Special Operations Forces Medical Handbook

6-49

Heat-Related Illnesses: Heat Exhaustion

LTC Richard Kramp, MC, USA

Introduction: Heat exhaustion is the most common heat illness. Heat exhaustion may develop over several
days and is a manifestation of strain on the cardiovascular system. It occurs when the demands for blood flow
(to the skin for temperature control through convection and sweating, to the muscles for work, and other vital
organs) exceed the cardiac output. Risk Factors: Dehydrated and sodium-deficient members are at risk after
strenuous physical activity in the heat. Operators that are not fully acclimatized are at increased risk.

Subjective: Symptoms
Profound fatigue, thirst, nausea/vomiting, tingling of the lips, shortness of breath, orthostatic dizziness,
headache, and syncope
Focused History: What have you had to eat and drink in the last 48 hours? (Water and salt intake may
be too low. If they have consumed several gallons of fluid in the past 2 hours consider hyponatremia- water
intoxication.) Do you know who you are, where you are and what day it is? (While heat exhaustion patients
may be confused, it is a common sign of heat stroke. A patient with mental status changes should be treated
as a heat stroke patient until it is proven otherwise.)

Objective: Signs
Inspection: Pale skin; anxiety and agitation; muscle spasms; vomiting; orthostatic hypotension and shortness
of breath. If the patient is confused, assume heat stroke until proven otherwise. IF THE RECTAL
TEMPERATURE CONTINUES TO RISE, TREAT AS A HEAT STROKE.
Auscultation: Hyperventilation
Palpation: Skin cool and moist to touch. It may be dry in desert environments where evaporation is rapid.

Assessment:

Differential Diagnosis - heat stroke, simple dehydration, febrile illness

Plan:

Treatment

1. Reduce the load on the heart with rest and cooling. Place casualty in shade and remove heavy clothing.
   Apply cool water to the skin if available.


2. Correct water and electrolyte depletion by administering oral or IV fluids. IV fluids replenish the volume
   and correct symptoms quickly. Patients with resting tachycardia or orthostatic hypotension should initially
   receive 200-250 cc boluses of normal saline (NS) repeatedly until these vital signs are corrected. No more
   than 2 liters of NS should be administered without laboratory surveillance. Subsequent IV fluid
   replacement should be D5/0.5 NS or D5/0.2 NS. Since this is seldom available, alternating D5W with NS
   or Ringers Lactate may be the best alternative. If patient can tolerate oral fluids use a 0.1% salt solution.

Patient Education
General: Maintain adequate fluid and water intake and work/rest cycles in heat. Avoid direct sunlight and
other risk factors.
Activity: Heat exhaustion patients have rapid clinical recovery. However, they all need at least 24 hours
of rest and re-hydration under first echelon or unit level medical supervision to reverse water-electrolyte
depletion.
Diet: Regular diet augmented with salted food and increased water intake.
Prevention and Hygiene: Acclimatize gradually with adequate water and dietary salt. Forced drinking may
help to avoid dehydration.
No improvement/Deterioration: Return quickly for reevaluation.