DIVERS ALERT NETWORK
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TIPS TO BEAT THE BENDS
D
ecompression sickness (DCS) occurs when nitrogen bubbles form in the blood. This can cause severe joint pain, among other symptoms. The common term ‘the bends’ comes from an affected person doubling over (bending) due to the intense pain caused by the condition. While a diver’s depth/time profile is, by far, the most-important factor in decompression sickness risk, other factors that may contribute to individual susceptibility.
Exertion
The timing and intensity of exercise (also known as workload) during a dive can substantially affect a diver’s risk of DCS. Exertion increases blood flow and its gas carrying capacity. Consequently, exertion during descent and the deepest phase of a dive increases the amount of gas dissolved in tissues and the subsequent decompression stress. Mild exercise during decompression speeds up off-gassing. Exertion immediately following a dive can stimulate bubble formation and increase the likelihood of bubbles passing through the lungs without being filtered out of the circulation.
Thermal stress
A diver’s body temperature can influence decompression risk. A warmer body absorbs more inert gas and releases it more readily. Conversely, a cooler body absorbs less gas during descent and releases less during ascent. Divers using protective suits without active heating should avoid long exposures that may chill them. When using heated garments, a diver should stay comfortably cool at depth and warm during decompression. Staying comfortably warm during decompression and after dive promotes inert gas elimination and reduces the risk of DCS.
Post-dive air travel
Flying after diving increases decompression stress because the pressure in an aircraft cabin is lower than atmospheric pressure on the ground. The
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recommended guidelines for flying after diving are as follows: • After a single no-decompression dive, a minimum preflight surface interval of 12 hours is suggested. • After multiple dives per day, or multiple days of diving, a minimum of 18 hours is suggested. • After dives requiring decompression stops, a preflight surface interval substantially longer than 24 hours is considered prudent. • Observing surface intervals longer than the recommended minimums helps to further reduce a diver’s risk.
ABOVE Dive conservatively to help avoid the bends
Medical and physical fitness
Poor health and physical fitness can compromise individual safety when diving and may increase risk of DCS. Regular exercise improves fitness and cardiovascular health, which mitigates risk of DCS: • At least two-and-a-half hours of moderate-intensity aerobic exercise per week to achieve health benefits, and five hours per week for fitness. • Muscle-strengthening activities at least two days per week. While individual susceptibility to DCS may vary, every diver can reduce their risk of decompression sickness by ascending slowly from every dive and following recreational diving guidelines. n
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