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 "The cheeks, palms, and soles of the feet are special areas," with
blood vessels that don't contract when cold packs are applied,
helping to remove heat from the skin surface and cool body
temperatures, said study co-author Dr. Grant Lipman, a researcher in
emergency medicine at Stanford University in California.
Heat-related illness is common, and can often be prevented by proper
hydration and limited exertion outside during the hottest parts of
the day. But left untreated, heat stroke can develop and be fatal.
The condition kills thousands of people every year, most during the
hottest months, and is a leading cause of death among young
athletes, the authors write in Wilderness & Environmental Medicine.
Warning signs for heat exhaustion, a precursor to heat stroke, can
include heavy sweating, clammy skin, weakness, nausea or vomiting,
and fainting, according to the U.S. Centers for Disease Control and
Prevention.
Heat stroke develops when the body temperature exceeds 39.44 degrees
Celsius (103 degrees Fahrenheit), requiring rapid cooling with cold
packs or an icy bath and then hospitalization.
Lipman and colleagues tested a new method for applying cold packs to
overheated athletes to see if their alternative might be more
effective than the traditional placement of cold packs on the skin
over large blood vessels in the neck, groin and armpits.
They dressed ten healthy men in insulated military clothes designed
to trap body heat, then asked the men to walk on a treadmill for 30
to 40 minutes in a room heated to about 40 C (104 F).
Each man did the treadmill test three times, with at least one day
between trials to allow for rest and recovery. First, they finished
with no treatment to help lower their body temperature. Then they
got cold packs the traditional way, applied at the neck, groin and
armpits. Last, they received cold packs using the new method, placed
on the cheeks, hands and feet.
The average body temperature after the treadmill test was 39.2 C
(102.6 F).
Without any treatment, the men cooled by an average of 0.3 degrees
Celsius after five minutes and by a total of 0.42 degrees (to 101.8
F) after 10 minutes.
Ice packs on the usual spots cooled the men by an average of 0.4
degrees after five minutes and 0.57 degrees after 10 minutes (to
101.5 F). With ice packs on the hands, feet and cheeks, the decline
in body temperature was steeper: 0.6 degrees after five minutes and
0.9 degrees after 10 minutes (to 100.9 F).
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One limitation of the study is related to ethics – the researchers
couldn't induce heat stroke so they instead tested the new cooling
method by giving the men hyperthermia, or heat exhaustion, which
isn't as dangerous and is easier to reverse.
The experiments also relied on young, healthy volunteers, even
though the majority of heat stroke deaths occur in the elderly.
Even so, the findings suggest that the new method could be used to
help cool down overheated athletes, particularly as a treatment
started in the field and continued by paramedics on the way to the
hospital, Lipman said by email.
Because the temperature-lowering effect was only about one degree
after 30 minutes, though, the cold packs regardless of placement may
not work fast enough help a heat stroke victim, said Dr. Edward
Otten, a professor of emergency medicine at the University of
Cincinnati. "That would be too slow and too little to make a
difference."
The new placement method for cold packs might be useful for less
severe heat illness, and work well at rehab stations for
firefighters or soldiers, or for cooling tents at marathons and
other athletic events, said Otten, who wasn't involved in the study.
"Intuitively it makes sense to place cold packs on large blood
vessels because most of the blood volume is going through them,"
Otten said in an email. "However, microcirculation in the palms,
soles and cheeks is such that heat transfer works more efficiently
through them."
SOURCE: http://bit.ly/1PoZXr2 Wilderness & Environmental Medicine,
online March 12, 2015.
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