August 13, 2017
I would like to start this report with a short explanation of Decompression Sickness: It occurs when a person moves from an area of high pressure to an area of low pressure without giving the body enough time to adjust. It occurs most commonly in divers who have been under water for too long, at too great a depth. When the body is exposed to high pressure, gas dissolves into the blood. If pressure decreases too rapidly, gas bubbles form in tissues and blood..this causes decompression sickness.
This is my account of the events (dives) leading up to and the incident and treatment of my decompression sickness from August 13, 2017.
We were spearfishing that day and as usual planned for a long day on the water; plenty of rest the night before and lots of fluids to stay hydrated. Below are dives one and two.
Regular profiles, no deco dives with 1 hour surface interval between dives. Notice there is only blue in the graph indicating there were no violations, no deco stops required, and no accelerated ascents. On my computer any violation, deco, or rapid ascent would be indicated with a red line or area. The computer is a Shearwater Perdix AI and is set to moderately conservative not on the edge but not ultra safe either. I have a conservative backup of 300 psi set so that it lets me know when air reaches critical level.
After another 1 hour 16 minute surface interval, the next dive starts and is shown below.
Dive number three has some red areas where the no decompression limit was reached and the obligation completed before reaching the level to perform a decompression stop. The computer goes back to blue because the ascent was slow enough that the safe threshold was reached before decompression started. Pushing the limits a little too close started here. However, with approximately 58 minutes of surface time once again, dive number four was started and as shown by the blue graph ended as another no decompression dive within the standard limits of safety.
Dive number five starts after a 22 minute surface interval and lasted 13 minutes.
Still within standard limits and no decompression dive.
The final 2 dives, number six and seven were both no decompression dives as well within the set limits.
After a 32 minute surface interval, I started dive six. While technically it was within standard safety limits for a no decompression dive, there were several issues that caused this to be an abnormal dive. First, the surface interval for the previous dive was short and the interval for dive six was also short. As mentioned before, I was spearfishing , so at this point in the day I was tired and time before we were coming in was getting shorter. After five dives shooting and fighting fish I am pretty fatigued. I will mention here that I did drink water and or Gatorade at each interval to stay hydrated. Because of my diving experience and the training I have received up to and including divemaster training, I have learned much about dive theory, physics and physiology of diving, etc. This is not an excuse for why this incident happened or justification on my part. This hit was deserved based on my knowledge and the choices I made. I have enough dives under me that I know and understand my breathing rates, limits , and how much is needed for each part of my dive (even under stress of spearfishing). That being said, this is what happened: dive 6, full tank, short interval, descend to around 125 – 120 ft look for and shoot a big snapper. The snapper pulls very hard and pulls stainless steel cable off my gun. I chase for a few minutes then decide to come up and get another gun to land a second shot. I get on the boat, get another gun and after 10 minutes, decide to go back down and finish him off. I had 900psi of air left in my tank and I know that with my breathing rate under stress I will in all likelihood run out of air and have to do an out of air ascent. I made a choice to accept that risk and continue. I drop back down, find the fish and put another shot in it. I immediately start heading for the surface after getting it under control. Around 75 ft I notice I only have a few breaths left. At 60 feet I have 2 breaths left. Around 55-50 feet I begin a controlled emergency ascent, surface, and swim to boat. I say controlled because as evidenced by the computer graph on dive seven, the graph stayed in the blue showing I did not ascend too fast to the surface. My ascent rate was controlled and at no time in the red or at an unsafe rate of ascent. With all that said the hit I took was preventable by several ways that I chose to ignore and therefore deserved as the consequences of my choices and actions.
I believe the reasons I ended up needing to go to the hyperbaric chamber were mainly caused by too short surface times before the last 2 or 3 dives and skipping the safety stop on dive 6 and 7. These led to decreased off gassing or not allowing enough time for the nitrogen gases to dissipate, causing nitrogen bubbles to form in my tissues and air spaces causing the “bends” in my elbow and shoulder. I had a successful 7 hour dive in the hyperbaric chamber and choose to use this experience to show how even though a computer says it’s ok, doesn’t mean you can’t stay aware and vigilant. Also make good decisions and be prepared for your consequences.
Tommy “OceanSniper” Phelps
Divemaster, CPR \ first aid instructor, DAN dive emergency management provider