By William G. Cowley
While there’s always some minimal possibility that
decompression sickness (DCS) will occur, even when you do
everything right, you should be aware that the primary reason
divers suffer DCS is from diver error. These errors cause
the diver to absorb more nitrogen than he should, of fail to
release nitrogen safely before surfacing. These include misuse
of, of failure to use dive tables or dive computer, exceeding
proper ascent rates, omitting emergency decompression stops,
running out of air (which can lead to exceeding proper ascent
rates and omitting emergency decompression/safety stops),
ignoring factors that predispose divers to DCS, and failure to
follow conservative diving practices.
A diver suffering from DCS may show various signs and
experience various symptoms, depending upon where bubbles form
in his body.
Signs and Systems
- Favoring an arm or leg, or rubbing a joint.
- Coughing spasms
- Blotchy skin Rash
- Pain, often in the limbs, and also often, but not
necessarily in the joints. The pain can move over time.
- Numbness, tingling or paralysis.
- Unusual fatigue or weakness
- Skin itch
- Shortness of breath
In the majority of instances, DCS occurs at the surface
within one to two hours of the dive. However, it can occur
underwater at a shallow depth, and symptoms can be delayed as
long as 48 hours. Furthermore, DCS may become more likely based
on these factors:
- Excess fat tissue. Fat tissue holds more dissolved
- Age. As a person ages, the circulatory system becomes
less efficient, therefore slowing nitrogen elimination.
People also tend to have more fat tissue as they get
- Heavy exertion before, during or after a deep dive.
Exertion before or after the dive can promote
micro-bubbles that grow as excess nitrogen dissolves into
them. Exertion during the dive speeds up the circulation,
accumulating more nitrogen than normal.
- Injuries and illness. These can effect circulation and
the ability to eliminated nitrogen.
- Dehydration. This reduces the quantity of blood
circulating to eliminate nitrogen.
- Use of Alcohol. Before the dive this can cause
dehydration and immediately after the dive it alters
circulation, possibly promoting bubble growth.
- Cold water. To save heat, the body restricts circulation
to parts of the body, thereby eliminating nitrogen less
- Hot showers or baths immediately after a dive. These
cause skin capillaries to dilate, altering circulation.
- Carbon dioxide increase. This is usually caused by
exertion or skip-breathing (breath holding) and interferes
with the blood’s ability to carry nitrogen.
- Exposure to altitude. Flying or diving to altitude after
diving, or diving at altitude requires special guidelines
because dive tables and computers base their calculations
on surfacing at sea level. Follow current recommendations
when flying or driving to altitude, get the proper
training in the PADI Altitude diver Specialty course.
To prevent DCS, adhere to safe, conservative diving
practices, Stay well within the limits of your dive table or
computer, and make safety stops at the end of every dive.
Emergency Care for Decompression Sickness
If a diver is suspected of decompression sickness, and
you are not diving with professional supervision, such as on
a charter boat, you should know the steps to take.
Have the diver lie down and administer 100 percent
oxygen, if available. Oxygen helps eliminate nitrogen and it
raises the blood oxygen level to assist tissues receiving
less than normal due to bubble blockage. For most cases,
have the diver lie on his back or left side, whichever is
more comfortable, but don’t let him sit up.
In severe cases, the diver may need CPR, which requires
laying him on his back. An unconscious breathing diver
should be laid on his left side.
After beginning first aid – or before if the diver is
unresponsive and you are alone – immediately contact the
local emergency medical system. In many areas, specialized
diver emergency networks can assist you and local medical
personnel in locating the chamber and consult in treating
the diver, The Divers Alert Network (DAN) provided this
service in the United States and Caribbean. In the South
Pacific, the Divers Emergency Service (DES) fills this