HONG KONG — It is not surprising that in India, which has had more than 25 million coronavirus infections and where beds and oxygen tanks are currently in short supply, a recent video on breathing while lying on the stomach, known as the prone position, went viral on Twitter.

India's health ministry followed with a statement recommending Covid-19 patients recovering at home use this method. This type of breathing, to help boost oxygen levels in the blood in patients with breathing difficulties, was discussed as far back as 1974 in the American Review of Respiratory Disease.

Studies worldwide since then have shown that the pronal position can have a significant positive impact, and experts suggest pronal breathing exercises to make breathing easier, especially in patients experiencing mild Covid-19 symptoms.

Pronal breathing, also known as proning, has been practised for thousands of years, in yoga as well as Chinese medicine, and its benefits are being rediscovered now during the drawn-out pandemic.

In his bestselling book Breath, American journalist James Nestor talks about his experience with respiratory problems and how breathing techniques helped him.

In an interview with America's National Public Radio, Mr Nestor noted that doctors have found Covid-19 patients could breathe a lot better when they lie on their sides or on their stomachs.

The reason? More of the lungs are near the back than the chest. On their stomachs, people's lungs can expand more efficiently.

WHAT IS PRONAL BREATHING?

Dr Sundeep Kaul, lead intensive care and respiratory medicine consultant at Harefield Hospital in the UK, says lying on your back is known as the supine position, and on your front is the prone position.

Lying in the supine position compresses the back portion of the lung, while the front portion gets overinflated. To get maximum efficiency in the lungs, it is best to lie in the prone position.

Dr Rimy Dey, an emergency doctor in New Delhi, recently shared an infographic on Twitter that shows the difference in oxygenation levels in the supine versus the prone position.

In a tweet issued on April 22, India's health ministry described the at-home method of proning as cycling through four positions, spending 30 minutes to two hours in each (for the same amount of time): Lying on your belly, with supporting cushions as necessary, then turning onto your right side, then sitting, then turning onto your left side.

It suggests not proning for at least an hour after meals, and that it can be done safely for up to 16 hours a day, through as many cycles as are comfortable.

Ms Nishara Antony, a senior yoga trainer at A1000Yoga in Bangalore, says that normally the lungs are slightly compressed by the heart and the diaphragm.

"In the prone position, more space is created for the lungs to expand, thereby increasing oxygenation. Prone breathing also helps our lungs' lower lobes to participate in breathing, whereas in normal breathing these lobes may not be used much."

She adds certain yoga poses, known as asanas, such as the downward facing dog pose, are typically recommended to improve breathing and increase oxygenation.

"Coughing in this pose can also help release mucus collected in the lungs or in the windpipe," she says.

DOS AND DON'TS

Pronal breathing is not advisable for pregnant women or those suffering from obesity, thrombosis, spinal conditions or cardiac complications.

"People with any spinal conditions need to practise pronal breathing with caution," Ms Antony says. "Others with any hip or pelvic surgery or chest trauma must also exercise caution or consult their doctor before starting the practice."

Dr Kaul says proning is done routinely in intensive care, but it is also relatively easy for a patient with Covid-19 symptoms to do at home. Though he says it is not a form of treatment, "it buys the patient time before they can get access to the necessary care and equipment at a hospital."

He adds that this method doesn't work all the time, because it depends on how the virus has affected the individual.

For example, in Covid-19, the back portion of the lung is usually badly affected, while the front is spared. "That's why a CAT scan is imperative, before making any decisions about effective treatment," he says.

LATEST RESEARCH

Proning has been practised for decades in the US, and it became more widely used with the onset of the Covid-19 pandemic, even though evidence to support its benefits were mostly anecdotal at the time.

In late 2020, researchers from The University of Pennsylvania Health System (Penn Medicine) and the division of Pulmonary and Critical Care at the University of Michigan developed specific strategies for proning, which are now in use at Penn Medicine, with the help of prone-positioning teams.

The teams offer advice on who should have prone positioning, as well as staffing and expertise to ensure that it is done correctly.

A study at the Royal London Hospital concluded that patients who were treated with prone positioning for more than an hour had relatively less need for intubation and mechanical ventilation, and either no admission to the intensive care unit or a shorter stay in it.

The study suggested that proning could be considered an early treatment method to manage patients with Covid-19.

On the flip side, a recent study in the American Journal of Physical Medicine & Rehabilitation outlines the potential complications of pronal breathing in patients with acute respiratory distress syndrome due to Covid-19, including airway obstruction and pressure injuries.

AROUND THE WORLD

Globally, doctors and yoga experts are recommending prone-position breathing to patients and students during the pandemic.

Dr Suneel Dhand, an internal medicine doctor in Boston and founder of Medstoic Lifestyle Medicine, recently shared the benefits of prone-position breathing during Covid-19 on his YouTube channel. The video has garnered more than 1.4 million views.

Dr Hansa Yogendra, director of The Yoga Institute in Mumbai — the world's oldest organised yoga centre, set up by her father-in-law Shri Yogendra — has discussed the proning technique in detail, likening the belly-down position to yoga's Crocodile pose (makarasana).

Dr Sarfaraz Munshi, urgent care lead at the NHS in London, made a video on pronal breathing last year, initially to circulate among his family and friends. After it was posted on YouTube in April 2020, it went viral, with over 4.6 million views. SOUTH CHINA MORNING POST