Advanced Trauma Life Support ATLS Student Course Manual 2018

269
APPENDIX B n Hypothermia and Heat Injuries
hypothermia who has sustained an anoxic event while
still normothermic and who has no pulse or respiration,
or one who has a serum potassium level greater than
10 mmol/L. Another exception is a patient who
presents with an otherwise fatal wound (transcerebral
gunshot wound, complete exsanguination, etc.)
and hypothermia.
heat injuries
Illnesses related to heat are common worldwide. In
the United States, on average over 600 deaths each
year result from heat overexposure. Heat exhaustion
and heat stroke, the most serious forms of heat injury,
are common and preventable conditions. Excessive
core temperature initiates a cascade of inflammatory
pathologic events that leads to mild heat exhaustion
and, if untreated, eventually to multi-organ failure
and death. The severity of heat stroke correlates with
the duration of hyperthermia. Rapid reduction of body
temperature is associated with improved survival.
Be sure to assess patients with hyperthermia for
use of psychotropic drugs or a history of exposure
to anesthetics.
Types of Heat Injuries
Heat exhaustion is a common disorder caused by
excessive loss of body water, electrolyte depletion,
or both. It represents an ill-defined spectrum of
symptoms, including headache, nausea, vomiting, lightheadedness,
malaise, and myalgia. It is distinguished
from heat stroke by having intact mental function and
a core temperature less than 39°C (102.2°F). Without
treatment, heat exhaustion can potentially lead to
heat stroke.
Heat stroke is a life-threatening systemic condition
that includes (1) elevated core body temperature
≥ 40°C (104°F); (2) involvement of the central
nervous system in the form of dizziness, confusion,
irritability, aggressiveness, apathy, disorientation,
seizures, or coma; and (3) systemic inflammatory
response with multiple organ failure that may include
encephalopathy, rhabdomyolysis, acute renal failure,
acute respiratory distress syndrome, myocardial
injury, hepatocellular injury, intestinal ischemia or
infarction, and hemotologic complications such as
disseminated intravascular coagulation (DIC) and
thrombocytopenia. n TABLE B-3 compares the physical
findings of patients with heat exhaustion and
heat stroke.
There are two forms of heat stroke. Classic, or
nonexertional heat stroke, frequently occurs during
environmental heat waves and involves passive
exposure to the environment. Individuals primarily
affected are young children, the elderly, and the
physically or mentally ill. A child left in a poorly
ventilated automobile parked in the sun is a classic form
of nonexertional heat stroke. Homeostatic mechanisms
fail under the high ambient temperature.
Exertional heat stroke usually occurs in healthy,
young, and physically active people who are engaged
in strenuous exercise or work in hot and humid
environments. Heat stroke occurs when the core body
temperature rises and the thermoregulatory system
fails to respond adequately.
The mortality of heat stroke varies from 10% to as
high as 33% in patients with classic heat stroke. Those
individuals who do survive may sustain permanent
neurological damage. Patients with heat stroke
will often be tachycardic and tachypnic. They may
be hypotensive or normotensive with a wide pulse
pressure. Core body temperature is ≥ 40°C (104°F). Skin
is usually warm and dry or clammy and diaphoretic.
Liver and muscle enzymes level will be elevated in
table b-3 physical findings in patients with heat exhaustion and heat stroke
PHYSICAL FINDINGS HEAT EXHAUSTION HEAT STROKE
Symptoms
Headache, nausea,
vomiting, dizziness,
malaise and myalgias
Headache, nausea, vomiting, dizziness, malaise and myalgias, mental
confusion, irritability, disorientation, seizure, coma
Temperature < 39° C (102.2° F) ≥ 40° C (104° F)
Systemic Signs
Syncope, low blood
pressure
Encephalopathy, hepatocellular injury, disseminated intravascular
coagulation (DIC), acute kidney injury, tachypnea, acute respiratory
distress syndrome, arrythmias
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