'COVID Calculus' Is Changing Medicine

F. Perry Wilson, MD, MSCE


April 07, 2020

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This transcript has been edited for clarity.

Welcome to Impact Factor, your weekly commentary on a new medical study. I'm Dr F. Perry Wilson.

I'm recording this after spending 2 weeks on the renal ICU service here at Yale in Connecticut. We are in the upswing of our COVID-19 surge.

I want to talk a bit about what I've learned and experienced in these 2 weeks, with the caveat that there is significant selection bias. Patients with COVID who end up needing renal on board are generally not doing very well; we've really been struggling to provide the best care possible.

So, some thoughts and observations. Obviously, due to privacy concerns I can't give you specific patient information.

In 2 weeks, we had many deaths and one successful extubation. These patients take a long time to heal, and prolonged ventilation—at least in those with renal failure—is the rule, not the exception. By the way, since I know people will ask, all of these patients received hydroxychloroquine; it is part of Yale's publicly accessible COVID-19 treatment algorithm.

Most of the patients had preexisting conditions, but typically they weren't severe; these were definitely not people who might have died anyway. We're talking about a preexisting condition of a BMI of 35, for example. And several patients, including a couple of young ones, had no medical history at all.

It's bizarre not seeing patients' families. So much of what we do when patients are critically ill is facilitate families' understanding of where they are and what might happen next. Doing that by phone is strange and impersonal and really hard.

Managing volume status in COVID-19 is complicated. My bias has always been to try to dry people out as much as possible in the setting of ARDS, but I'm not totally sure that's the best thing here. In particular, a lot of these patients need high PEEP, and that makes me worry that aggressive volume removal could lead to V/Q mismatch and worsening ventilation. The ICU docs have been invaluable in guiding our assessments here.

Speaking of the ICU docs, I have seen so much heroism these past 2 weeks from the ICU doctors, nurses, and medical assistants who are in and out of those rooms all day. Thank you.

And can we please acknowledge our medical trainees—the residents and fellows—who are doing so much for these patients? They are truly on the front lines, and getting paid about a quarter of what attending physicians are.

More than anything else, the thing that has struck me is something I'm calling "COVID calculus." It's this change in how we practice hospital medicine. It's based on the fact that our decisions now aren't simply about trying to balance risk and benefit in our patients, but in our providers as well—in the whole hospital system, really.

Here's a simple example. If I don't have prior kidney imaging on a patient, I usually get a renal ultrasound in the setting of AKI. Is it high-yield? No, but I do it to be complete—to see if the patient has hydronephrosis, how big the kidneys are, etc. Every once in a while, it matters.

Now, I have to stop and think: Is it worth exposing the ultrasound tech to the risk of going in the room? Will the machine be properly decontaminated? If the tech gets sick, is there someone to replace them? Is the benefit worth the risk?

This is happening all over. Last week, it was reported that New York City EMS is being instructed not to bring cardiac arrest patients to the ED unless they can get return of spontaneous circulation in the field. The risk of exposing ED workers to the virus is just too high.

This is echoed by hospital policies regarding CPR. Historically, we know that cardiac arrest that occurs in the hospital is associated with fairly poor outcomes; just 20% make it to discharge, according to this seminal article from the New England Journal of Medicine.

We still resuscitate these patients, though. But COVID calculus may change this. The risk of aerosolizing virus during CPR is high, and a lot of people need to be in the room to run a code. Some hospitals are modifying their DNR policies to mitigate this risk.

The insidious thing about COVID calculus is that it gets worse as the epidemic gets worse.

But it's not all bad. One thing COVID calculus eliminates is low-value care, and we're quickly learning what that is. When this is all over, will I go back to ordering renal ultrasounds on everyone with AKI? Will we demand that patients see us in the office for follow-up when it's easier to do a telehealth visit?

Whatever the outcome, it seems clear that the world 12 months from now will be unrecognizable compared with the world 12 months ago. I hope you're all safe and protected.

F. Perry Wilson, MD, MSCE, is an associate professor of medicine and director of Yale's Program of Applied Translational Research. His science communication work can be found in the Huffington Post, on NPR, and here on Medscape. He tweets @methodsmanmd and hosts a repository of his communication work at

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