Incident: 14/12/2002

For about nine months now, a small group of Sydney deep divers have been involved in something called 'The Sydney Project'. This project is operated as a group, with no one in particular being the leader. Everyone has an equal say in what we do, and we're all experienced enough to know what we're individually capable of and to make our own decisions. This project aims to find and dive new deep wrecks off Sydney. Sydney has quite a few wrecks, and many are regularly dived in the 45 to 78 metre depth range. Unfortunately, most of the wrecks which are yet to be found are likely located in depths of over 100 metres. In Sydney, most deep diving is done with the 'Same ocean buddy system', ie, there are other guys diving off the same boat, but it's pretty much every man for himself once the boat pulls up on site. Also, there is usually only the boat driver who remains on the boat, and sometimes even he will dive, leaving no one on the boat.

Seeing these methods as unsatisfactory for very deep diving, the members of the Sydney Project have been refining their methods, with an emphasis on safety. To this end we've been employing the use of a support diver, who is on the boat to assist the bottom divers when they ascend and are carrying out their long decompression obligations. We've also been using another person on the boat in addition to the driver, to assist divers when they are on the boat or at the surface. These methods may be scoffed at as being overkill by many divers, but they really paid dividends when I had an incident recently.

There's been a lot of interest over my incident, so here is the story from my point of view. For portions of the incident I was either unconscious or incapacitated, so for these parts I'm relying on what I've been told by people who were right there on the scene.

The Dive

The dive site was a location known as 'The Peak', a well known game fishing site about 10km off Maroubra. Our reason for diving here was that we wanted to go a bit deeper than most of us had been before, in preparation for the deeper wrecks, and the Peak was believed to provide a range of depths from 65 to 120 metres. It's also known to have an abundance of big fish life, which would make things a bit more interesting than a deep sand dive.

On this particular day, Saturday 14th December, we had organised our team as follows. Bottom Divers were buddy pairs comprising Dave Apperley (Twin Inspiration) and Samir Alhafith (Open Circuit), and Dr Simon Mitchell (Mk15.5) and Jason McHattan (Mk15). Support diver was Kevin Okeby, and Dr Mark Spencer was also to be 'in-water' taking photos of the divers on decompression. Surface support was Simon Hadwin, and boat driver was Timbo.

All bottom divers were carrying enough bailout on their person to perform their decompression alone if separated from the boat. As we were unsure of the actual dive depth, we all had diveplans prepared for depths between 100 and 120m.

My personal setup was as follows;
- Mk15 closed circuit rebreather (CCR) with onboard oxygen and Trimix 10/57 diluent (10% Oxygen, 57% Helium, 33% Nitrogen). I was running the unit manually this day, as I have done many times in the past. Setpoint was 1.3Ata PPO2. The rebreather is fitted with Dive-Rite Dual Rec wings (second wing inflator not connected) and Transpac II harness.
- 1st sling cylinder comprising:
95 cu.ft. aluminium filled with air to 260 bar.
Apeks 1st stage
Dacor Viper 2nd stage
Button pressure guage
Inflator hose
Whip for attachment as 2nd diluent to rebreather.
DIR style rigging
- 2nd sling cylinder comprising:
95 cu.ft. aluminium cylinder filled with Nitrox50 to 260 bar.
Apeks 1st stage
Apeks T50D 2nd stage
Button pressure guage
Inflator hose
DIR style rigging
- 7 cu.ft. steel cylinder filled with air to 200 bar for drysuit inflation.
- Hydrotech shell type drysuit, with Weezle undersuit, thermal top, and 2mm neoprene vest.
- Usual tech kit of mask, fins, reel, torch, gloves, hood etc.
- Weight belt

Upon arriving at the site we scouted around for an appropriate depth, much to the amusement of the fishermen on the boats that were already out there. We anchored in a depth of 110 metres, so I arranged my deco tables with a 110m 12min at the front. Taking into account a four minute descent, this meant we would have eight minutes on the bottom. I always use Zplan with 2 minute Pyle stops and 15% conservatism, so this meant a diveplan as follows.

Dr Simon and I geared up first and entered the water at around 8:30am, Simon ahead by about a minute, Dave and Samir were to start their dive about five minutes behind us. As I descended I felt like I was exerting a bit of effort, but not too much as to be uncomfortable. When I reached the rocky slope bottom at 109 metres at about the five minute mark, Simon was sitting just off the anchor waiting for me. As is usual, I did a few checks, including bringing the PPO2 up to the setpoint of 1.3, but as I did this I felt a bit short of breath. After another minute I knew something was wrong. I swam over to Simon and indicated that I was calling the dive short, but it was ok for him to remain on the bottom. He questioned me, but I assured him it was ok. I turned, swam back to the anchor, and started to ascend. As I made my way up through 100 metres I knew I was in trouble. My breathing had deteriorated to short shallow panting, and I had an incredible feeling of anxiety, sure symptoms of Carbon Dioxide poisoning.

By this stage I knew exactly what was happening, and what I had to do to fix it, but I was too far gone. The first thing you would normally do is perform a diluent flush, which I've done on several occasions in the past, replacing the bad gas in the loop with fresh gas from the tank, but this didn't even enter my mind. I had to go to open circuit bailout, but there was no way I was going to take the mouthpiece out of my mouth. The anxiety is debilitating. There was nothing my mind would let me do but continue to ascend. At 88m I passed Samir on his descent. He gave me the ok sign, and I answered that I was ascending but ok. This is the last thing I remember underwater. Dave Apperley met me at 80m, and apparently I told him I was ok, but luckily he didn't believe me after seeing my eyes rolling around in my head. He then took hold of me and we did a 10m per minute ascent to 40m, where he says I passed out. He checked my readout and the loop PPO2 was still up over 1.0, so I'd still been adding oxygen up to that point. At this stage the buoyancy in my wings and drysuit was getting too much for Dave to effectively dump. Our ascent quickened until at 24m Dave had to let me go. Here's a picture of the dive profile downloaded from my VR3 dive computer. The red line is the dive, depth versus time, disregard the blue line.

The Rescue

I ascended to the surface uncontrolled and unconscious. Timbo saw me hit the surface about 20m from the boat, but initially thought I was ok, until I rolled over face first and didn't move. Kevin and Mark then jumped in the water and retrieved me back to the boat. My gear was removed quickly, thanks to the quick release buckles on the harness, then Timbo and Simon H, each being nearly twice my size, had no trouble rag dolling me over the side and onto the deck of the boat. I was not breathing, had no heartbeat, and blood was frothing from my mouth. The boat was carrying an Oxy-Viva, which supplies 100% oxygen under pressure to a non-breathing patient. This was quickly applied, and Mark started perfoming cardiac compresssion. Soon after this I regained consciousness, and rejected Mark's further efforts.

I was in incredible pain throughout my whole body, and felt like I couldn't get enough gas to breathe. The Oxy-Viva was breathed dry in about five minutes, and the next richest gas on the boat was my 50% Nitrox mix. The regulator for that was put in my mouth, but I didn't like it, I just couldn't breathe. I took it out of my mouth and threw it away. It was about this point that I noticed my legs were going numb. We had 100% oxygen on a line over the side of the boat at 6m for an in-water emergency, so the guys were now pulling this up onto the boat. By now I had no feeling or movement below my ribcage due to bubbles in the spinal chord, and the rest of my body just felt like it was burning up. At this point I thought it was all over, my body was rooted, my breathing was almost gone, and things were only getting worse. I rolled my head to the side, closed my eyes, and waited for the end. There was no bright light, no life flashing before me, no regrets as to an unfulfilled life, just the certain knowledge that it was finished, and if this is what death is like, then it's not too bad after all. This probably didn't last very long, as I was rudely interupted by one of the guys shoving another regulator in my face. After a few breaths of oxygen I looked up to see four concerned faces looking down at me, then I heard the helicopter on its way. Things were looking better. Timbo had called 000 and been put through to the Westpac Rescue Helicopter. He told them our GPS location and they were with us in eight minutes.

I remember seeing the chopper hovering behind the boat and a guy jumping from it into the water. Next thing I knew he was in front of me, asking my name, and telling me what was going on. I yelled at him, telling him my condition and that he should get me to the chamber NOW. I'm sure he didn't need me to tell him his job! There wasn't much stuffing about, he and the guys lifted me onto the transom at the back of the boat, he sat next to me, and grabbed the line that the helicopter had lowered. As the boat has a full canopy over it, we had to get back in the water so we could be safely winched up. I wasn't too keen on this, as I couldn't us my legs, my arms were weak, and my breathing was fast and shallow. But it had to be done, so after clipping my harness on just below his, he jumped us into the water. I went straight under, taking a decent amount of water into my lungs, before the winch line took up the tension. Up we went, and were pulled into the chopper. I was laid out on the floor and promptly the lights went out again. I briefly regained consciousness when they were getting me out the back of the chopper at the hospital.

The Treatment

**The case has been written up and published in the 'SPUMS Journal' by Dr Barbara Trytko and Dr Simon Mitchell. As this is a copyrighted publication, I can't post the article here.**
From here there's not much I can tell you as I was again out to it. Some things I've been told by the doctors are;
- My blood was like treacle. I was given ten litres of fluid to help thin it out.
- My haemoglobin was extraordinarily high.
- I was given Lignocaine and morphine continuously via internal lines for the next 48 hrs.
- I was given an extended and modified USN Table 6 recompression as initial treatment. 6.5 Hours.
- "You're the sickest person I've seen, who's lived."

I awoke for a few seconds about 9:30 that night, with family, friends, and doctors standing around my bed in the Intensive Care Unit at Prince of Wales Hospital, which was a wonderful feeling. The next thing I knew, it was about 5am the next morning, and I was hooked up to a multitude of machines that went 'ping'. I had central lines in the right and left groin, a peripheral line in the left arm, and a couple of other needles in my arms. These were supplying Lignocaine and morphine, as well as monitoring various body functions. My blood-oxygen percentage was low, due to lung damage, and I was on oxygen to help with this. At 8am, after a chest x-ray and removal of the tube from my throat, I was wheeled into the chamber for a 2 hour soak. After this treatment my neurolicical functions and Rhomberg results were very good, almost good enough to go home. Later in the day I complained of pain in the left leg, so for the next two days I had further 2 hour soaks in the chamber as a precaution. The lungs were the main reason I wasn't out of hospital two days after the incident, not coming good enough to be taken off oxygen until the fifth day. I've had other complications which kept me in hospital until the 23rd of December, and will necessitate several further returns. As for the bend, the experts say it was totally resolved. I've been a very lucky boy. The details of the medical and hyperbaric treatment will remain unclear until I can have a read of my hospital notes.

There are a number of people who I must thank for my life, in order of appearance.
Dave Apperley, who wouldn't take "I'm ok" for an answer in the water.
Tim Clarke, Kevin Okeby, Dr Mark Spencer, and Simon Hadwin for resuscitation and more on the boat.
The Westpac helicopter crew.
The Hyperbaric team at Prince of Wales Hospital, especially Dr Barbara Trytko who was on duty when I arrived, and looked after me throughout. Barbara, I thank you from the bottom of my heart.
The Intensive Care Unit at Prince of Wales Hospital.

Also, I'd like to thank all the friends and family who both visited me in hospital and sent messages, flowers and stuff. Some of you I've known forever, and some for only a short time, but every one of you have made me thankful that I can call you my friends.

Analysis

1) After getting the gear back from the Water Police, I stripped it down with witnesses present, and found the cause of the gas problem. The Mk15 has an internal natural rubber seal which stops gas bypassing the scrubber cannister. This was found to be still folded down, and not folded up to its operational position. So in effect, the gas was going around the loop but not passing through the carbon dioxide absorbent. It was a stupid mistake made by me when setting up the unit. Something must have sidetracked me. It won't happen again.

2) Why was it that I couldn't go to open circuit bailout during the dive? It's something I've trained for, and practiced regularly, yet I couldn't do it when I had to. I suspect it was the effect the CO2 had on my mind.

3) Our safety methods worked well, and things would not have worked out so well if we had no safety divers, or no Oxy-Viva on the boat.

To all those involved, you have my sincerest thanks,
Jason McHattan.

Addendum

Totally resolved was stretching it a bit. I've had a number of ongoing issues, but nothing that limits me in any way. Sure, I carry a bottle in the glove box of the car in case I get caught short in traffic, but hey, it's so much better than the alternative!
I went back to diving after four months, starting with 50 metres dives, then working up to 100 metres. It scares the Christ out of me each time I get in the water, but it's a hard passion to give up.