The hyperbaric chamber. The pot. The place every diver wants to avoid. So it may surprise you to read that I volunteered to fight my way through Auckland traffic to get in one. More than once.
I've been participating as a test subject in a University of Auckland study into the narcotic effects of various gasses under pressure, in an effort to increase understanding of what happens to divers at depth and in the long run, make diving safer. I made my way up to the Devonport Naval Base and the Slark hyperbaric unit where I would be spending some time inside a big metal tube.
After getting buzzed in, being briefed on what we were going to be doing and practising the tasks I would be assigned, I was directed to change into some, I'm sure you'll agree rather fetching, cotton scrubs (with “HYPERBARIC UNIT” helpfully stencilled onto them, presumably in case I forgot where I was).
With that done the scrubs were then complimented with a rather stylish EEG cap and I was hooked up to the machine which would be recording my brain activity during the exercise. Despite all previous evidence I was assured that there is, in fact, one in there. Conductive gel was applied, electrodes put in place and then I was lead into the chamber by Hannah, who did an excellent job of looking after me through all of my exposures.
With everything in place, me inside the chamber, seals checked and the door secured we were ready to begin. Then we started the “blow down” to simulated depth. My first impression of being in a chamber during operation is that it was very hot and very loud. It is essentially like being inside a giant scuba cylinder being filled. Even through the ear defenders. Once the required depth was reached the tests began. I carried them out and was asked to rate my own performance.
Different exposures required different depths and had very different effects – 50 metres on air is a very different experience to 18 metres on 100% O2! Each gas mix had a different feeling, most interesting to me was using heliox (a mixture of oxygen and helium used at depths beyond recreational diving limits) for the first time. Suffice to say that at depth the difference between air and heliox is like night and day – one leaves you unfocussed and dull witted, the other feels almost like being on the surface.
With the tests done, it was time to head back up. Once again it was exceptionally loud but this time round the stifling heat and humidity of the descent was replaced by an icy chill. Wearing my big, woolly socks was definitely the right call. As we ascended our gas mix was switched over to speed decompression and depending on the dive profile we spent up to an hour waiting to be returned to a condition where we could exit. The book I was advised to bring was indeed vital equipment.
The chamber was something very different for me and I feel very lucky to have had the chance to take part in Xavier's study. While I certainly don't want to head there for treatment following a real incident any more than I did before, it has been fantastic to experience it under controlled conditions.