One of the most fascinating and ominous things about COVID19 is that as clinicians and researchers have learned more about it that knowledge has not simply filled out the details of a broadly understood story. Rather, more knowledge has confirmed how little we knew and still know about the disease. For lay people like most of us the original story was that COVID19 was a viral respiratory tract infection. It was more deadly, less predictable in its course and had no known therapies to treat it. But broadly speaking a disease that attack the lungs, leads in severe cases to pneumonia and from there a cascading series of failures that can lead to death. Doctors had a more sophisticated but broadly comparable understanding. Four months plus into the history of the disease they know that COVI19 can attack most of the body’s major organs – heart, liver, kidneys, brain, et al. It’s far more insidious and copious in its range of potential attacks on the human body than they realized only six weeks ago.
A new emerging issue is how COVID19 attacks or disrupts a patient’s blood – specifically the delicate and critical balance of regulating when to flow and when to clot. When I first read articles about this I assumed these clotting issues were just part and parcel of the failure or near failure of the various organ systems. COVID19 attacks your liver or kidneys and clotting issues are just a manifestation of injury. But that does not seem to be the case. It seems to be a distinct way COVID19 attacks the body.
This article in The Washington Post, which describes one of new studies of this clotting issue, notes that on autopsy lungs of COVID19 patients which doctors expected to find with typical evidence of pneumonia instead were filled with numerous blood clots. This article reports how young and middle aged COVID19 patients, with very limited symptoms, are dying from strokes. One doctor interviewed in the article describes removing a clot from a patient’s brain and seeing new clots forming in real time as he worked – something he said he’d never seen before. (Here’s another write-up of the same study in Medscape.) According to the article, the clotting issue is so concerning that some doctors have discussed giving all COVID19 patients limited blood thinning therapy as a way to head off the problem. But this study notes that many patients with severe COVID19 die from bleeding disorders and hemorrhages. So it appears that the disequilibrium is operating on both sides of the spectrum – excessive clotting and excessive bleeding.
One surmise that comes in expert discussions of COVID19 is that the seeming randomness of who gets and doesn’t get severe disease may not be so random. Many suspect that there must be some logic, some genetic dimension or some as yet unknown underlying factor, which makes the disease progress so differently in different people, even after controlling for age and the big preexisting conditions. Some of the discussions I’ve linked above appear to hint at the possibility that subtle, pre-existing differences in blood chemistry – ones which may have little or no impact on health in general – may drive these very different outcomes in COVID19 disease.
Let me conclude by noting another emerging discussion in COVID19 treatment. About three weeks ago I mentioned this odd video by a emergency medicine doctor in New York who said that the cases of pneumonia and ARDS (Acute Respiratory Distress Syndrome) his team were seeing seemed very different from what they expected and suggested that doctors may be moving too quickly to put these patients on ventilators. While the implications for treatment were not clear, doctors in other parts of the country were seeing similar things. What unites all these discussions is that many COVID19 patients present with blood oxygen levels which should leave them gasping for air or even on the verge of death. And yet, they’re neither. Indeed, doctors report patients using their iPhones or being otherwise aware and functional just before being intubated. This has led some to ask whether earlier and less invasive breathing assistance could be a better approach for at least some patients.
It’s this issue that is at the center of an opinion column which appeared on April 20th in The New York Times. Dr. Richard Levitan is an emergency medicine doctor who’s been in practice for thirty years and is also the inventor of a system for teaching intubation. In other words, he’s literally in the intubation business. Levitan spent ten days volunteering at Bellevue hospital in New York during the height of the crisis and he saw the same issue: patients coming into emergency rooms with mild shortness of breath already had blood oxygen levels that made it surprising they weren’t in acute distress or even still alive.
The earlier discussions I note above suggested doctors were rushing to invasive treatments when less invasive approaches might have been outcomes. And that may be the case. But Levitan makes a different point. Many of these patients had already become critically ill at home without even knowing it, without the symptoms that would lead someone to know they were in critical condition. That may be even more the case since public health systems are telling people not to come to the hospital unless they become seriously ill. As Levitan put it, “Their pneumonia had clearly been going on for days, but by the time they felt they had to go to the hospital, they were often already in critical condition.”
The next part is worth quoting at length.
Patients compensate for the low oxygen in their blood by breathing faster and deeper — and this happens without their realizing it. This silent hypoxia, and the patient’s physiological response to it, causes even more inflammation and more air sacs to collapse, and the pneumonia worsens until oxygen levels plummet. In effect, patients are injuring their own lungs by breathing harder and harder. Twenty percent of Covid pneumonia patients then go on to a second and deadlier phase of lung injury. Fluid builds up and the lungs become stiff, carbon dioxide rises, and patients develop acute respiratory failure.
What Levitan draws from all this is that pulse oximeters – those little gadgets doctors sometimes put on the end of your finger to get a quick pulse and blood oxygen read – could be critical for patients to be using at home. If you’re riding out COVID19 at home with generally mild or moderate symptoms, you test your blood oxygen levels a few times a day. If it stays in the normal range of 94% to a 100% you keep at it. But if it starts to drop you know to get medical assistance right away.
It wasn’t clear to me from the Times piece or a separate interview Levitan in Medscape what different treatment doctors would provide. The issue seems more than earlier intervention could prevent the lung damage which leads to a rapid deterioration for many patients. “If we could detect it earlier,” Levitan told Medscape, “we could initiate treatment earlier. We need to change messaging to the public, to physicians, to get earlier recognition of the disease.”
Public service announcement: don’t rush out to buy a pulse oximeter! They’re relatively cheap and low tech. But medical supply chains are not remotely up to the challenge of producing enough of these to allow every household to have one on hand just in case. Levitan’s twitter feed is already awash in discussions on this point: and the need to prioritize their use first in assisted living facilities and then in people who’ve been diagnosed with COVID19. The relevant point is that the progression of COVID19 can often occur without the patient knowing it, especially the progression of COVID19 pneumonia that gets to a critical stage before patients and their remote physicians even know they’re in trouble.
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