New Delhi: Ventilators have emerged as the last resort to save lives across the world even as the global Covid-19 toll has crossed 2 lakh.
India too is racing to secure enough ventilators to sustain the outbreak with thousands of procurement orders already on its way and domestic production in full swing.
But critical care experts believe the non-invasive oxygen therapy may be equally if not more effective than ventilation.
Doctors are now increasingly reluctant to put patients with breathing difficulties straight onto mechanical ventilators as opposed to the initial days of the pandemic, when they relied heavily on the machines for critical patients.
Ventilators are machines that take over breathing and require tubes to be inserted into the lungs of a patient through the throat — a process called intubation. Oxygen therapy, meanwhile, is a non-invasive procedure in which oxygen is supplied through a face mask or through a nasal cannulae or tube.
“As the disease has evolved, the understanding has evolved too. While initially, intensive care units had patients on ventilators, now we have explored other options and use of ventilators has now been limited for severe cases,” said Dr Animesh Arya, senior consultant in respiratory medicine at Delhi-based Sri Balaji Action Medical Institute.
C.K. Mishra, chairman of the government task force on health infrastructure and preparedness, in a press briefing on 23 April spoke about the same trend.
“We have been talking for a long time about ICU care and ventilation, but if you look at the patient profile, the critical thing today is oxygen and our entire hospital preparation is to provide oxygen to patients,” Mishra said. “We will try to get patients to improve at this level itself.”
Another top health expert, Dr Randeep Guleria, who is also part of the task force and the director of country’s premier All India Institute of Medical Sciences (AIIMS), backed the trend. “Twenty per cent of the patients need oxygen therapy and 5 per cent need ventilation,” he said.
The critical aspect, according to Dr Dhruva Choudhary, Senior Professor and Head, Department of Pulmonary and Critical Care Medicine, University of Health Sciences in Rohtak, is oxygen supply itself.
“We need to increase our oxygen capacity and more ways to deliver oxygen and to train people on it,” he said. “For me, getting good quality and continuous supply of oxygen is very important as it is needed for oxygen therapy and ventilators.”
He added that out of 100 patients, 60 would get better with oxygen but 40 would still need a ventilator.
The ventilators or oxygen therapy debate
Critical Covid-19 patients require oxygen supply as the infection targets the lungs.
“In Covid-19 cases, the lung’s capacity to carry oxygen towards tissues is reduced; hence, it can be said that more oxygen supply increases the chances of a patient to come back to the normal condition than to be on a ventilator,” Dr Arya said.
As these patients tend to get low levels of oxygen saturation also called as hypoxia and often without symptoms, non-invasive medical device “pulse oximeters” are needed to monitor the oxygen levels. Based on the indication of the device — which measures the proportion of oxygen filled in haemoglobin in the blood — experts start oxygen therapy.
“Standard treatment of pneumonia should be given, high flow of oxygen supply should be available and the treatment of ventilator should be given only when it is the only option,” Dr Arya said.
It helps the muscles of lungs to heal. “Ventilators are used when the muscles of the lungs that pump air fail and it is a tactic to buy time as the muscles heal and the lungs can breathe on their own,” said Dr Choudhary.
When to use ventilators?
According to Dr Sushila Kataria, an expert in infectious diseases at Medanta Hospital, ventilators are required for severely ill patients.
“The choice between oxygen therapy and ventilation depends on the oxygen requirement of the patient,” said Dr Kataria, who co-headed the team that treated 14 Italian patients in the hospital. She is now treating 54 Covid-19 patients.
She explained that the patients with low external oxygen requirement, of around 2-6 litres per minute, are given nasal cannula-based oxygen therapy whereas patients with normal requirement of oxygen, around 6-15 litre, are given mask-based oxygen therapy.
“Patients with 15-50 litre requirements are given high frequency nasal cannula oxygen therapy whereas ventilator support is given for requirements above 50 litre,” she said.
Of the 54 patients she is currently handling, 10 are being given oxygen therapy whereas only one patient is on a ventilator.
Other experts echoed similar observations.
“We can’t actually choose between the two as patients are managed on oxygen therapy as long as they can but once the patient gets serious, ventilation is required,” said Dr Tanu Singhal, an infectious disease expert at the Kokilaben Dhirubhai Ambani Hospital, Mumbai. “Since the patients on ventilators are very serious, their outcomes are poor.
“What we know in Covid-19 is that you need to wait for a higher threshold before beginning ventilation to see if they will get better on their own,” she said.
Compared to oxygen therapy, which is simpler to deliver, ventilators need trained personnel. Amid the Covid-19 outbreak, the high mortality on ventilators could also be due to overwhelmed health staff handling too many critically ill patients, Dr Choudhary said.
“At the moment, we first need to focus on getting the oxygen delivery systems and supply chains rather than on ventilators,” Choudhary said, adding that there should be enough trucks to carry the liquid oxygen and enough manufacturers of oxygen.
Ventilation reduces chances of survival : Experts
A report by Associated Press showed 80 per cent of the critically ill Covid-19 patients on ventilators in New York died.
Similar high mortality levels were found in hospitals across the US and even China, the report said. The reason is heavy lung damage due to the coronavirus, which is far worse than the damage caused due to other lung infections such as the acute respiratory distress syndrome. At these times ventilators, sometimes, end up worsening the damage further.
“Survival rate on ventilators plunge significantly,” Dr Kataria said. “In my recent experience with Covid-19 patients, I have seen five patients on ventilator, of whom only one survived.”