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Staying safe in the heat: understanding heat stroke

With football in full swing and the temperatures outside reaching into the 90’s, a few words on the risks associated with heat exposure are probably wise.  Heat stroke deaths in sport have remained high over the last 35 years and may be increasing, if anything, based on data we have from 2005 to 2009.  Perhaps the best way to reduce risk of heat stroke is proper acclimatization (gradual exposure of the body) to heat before the season.  Once the season is underway, however, emphasis should shift to other forms of risk reduction, proper identification of athletes who are experiencing heat-related illness, and proper management of those athletes who are suffering from heat stroke.

The diagnosis of heat stroke requires both elevated temperature (> 104° F) and central nervous system alteration.  Patients who appear “out of it,” are not always suffering from heat stroke.  Moreover, patients with heat stroke will often have a period of time where their mental status appears to be normal.  Thus, a high index of suspicion and accurate temperature assessment in athletes who are struggling is vitally important.  If you take only two points away from this article, let this be the first:  The only readily-available, accurate method of temperature assessment in athletes with suspected heat stroke is a rectal temperature.  Methods that measure temperature from the mouth, armpit, ear or skin are not valid and have been proven to significantly underestimate true core body temperature.  Parents should be aware of the school policy for emergency assessment in this regard and insist on an emergency protocol that takes this into account.

Other than high ambient temperature, risk factors that have been shown to predispose one to heat stroke include low fitness level, sleep deprivation, certain medications, and dehydration.  Medications that can increase the risk include but are not limited to, antihistamines, some blood pressure medications, hormones in birth control pills and high doses of aspirin.  Active ingredients in some energy drinks also can potentially increase the risk of heat stroke.  Consult a physician if you have questions as to whether what you are taking is associated with a higher risk.  Sleep can and should be enforced by parents of student-athletes.  Hydration status can be monitored by weighing athletes before and after practice and ensuring fluid replacement to restore weight.  Some studies have determined that upwards of two-thirds of athletes show up for practice clinically dehydrated.

Once heat stroke occurs, it is vital that emergency care be initiated on-site.  The first and most important aspect of this is proper recognition.  This speaks to having personnel who are properly qualified on the sidelines who can initiate proper treatment on the field, and ensuring that emergency protocols are in place for accurate temperature assessment.  An athlete who is struggling should never be left alone to try to recover.  Deterioration over time can occur.  Fatalities in heat stroke are less related to the peak temperature achieved and more to the total amount of time that an athlete spends above 104 degrees.  This is because the longer an athlete’s temperature remains in the critical zone, the higher the rate of cell death in the body.  Research in emergency outcomes on heat stroke patients shows that if a patient’s temperature can be brought to less than 104° within thirty minutes of collapse, survival will approach 100%.

Here is the second point regarding heat stroke that you should remember: When one considers that an athlete who is transported by ambulance to a hospital for emergency treatment will not begin to receive definitive care (immersion cooling of the athlete in cold water or ice water [35-57°]) for at least 30 minutes, it should become obvious to parents that immersion should be done on-site, prior to transport.  Athletes with known heat stroke can increase survival to nearly 100% if this occurs.  Transport should occur once the athlete’s core temperature has decreased to between 102-104°.  This is controversial because of school concerns for medical liability, but considering the principle of “first do no harm,” it should not be.  Athletes with heat stroke who are immersed in ice water at 35 degrees will bring down their temperature an average of 0.63° F/minute.  This is about twice the rate of cooling that occurs in 46 degree water.  Water should be circulated around the athlete to promote transfer of heat from the body to the water.  Moreover, there is no evidence that immersion in cold water is dangerous to the athlete.  When more ineffective cooling efforts are undertaken, core temperature can continue to rise, increasing the amount of time an athlete spends in the critical temperature zone and decreasing chances of survival.

Once successfully treated, athletes who have had a documented episode of heat stroke should be evaluated by a qualified physician prior to return to play.  Every prevention strategy should be implemented to minimize risk of recurrence.

Heat stroke is one illness that can always be prevented and never needs to happen.  Athletes can learn prevention techniques to put them in the best position to succeed in the heat.  Schools can reduce the risks associated with the heat by ensuring that proper emergency protocols are in place beforehand.  Parents should inquire about these protocols and encourage schools that do not currently have formal emergency guidelines to create them, based on appropriate medical evidence.

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