HYDRATION PREVENTS HEAT EXHAUSTION
HEALTH & SAFETY
THE PONDEROSA Volunteer Fire Department, located in Harris County, north of Houston, Texas, serves a population of approximately 35,000. We operate three engines, a platform, a heavy rescue, and an equipment truck with 50 volunteers. During 1988 we received more than 6,700 man-hours of training and responded to 660 emergencies. We have taken an aggressive approach to prevent heat exhaustion— “prehydration.”
The idea came from last year’s International Association of Fire Chiefs conference in Washington, D.C. In the seminar “Water, Water Everywhere, But Not a Drop to Drink,” Dr. Benjamin Newman of the Seminole County, Florida Fire Department reiterated a simple solution to this age-old problem: Water will help prevent heat exhaustion.
EFFECTS ON THE BODY
Let’s review the effects of heat exhaustion. It does not occur until the body reaches a loss of greater than five percent of liquid. There are some telltale symptoms during the one-to-fivepercent phase. Your body slows down, and you have flushed skin and an increased pulse rate. Your body temperature and perspiration rate increase. Thirst occurs at about four percent by volume dehydration.
At six to 10 percent dehydration you become dizzy, experience shortness of breath, and may feel a tingling in your hands and feet. You stop sweating and become cyanotic (a condition marked by bluish discoloration of the skin brought on by inadequate oxygenation in the blood) and without intervention, your condition worsens and you experience speech and walking difficulties. It may be too late to prevent heat stroke, a very serious problem.
During World War II Field Marshal Rommel set forth across the Sahara Desert with his German troops. He knew he would have problems keeping his soldiers physically fit just during the crossing, not to mention keeping them fit for battle. So before crossing, Rommell decided to experiment. He took three companies of soldiers and designated them as groups A, B, and C.
He ordered group A to march as far as possible without water. They made it just 10 miles. He ordered group B to march as far as possible but told them to drink as much water as they wanted. They made it 17 miles. Then, he told group C to march one hour, stop, then replace their weight loss with water. Every hour, group C was weighed and forced to replace that weight loss with the same amount of water. They marched 26 miles—260 percent farther than group A and 55 percent farther than group B.
This experiment shows that if you forcibly increase your fluid intake, you can perform much longer. Further studies have shown that a six percent weight loss will equal a 15 percent plasma loss.
Those of you who are medically trained know that blood plasma carries nutrients. What would happen if you lose the efffectiveness of plasma? You cannot perform, because your body will not be able to. Dehydration causes your plasma to lose its water, and that affects all of your functions. Dehydration shows in your urine, causing it to turn a deep yellow or brown. If you dehydrate enough, kidney and other bodily functions will not perform properly.
THE BENEFITS OF WATER
We know that dehydration prevents performance, and that hinders our firesuppression and injury prevention efforts. We also know that water will help prevent dehydration, which further prevents heat exhaustion and heat stroke. If we can add water to our bodies, we can prevent injury. This is how it works:
The pyloric valve is located at the entrance to the small intestine and acts as a flow controller. The small intestine allows some of the water and most other nutrients to be absorbed directly into the boodstream. Most people average about three-quarters of a quart of water flow per hour through the pyloric valve. Protective clothing retains our body heat, and tests have shown that ambient temperatures inside bunker gear may reach as high as 160° F. Combat firefighters in full bunker gear will lose up to two quarts of body fluid per hour. If we can only “absorb” threequarters of a quart per hour and we lose up to two quarts, we are fighting a losing battle trying to “rehydrate.”
In addition, sugar reduces the flow rate of the pyloric valve. A greater than two percent sugar content (glucose, fructose, or sucrose) inhibits pyloric passage. Sugar makes up more than five percent of the flavored “power” (electrolyte replacement) drinks! Dr. Newman cited a test in which three common “power” drinks were measured for the rates at which they are absorbed by the body. In all three cases, water was absorbed at a 35 to 39 percent greater rate than the drinks. What about soda? The sugar content of soda is much greater!
Volume increases through the pyloric valve can be achieved by drinking cold water, increasing the volume, and diluting sugar-laden liquids to prevent sugar intake. Studies have shown that cold water does not cause cramps. Cramps are generally caused when the by-products of muscle exertion are not taken away fast enough by the plasma. And remember, if we dehydrate, the plasma quality decreases, compounding the problem of cramping.
One other point is that salt intake is not necessary. Our bodies require only 400 milligrams of salt per day and we normally consume thousands of milligrams every day.
We must drink on command, just like company C did walking through the desert. We need to produce a system of prehydration that will prevent or minimize the effects of heat exhaustion.
A PLAN TO COMBAT THIRST
Our system of hydration is to prehydrate at home during the hot periods. We purchased sports-type squeeze bottles that are imprinted with our logo and the message “Hydrate.” Members are issued these bottles for personal use and are encouraged to always have them available.
Prior to boarding apparatus we drink a cup of water. That begins the hydration process before arrival on the emergency scene. Our stations have strategically placed water dispensers for easy access.
All apparatus have ice water that is supplied every day from ice machines in our stations. We have instituted a water cooler cleanliness program and have purchased water purifiers for the ice machines, and we make sure there’s a supply of sanitary drinking cups on the apparatus. When changing SCBA bottles, users are required to drink one cup of water prior to reentering. This allows a slight rest period as well as continues the rehydration process.
During extended operations, our auxiliary establishes a supervised rehab area that is supplied with ice water and a shower. A salvage cover is placed on the ground to make the area more comfortable, and an electric smoke blower is provided for air movement. The shower is a plastic beach-style folding assembly that is adapted to a pumper outlet via garden hose. Our rescue truck is having a camper-type awning installed on the driver’s side to create a shaded area (the passenger side has the engine exhaust). We always encourage our people to “get wet,” especially their heads and upper torso, to make individual cool-down more complete.