What do I need to know about ventilators in light of COVID-19?

Throughout the pandemic, there's been a lot of focus on having enough ventilators to help critically ill patients who struggle to breathe.

But concerns have been raised that, for some COVID-19 patients, mechanical ventilators may do more harm than good. 

While it's too early to know for certain, it's a good idea to understand how ventilators work and the risks associated with their use.

Dr. Brian Goldman, host of CBC podcast The Dose, spoke with emergency physician Dr. Reuben Strayer and associate medical director at Maimonides Medical Center in Brooklyn, New York. He and his hospital have seen a crush of COVID-19 patients since the outbreak began. Dr. Strayer says physicians in New York are still learning about COVID-19, and as a result some have changed their approach to using ventilators. He's an expert on managing critically ill patients with airway and breathing problems, and the author of the widely-read blog Emergency Medicine Updates. 

Here is part of that conversation.

You are home sick from work with COVID yourself. How are you feeling today? 

I'm hanging in there. I'm [on] day of illness number five or so. It's like a really bad flu. But I think I'm gonna pull through. 

Let's start with the basics. How do ventilators work?

So mechanical ventilation is a way that we support the respiration of people who can't breathe by themselves. The way that conventional mechanical ventilation works is that when someone has respiratory failure — so they're not breathing — we make them unconscious so they'll tolerate us putting a tube down their throat... And then we connect that plastic tube to a mechanical ventilator machine that allows us to fully control the patient's lungs so we can breathe for the patient.

There are many reasons why we have to put patients on a ventilator. The most easy to understand would be someone with terrible pneumonia … There's so much infection in their lung that … their breathing just isn't adequate to get enough oxygen into the body. A ventilator ... allows us to do two things. Number one, we can provide 100 per cent oxygen through that, and number two … we can blow the air into their lungs with pressure to take over their work of breathing, especially for patients who are tiring [from] breathing really hard for days.

In the case of severe respiratory illness, at what point do you start thinking that a patient needs a ventilator?

Until recently, I think most emergency docs had a good idea about what kind of patients needed to be put on a ventilator. This has all been turned on its head in the coronavirus pandemic because coronavirus patients behave differently.  

We commonly use oxygen saturation (the level of oxygen in the blood) to give us a marker of exactly when the patient's lungs are failing badly. So normal oxygen saturation on someone breathing room air … would be above 95 per cent. And when the saturation falls, let's say below 90 per cent or 85 per cent, that's a good indication to us that that patient's lungs are not doing well.

With coronavirus we've just seen that … their saturation doesn't seem to be a good reflection of how well their lungs are working. Patients have come to the emergency room … a little bit short of breath, but not particularly, and they would be speaking in full sentences and they'd have a normal mental status. But they would have sometimes alarmingly low saturations.

How have COVID-19 patients been doing on ventilators?

There's been a big shift in how we think about intubating COVID patients over the past month based on the experience of the countries that were hit hardest early on. [Initially] we adopted the advice, mostly from the Italians, that suggested that with patients who come in with COVID who aren't able to be adequately supported with low-flow oxygen — like a standard  nasal cannula, that little plastic thing that just fits in your nose, or just a simple face mask — we should just jump immediately to … a ventilator.

And so when the first wave of critically ill COVID patients arrived in New York City about a month ago, we were following that advice. And it became obvious that this was not a sustainable strategy, because we were intubating five, six, seven, eight patients in a single shift. 

Furthermore, around that time, we started to learn of … data from China and Italy that was showing alarmingly poor outcomes from patients who were being intubated. The early reports … demonstrated that people who were being put on ventilators were doing very, very poorly with mortality upwards of 70 per cent, which is just an extraordinary burden of mortality. So … we pivoted.

We figured this out over social media, in fact, and through lots of discussions, sort of decided as a unit that we were going to try to [treat] these patients with non-invasive oxygenation therapies, so that we could either prevent intubation or delay intubation. Which is a huge win for everyone, especially the patient.

How so? 

Because every day that a person is on mechanical ventilation is a day that they are extremely vulnerable, and a day that they require an extraordinary, extraordinary level of intensive care to keep them safe.

Within an ICU, you have one nurse to one patient, or one nurse to two patients. And that allows … nurses to spend a lot of time with each of their patients so that they can very closely monitor any change that's happening … so they can react to it. 

People may hear discussion around the need to produce more ventilators and assume that it's a magic bullet to save people from COVID-19. But even outside of this disease, ventilation comes with risks. What are those?

The first kinds of harms have to do with the fact that they are paralyzed and sedated, motionless in a bed. That sets up the patient for infections, bed sores, other types of problems...

Having that endotracheal tube in your trachea … is an infection risk. Also, the lung is designed to work with negative pressure, meaning when you take a breath. With a ventilator, you're applying positive pressure — you're blowing the air into the lung. And that's maybe necessary to save the patient's life, but on some level it also injures the lungs. So it's a tightrope … of how much support to provide to maximize health outcomes, while minimizing the harm caused by the ventilator itself.

How do people incorporate this new knowledge into making a decision beforehand or about what they would want should they need a ventilator due to COVID-19?

Physicians are really struggling with very incomplete knowledge… so if physicians don't know, it's really difficult to put that on the patient and to think that a patient is gonna be able to make an informed choice. 

There are some patients with COVID who are so severely affected that they have profound respiratory failure. And there's clearly no other option than to put them on the ventilator. For everyone else, the benefits of mechanical ventilation have to be weighed against the harms, which is extraordinarily difficult to do right now. Because at the moment, we just don't have enough data to make informed decisions. 

Written by Brandie Weikle. Interview produced by Arianne Robinson and Dawna Dingwall. Technical assistance from Austin Pomeroy.