The Split is a flat topped reef (which makes for difficult anchoring) at about 21 to 22 metres with a split in the rock which is 25 metres deep. The maximum depth is 27 metres. Average depth would be 24 to 25 metres.

While underwater, the strong wind blowing caused the anchor to lose its grip (no alternative spots to place the anchor were seen once we were submerged) and when the three returned to the anchor site they could not relocate it. This group had spent 20 minutes on the bottom and decided to ascend as one of them was a bit low on air. A blue water ascent was required from 21 metres.

Two minutes were taken up in the ascent and a two minutes safety stop performed. Ascent was by an Aladin Pro and at no time did its ascent alarm sound. The dive was well within the constraints of the computer's profile and also 10 minutes under the US Navy table limits and 5 minutes under NAUI and PADI RDP (metric) tables and 2 minutes under BS-AC '88 tables. It was at the limit of some other tables (Buehlmann, DCIEM and PADI RDP [imperial]), but in my opinion still fairly safe, although I would have done a longer safety stop.

The divers surfaced at 1008 just in front of the boat and after an easy swim they climbed back on the boat. No problems had been encountered by this group and all were feeling well. About 7 minutes later the other four divers (including me) surfaced. As an example, I had dived 25 minutes to over 28 metres, averaged 25 metres, took two minutes to ascend to five metres and did a five minute safety stop.

After pulling in the anchor, the boat went into Port Hacking where we anchored at Jibbon Beach for a cup of tea. About 20 minutes after ascending, one of the females (let's call her Pam) started feeling a bit off. She had a slight headache and a stomach-ache. It was so minor that she did not mention it to anyone.

At 1115 we left Jibbon to return to the wharf. At this time Pam told her two buddies that she was not well. There was still no real concern at this stage. After off-loading our gear, we drove up to the local dive shop in individual groups. After I was there 10 minutes or so, Pam and her two buddies arrived and came in the shop. The male buddy took me aside and told me what he knew. I went outside and spoke to Pam. By this time, she had a very bad headache and was feeling quite ill. She had also started to feel a bit dizzy when standing. She was pale and her eyes were like pinpricks.

As the three symptoms were possible signs of Type 2 DCS (Cerebral DCS) I decided that it was a possibility that she had DCS but that we needed further advice from the Diver Emergency Service (DES). Just before 1215 the male buddy phoned DES and within a few minutes was talking to the duty doctor.

After a few questions, the doctor decided that Pam should be taken to the Hyperbaric Unit at Prince Henry Hospital at Little Bay for further assessment. Her buddies decided to drive her to hospital but by now she was feeling worse. While on the phone, a divemaster from the local shop assisted and soon after an instructor also arrived. As Pam's condition had worsened (she was beginning to show signs of shock) it was agreed an ambulance was needed.

A few minutes later the ambulance arrived and Pam was placed on oxygen and had a saline drip inserted. Despite informing them of our previous contact with DES and the doctor's advice, the ambulance officers decided to transport her to nearby Sutherland Hospital. However, before they arrived there, they decided to go straight to Prince Henry (had they spoken to a doctor?).

Upon arriving at Prince Henry, a series of tests were run on Pam. These included blood and urine tests and X-rays of her sinuses. The X-rays showed no damage to the sinuses and the tests showed no abnormalities. At about 1600 she was placed in the medium sized chamber to start the standard US and Royal Navy treatment for Type 2 DCS. This comprised treatment for 1 hour at 18 metres, a 15 minute ascent to 9 metres followed by 3 hours and 15 minutes at this depth and another 15 minutes to return to the surface. During the recompression Pam was treated on pure oxygen as follows; 20 minutes on, 5 minutes off, 20 on, 5 off, 20 on, 5 off, 45 on, 15 off, 60 on, 15 off and 60 on. The pain did not go until two hours into the treatment. It did not subsequently reappear but three days later a similar (but less intense) headache occurred for a few hours. At 2100 she came out of the chamber and was kept under observation for the night and released the next day.

Doctors at the Hyperbaric Unit in the end were unsure whether in fact Pam had suffered from DCS. After review, I must agree that it was not at all clear that it was DCS when you consider the situation that occurred and the fact that the headache did not quickly subside once recompressed. It is accepted that relief of the symptoms should occur within 20 minutes at 18 metres and when this does not happen the diagnosis of DCS may be questioned.

Some details about Pam:
Contributing factors?

Pam had gone out on the Friday night and was, to quote her in less blunt words, "very tired and emotional". She also did not get to bed till very late (early on Saturday) and only slept for a few hours. She worked on Saturday and on Saturday night went out to dinner. Prior to dinner she had one beer and at dinner consumed three glasses of wine. She went to bed relatively early but woke early and only had about five and a half hours sleep. She was certainly not hung over on the Sunday morning as she was quite cheery but was probably dehydrated as she drank a can of cola before the dive.

As you are probably aware, alcohol is a diuretic and dehydrates the body, especially the brain. In his book "Deeper into Diving", John Lippmann states that "it has been shown that dehydration of the brain lasts long after the hangover itself. A dehydrated diver is more prone to bends, particularly neurological bends...". Alcohol also reduces surface tension of the blood. It is surface tension that hinders the growth of bubbles and therefore the presence of minute amounts of alcohol may increase bubble formation.

The obvious questions to be asked are:-

Things to be learnt?

A final comment. Pam is now unable to dive for at least six weeks and will miss a trip to Montague Island to dive with seals that she had so much been looking forward to. If it was DCS, she is lucky that this is all she will have to give up.

References: