Newsletter February 2007

Not a Heat Wave.
This was according to the SA Weather Bureau on the 7th of February. They also “promised” cooler weather. They also could not foresee any real danger to the Mozambican coastline due to the summer cyclone season.
I’m beginning to trust them as much as the Department of Health.
“Did I say that your Honour?”

Question: If you saw a heat wave, would you wave back?
OK. Yes it has been slightly warmer than expected. And why would three air conditioners decide to pack up in a relative short period of time, right in the middle of a supposedly non existing heat wave? I do not know the answer to these and other questions but what I do know is that this type of excessive heat combined with the high humidity experienced lately, is quite dangerous. Yes, not only is there a high discomfort index involved, there is actually a high risk index as well.
Apart from running out of beer halfway through the next Sharks game, there is a very real threat of Dehydration, Heat injury, Heat fatigue, and with those, the very dangerous possibility of Over-Hydration due to the wrong advice and subsequent incorrect ways to treat or prevent Heat related conditions.
So in the midst of this slight heat ripple (ala SA Weather), let me elaborate a bit on the body’s ways to handle or sometimes not handle such heat.

Core Temperature:
The body's dominant forms of heat loss in a hot environment are radiation and evaporation. However, when air temperature exceeds 35°C, radiation of heat from the body ceases and evaporation becomes the only means of heat loss. Evaporation is maximally efficient in a dry environment. If humidity reaches 100%, evaporation of sweat is no longer possible and the body loses its ability to dissipate heat. Now, to cool down, it becomes dependant on electric aids like fans and air conditioners, or riding on the back of a very fast and very tough Ford Bantam, or cycling downhill all day. If these are not available, your core temperature will gradually increase, dependant on the level of activity, until it reaches dangerous levels.
If one tries to keep your level of activity as low as possible, seek out cooler areas, and rehydrate correctly, the core temperature will not readily go to dangerous levels.

Dehydration:
Sweating is the way in which the body maintains its core temperature at 37 degrees centigrade. This also results in the loss of body fluid and electrolytes (minerals such as chloride, calcium, magnesium, sodium and potassium) and if unchecked will lead to dehydration and eventually circulatory collapse and heat stroke. The progressive effect of fluid and electrolyte loss on the body is as follows:
% body weight lost as sweat & the physiological effect:
2% - Impaired performance
4% - Capacity for muscular work declines
5% - Heat exhaustion
7% - Hallucinations
10% - Circulatory collapse and heat stroke
Electrolytes serve three general functions in the body: Many are essential minerals, they control movement of water between body compartments, and they help maintain the acid-base balance required for normal cellular activities. A liter of sweat typically contains 0.02g Calcium, 0.05g Magnesium, 1.15g Sodium, 0.23g Potassium and 1.48g Chloride. This composition will vary from person to person.
Elderly persons are at increased risk for heat-related problems because of underlying illness, medication use, declining adaptive thermoregulatory mechanisms, poor access to air-conditioning. Neonates have an increased risk of heat-related illness because of poorly developed thermoregulatory mechanisms and inability to make behavioural adjustments.
Chemical items that may affect the ability to regulate temperature are amongst others; Beta-blockers, Certain cold & flu medications, Diuretics, Ethanol, Antihistamines, Certain older antidepressants, Aspirin (regular use), etc.
Rehydration is the replenishment of water and electrolytes lost through dehydration. It can be performed by oral rehydration therapy (drinking an electrolyte solution) or by intravenous therapy (adding fluid and electrolytes directly into the blood stream).
As oral rehydration is less painful, less invasive, less expensive, and easier to provide, it is the treatment of choice for mild dehydration. Because severe dehydration can rapidly cause permanent injury or even death, intravenous rehydration is the ultimate treatment of choice for that condition.
Drinking plain water causes bloating, suppresses thirst and could lead to over hydration. It is a poor choice where high fluid intake is required. Water contains no carbohydrates or electrolytes.
Concerns about the potential risks of Over-hydration and consequential hyponatraemia (low blood sodium levels) for endurance athletes have been raised in several quarters following the death of a female runner during the 2002 Boston marathon.
The athlete, who died of hyponatraemic encephalopathy (swelling of the brain caused by severely reduced blood sodium), had reportedly ingested excessive amounts of fluids before, and during the race.
Hyponatraemia results from an abnormally low concentration of sodium in blood plasma. A sustained decrease in plasma sodium concentration disrupts the osmotic balance across the blood-brain barrier, leading to a rapid influx of water into the brain. This, in turn, leads to swelling of the brain, which can progress to confusion, seizure, coma and even death.
Various factors can lead to a fall in sodium concentration, including loss of sodium in sweat and decreased sodium intake. But the rapid intake of large quantities of fluids, which effectively dilutes the blood, appears to be the major cause of dangerous reductions.

Now that I have your attention, what am I trying to say? Only that when nature turns tough, our frailty becomes very evident. Temperature goes up, humidity goes way up, lawn needs a trim, out you go with your old army-issue green metal water bottle strapped to your locally made leather belt, filled with the goodness of H2O. Under the fig tree, there is the regulation Coleman cooler, filled with more water and lots of ice.
For two hours you toil away, all the time feeling thirsty and sweating like the proverbial Hog. Dizziness starts to bother you every time you take the sharp left turn around the bed of Malva parviflora,, nothing much, must be the new beta blocker you started last week. At the next turn, you will allow yourself ten minutes and enjoy a cold beer or two.
One hour later, the headache hits you. Extreme thirst! Drink more water. Take two, no, take three aspirins for the bloody headache!
You are in trouble. You went from high core temperature to hyponatraemia via dehydration and because of the wrong rehydration.
Making no sense?
In brief, and in conclusion:
Nothing wrong with mowing the lawn. Wrong time of the year / day though.
Nothing wrong with alcoholic refreshments. But not when you are already severely dehydrated.
Nothing wrong with drinking water. But it has NO ELECTROLYTES!
Drink the right stuff! Rehydrate with either a good sports drink, or even some rehydration preparations sold as conjunctive treatment for severe gastro-enteritis. Or contact me for a cheap homemade emergency recipe.
Most importantly, know your body and how much heat it can handle; know how much your body loses through perspiration.
We have less than a month for this heat to make way for the wonderful autumn weather we know so well and can only dream of at this moment.
Enough of the clammy stuff. Greetings from the pool,
Pieter & Renette Naudé Will be in Cape Town for the middle two weeks of March. Hopefully cooler down there! Keep healthy and hydrated! See soon.