Background
- Decompression Sickness (DCS) developed on the second day of a liveaboard diving trip.
- 3 dives were completed on the first day of the trip, and 3 dives completed on the second day of the trip.
- All dives were between 90 and 100ft of depth for 55 to 66 minutes in duration.
Reported Story
This is a report of decompression sickness (DCS) I experienced while diving from a liveaboard off an island in the eastern Pacific. I am a 61-year-old woman; I’m healthy, weigh 130 pounds (59 kilograms) and take no medication except Dramamine, which I take once a day at night when on a liveaboard.
I developed DCS during the second day on the liveaboard after three dives that day and three dives the previous day. All the dives were deep (90 to 100 feet, or 27 to 30 meters) and long (55 to 66 minutes). All were within the limits of my computer. About one hour after the last dive, I was resting in my room, preparing for the fourth dive. I developed a rash and pain under the skin of my legs and thorax. My husband immediately thought of skin bends and went to look for the instructor.
I walked behind my husband, climbed the stairs and sat on a chair. Then, for the first time in my life, I fainted and fell. Later I fainted two more times. My blood pressure was very low. They gave me oxygen, but I had problems breathing. I was coughing and experiencing severe pain in my right shoulder. As I didn’t get better after three hours on oxygen, the captain and crew initiated an emergency evacuation with a speedboat to the neighboring island.
From there, I was transferred to a town where I was examined by a doctor who specialized in hyperbaric medicine. He decided to send me to a hyperbaric chamber where I was treated with one hyperbaric treatment that lasted for about three hours. Though my symptoms diminished, I felt very weak. Two days later I flew to a major city, and after another two days, I took a transcontinental flight back to my home country. At home I was evaluated by my doctors, and everything was fine. I returned to diving recently and did 10 dives in five days with no issues.
When reflecting on possible causes, this is what I came up with:
- Before the last dive I had climbed a small hill (165 feet, or 50 meters) with a group and perhaps felt a little tired. It was very hot. All the others in the group were younger than me (25 to 35 years old). My husband didn’t climb.
- I think I was diving close to the limits. Repeated dives that were too deep and too long affected my body.
- My computer showed that I was close to incurring a decompression obligation. On a previous dive, I had informed the instructor of my situation. He said my computer was overly sensitive, and that his computer and my husband’s computer didn’t indicate any reasons for concern, so I should follow my husband. This was a mistake.
For a longer dive, the staff exchanged my husband’s tank for a larger one (15 liters instead of 11 liters). My husband usually runs low on air before me. With the larger tank, this parameter for ending the dive was lost.
Review
The diver correctly reflects on some possible contributors to her DCS incident. She was a little exhausted, diving close to or maybe even beyond her limits on that day, and following faulty advice from a dive professional to rely on someone else’s computer.
However, there is one other factor we should reflect on in this particular case. To give her and her husband a longer dive experience, the dive operator provided the husband, who routinely had the higher surface air consumption rate, with a bigger tank to maximize bottom time. This is a common practice in many dive operations and is usually appreciated by the paying customer.
Recommendations
What many divers neglect is the amount of decompression stress they can incur with repeated dive days of three to four deep dives with long bottom times. While some divers tolerate this decompression stress without issues, it can lead to serious trouble in others. The reaction to increased decompression stress is highly individual and unfortunately also changes with age and many other factors.
In the multi–day, multi–dive situations common on liveaboards, sensible dive planning becomes even more important. The No. 1 limiting factor for your dives should not be the pressure gauge.