Dehydration and Decompression Sickness
Alcohol, milk, coffee, chocolate and fizzy drinks should be avoided before a dive as they will contribute to dehydration and high stomach acid. Water is absorbed quickly as it does not need to be metabolised. Drinks with sugar, dyes, fats, or proteins in them take longer to absorb. Tea and juice take about 30 minutes while more complex drinks may take an hour or more.
Decompression sickness is a major risk for scuba divers due to the increased formation of nitrogen bubbles in blood and tissues during and after ascent. About 51% of our blood is water and we need that blood to carry the nitrogen bubbles from our tissue to our lungs for exhaling. We lose a significant percentage of body fluid by sweating as we get ready for a dive and then by breathing dry filtered air from our scuba cylinder. The result is reduced fluid levels. Dehydration is a major cause of decompression sickness or the ‘bends’, so rehydration is necessary to help safely remove the bubbles from our tissue during and after ascent.
The idea is to be well hydrated before you go diving. That does not mean downing a glass of water just before a dive. If you do that, you end up peeing it all into your wet suit or drysuit. Remember that as we descend, pressure on our body increases. That increased pressure squeezes additional blood volume into our major organs and blood vessels. Your brain will interpret this increased blood volume as an excess of fluid. The kidneys respond by producing urine to lower the core fluid volume and that will make you want to pee. So much for the glass of water you just drank!
Try to get in the habit of increasing your water consumption at least 24 hours before your dive as this will give time for the water to be absorbed into your tissue. At the same time, reduce any alcohol intake as alcohol has long lasting dehydration effects. On the day of your dive, slow down your water intake to smaller amounts spread over the day at regular intervals. This will help keep you ‘topped up’ without you wanting to pee so much. Another thing you can do to be more comfortable during your dive, especially if you have a drysuit, is to pee just before you don your dive gear. This is getting rid of fluid which is already urine.
If you are going diving, plan your food and water intake, particularly if you are prone to motion sickness. Stay away from alcohol before and during the dives. Make every dive a safe (and enjoyable) dive. For more advice, call us on 04 233-8238.
