Dive accident insights: Decompression Illness

Overview of a Decompression Illness incident courtesy of DAN - the Divers Alert Network

September 7, 2022

Stock image only depicting on-surface rescue technique

The Diver started diving at age 48 and is an Advanced Open Water Diver with a Computer Nitrox Diver certification. The diver is in good overall health though infrequently suffers from migraines.

Diver’s Experience130 logged dives. Prior to this trip, the deepest dive completed was to 35m.

The Trip
An organised club trip to Vanuatu.

The Dives
Two dives per day for two days, at which point symptoms developed and the diver ceased diving.

Dive Profiles

Day 1

Dive 1: Max depth 33m, with a total dive time TDT of 44 minutes, a safety stop at 5m for around 10 minutes. Surface interval SI of 4 hours 45 minutes.
Dive2: Max depth 33m, with a total dive time TDT of 44 minutes, a safety stop at 5m for around 10 minutes. Surface interval SI of 4 hours 45 minutes.

Day 2

Dive 1: Max depth 45m, TDT 61 minutes, including a 2 minute safety stop at 10m, a 2 minute safety stop at 8m and a 20 minute safety stop at 4-5m. SI of 4 hours 29 mins.
Dive2: Max depth 38.9m, TDT 59 minutes. This included a 2 minute safety stop at 10m, 2 minute safety stop at 8m and a 15 minute safety stop at 4-5m.

Onset of Symptoms
After the second dive on day two the diver developed an ache in her abdomen which quickly increased in intensity. A strong pain also developed in her left breast. The diver was travelling with her children and didn’t want to make a fuss but on exiting the bus after the short trip back to the dive shop her legs turned to jelly. She staggered to sit down and had to admit she was unwell.

Diagnosis
Decompression Illness.

Treatment
The dive shop manager immediately commenced oxygen (O₂) first aid: 20 minutes on with a five minute break. This pattern continued and DAN AP was called. Whilst breathing O₂ the diver also developed a strong itch across her abdomen. On DAN AP’s recommendation the diver was taken to Santo Hospital, however the medical team lacked experience and the diver chose to return to her hotel and continued breathing O₂ via the dive shops O₂unit. The next day she continued breathing O₂ and was in regular contact with DAN AP. DAN AP offered to evacuate the diver to Port Villa for recompression but she chose to stay with her family and continue breathing O₂. The pain in her abdomen was subsiding though the itch remained.

Two days after the first onset of symptoms, the diver suffered a relapse, with the pain in her abdomen and chest recurring, and increasing in intensity. It was decided to evacuate her to Port Villa and she was immediately put into the hyperbaric chamber.
The diver received three separate recompression treatments, with ‘no fly’ orders for a week.
• 1 x Table 6
• 2 x Table 5

Recovery
A week after returning to Australia the diver saw a specialist dive physician who referred her for a bubble test that confirmed she had a PFO (patent foramen ovale). She has since had this closed and is awaiting clearance to return to diving.

Costs
Evacuation US$8,000 with treatment costs a further US$7,700

Analysis

The four dives completed, while not excessive, are relatively deep and would have contributed to greater bubble loading.
The diver responded well by advising the dive shop staff quickly, and the team acted correctly by providing oxygen therapy. It is important to check the Oxygen Preparedness of dive operators prior to booking your next dive holiday.
By staying on oxygen for an extended period the diver resolved many of her symptoms. However, when the oxygen therapy stopped, the diver’s symptoms returned, which is not unusual.
Air breaks during the provision of oxygen are not required. DAN’s advice is to provide ongoing oxygen first aid, with no breaks, until advised otherwise. The only reason that doctors provide air breaks during treatments is to prevent oxygen toxicity – this is not of concern to the first aider. Oxygen should be always provided at the highest possible concentration from the first onset of symptoms until advised by the diving doctor to stop.
Not travelling to Port Vila when DAN AP first recommended recompression increased the risk of symptoms worsening or embedding. It is also the likely reason that the diver ultimately needed three treatments. Earlier action may have resulted in fewer treatments.
PFO-related bends are becoming more common. This is likely a result of divers diving more aggressively, using computers to increase the number of daily dives and the duration of those dives, as well as to minimise surface intervals, all factors that increase the bubble loading