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Excessive Heat Brings Risk of Dehydration

16 June 2015   Kent Courtney
It’s hot outside. So hot that communities lower than 4000 feet in elevation are being warned of excessive heat for the next several days. With heat comes the risk of dehydration. Here’s what to do to avoid that. 

The human body is a complex machine. It is resilient, tough, resourceful, adaptive, and capable of self-repair. But it also has limitations. What the limitations are depends on our age, underlying general health, attitude, medications we are taking, nutritional status, and hydration status.

It is said that you can only live three minutes without oxygen, three days without water, and three weeks without food. It is not suggested that these times apply to everyone equally or that you will be healthy during the latter part of your hypoxic event, period of dehydration, or period of starvation. Your brain needs fuel! A lack of fuel equals lack of performance… kind of like your car.

The human body seeks to be balanced (Hemostasis) not having too much of anything or too little of anything. Even too much oxygen is harmful to the body and so is too much water (can be fatal) or too much food. A lack of water dries your lungs resulting in difficulty breathing and with poor breathing metabolism of food declines as well as absorption of nutrients – it’s like Dominos... one falls over and knocks over the other two.

Considering that air containing oxygen is plentiful, and I can always stand to miss a meal or two by relying on my “reserve” (also called “spare tire” or simply FAT!), I will concentrate on dehydration in this article.

The human body is approximately 60% water. Blood is 92% water, the brain and muscles are 75% water, and bones are about 22% water. All body tissues contain water and it is water that miraculously keeps our body working smoothly and in balance. Our ability to gain nutrition from the food we eat, maintain our blood pressure, adjust the balance of electrolytes in our body, remove waste products, and produce blood cells are just a few of the things that makes proper hydration critical.

How do we gain or lose water in our bodies?

Obviously we drink water. But there is more to it. A balance of sodium (salt) is crucial in maintaining a balance of water. Water moves towards sodium, so too much salt in our diet can increase water retention and even raise our blood pressure (this is why people with high blood pressure often are on salt restrictions). Too little sodium in known as hyponatremia and is equally dangerous if not more so. You can have a seizure, go into a coma, or die from a lack of salt and dehydration.

So the best plan to stay well hydrated is to balance nutrition with fluid intake. There is more than enough salt in the food we eat so salt supplements are only considered in a hospital setting and shouldn’t be considered as a remedy for dehydration – in fact, salt water is an emetic (causes vomiting) and can potentially cause worsening dehydration.  A sports drink is a good source of electrolytes, but don’t drink ONLY sports drinks or you will have too many electrolytes and be “out of balance” – alternate water with the sports drinks to prevent an overdose of either. Remember, people die from drinking too much water (blood can’t carry oxygen, clot, or carry nutrients when it is diluted). Soda-pop, beer (any form of alcohol), caffeine, or highly sweetened drinks should be avoided (sugar and artificial sweeteners both worsen dehydration).

A good solution is to reduce water loss by avoiding sweating, not breathing too fast (an adult can lose more than 2 liters of water a day just by breathing hard!), not drinking coffee or alcohol (both are diuretics removing water from your system), and proper nutrition.  Stay in the shade as much as possible and keep your skin protected (sweating into your clothes actually cools your body and protects you from evaporation and the sun’s radiation). Dress like the people who live in arid climates dress (you don’t see them going shirtless!). When it is hot our body needs water to make perspiration which is delivered to the skin’s surface where it evaporates and cools us off – think “evaporative cooler” on your house, or lick your finger and blow on it – does it feel cool? 

The average adult loses about one liter of water a day from sweating and evaporation during “normal activity” and about one-half liter per day from just breathing normally. With exercise both numbers increase sharply, often in excess of three liters combined – this is about half your total blood volume!  We should use common sense and work outside in the cool of the morning, move purposefully without excessive exertion, rest often, eat right, and stay properly hydrated. Use more caution in high humidity where evaporative loss is less, but heat stroke is more common because there is too much moisture in the air to allow our bodies to cool themselves (you swamp cooler doesn’t work well during the monsoon because the water on the cooler pads doesn’t evaporate – same principle applies to our body).

If you get dehydrated, you can’t sweat and your body over heats causing a life threatening emergency called HEAT STROKE!  The treatment for heat stroke is to remove all restrictive clothing, get into a shady or cool place with good air flow, wet the person down, and then fan them to cool them off. In EMS (emergency medical services) we often use ice water, fans, cold packs or whatever is available to rapidly cool the patient to prevent seizures and brain cell death, and then rehydrate them with intravenous fluids (IVs). Seizures increase metabolism which in turn increases HEAT – quick cooling may prevent seizures. This person’s skin will feel very HOT because their brain isn’t functioning properly and their hypothalamus works like a thermostat rapidly increasing the heat to fatal levels (like when you have a fever but get chills and shiver worsening the fever).  They can no longer compensate by sweating to cool their body and the condition progresses rapidly. Sometimes they feel HOT and DRY, but always the skin is HOT if it’s HEAT STROKE.

For simple HEAT CRAMPS or HEAT EXHAUSTION, rest in a cool place and drink alternating water and sports drinks. The cramps and exhaustion are caused primarily by loss of electrolytes carried away by sweat or depleted by poor nutrition.  This person’s skin will feel COOL because the body is still compensating (lick your finger and blow on it – it’s the same principle).  

How are you doing?

Signs that you are dehydrated:

  1.  Urine is dark colored and infrequent – should be very light yellow.
  2.  Skin is dry and itchy and “tents” (stays up when pinched).
  3.  You have a headache and are unable to concentrate.
  4.  You feel dizzy especially upon standing up from a setting or lying position.
  5.  You are becoming constipated.
  6.  Your heart rate is increased and your blood pressure may be decreased.
  7.  Eyes have a “lack luster” appearance – they appear dry and sunken.
  8.  You feel anxious and jittery.
  9.  You are thirsty with a dry mouth.
  10.  You crave salt. 

Now, just for fun, do you remember those old movies where the cowboy’s horse gets killed and he sets out on foot across a desert? Think about what you just read and how you would diagnose dehydration and then treat it. Why does the cowboy begin to hallucinate, stumble, and get profoundly weak? Would putting a pebble in your mouth and sucking on it really help? Could you drink your own urine to survive? 

You should be able to answer the first question from the information provided here. On the pebble issue, yes it does help by keeping moisture concentrated in your mouth and keeping your airway and lungs moist longer – but don’t accidently swallow it! On the drinking urine issue… NO! Drinking urine may give you some very temporary relief, but in the long-run it worsens dehydration and chemical imbalances in your body. Stories you hear about where survival is attributed to drinking urine aren’t true – they survived in spite of drinking the urine (if you mixed the urine with at least 75% water it might be okay to extend your water supply though).  It’s like “eating toothpaste” to survive… NO! Read the label – if you ingest more than what is used to brush your teeth you are supposed to contact POISON CONTROL immediately! 

Drink up!