May everybody enjoy a safe and pleasant diving vacation!

A GREAT THANK
TO DR./ HOSSAM NASSEF
&
DR./ HANAA M. NESSIM
FOR THE GREAT HELP & COAPERATION

Dehydration: A major risk factor in diving practice

Dehydration (the decrease of the fluid content of the body) is one of the major predisposing factors in the occurrence of Decompression Sickness (DCS) as it renders the blood more viscous. This condition reduces perfusion of tissues interfering with the effective elimination of inert gas from the body.
During diving there is a continuous loss in body fluids due to three factors:
1. Perspiration, especially on a hot day (a common hazard of diving in the tropics)
2. Dry gas breathing that needs to be humidified mainly by extracting water vapor from the lungs.
3. Immersion (even in warmer waters) that, in itself, increases urination by shifting blood from extremities to the core of the body. This gives body receptors a false feeling that the blood volume has increased, thereby enhancing urine formation.
* Immersion in clod water would excessively increase urine formation by the same blood shifting mechanism due to closure of the peripheral blood vessels.
Dehydration can happen as a result of:
1. Inadequate fluid intake
2. Drinking dehydrating agents like all kinds of alcohol and strong coffee
3. Conditions causing body fluid loss such as diarrhea and vomiting.
So, divers coming to dive in the tropics from relatively temperate climates cannot simply import their drinking habits with them. Drinking enough fluids is supposed to be top of the list when briefing newcomers to a diving resort especially in the summer.
However, drinking excessive amounts of water without adequate salt intake will eventually lead to the wash out of salts from the body leading to a status of imbalance in the body electrolytes. This can lead to symptoms of tiredness, malaise, nausea, dizziness and sometimes vomiting. Therefore divers on a dive vacation in the tropics and subtropics are advised to take sufficient rehydration salts in addition to drinking enough fluids, especially when hot.
Divers should also be advised to avoid drinking dehydrating agents, and to avoid diving, when suffering from severe diarrhea or vomiting. Instructors and dive masters should also avoid allowing students or divers to sweat in their wet suits while waiting for the other divers to get ready by effectively coordinating their diving activities.
In the few days preceding menstruation, the hormonal changes in the body tend to shift the body fluids from the blood and lymphatic systems to the body tissues (the so called third body compartment) leading to their engorgement (edema) Which forms an odd form of dehydration that would also render the blood more viscous with the increased incidence of DCS. Drinking sufficient fluids does not actually help much in the adjustment of this situation, so female divers should take in consideration employing much safer dive profiles in this period.
Amongst the other conditions that increase the viscosity of blood are high blood cholesterol level and using drugs that can increase the coagulability of blood such as oral contraceptives (birth control pills).

 
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