Happy Hypoxia

So I wanted to talk today about the coronavirus and one of these kind of strange clinical things that we're seeing, something that is now being termed in medical communities as the happy hypoxemic patient. And first, let me say that this COVID 19 disease has been a very humbling disease. It's sort of challenging a lot of the things that we thought we knew in medicine, and it's producing some clinical syndromes that we've never seen before in our lifetimes. And this hypoxemic patient scenario is certainly one of these. And this is an area where normally when you have an oxygen saturation that's really low, that's called hypoxemia, that causes hypoxia, which is not enough oxygen at the tissue level. And normally those two match and equal each other. So you might have an O2 saturation, say 70% or so. And that normally means that the cells in the body are not getting enough oxygen. And that means the cells start metabolizing in something we call an anaerobic metabolic rate, which typically produces lactic acidosis and typically gives the patient a number of symptoms of being air hungry and obvious hypoxic symptoms, altered mental status, things like that. We're not seeing that with this case, where what we're seeing is these very low oxygen saturations which do correlate to measured oxygen, arterial blood gases. So it really is low blood oxygen levels in the bloodstream. Yet their tissues seem to be handling this stress just fine. So it's sort of been equated to being like on high altitude, where you're acclimated to high altitude, and even though your oxygen level is lower than normal, your body's acclimated to this. So that's called moving the oxyhemoglobin curve off to the right, A shift of the oxyhemoglobin curve off to the right. We don't know why this is occurring, but it does bring up some clinical things that we need to address. So the first is normally we would intubate somebody who has an O2 saturation of 70%. But what we found in Italy and New York and other places that were real hotspots early on in this pandemic is that intubation is absolutely the wrong thing to do for these folks. Putting folks on ventilators should be an absolute last resort, because now you're combining the barotrauma, basically the pressure of the ventilator on the lungs, that damage that the pressure of the ventilator forced air on the lungs with the infection. And the death rates were tremendously high, up to 85% once you're on a ventilator. So really, we have to rethink our strategies and think that we have to do whatever it takes to keep these people off of ventilators. So the first thing that I want to talk about is the use of just supplemental oxygen. So these folks usually require lots and lots of oxygen. So oxygen should be a first step for these. Trust your pulse ox. Even though the patient may look good and they're speaking to you and cooperating with you, they have a low O2 set. It's real. Even though they seem to be tolerating it well, sort of the happy hypoxemic patient put them on high, high levels of oxygen. So as much as you can give them, and if that does not raise up their oxygen level, then the next thing we need to do is position the patient in a manner that recruits more lung tissue. So this is something called proning, and you may have heard about proning that's been used for many years for patients with adult respiratory distress syndrome. And it's basically to allow gravity to be your friend. Normally, when we lay patients on their back, the back of the lungs experience all the weight of the front of your chest, the front of your lungs and sort of collapses the alveoli in the back of the lungs. Simply taking that patient and putting them off in a lateral position, or even on their abdomen in a prone position, relieves the stress of gravity on those posterior alveoli, opens those alveoli up, and literally within five or 10 minutes, in these particular patients, these COVID patients, you can see a big jump in your O2 saturations. So this is a critical thing to be doing even pre hospital, because, number one, it costs us nothing, and number two, it dramatically increases the oxygen saturation and then takes us away from that red zone of having to be intubated. And again, everything we want to do is to keep them from getting intubated, because we know that that's really not good for these patients. So for your awake, cooperative patients who have the ability to turn over onto their side or onto their belly without dislodging their oxygen, it's very critical that their oxygen, however you're supplying it, whether by face mask, nasal cannula, both, or other methods that we'll talk about in a moment, that has to stay in place. If they can do that, please do that even while you're on route to the hospital and can cause dramatic changes. Now, if you put patients in these positions and for whatever reason, they don't seem to be tolerating it. Well, just undo it, you know, just go back to where you were before. But if they are tolerating it, stick with it and keep that all the way into the hospital. Early on in this pandemic, we were very concerned about aerosolization. And that's because its aerosolization can cause more danger to the healthcare team. And that includes us in EMS and fire rescue. So we shied away from things like cpap. But again, back on this strategy that we know if we can keep these patients off of ventilators, more of them will buy them enough time to recover and leave the hospital versus going straight to a ventilator where high risk of death. That makes us have to revisit things like non invasive positive pressure ventilation such as cpap. And there are other things the hospitals can do, such as a device called a high flow nasal cannula. Now, the hospitals and fire rescue, all of us, we're a little uncomfortable with aerosolized procedures because we know that makes it a little more risky for us. Just keep in mind that when you do any of these things, you have to have a good level of ppe. And just like you wear protective equipment when you go into the fire, there's equipment you can use for this. It will protect you. So we want you to have the full PPE and we're talking about eye protection, an N95 mask or higher. And you know, you can use half mask and other things. N95 is your minimum protection gown and gloves. And certainly anytime you do anything that aerosolizes the virus, that mask is not going to be reused. You're going to take that mask off and get a new mask for the rest of your shift. Now, we may be able to clean that mask. That's. That's topic for another. That's another talk. But you're not going to keep wearing that mask. But back to the patient, we can use cpap. What we're doing now is trying to find a way to give them high levels of oxygen with CPAP in a manner that mitigates the risk to the healthcare workers. So we've come up with a way to use a HEPA filter in line with our CPAP that minimizes the offloading of viral particles into the air. So we're going to combine that with our standard CPAP procedures to mitigate the risk. Plus you're going to wear that highest level of PPE that you can and then you will Transport those patients in. Now, if these patients are awake and cooperative, you can still combine the CPAP with placing them in a lateral position, either left or right lateral. Maybe a little more difficult to place them all the way on their front because of the way the device is. It's critical that these folks, that the auction doesn't fall off so you can stop just at the lateral position on those folks. The hospitals may be a little uncomfortable as you come in with these things because they also, everybody's, let's face it, everybody's afraid in this pandemic. There's a lot of unknowns and we want to be careful for ourselves and for our families that we don't bring this home. But we do know that proper ppe, when used the way it's recommended, does prevent you from getting this illness. In fact, you look at the Singapore data where they experienced SARS outbreak. SARS 1, and this is SARS 2, right? So SARS 1, they started wearing masks in their ER all the time. All the time. And they've been doing for years now, for over a decade. So when SARS 2 came, this current Covid thing that we're in now, they report, I was speaking with one of their EMS medical directors there. They have zero healthcare workers that have converted to this because they've been trained so to use their PPE properly. So we know that the PPE works if you use it properly and use it for every single patient. That's no different with this, even if you use the cpap. So the hospitals will work with them to explain why we're doing this. It's certainly in the patient's best interest to try to keep them from getting on a ventilator. And that may mean the use of positive pressure, non invasive, positive pressure ventilation like cpap. And we'll mitigate that risk by using these HEPA filters. One last thing is even though we're in the midst of this pandemic and we're still learning things about it, we're still going to stick to our normal high level of care that the county has come to know. That means if they're supposed to have IVs or whatever other kind of treatment you're supposed to give them, please continue to do that. Please know that you are safe if you're wearing your PPE at an appropriate level. And let's continue to do the good job for these citizens that we've always done.