Groote Schuur doctors on benefits of high-flow nasal oxygen — Spotlight report

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Spotlight reports that doctors at two of the Western Cape’s most impacted COVID-19 hospitals say they have seen positive outcomes from using high-flow nasal oxygen (HFNO), a non-invasive oxygen therapy, instead of mechanical ventilation. They say they are now using HFNO for many patients who would have been intubated in the early days of the epidemic.

Dr Saadiq Kariem, chief of operations for the Western Cape Health Department, said that the province had 121 HFNO machines available at hospitals, with another 42 on order, bringing the province’s total to 163. “It’s made a real difference in Groote Schuur Hospital and Tygerberg Hospital and preparing for high-flow oxygen as an alternative to people having to be on ventilators,” says Kariem. “(HFNO) can be provided not only in a high-care bed, but we have also been providing (it) in a normal, acute bed. That relieves some pressure on our high-care beds, and that’s generally the strategy at all our hospitals and facilities.”

Professor Coenie Koegelenberg co-manages the Tygerberg COVID-19 ICU and speaking to Spotlight, he says that more recent data from the hospital’s first 70 ICU patients shows a mortality rate of roughly 40%, compared to roughly 85%-90% for patients who did not receive HFNO and were mechanically ventilated.

Along with Tygerberg, Cape Town’s other leading COVID-19 hospital Groote Schuur (GSH), has also been using HFNO as a first resort for patients with severe disease. Koegelenberg says that in early April, Tygerberg and Groote Schuur clinical staff were already in discussions on how to limit intubation by using this method.

Tygerberg administers HFNO in their ICU, while Groote Schuur provides it in medical wards, and only admits ventilated patients to ICU.

“It’s important to demystify (the HFNO machine),” says Professor Greg Calligaro, a specialist pulmonologist at GSH working on the frontlines.

For COVID-19 patients with severe disease, doctors find that oxygen levels in these patients are dangerously low, or in medical terms, patients are ‘hypoxic’, and classified as having what is called Acute Respiratory Distress Syndrome (ARDS).

“ARDS can be caused by many things (pneumonia being the most common cause), but essentially lung water builds up in between the air sacs of the lung and eventually fluid goes into (these air sacs, called alveoli) and then the lung becomes stiff, like a very stiff balloon and it’s very difficult to inflate,” says Koegelenberg. Stiff lungs like this are considered ‘non-compliant’, meaning that they cannot breathe without the help of pressure from a ventilator.

“Lungs are normally very compliant, it takes very little effort for (a healthy person) to breathe. ARDS is an extreme form where the lung is so stiff that just by blowing in oxygen it won’t work, you need to give it pressure as well and that’s where intubation will always be needed,” says Koegelenberg.

Calligaro explains that HFNO works by continuously flushing out the amount of oxygen that a patient breathes at the level of the alveoli. “That’s why you need the 60l flow, which is much more than what ventilation is in litres, so it’s washing out the lungs with this high concentration of oxygen,” he says.

Spotlight reports that both Tygerberg and GSH have patients on HFNO prone themselves, meaning patients will rotate their bodies every two hours to allow oxygenated blood into different parts of the lung. For this, a patient will lie on their back, their left and right side, and on their stomach for two hours at a time. For ventilated patients, ICU staff are responsible for manually proning patients.

“Proning is a very effective way of pushing up oxygen levels,” says Koegelenberg.

While HFNO and proning have lent themselves to decreasing mortality rates, Calligaro says they are not a cure for COVID-19. Together, these two methods treat low oxygen levels in patients with severe COVID-19 disease, but do not actively treat the virus itself.

From a paediatric perspective, Professor Andrew Argent, head of the department of paediatrics and child health at the Red Cross War Memorial Children’s Hospital, says HFNO has been used to treat respiratory illness in children for years and while kids may not be needing it for COVID-19, they definitely need it for other illnesses.

Argent says that HFNO therapy is child-friendly and largely tolerated by these young patients.

With HFNO becoming a common form of treatment for severe COVID-19, Calligaro raises concerns that hospitals could be limited by their pre-existing piping infrastructure and the availability of oxygen supply – an issue that South Africa will undoubtedly face in the future.

Calligaro says that there are two considerations for hospitals giving this treatment, how much oxygen they have and if there is sufficient piping to support multiple HFNO machines. He also warns that hospital oxygen supply must also service theatre, maternity and other ICU wards and COVID-19 patients. “You’ve got to speak closely with engineers to ensure the amount of oxygen you’re providing through these machines is not going to jeopardise the (hospital’s) oxygen supply.”

 

Full Spotlight report

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