Dr. Kevin Most: Heat related illness
Hopefully you all had a cool Father’s Day, if you did, you were inside as it appears that summer has finally hit. Heat indexes hitting over 100 this past weekend and today appears to be the same. Now when the heat hits over the weekend we can control our environment by staying inside, however when it goes into the work week it raises some concerns. We thought we would take a few minutes and remind everyone what they can do to stay safe as we approach the days of summer heat. A lot of what we discuss may be common sense but hopefully we will provide some education on what to look for to prevent an emergency and how to make sure you are prepared.
The body is pretty amazing, it has a goal of keeping the body at a temperature that allows all parts of the body to function properly. Think of the range of temperature your body can function in, from 30 below zero in the winter to 105 in the summer. The range of 135 degrees, yet our body has ways to manage these temperature swings and allow the body to function normally. In the winter we try to make sure that we maintain our body temperature from the extreme cold. We discuss the moves that people can make to prevent frostbite during the winter. Now during the summer we discuss what the body will do to cool itself down to prevent heat related illness and injuries.
We do have some people who are at a higher risk of heat related illness. They include people over the age of 65 as the cooling system in seniors is not as functional as it was in younger years. Infants especially newborns are susceptible as well, they are often bundled up, and they can’t tell you they are thirsty or hot. Couple that with a high metabolic rate where they produce more heat and issues can occur quickly. Individuals who take some medications are also more at risk, antihistamines for allergies impact your cooling, diuretics for blood pressure can lead to dehydration. Some antidepressants also put you at a higher risk.
So when the temperature warms our body makes changes to keep us cool. We all think of sweating as something the body does as we work out or with heavy activity. How many times have you heard someone say “I worked up a good sweat today” Although it is a reaction to activity, the reason for sweating is to keep our body cool. The sweat actually acts as a cooling agent as air blows over it and speeds its evaporation. So essentially the air blowing over the sweat allows us to dissipate heat from our body and helps keep our core temperature in a functional zone.
“It’s not the heat, it’s the humidity,” How many times have you heard that? The concept of sweat is great and very functional, the problem we run into is when the humidity is high, the ability for the sweat to evaporate and cool us is hindered and thus not as effective as a cooling mechanism. Our 4 million sweat glands have no chance when the humidity is high. A relative humidity of over 60% slows or hampers the ideal body cooling, now I am not sure if we are ever at a relative humidity below 60 from May thru October. For example the relative humidity over the past weekend has been in the 90 % range, so sweat at that time does not evaporate and aid in cooling. You also may hear them discuss the Dew Point, this is an indicator of the total amount of moisture in the air, the number where we feel discomfort here is in the 70 degree or higher range
The combination of temperature and relative humidity allow us to calculate the heat index. This is the “feels like” temperature. We get concerned when that heat index approaches 100 degrees. For example an air temp of 90 degrees with a relative humidity of 60% equates to a heat index of 100, these are levels that concern us. So when planning an outdoor activity please look at the heat index expected for that activity. This is important for us in the Midwest, we hear all the time about the “dry heat” in the southwest and from a comfort and body cooling view this is very true. The dry heat allows for our sweating mechanism to work and cools us.
As we do with many of our talks, let’s talk about prevention, identification and treatment. Each of these are important and understanding what to do in preparation for heat waves will save inconvenience as well as lives. One of the most important is, do not leave children or pets in a car, even with a window partially open the car can heat up quickly and cause problems.
Before we touch on the more dangerous heat related illnesses, let’s talk more about what you can do to minimize your chances of any heat related illnesses. First is be aware of the heat index for any activity you have planned that will not be in an environment where a cooling option is not close. If you do not have access to a cool environment, find out if a cooling center is close by and make arrangements to stay there. Anyone who is going to be outside for an extended period of time should take a few minutes to see what the temperature and humidity are going to be that day. When possible move those activities to the morning when it will be the coolest portion of the day. If you have to do activities outside, pace yourself. Make sure you have access to fluids, taking 8 -12 ounces immediately before the activity and then continually thru the day, drinking 8-12 ounces every 30 minutes is key to fluid balance. I am an advocate of alternating water with sports drinks. Sports drinks help replenish some electrolytes as well as provide some glucose. This is important as some individuals lose their sense of thirst when going thru heat stress, having a good tasting fluid encourages them to drink more, this is another reason companies are using Gatorade in the factory settings. This encourages individuals to drink more and thus decreases the chance of dehydration.
Wearing light loose fitting clothing is also important, this allows for air circulation as well as not acting as an insulation layer. Remember this is the opposite of what we do in the winter as a tight fitting polyester base layer helps us retain heat.
As far as type of clothing, loose breathable fabrics are great as well as polyester that repels sweat. Try to arrange for frequent breaks from the activity. (cut the grass in sections, rest after 9 holes) also consider changing your active periods to early in the morning or in the evening when the temperature has dropped.
Let’s now discuss what the conditions are that we should be concerned about and how do we identify and treat them
Heat Exhaustion and heat cramps are the conditions we find after the body loses large amounts of fluids and electrolytes following exposure to high temperature and physical activity. This occurs more quickly with individuals who are dehydrated as well as in individuals who take medications that impact their hydration status. Individuals who are suffering from heat exhaustion often are suffering from a combination of dehydration as well as electrolyte depletion. These individuals will show signs of thirst, weakness, headache, nausea, vomiting and muscle cramps. These patients may also have profuse sweating and show flushed skin as the body does everything it can to cool itself. Each of these signs a hint that early dehydration is causing this, more than excessive retention of body heat. It will occur on those days where sweating alone may not help cool the body.
The treatment of this condition can often be treated at home or in the field. The goal is to cool the patient as well as replenish the fluids in the individual. Getting the patient into an air conditioned facility is best however treatment can also be done outside if indoor cooling is not an option. Cooling techniques include removing tight or unnecessary clothing, place cool wet towels or ice towels on the skin and encourage intake of fluids. Fanning or moving air also helps cool the individual. You want to refrain from alcohol or caffeine based drinks. Caffeine and alcohol actually work as diuretics, so although you are thinking you are taking in fluids the net is negative. I personally like the combo of water and sports drinks as they not only replenish the water they also deliver some of the lost electrolytes and deliver some sugar as well. Alternating the two is my recommendation. Understand that Monster and some energy drinks are not sports drinks, they are often loaded with Caffeine.
Just like we have discussed with frostbite the treatment immediately following is important, patients who have experienced heat exhaustion will be more prone to heat exhaustion for the next week. It is important to be careful with any activity the following week. Individuals at risk include all who are working outside, individuals who take diuretics for blood pressure, young kids and infants and seniors are at the highest risk.
So let’s now talk about Heat Stroke, this is a life threatening emergency and must be identified and treated quickly. In these individuals the bodies cooling system has shut down and the core body temperature continues to rise. This can cause major organ damage, brain damage and death. For any patient you think heat stroke may be a possibility, call 911 and start the cooling process while waiting for the paramedics. These patients may be unable to take fluids and in those cases do not force fluids, do the other measures to lower the body temperature. Water on the skin, remove excess clothing, fan or forced air blowing over the skin, ice packs in the axilla and groin may be used but refrain from them in seniors and young children. These patients will often need IV fluids to replenish their system and prevent any organ damage
So what does a heat stroke patient look like, this is an individual with a temp that may approach 104 degrees. Often they are confused, agitated and have slurred speech. Do not assume this is due to alcohol intake. These individuals often have dry hot skin as the sweating mechanism has shut down. These individuals have flushed skin, rapid breathing and heart rate that is often well over 100. The key to identifying these patients is the change in skin color, no sweating and the mental status changes. These are the individuals that will need emergent lifesaving medical treatment.
Please take the time to check on neighbors and their pets, especially if you know they do not have air conditioning.