Bends? Not you!

Not long ago I was speaking with a diver who described a situation that many divers find puzzling. 

A group of buddies entered the water together, completed exactly the same dive, same depth, same bottom time, same ascent profile. Yet shortly after the dive, one diver developed decompression sickness while the others showed little or no symptoms at all.

So the obvious question arises: how can divers follow the same profile, yet only one diver gets bent?

I explained the probable reasons and thought members would also like to know the answer.  This information could help other divers understand that decompression models manage risk, they do not eliminate it completely!

Why Decompression Sickness Can Be Unpredictable

Three divers do exactly the same dive, only one gets decompression sickness! All divers dived to the same maximum depth of forty metres, with a bottom time of twenty minutes, all divers used the same gas, same ascent rate and same decompression stops.

All three divers followed their dive computers perfectly, yet the outcome was completely different for each diver.

Diver 1 – No Problems

Diver #1 surfaces feeling great.

• No symptoms
• Completely normal dive
• Relaxed after the dive
• Ready to plan another dive

Result- This diver’s body handled the dissolved nitrogen easily.

Diver 2 – Mild Symptoms

Diver #2 notices some joint discomfort later in the day. This could be minor decompression stress response. Possible contributing factors:

• Mild dehydration
• Slight fatigue
• Slightly slower circulation in certain tissues

Goes on 100% Oxygen for an hour, drinks plenty of water. Symptoms relieve themselves in a few hours, diver feels good but is hesitant to plan another dive, straight away.

Diver 3 – Decompression Sickness

Diver #3 develops clear symptoms of decompression sickness. Joint pain tingling in hands, nausea, headaches and skin blotches.

Goes onto 100% Oxygen, gets loaded into a helicopter and goes for a dive in a recompression chamber to clear out the excess nitrogen. Very hesitant to go diving again!! Possible reasons could include:

• Dehydration
• Cold exposure
• Heavy workload during the dive
• Poor circulation
• Individual physiological differences

Even though the dive profiles were identical, the human body is not identical.

Remembering from your open water diver course, many factors can influence decompression risks, they include:

• dehydration
• fatigue
• age
• body composition
• fitness
• temperature
• workload during the dive
• repetitive dives
• previous injuries

Because of these variables, decompression tables and dive computers manage probability, not certainty. I always remind divers, when planning deep dives- “Dive computers calculate decompression for an average human.

None of us are average.” This is why conservative diving habits matter.

Always think of yourself as the most important person you know. Encourage other divers to remember good habits that will hopefully reduce any decompression risk.Those good habits include:

• Always ascend slowly from every dive
• Perform a proper level safety stop
• Stay well hydrated
• Avoid heavy exertion after diving
• Keep yourself warm
• Avoid flying too soon
• Dive conservatively

What can you take away from this? There is one very important principle:
Dive tables and the most expensive dive computers reduce the risk - divers behaviour manages the rest!

Lets go Diving!