Podcast – Hyperbaric Medicine with Jeff Kerrie at LTC

Welcome to the St. Emlyn’s podcast. I’m Iain Beardsell 

and I’m Natalie May.

And we are at the London Trauma Conference in Kensington, December 2024. We are here to talk a bit about hyperbaric medicine and it’s a delight to have with us Jeff Kerrie, a Canadian who’s over here visiting to talk specially at this conference.

Jeff, why don’t you introduce yourself and we can get into the meat of just what hyperbaric medicine means.

Sure, thank you so much for having me. Jeff Kerrie, I’m, an internal medicine physician based in both Victoria and Vancouver. And I also do some work in dive and hyperbaric medicine, as you mentioned, out of Vancouver General in Vancouver, and I’m an assistant professor at UBC as well as University of Victoria in BC.

So, keep my fingers in a lot of pies.

 Start us off, Jeff, by telling us a little bit about hyperbaric therapy. What is it? How does it work? Why might we want to be thinking about it for our patients?

 Hyperbaric medicine by the word itself is increased pressure and it’s using increased pressure to deliver oxygen to tissues that need more oxygen.

And there’s a number of effects from that. The most common case that usually you think about is divers and decompression illness, which is where the whole profession got started, 200 years ago or so. but now there are, at least in Canada and the US, we think of about 14 indications where there’s physiological plausibility as well as some scientific evidence for treatment.

 Let’s start off with a bit about dive medicine, cause as you say, that’s the indication that we tend to think about for the emergency department and for us to work in the prehospital environment. And that’s what comes up in our exams. So, tell us a little bit about those patients that we see after dive incidents when we might be thinking that they have the bends and when we could pull the trigger and think about starting hyperbaric therapy.

Rule number one, we always say is call us like at least in Canada, we’re on call 24/7 as hyperbaric dive consultants and we want to talk to emergency doctors. So, let’s work through it together. The physiology is such that as divers go deeper, every 33 ft of seawater is an atmosphere.

 As you go deeper, you dissolve more of the nitrogen gas into your blood and tissues, which is fine, as long as you come up very slowly later and allow that tissue to off gas again. But there’s a number of reasons why you may get, as you mentioned, the bends, which is the nitrogen gas coming out in the tissue, coming out in the blood, collecting in places we don’t want it to collect.

And that can be very serious, including strokes and spinal cord hits.

And just tell us a little bit about those, that kind of patient manifestation and what does that look like? When should we think about it in patients who’ve been involved in diving.

A takeaway I always want to pass along is that even the divers who are following their dive computers, their dive tables, and they say, I did it all right.

There’s still a bend rate built into that. So people are going to get bent, even under the best dive conditions, so you have to have that, that concern for the bends and at the same time also not think because it’s a diver, it must be the bends and not forgetting to rule out all those other things like thromboembolic disease and that sort of thing.

So, the patients we see are ones who are we’re looking for specific symptoms. The common ones are the joint pain as the bubbles collect in the joints, and that’s the simplest type. There’s the skin bends as well, which is a very specific rash and itchiness that we used to think was pretty benign, and now there’s some thought that may be related to brainstem infarct. interesting research on that as well.

 So, the patient’s been diving, they’ve got joint pain, they’ve got the skin, and it can be much worse than that as well, can’t it, with cerebral manifestations.

At what point does that then turn from something that’s relatively benign into we’re on the phone to you asking for advice? Where’s that tipping point which is that bit of bend you can expect from diving into a medical emergency?

 It’s interesting when you talk about expecting from diving.

Certainly, if you look with an ultrasound at blood vessels after diving, everybody has bubbles. So, bubbles don’t necessarily mean you’re gonna get the bends. The skin bends, as I say, we treat pretty conservatively, but when they’re having joint pain, that’s the minimum to where I would put them in a chamber and do a proper dive treatment.

And then if it’s anything more serious, neurological, that’s a, I don’t want to say a no brainer, but we would treat urgently with that.

So, the divers come up, they’ve got some bends, they’ve hopefully got people experienced with them or they’ve had as part of their qualification, the idea of what to look out for.

They come to an emergency department. I work in Southampton in the UK, so this is not a million miles from possible for me, I’m on the coast. I get on the phone, what would be the actual thing that happens next from not just the practicality but the physiology of going into a chamber?

Early on and we talk about the prehospital portion if you can get them on oxygen early So, 15 litre rebreather as much as you can get into them.

That’s step one. In the hospital they’re continuing that as you’re talking to the hyperbaric team, I’m not sure exactly how it works in the UK where I am I would get a phone call, make a decision to treat. We call in a team that’s on call 24 /7, and then we would take that patient into our unit and there’s quite an extensive checklist,

so, they have to be cooperative. They have to not be claustrophobic going inside the chamber. They have to be able to clear their ears or else they may need myringotomies or T tubes. There’s a lot of logistical pieces like that, and then it’s a matter of really running the chamber, which is a team sport.

 Are there certain things that we can say on the phone call that will make that decision making easier for you? Because this is one of those things that will happen to us pretty rarely, I would think, particularly in the UK, particularly for most of the people who are inland.

What is the key information you need, when you’re trying to make a decision about whether hyperbaric therapy will be a benefit.

 It’s ideal if you have some information about their dive profile, you can ask them, the divers will be able to tell you how deep they went and for how long, that can be helpful to us. And then really, a good physical exam, looking for the neurological deficits and understanding that good history taking of where the pain is and whatnot. that’s how we’re going to make that decision.

And so, this is history taking, there’s not numbers we can look at. There’s not a blood test you can run or a set of vital signs you can do. This is about actually back to good old fashioned medical history and examination.

It is absolutely a history and examination. There are some studies going on trying to look for biomarkers, but there’s been nothing successful I’m aware of so back to the basics.

Let’s take it right the way back because you made an allusion to the history of hyperbaric therapy. The name the bends comes from some of that, and I found that really interesting.

Just run us through that

 It was originally called the Caisson’s disease. A caisson is a big tube that gets pressurized into a river so they can send people down to poor concrete and build pilings for bridges. And this was in the 1800s. And they realized from about 18 20 on that a lot of these workers were coming up literally bent over that’s where the term the bends comes from and that was because they had a spinal hit of a decompression illness. And so, when you look at the bridges along the way some of them had 25 to 50 percent deaths or maiming because of this and so that’s where we get the bends.

So, the patient’s got the bends, and we’ve identified them.

Often, we then, like many patients, we refer the patient on and something magical happens. They have an operation, they get some medicine, they have some therapy, whatever it might be. What is the magic that happens in a hyperbaric chamber? We may never see it, but I always think that if we can have a picture of what’s going to happen next, it gives an understanding of how to look after the patient and make it happen.

I don’t really understand how a chamber would work. Can you just give us an idea of what the patient would go through?

There are two types of chambers. There’s mono place or a clamshell, which kind of what you might’ve seen on TV where one person gets put in. The one I work at is a multi-place. So, it’s, it looks like a small airplane tube. You can stand up in it. There are seats for eight or nine patients. And then there’s a doctor and nurse. We take them in, we pressurize them down based on specific dive tables, we use. All based on us Navy work from the past a hundred years. and when they’re at pressure, then we apply the oxygen treatment. And that oxygen treatment then is going to help wash out the nitrogen that’s in the blood, as we slowly bring to them to the surface over anywhere from five to nine hours, if it’s the bends.

So, the treatment is going to take a considerable amount of time, and this is to reverse the process that probably took some time to accumulate. Is it one treatment and you’re done?

It really depends how severe your symptoms are for the basic bends, which would be the itchiness, a joint pain, that sort of thing, often we’re good with one dive, sometimes two or three. The case we talked about today of a spinal decompression illness that was quite severe with essentially a poor person left wheelchair bound without any sensation and cauda equina type symptoms, we treated that for almost 14 days till the symptoms really stabilized and we knew what we were dealing with.

And what’s the risk if we miss this? So, we perhaps don’t get that idea of that threshold for making the call. What could happen if the patient has decompression illness and we don’t do something, we don’t get them to somebody like yourself? The consequences are pretty significant, aren’t they?

Yeah, if you’re looking at bubbles in the joints can cause inflammation and damage to the joints over time.

And then as we’ve said here, those more significant hits of the brain, spinal cord, can be life altering. There is also the second part of this is arterial gas emboli. So when you think of the bends, we’re thinking about bubbles on the venous side, or coming out of tissue like the spinal cord, sometimes If you have a PFO, which one third of the population does, or if you have so many bubbles that your lungs can’t filter them out, that goes to the arterial side, and that’s where you get the really serious spinal and brain and cerebellar hits, and those are, those are debilitating.

But your patient that you talked about today actually had an amazing outcome despite that significant level of disability pretreatment.

We got lucky. That patient had been, delayed in treatment by a few days because of international travel and came in quite sick, essentially in a wheelchair with loss of sensation from the waist down, and after the 14 treatments, I think the residual deficit was a little bit of neurological deficit in one foot. And she was walking again, and it was, yeah, very satisfying.

 We’ve talked all about the dive medicine side, but tell us a bit about the other indications, the other things that we can use hyperbaric therapy for, because it’s not just about the bends.

Yeah. And I’ll start with the negatives as I did in my talk. We got to remember that this is a treatment looking for a disease over the last a hundred years and you have to be really careful about using certified chambers, which are treating things with some amount of scientific plausibility.

There are private chambers that will treat your headaches, your cancer, your autism. There’s no evidence for that. The other indications we do it for include things like, sudden sensory neural hearing loss, there’s some evidence for, adjunct to steroids. Delayed type radiation injuries, so someone’s had head, neck cancer or genital urinary cancer. They get bladder radiation cystitis. We can treat that. Those are some of the most satisfying. These are people who haven’t left their house in a year because they’re going to the bathroom every 20 minutes with blood, and we can get them back to functioning. It’s a two-month course of treatment, but it works. some of the emergency stuff includes carbon monoxide poisoning, clostridial infections, even nec. fasc.

And that’s fascinating. So, the nec. fasc idea, obviously we see that as a surgical emergency. What would be the patient with nec. fasc?

What would be their pathway to coming to you in a chamber?

So nec. fasc still, the definitive treatment as I’m sure all your listeners know is the surgical portion and antibiotics, but there’s evidence for, increased healing, antibiotic delivery, decreased oedema, to help with wound healing.

So, it’s an adjunct certainly. With the clostridial necrosis. When it’s an anaerobic bug, it’s the one time where we say, yeah, do the surgery first, but the surgery should be a little briefer and get them into the chamber because that direct oxygen toxicity effect is so powerful.

And you’ve mentioned in passing, perhaps just to finish off about those, what should we say, non-licensed uses. It must feel frustrating to you that there are, we have one near me, a chamber where people are purporting it, particularly in our area as a cure for Lyme disease, chronic Lyme disease. How does that feel when you see people doing this sort of work in your area of specialty?

Yeah, it’s disappointing that there’s so little regulation, definitely in Canada. And I know when I was preparing for this talk, looking around Europe, it’s very similar. It’s a bit puzzling, why we’d have unregulated medical treatments occurring at great expense and at some danger to patients. As we talked about during the talk today, you can get oxygen toxicity seizures. If you have a fire, it could be an explosion. I mean, people have died in these chambers around the world. And so, you want a safe regulated chamber. And so, it’s, yeah, it’s upsetting. Let’s say to see, those chambers.

Jeff, thank you so much for your time. This is one of those areas that I think knowing a little bit about for us can be incredibly empowering and also might mean that the one or two cases we see, we’re reminded to make that call.

And I think your first point of pick up the phone and have a conversation is perhaps the most important. It’s been really interesting to chat, and I’m fascinated by some of these things that are being used around the world, both in the UK and beyond. And thank you so much again for your time.

Thanks so much for having me.