Saturday, 17 August 2002 00:00

Recompression Therapy - What Exactly Happens?

By Neil Miller


So, you've been diving and you have some pain in a joint or two, you think you may be bent, what do you do now? Well, first off, ring the Divers Emergency Service (DES) - 1800 088 200 and talk to them for starters and let them decide whether you really are bent and whether you need to present yourself to a chamber for recompression therapy.

This article is more about my personal experiences from the time I first felt any symptoms, to the time I finished my recompression therapy. It is not about what happened, why it happened etc. Remember, these are MY personal recollections on what I felt and experienced, it does not mean that if you were bent, you would feel exactly the same way.

Part 1

This is the situation I found myself in recently after a 5 day diving trip. Towards the end of the trip, I noticed a very slight sensation in my left knee after the last dive on the 2nd last day. As I could only just notice it was there, I was not concerned and put it down to the knee complaining about having quite a bit of extra weight on my back with diving twins, pony etc for the first time for this number of day's straight. I subsequently did 2 extra dives the following day, where the pain/sensation did not get worse, or better for that matter. However, because the pain was really nothing more than a minor ache, rather than pain, I gave it no extra thought.

The night before we left to drive back to Sydney, we all went out for dinner and I was feeling quite tired, nothing unusual considering the number of dives etc. However, the next day on our trip back to Sydney, we crossed a number of high mountains, one of which topped out at 1300mtrs. At this point; I well and truly knew I had problems. Pain in all major joints including knees, elbows, shoulders, toes, and ankles as well as at one point, stabbing pains in the scalp. Not fun stuff. When we stopped for lunch on the Saturday, when I sat down, Kiwi and Steve remarked I looked like crap, plus, I really felt like I had a huge weight pushing down on my head and shoulders.

Once we had arrived back in Sydney, most of the pain had gone away, as it can when you come back down from altitude. But, later that night, the knee pain had worsened and I was getting pain in various joints that was coming and going. I rang DES that night at around 11:30pm and spoke to the ambo that answered the line, described what I had been doing as far as the diving went, what I had been feeling, and the trip home. He then put me through to a hyperbaric doctor at the chamber in Adelaide. We talked for a while and went back over everything I had covered with the first person. He agreed that I was bent and that I should call the chamber in Sydney at the Prince of Wales hospital, so, he gave me their number and I called them straight away.

Part 2

I was quickly put through to one of the hyperbaric doctors on call and again, we went over the whole story etc, he also agreed that it was in the pot for me. I told him it would take me a good hour or more to get there and he said it would also take him a good 90 minutes to round up the staff required to operate the chamber. Since my symptoms where only mild and not a discomfort to me, he suggested I front up at 7:30am the next morning and go in with the normal run of patients.

After getting off the phone, I went and woke the wife and told her what was about to start happening. Being an ex diver herself, she knew what I was talking about but took some convincing that I had done nothing wrong on the trip to end up this way. I arrived at the chamber around 7:30am, however, the doors do not open till 8:00am so I had to wait. The doctor I spoke to on the phone was already about to finish his shift and I did not see him till later on. I was seen by one of the other hyperbaric doctors, of which there seem to be many.

We started off by going through the story of what had happened and going over the dive profiles that I had done. I had dumped these from my Vyper and printed them out the night before to make life easier to remember what I had done on the trip. This took some time as we went over each profile in detail as the doctor took notes on run times, deco stops, mixes etc.

Once we had done this, I was handed over to one of the other chamber staff to do a series of cognitive tests to see how I was doing mentally etc. Also in attendance were two trainees, one from the Navy and one from the Army. I passed all the tests apart from one, as I was on holidays, I generally do not keep track of dates and time and I failed to know what date it was, I was out by one day. ;-)

I was then back in with the hyperbaric doctor who then proceeded to do a number of physical tests for pain, reflexes, vision, eye hand co-ordination and balance etc. Apart from some pain near my right kidney, and my normal double vision making the vision tests a bit hard, there were no problems.

Before commencing the first treatment, I was also told about a new study they had just completed and were yet to publish in medical journals, which detailed the use of an anti-inflammatory drug to help with the whole re-compression treatment. I elected to take these tablets, one a day for the next 7 days. Whether it made any difference to me, I have no way of knowing, but if it did then great.

All this took a number of hours as they are very thorough in the number of tests they do. So, sometime around 11:30am, I was informed I would be going into the chamber for what is called a "Table 62". A Table 62 is where you are initially recompressed to 2.8 atmospheres (equivalent to 18mtrs of sea water) while breathing 100% O2 for a period of approximately 60 minutes with a number of 5-minute air breaks during this time. Then you are slowly brought up to 1.9 atmospheres (9mtrs) for the remainder of the nearly 5 hour treatment. During this remaining time, you are given a number of 15-minute air breaks from the O2.

Part 3

The chamber at Prince of Wales is divided into 3 chambers, a lock that can be pressurised if required, a large chamber for the normal day to day treatments and a smaller chamber that will sit 4, maybe 5 at a pinch. This smaller chamber is where I had my first treatment. In the chamber with me were the two trainees and the chamber nurse who did my cognitive tests. O2 is administered via an O2 mask which is held in place by straps that pass through a rubber bit on the back of the head, more on this later.

Looking into each chamber are small portholes, and also cameras positioned in these portholes so that the operators of the chamber can see what is going on inside. The nurse who is inside the chamber also has a headset and microphone so they can talk to the doctors and or operators outside.

One of the big things that people say when you talk to people who have had recompression therapy, is that it is so hot. Well, yes, it is (up to 35oC) whilst the chamber is being pressurized, but, once you are there, it is quite cool, and during depressurizationbecomes very cold (down to 12oC). Blankets are supplied as part of the garb you wear to try and help you keep warm. Speaking of which, when you first start your treatment, you are given a set of "scrubs" to wear. This consists of a pair of long pants, short sleeved top and slip over cloth moccasin type foot wear, a blanket and a large plastic bag to put your normal clothes into. Not the warmest clothes in the world I can tell you.

One other thing, is, it is quite noisy in the chamber, whilst your therapy is in progress, you can speak, but, with the mask on it's not easy.

At 2.8 atmospheres (18mtrs) on 100%O2, I was pretty light headed and because I did not bring my glasses I use when on the PC, I had lots of trouble keeping both my eyes in sync and just could not read properly so I gave up trying to do that. At every air break, my blood pressure and pulse was taken, my pulse was described as "irregular irregular". At this depth, any of the pain I had was now gone, with just occasional fleeting stabs of pain from time to time in some of the joints. Because they were worried about the heart rate etc and lower blood pressure, they brought in a very small ECG machine through the small lock in the side of the chamber to hook me up. I was rather disappointed it was not one of those machines from Monty Python that go "PING". Everything was found to be ok.

Whilst in the chamber, I was asked to fill in a DAN survey form which asks you lots of questions about medical background and the incident etc. If you get asked to fill one in, do so. This enables DAN to gather important information to better educate us on incidents of DCS etc.

Of course, being on 100% O2 at this sort of depth, there is the real chance that someone can go into an O2 fit. Well, I did not but I may have given the female trainee sitting next to me a bit of a cause for concern. After I had given up trying to read, I started to doze off and a few times I did actually fall asleep. But this one time, I awoke with a start straight after falling asleep and my legs sort of jerked as I woke up. This gave her quite a bit of a start as I somehow don't think she was expecting that sort of thing to happen. Apparently they have only had like 1 in every 1,000 patients fit whilst on the O2 and it passes very quickly after removing of the O2 mask.

Part 4

All went OK and at the first 15 minute air break, which was very welcome, as the bridge of my nose was getting rather sore from the mask and the back of my head was getting quite numb, we were served some lunch. This was a relief as I had last eaten some 7-8 hours earlier. Again, pulse and blood pressure were checked before I went back onto the O2.

There is really not a lot to keep you entertained inside a recompression chamber, it's painted beige, which I hate at the best of times, and there is only so many times you can stare at the depth gauge. If you do need to go to chamber, take something to read, and remember your glasses if you need them too.

I can tell you, I was really starting to watch the clock as I waited for the session to finish. My nose and back of head were feeling pretty sore and numb and I got to the point where I just wanted to rip the damn thing off. But, you put up with it, it's doing you good.

During the final hours of the treatment, again, I had the odd pains but not a lot. Though, thinking back now, I do remember the stabbing pain I had in the LHS of my left knee, this was the worst pain I had experienced so far and on a scale of 1 to 10, I rated this at a 7, it passed after just a couple of stabs of pain.

When it finally came time to ascend from our final depth of 18mtrs, the other 3 in the chamber went onto 100% O2, the rest of the time they had been doing this on air. Everything went ok whilst coming up, apart from in my left leg, I started to get some pretty weird muscle contractions etc that can best be described as the muscles were like "rolling" near my knee and were causing the leg to move left and right without me doing it. I pointed this out to the nurse and she said she had never seen it before. These "contractions" stopped after a few minutes.

Once out of the chamber, I was quite wobbly and light headed. Back in with the doctor for more questions and more tests on balance and pain levels etc. Due to the light headedness, it was pretty hard to pass the balance test. As for the pain levels, all had gone away or down to a very low level. I was told that it was back in tomorrow for a 90 minute treatment at 2.4 atmosphere (14 meters).

After arriving on Tuesday, I had another session with the doctor who had been looking after me the day before. Whilst I saw numerous other doctors over the 5 day period, I had this one doctor as my main specialist. We talked about my pain levels and how I was feeling etc. I told him that the pain was back in my knees and had also re-appeared in a few other joints like elbows and shoulders etc. But, not to the same levels as first experienced. This is fairly typical of how things develop during treatment for musculoskeletal DCI, especially if there has been any sort of delay in obtaining treatment.

Today's treatment and all the following ones were conducted in the bigger room of the chamber, in with the "general" population of people receiving O2 therapy for one reason or another. There were 6 patients including myself and a nurse. The difference between my treatment and the other patients was, I was on O2 from the very beginning, whereas, they did not go on to O2 till we had reached the maximum depth.

Today, I made a point of bringing my glasses so I was able to happily pass the time and read. Again, I learned to hate the O2 mask. Pulse and blood pressure were taken as per usual. And apart from some very minor fleeting pains, it all went smoothly. By the time I got out, I had very little pain, if at all, so was feeling pretty good. However, on the drive home, most of the pain returned, and in some cases, was worse than when we started. This series of pains continued on into the night, but was never to a point where it was uncomfortable.

Part 5

Come Wednesday, and again, in with my doctor to discuss how I was feeling etc. Back in the chamber for another 90 minute treatment like the day before. Before I went in, I noticed another diver had arrived and was just about to start the interview process with the doctors. When I came out of my treatment, he was about to start his initial 5 hour treatment. My treatment was much the same as the day before, get into the chamber, wrap the blanket around, sit down, mask on, pulse, blood pressure, read, hate the O2 mask, freeze, get out. Another session with my Doctor and we talked about the pain levels etc, at this time, I had no pain at all. Again, later that afternoon, some of the pain returned.

Thursday and Friday were pretty much repeats of Wednesday, have the interview in the morning, have the 90 minute treatment, hate the O2 mask all over again, another quick interview to decide how many more treatments we still had left to do. By Thursday morning, the treatments were no longer doing anything to the pain, and when I say pain at this point, it is nothing more than a dull sensation in whatever joint, mainly my left knee where it all started, no sharp stabbing pains etc. After more consultations with my doctor and the specialist that was in on that day, it was decided after my Thursday treatment, that Friday was to be my last. My nose and back of head were most relieved to hear this news.

Friday, the other diver was in with us for this treatment, so I got to find out what happened to him, but, that's another story.

So, after 5 treatments, and the offer of a 6th which I declined as it was no longer doing anything, I was given the news that there was to be no diving for at least 4 weeks and then after than, in moderation etc. No going above 300mtrs or flying etc, no heavy exercise and come back in 4 weeks for a follow-up.

So there ended my recompression experience. I still have the occasional minor knee pain, but that will fade with time. We concluded that there was no single dive that "bent" me, but it was more a case of a N2 build-up and possible dehydration. Ten dives over 4 days to me is not really a lot, they were a mixture of deco and non-deco dives on air or nitrox and were always done by the tables and then by computers if they still required time to clear.

I look at this whole experience as just that, an amazing learning experience. Of course there is this perception of a ridiculous "stigma" attached to being bent. People always seem to assume, frequently wrongly, that you screwed up. This is not the case in at least 50% of DCS cases and if people were better educated in what can cause DCS and how it gets treated, we may even be able to start to remove this stigma.

I hope that by writing this article I have given you a better understanding of what happens when you undergo recompression therapy. It's not that scary, the doctors are not there to pass judgement on you because you are bent, they are quite the opposite and just want to help you get better as quickly as possible. Whilst I would not want to be bent again, it's a fact of life being a diver, there is a good chance it can happen, no matter how many steps you take to minimise that possibility. Remember, you don't have to screw up to get bent; there are plenty of reasons why you can get bent that do not include doing a rocket ascent to the surface.

The main thing to remember, if you have been diving, and you have pain, don't put it off, ring DES and let them decide if you are or not. It only costs you a phone call to chat to the experts and the quicker you can get treatment, the better it will be for you.

If you have further questions, then I am happy to answer them for you:

Thanks to Dr Simon Mitchell who supplied some of the technical info for this article.