Articles
Exertional Heat Stroke:
A short clinical review on the Israeli experience
Heat stroke is the most severe form of heat- related illnesses. It is classified into two main forms. A classic heat stroke, which usually affects older people in a hot climate environment, typically in heat waves, such as the one that occurred in Western Europe in the summer of 2003 and caused the death of thousands of mostly senior citizens1. The second form is an exertional heat stroke (EHS) which is more common in young, active people, and results from a rather intense physical activity in a relatively hot climate. This type is a major concern among professional athletes and, in Israel, specifically among training soldiers. The reported rising incidence of EHS in the last years2, combining with its’ sudden appearance and potential lethal results, demands an appropriate education of both medical and commanding staff. This report will describe the predisposition, the diagnosis and the treatment of EHS among Israeli soldiers.
Diagnosis of EHS is a clinical one. There are no
universal diagnosis criteria in the literature. However,
most authors define this entity as a combination
of an elevated core body temperature above
40 °C, consciousness level alternations3. Laboratory
findings, such as elevated liver enzymes,
impaired renal function and coagulopathies usually
help to support this diagnosis, as well as a
pathological heat tolerance test, performed several
weeks after the event4.
EHS incidence varies, according to definition, in
different reports. In a study performed among U.S
Air Force basic trainees, the rate of heat -related
illnesses was 1.3 cases per 10,000 soldiers5. The
mortality rate from EHS among U.S army soldiers
between the years 1980 to 2002 was 0.3 per
100,000-soldier year2.
Several risk factors are linked to heat stroke
evolvement: dehydration, poor physical fitness,
lack of acclimatization, obesity, older age, fatigue,
high motivation and concurrent illness6. Focusing
on these factors might help to decrease morbidity
and mortality rates.
EHS AMONG ISRAELI SOLDIERS:
EHS is relatively common in the Israel Defense
Force, with 10-20 cases per year, mostly during
summer season and responsible for more then 15
deaths during the last decades. Many of these
cases occur during basic-training programs, which
generally take place in hot climate areas. The
trainees are in their first weeks of military service;
hence, usually not well acclimatized and tend to
have a relatively poor physical fitness level. Furthermore,
they tend to hide relevant medical
history during the first phase of their military
service due to high motivation.
PREVENTION:
To decrease morbidity and to minimize potentially
avoidable risk factors, experts in physical fitness,
physiology and sports medicine are involved in
determining physical scales in different stages of
the training. All trainees and commanders are
debriefed once a year regarding EHS, and all
members of medical staff are trained to diagnose
and treat. To decide on the degree of physical
training authorized, the weather conditions (as
measured by heat-load units) are measured
carefully before and during each exercise. The
results are then compared to a standard table
which correlates heat-load to effort levels and
expressed as "heat discomfort index". Before
carrying out a major physical exercise, a few more
sleeping hours are given to the trainees, they are
encouraged to drink regularly and go through a
short medical triage, to recognize acute illness
before starting the exercise. A fifteen minutes
break takes place every 45 minutes of a hard physical
exercise and fifteen minutes every half hour,
when wheather conditions are extreme.
DIAGNOSIS:
The typical EHS soldier is the “failing trainee”. Any
trainee "falling behind" his friends, or collapsing
during or shortly after an exercise is suspected to
suffer from heat stroke. Consequently, commanding
personnel and medical staff are taught to look for
these signs and take immediate vigorous steps
(including total body cooling rectal temperature
measurement and evacuation to the nearest emergency
room). EHS can also present atypically: a
recent case in the IDF (in press) presented as an
acute psychotic episode during a vigorous exercise.
The patient was not recognized as EHS victim at the
scene or at the referral hospital. EHS was only recognized
when another soldier with EHS, this time
with a typical presentation, was admitted to the
same hospital the next day.
TREATMENT:
Our treatment algorithm emphasizes the importance
of vigorous treatment actions to be commenced as
early as possible. Therefore, a large amount of water
should be available in the fields during every physical
training and medical and commanding staff are
encouraged to treat every suspicious case by full,
rapid undressing, immersion in large amounts of
water, intravenous fluids administration and rapid
evacuation to the nearest emergency room. Other
cooling methods such as ice packing or dantrolene
administration (which is the drug of choice in treating
malignant hyperthermia)3, 8 are not part of the treatment
protocols.
CONCLUSIONS:
Exertional heat stroke is a potentially lethal illness
typically endangers Israeli trainees, during their first
weeks of military service, because of a relatively poor
physical fitness and the need to train in hot climate
conditions. Since it is a preventable event, many
education efforts are given to instruct soldiers,
commanding staff and medical personnel regarding
EHS and it’s potential dangers.
For diagnosis, a very high "index of suspicion"
is applied and every trainee "falling behind" his
friends is given an early aggressive treatment. We
strongly believe that this protocol improves the prognosis
of EHS patient9. di
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