UPDATE April 22, 2020: I’ve put a summary of key points at the bottom of this below earlier updates. I still recommend reading the whole post here if you haven’t already, and follow up the links and comments if you have questions. I would also appreciate additional information on this as it appears.
The NY Times reports what may be an important observation on treating Covid 19 infections more effectively.
This is what I learned during 10 days of treating Covid pneumonia at Bellevue Hospital.
Doctor Richard Levitan is someone with an important background in intubation and teaching how to use ventilators. He found something puzzling when working with Covid 19 patients. They were coming in with lungs filling up with fluid — pneumonia — but they weren’t having the usual distress that normally occurs when that happens.
And here is what really surprised us: These patients did not report any sensation of breathing problems, even though their chest X-rays showed diffuse pneumonia and their oxygen was below normal. How could this be?
We are just beginning to recognize that Covid pneumonia initially causes a form of oxygen deprivation we call “silent hypoxia” — “silent” because of its insidious, hard-to-detect nature.
Pneumonia is an infection of the lungs in which the air sacs fill with fluid or pus. Normally, patients develop chest discomfort, pain with breathing and other breathing problems. But when Covid pneumonia first strikes, patients don’t feel short of breath, even as their oxygen levels fall. And by the time they do, they have alarmingly low oxygen levels and moderate-to-severe pneumonia (as seen on chest X-rays). Normal oxygen saturation for most persons at sea level is 94 percent to 100 percent; Covid pneumonia patients I saw had oxygen saturations as low as 50 percent.
Josh Marshall at Talking Points Memo had been looking into this back on April 7 and on April 8 when he began following up reports that there was something different about the way Covid 19 affected the lungs and that standard ventilator protocols might be doing damage to the lungs because of that.
...Yesterday I noticed this grainy youtube video posted on March 31st by a New York City emergency and critical care physician, Cameron Kyle-Sidell. Kyle-Sidell said that he thought the treatment protocol and basic understanding of acute COVID-19-induced respiratory distress were both wrong. He said that what he is seeing in his ICU does not look like pneumonia but rather oxygen deprivation (hypoxia). Thus the treatment shouldn’t be focused on high pressure for someone whose lungs aren’t able to function but rather more effective ways of delivering additional oxygen. Critically, he argued that the high pressure ventilation might be damaging the lungs. He also said his impressions were based both on his ICU work over the previous two weeks and conversations with other clinicians around the country.
(Diary about it here.)
Dr. Levitan appears to have figured out what is going on. Patients with Covid 19 infection are having their lungs filling up with fluid in a way that degrades their ability to take in oxygen, but still lets them flush CO2 out of the body. It’s rising CO2 levels in the blood that normally trigger the feeling of being short of breath. Patients develop what Levitan calls silent hypoxia — what Dr. Kyle-Siddell had been seeing. As Levitan notes:
...The coronavirus attacks lung cells that make surfactant. This substance helps keep the air sacs in the lungs stay open between breaths and is critical to normal lung function. As the inflammation from Covid pneumonia starts, it causes the air sacs to collapse, and oxygen levels fall. Yet the lungs initially remain “compliant,” not yet stiff or heavy with fluid. This means patients can still expel carbon dioxide — and without a buildup of carbon dioxide, patients do not feel short of breath.
By the time patients begin to feel short of breath, the pneumonia in the lungs has already progressed to dangerous levels. The key is detecting falling oxygen levels in the blood so that treatment can start before that happens, and avoid using ventilators if at all possible. That can be done with a simple non-invasive device, a pulse oximeter.
There are many commercial products available, and they can be purchased without a prescription — but their use should be done in consultation with a doctor in order to make sure the user understands what the devices are showing them.
Early detection of Covid 19 pneumonia can allow treatment with less intensive measures.
A study based on this developing understanding of how Covid 19 attacks the lungs appears to be producing significant results.
There are other things we can do as well to avoid immediately resorting to intubation and a ventilator. Patient positioning maneuvers (having patients lie on their stomach and sides) opens up the lower and posterior lungs most affected in Covid pneumonia. Oxygenation and positioning helped patients breathe easier and seemed to prevent progression of the disease in many cases. In a preliminary study by Dr. Caputo, this strategy helped keep three out of four patients with advanced Covid pneumonia from needing a ventilator in the first 24 hours.
There’s no denying that having ventilators available during the pandemic is going to be critical. However, what looks like even more important is identifying patients developing Covid 19 pneumonia early so treatment can start before they need to be intubated and put on a ventilator. Dr. Levitan offers this recommendation:
All patients who have tested positive for the coronavirus should have pulse oximetry monitoring for two weeks, the period during which Covid pneumonia typically develops. All persons with cough, fatigue and fevers should also have pulse oximeter monitoring even if they have not had virus testing, or even if their swab test was negative, because those tests are only about 70 percent accurate. A vast majority of Americans who have been exposed to the virus don’t know it.
Understandably, there has been a fixation on ventilators as a treatment for critical cases of Covid 19 infection. When a patient becomes unable to breathe, mechanical assistance is the only resort. Big and impressive technology has its own appeal, especially when people are desperate to do something. Unfortunately, the success rate is not good; 80% of patients in New York who have been put on ventilators have died. Experiences elsewhere around the world have also had physicians rethinking ventilator use. (See the earlier diary on that here.)
There’s a lot we are still finding out about Covid 19. (For example, does recovering from it produce lasting immunity or not?) While Dr. Levitan’s work promises to improve treatment, there will still be patients that can't can’t be saved. Early detection of silent hypoxia could be a major advance though; Read The Whole Thing.
NOTE: Levitan’s hypothesis on how to modify handling Covid 19 infections is still preliminary. The NY Times hedged their bets by placing in it their Opinion Section. You can bet there will be a lot of people hurrying to follow up on this though.
Also to be expected: there will be a run on pulse oximeters as the news about this gets out. Fortunately they are relatively simple to make, readily available, and not all that expensive (at least compared with a ventilator) — but watch what happens to pricing and availability. Given the way the Trump administration and Jared Kushner’s shadow virus task force have been operating to seize and selectively hand out critical medical supplies, and the profiteering that is taking place, it could get crazy quickly.
Stay safe, don’t give up precautions, and let’s also ramp up testing as fast as we can.
UPDATE: It occurs to me that a simple device like an oximeter ties in with something else in electronic diagnostic tools. Because of the health risks from virus exposure, doctors are resorting to telemedicine. Having ‘smart’ diagnostic tools at home could make getting proper medical care promptly a lifesaver.
It’s one of the things that spurred a competition to develop a real world Star Trek medical tricorder. The health apps on my Apple Watch are like having a personal ‘black box’ between the data they and my iPhone can track. Going forward, figuring out how to make best use of this technology could be an important part of healthcare reform. This could be one of the additional impacts of the pandemic — especially as climate change and economic stress generate new health problems...
Tuesday, Apr 21, 2020 · 6:06:42 PM +00:00 · xaxnar
Update: Here’s a Post by Jen Hayden on breathing exercises that are reported to help with Covid 19.
UPDATE: Kevin Drum saw the NY Times Editorial on this: here’s his take. P.S. He went out and got an oximeter.
SUMMARY OF KEY POINTS:
Here’s how it works:
People developing Covid 19 pneumonia may be spotted early by using a simple device called a pulse oximeter. It’s non-invasive and clips on a finger tip to get a reading. Used correctly, it can give a measure of how much oxygen is in the blood very quickly. A drop in blood oxygen levels is an early warning that someone may be developing Covid 19 pneumonia even before they begin to experience difficulty breathing. It’s called silent hypoxia because people can have it without feeling it.
Who should use an oximeter:
- People who have tested positive for Covid 19, but have no symptoms. It can give early warning if they are developing pneumonia while they are waiting out quarantine.
- People who have Covid 19 symptoms – coughing, fever, etc. It can warn if they are slipping into pneumonia. They should use it even if they have tested negative for Covid 19, because the tests are not always accurate.
- Not specifically recommended, but people who have been exposed and are self-isolating may want to add an oximeter check along with watching for fever while they wait out isolation.
- People with other health conditions who need to monitor their blood oxygen levels.
Why this is significant:
Detecting developing Covid 19 pneumonia early gives time for other treatments to be used. Putting patients on oxygen, breathing exercises, and positioning in ways that help the lungs function may help people recover without having to be put on a ventilator.
Cautions:
This is a developing story; the recommendations are based on observation and experience by a healthcare expert in consultation with others, but there has not been time to do controlled studies or explore all of the implications of these preliminary findings.
While oximeters are relatively easy to use, they have to be used correctly, and people should consult with a doctor if they get measurements that seem to be of concern. Low blood oxygen levels can have other causes than Covid 19.
Covid 19 can manifest in a variety of ways – oximeter measurements are only one tool in the tool box and the total health picture needs to be kept in mind.
Some people will still become so sick that a ventilator is the only option.
Maintain social distancing, wear masks, wash hands, avoid touching your face, and stay safe.