district hospitals were trained at SKIMS and GMC; the programme implementation and operation were smooth and benefitted thousands of patients. A similar analogy can be applied for running the centralised medical gas and manifold services in district hospitals that should depute their staff at the earliest to tertiary care hospitals having expertise in such services for very short courses. This will ensure that the plants set up in these healthcare facilities are utilised when most needed, moderate cases are treated in the district hospitals and an informed referral system is followed when a patient’s condition deteriorates.

Hospitals in the country which are solely dependent on liquid oxygen should necessarily install onsite oxygen concentrator plants as a second source. This will cut down the lead time spent in transporting oxygen and save precious lives.

Every individual is responsible for his/her own health and of their loved ones (and therefore of whole society) for which reason we all should follow Covid-appropriate behaviour and vaccination. We have witnessed enough vaccine hesitancy and missed opportunities earlier on. People finally woke up to the call of vaccines but a bit late.

Once again, I reiterate and request people not to unnecessarily keep portable oxygen concentrators and cylinders at standby. Maybe someone else desperately needs it. Many philanthropic agencies in the country and in our UT have been lending out oxygen concentrators/cylinders to the poor for free and to those who can afford it on a rental basis.

(Dr Samina Mufti is an assistant professor of hospital administration at Sher-I-Kashmir Institute of Medical Sciences, or SKIMS, J&K. Views are personal)

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first published:May 10, 2021, 15:29 IST