Alexander ch41 lecture

Copyright © 2017, 2012 Pearson Education, Inc. All Rights Reserved.
Advanced EMT
A Clinical-Reasoning Approach, 2nd Edition
Chapter 41
Environmental
Emergencies

• The Advanced EMT applies fundamental
knowledge to provide basic and selected
advanced emergency care and transportation
based on assessment findings for an acutely
injured patient.
Advanced EMT Education Standard

1. Define key terms introduced in this chapter.
2. Explain actions you should take to protect your own
safety when responding to environmental emergencies.
3. Describe the scene size-up, primary and secondary
assessments, and management of environmental
emergencies including deep-water diving injuries, high-
altitude sickness, lightning strike, local cold injuries,
drowning, and systemic heat and cold injuries.
4. Explain the process of thermoregulation, including
mechanisms by which the body gains and loses heat.
Objectives

5. Explain the risk factors, pathophysiology, signs,
symptoms, assessment, and management of heat
cramps, heat exhaustion, heatstroke (classical and
exertional), local cold injury, and mild, moderate, and
severe hypothermia.
symptoms, assessment, and management of lightning
strike injuries.
7. Explain the following gas laws as they relate to high
altitude and deep-water diving emergencies: Boyle’s law,
Charles’s law, Dalton’s law, and Henry’s law.
Objectives (2 of 4)

symptoms, assessment, and management of high-
altitude sickness and dysbarism to include acute
mountain sickness, arterial gas embolism, barotrauma,
decompression sickness, high-altitude cerebral edema,
high-altitude pulmonary edema, and nitrogen narcosis.
symptoms, assessment, and management of drowning.
Objectives (3 of 4)

10.Recognize additional mechanisms of injury and illness
that are associated with drowning, such as trauma and
hypothermia.
11.Explain factors that affect the likelihood of survival from
drowning.
Objectives (4 of 4)

Introduction (1 of 2)
• Environmental emergencies occur when normal
body processes are affected by external
conditions.
– Temperature, submersion in water, lightning, and
changes in atmospheric pressure
• When cold, body conserves heat; when hot, body
eliminates heat.

Introduction (2 of 2)
• When body mechanisms are no longer effective,
emergency situation occurs.
• Be aware of risks; take measures to protect
yourself, then protect patient.

Think About It
• What problems do you think Jennifer and Harry
have identified so far?
• What hypotheses should Jennifer and Harry be
developing?
• What information supports each hypothesis
Jennifer and Harry may be developing?

Think About It
• What will Jennifer and Harry need to find out to
test each hypothesis?
• What should be Jennifer and Harry’s immediate
actions?

Heat- and Cold-Related Emergencies
(1 of 2)
• Body maintains normal core temperature through
thermoregulation.
• In extreme environmental temperatures, body’s
thermoregulatory mechanisms are overwhelmed.

(2 of 2)
• Body temperature increases or decreases, leading
to illness.
• Hot conditions
– Hypovolemia, loss of electrolytes
• Cold conditions
– Frostbite and related conditions

Anatomy and Physiology Review
(1 of 4)
• Thermoregulation
– Process by which body regulates core body
temperature
• Core temperature
– Temperature of blood and internal organs
• Body detects core temperature through
thermoreceptors
– Sensory nerve endings that monitor temperature within
body

(2 of 4)
• Hypothalamus activates temperature regulatory
mechanisms.
• Thermal gradient
– Difference between body and environmental
temperatures
• Thermogenesis
– Process of generating heat
• Thermolysis
– Process of transferring heat from body to environment

(3 of 4)
• Conduction
– Heat transfer from body to cooler object by direct
contact
• Convection
– Heat transfer to air molecules passed across skin due
to moving air current
• Radiation
– Heat transfer from body without physical contact

(4 of 4)
• Evaporation
– Sweat vaporizing and dissipating from skin carries heat
• Respiration
– Heat lost through exhalation of warm air and inhalation
of cold air

• Risk factors for heat-and cold-related
emergencies
– Patient age
– Patient health
– Medications
– Length of exposure
– Intensity of exposure
– Socioeconomic factors

Figure 41-2
The risk of heat-related emergencies increases with increased heat and humidity.

General Assessment (1 of 6)
• Environment does not have to be extreme for
problems to occur.
• Patients with impaired thermoregulation at
increased risk.
• During scene size-up, look for clues to nature of
emergency and for potential hazards.

• Scene size-up
– Temperatures of 90°F or greater/relative humidity of
greater than 75% ideal for heat emergencies
– Identify number of patients.
– Determine need for additional resources.
– Form general impression.

• Scene size-up
– Protect your health.
 Maintain adequate fluid intake.
 Allow time for gradual acclimatization to heat prior to physical
exertion.
 Limit time of exposure.
 In cold weather, dress appropriately.

• Primary assessment
– Decreased level of responsiveness (LOR) jeopardizes
ability to maintain airway.
– Extremes in temperature can affect circulation,
affecting heart function and fluid loss.
– Ensure adequacy of airway, breathing, circulation.
– Address immediate life threats.
– Remove patient from environment.
– Take measures to stabilize body temperature.

• Primary assessment (continued)
– Determine if critical or noncritical. Perform rapid
secondary exam to identify potentially life-threatening
conditions.
• Secondary assessment
– Obtain baseline vital signs and medical history; perform
head-to-toe or focused examination.

• Secondary assessment (continued)
– Use pulse oximetry, blood glucose monitoring, end tidal
CO2 monitoring, cardiac monitoring per protocols.
– Obtain information related to events leading up to
emergency (temperature, humidity, wind, length of
exposure to environment).
• Reassessment
– Reassess critical patients every 5 minutes, every 15
minutes for noncritical patients.

Specific Heat-Related Emergencies
(1 of 19)
• Categories
– Heat cramps
– Heat exhaustion
– Heatstroke

(2 of 19)
• Heat cramps
– Least severe of all heat-related emergencies
– Muscle groups cramp in response to overexertion and
dehydration in hot environment.
– Primary problem: loss of electrolytes (sodium and
chloride)

(3 of 19)
• Heat cramps (continued)
– Signs and symptoms
 Cramping of the larger muscle of body
 Weakness
 Possible complaints of lightheadedness or dizziness
• Management
– Remove patient from hot environment.
– Administer oral electrolyte replacement fluid.
– Gentle massage.

(4 of 19)
• Heat exhaustion
– Moderate heat-related illness
– Inadequate perfusion; mild state of shock
– Increased vasodilation in peripheral circulation.
– Prolonged and profuse sweating leads to loss of
circulating blood volume and thus inadequate
circulation.

(5 of 19)
• Heat exhaustion (continued)
 Body temperature greater than 100°F (37.8°C)
 Cool and diaphoretic skin
 Tachypnea
 Weak pulses
 Possible muscle cramping
 Weakness/headache/dizziness
 Anxiety
 Altered mental status (possible loss of consciousness)

(6 of 19)
• Heat exhaustion (continued)
– Remove patient from hot environment.
– Remove heavy clothing.
– Do not allow patient to become chilled.
– Administer fluids orally if patient alert and not
nauseated.

(7 of 19)
• Heatstroke
– Life-threatening condition
– Body’s thermoregulatory mechanisms cease to work
– Core body temperature of greater than 104°F.
– Mortality rate 20% to 80%
– Core body temperature rises uncontrollably, resulting in
destruction of brain cells.

(8 of 19)
• Heatstroke (continued)
– Classic heatstroke
– Elderly or ill person unable to escape hot environment.
– Exertional heatstroke
– Those working in hot environment; concern for
firefighters

(9 of 19)
 Altered mental status
 Cessation of sweating
 Hot, flushed skin
 High core body temperature
 Deep, rapid respiration, which can become slow and shallow
 Tachycardia, which can proceed to bradycardia
 Possible seizures

(10 of 19)
– Rapid identification and rapid, effective treatment can
decrease morbidity and mortality rates.
– Remove from hot environment.
– Rapidly cool by removing clothing.
– Initiate two large-bore IVs of isotonic crystalloid
solution. Follow your protocols
– Be prepared to manage seizures.

Think About It
• What hypotheses might have moved higher on
Jennifer and Harry’s list, and which hypotheses
might have moved lower?
• How might the information obtained have changed
Jennifer and Harry’s priorities for patient care and
transport?
• What should be their next actions?

Specific Cold-Related Emergencies
(11 of 19)
• Generalized hypothermia
– Core body temperature drops below 95°F.
– Severe hypothermia is a life-threatening condition;
mortality rate of more than 80%.

(12 of 19)
• Generalized hypothermia (continued)
– Body’s thermoregulation mechanisms fail.
– Core body temperature falls quickly.
– Cardiac output decreases and can lead to cardiac
arrest.
– Death can occur quickly.

(13 of 19)
• Generalized hypothermia (continued)
– Mild hypothermia
 Core body temperature is between 90°F and 95°F.
– Severe hypothermia
 Core body temperature is less than 90°F.
– Treatment depends on degree of hypothermia.
– Remove from the cold environment.

Figure 41-3
Five stages of hypothermia.

(14 of 19)
• Generalized hypothermia
– Stabilize temperature.
– Handle gently.
– Remove wet clothing.
– Cover with blankets and moisture barriers.
– Monitor core temperature.
– Monitor cardiac rhythm.

(15 of 19)
• Mild hypothermia
– Apply heat packs.
– Start IVs with warmed fluids.
– Give warm, sweetened fluids orally to patients who are
alert and not nauseated.
– Do not give beverages that contain alcohol or caffeine.

(16 of 19)
• Severe hypothermia
– Do not attempt active rewarming with hot packs or IV
fluids.
– If pulseless, start cardiopulmonary resuscitation (CPR)
and apply automated external defibrillator (AED).
– Use advanced airway to provide adequate airway and
ventilation.
– Consider transportation to facility with cardiac bypass
capabilities.

Figure 41-5
Deep local cold injury.
(© Edward T. Dickinson, MD)

(17 of 19)
• Local cold injury
– Frostbite
 Intracellular fluid freezes; frozen fluid crystallizes and expands,
causing tissue damage.
– Superficial frostbite or frostnip
 Superficial layers of tissue affected.
 Tissue feels firm superficially but soft beneath.

(18 of 19)
• Local cold injury (continued)
– Frostbitten areas not thawed in prehospital
management.
– Do not massage area or rub it.
– If you must allow area to thaw, first administer
analgesia.
– Transport patient to hospital for rewarming.
– Cover frozen or thawed part with dry, sterile dressings,
placing dressings between fingers and toes, and
bandage loosely.
– Avoid breaking blisters; keep part elevated.

(19 of 19)
– To protect yourself from frostbite:
 Tight shoes or boots reduce circulation to feet, increasing risk
of frostbite.
 Windy conditions increase rate of heat loss.
 Be aware of wind chill factor.
 Cover exposed parts.
 Caffeine and nicotine increase risk of frostbite.

– Trench foot (immersion foot)
 Localized cold injury that occurs when feet are immersed in
cold water for prolonged periods.

Drowning (1 of 2)
• Adolescents and adults drown most often in
ponds, lakes, rivers, and oceans.
• Spinal motion restriction may be considered if
obvious signs of trauma.
• Remove patient from water before attempting to
begin chest compressions
• Victim may live or die after this process; whatever
the outcome, he or she has been involved in
drowning incident.

Drowning (2 of 2)
• Possible underlying medical conditions
– Hypoglycemia
– Seizures
– Syncope
– Myocardial infarction
– Stroke
– Anxiety disorder
– Exhaustion
– Hypothermia
– Alcohol or drug use

Pathophysiology of Drowning (1 of 3)
• Following submersion in liquid medium, patient
first voluntarily holds breath.
• Reflex swallowing of water occurs.
• If patient aspirates small amount of water,
laryngospasm occurs, which constricts airway.
• Carbon dioxide level in blood increases; oxygen
level decreases.

• Laryngospasm relaxes, active respiration but gas
exchange cannot occur.
• Hypoxia, hypercapnia, acidosis lead to cardiac
arrest and organ injury.
• Longer patient submerged, the poorer the
prognosis.

• Other factors
– Water cleanliness
 Contains pathogens and chemicals
– Water temperature
 Patient can be apneic for longer time while hypothermic than
while normothermic.
– Patient health
 Patients with preexisting medical conditions cannot tolerate
hypoxia due to submersion.

Assessment and Management (1 of 8)
• May or may not be out of water when you arrive at
scene.
• If you are not trained in water rescue and do not
have proper equipment, do not enter water to
attempt rescue.
• If water rescue resources have not already been
dispatched, request them immediately.

• Remove from water as quickly as possible.
• Delaying resuscitation to perform spinal motion
restriction in water will result in further hypoxia.
• Chest compressions are not effective until patient
is out of water.

• Detect and correct threats to airway, breathing,
circulation.
• Correct hypoxia.
• Assess for underlying medical problems,
hypothermia, injuries.

• Scene size-up
– Assess scene for hazards.
– Ensure your safety.
– Determine what circumstances led patient to be
submerged.
– Decide if cervical-spine stabilization needed.
– Develop general impression.

• Primary assessment
– If no pulse, begin chest compressions as partner
applies AED.
 Be sure to dry patient quickly before applying AED pads.
– If pulse is present, assess ABCs and correct life-
threatening problems.

• Primary assessment (continued)
– Suction fluid and use manual maneuvers to open
airway.
– Assist ventilations, if necessary.
– Check for and control external bleeding.
– Assess patient’s oxygen saturation.

• Secondary assessment
– Perform rapid trauma exam for unresponsive patient or
patient with decreased level of responsiveness.
– Obtain baseline vital signs and patient history.
– Perform focused exam for conscious/oriented patients.
– Perform head-to-toe exam if decreased level of
responsiveness.

• Management and reassessment
– Management aimed at improving oxygenation and
perfusion.
– Be alert to the possibility of hypothermia.
– En route reassess every 5 minutes for critical patients
and every 15 for noncritical.

Diving Emergencies
• Diving emergencies occur due to effects of
pressure exerted on body in deep water,
particularly when diver breathes compressed air
from self-contained underwater breathing
apparatus (SCUBA).

Diving Emergencies (2 of 15)
• Effects of pressure
– Underwater depth and pressure directly related; deeper
you go, more pressure, or weight, exerted on you and
on gases you breathe.
– Dysbarism
 Medical condition resulting from changes in pressure
– Water exerts more pressure than air.
 Every 33 feet of water exerts one atmosphere of pressure.

• Effects of pressure (continued)
– Boyle’s law
 Volume of a gas is inversely proportional to its pressure.
– Dalton’s law
 Total pressure of a gaseous mixture is equal to sum of partial
pressures of each of the individual gases in mixture.

• Effects of pressure (continued)
– Henry’s law
 Solubility of a gas in a liquid at a particular temperature is
proportional to pressure of that gas above liquid.
– Charles’s law
 All gases will expand equally when heated.

• General assessment and management
– Time of onset of signs and symptoms
– Type of breathing equipment used
– Depth of dive
– Number of dives
– Duration of each dive

(continued)
– Whether aircraft travel followed dive and whether cabin
was pressurized or unpressurized
– Rate of ascent
– Experience of diver
– Previous decompression illnesses
– Medications
– Alcohol or drug use

• Barotrauma
– When air pressure in hollow spaces of body rises too
high or drops too low.
– During descent diving, barotrauma called the squeeze.
– When pressure within sinuses cannot be equalized,
injury can occur.

• Barotrauma (continued)
 Mild to severe pain in ears or sinus regions
 Discharge of clear fluid or blood from nose or ears
 Dizziness
 Tinnitus
 Hearing loss

• Decompression sickness
– “The bends”
– Nitrogen gas bubbles are produced and accumulate in
blood and tissues as a result of rapid ascent during
dive.
– Controlled ascent (staged ascent)
 Diver will ascend certain amount and then pause to allow
equilibrium of pressure to occur.

• Decompression sickness (continued)
– Acts as air embolism in bloodstream
– Stretch blood vessels and nerves of body
– Severe pain, usually in joints and abdomen

• Type I decompression sickness
– Mild form that affects skin
• Type II decompression sickness
– Caused by nitrogen bubbles in nervous, respiratory,
and circulatory system.
– What are signs and symptoms of Type II
decompression sickness?

• Decompression sickness
– Recompression
 Place patient in hyperbaric chamber.
– Patient subjected to pressurized oxygen therapy to
force nitrogen to redissolve.
– Gradually decompressing to allow nitrogen to escape
again without formation of bubbles

• Decompression sickness (continued)
– Manage airway, breathing, circulation.
– Provide high-flow oxygen.
– Transport in supine position.
– IV access and fluid therapy as indicated.
– If air transport used, patient must not be exposed to
decreased barometric pressure.

• Arterial gas embolism
– If ascent occurs too rapidly or if diver holds his breath,
nitrogen bubbles will form in arterial bloodstream.
– Condition can be rapidly fatal.
• What are some of the signs and symptoms of an
arterial gas embolism?

• Nitrogen narcosis
– Commonly called “rapture of the deep”: state of stupor
resulting from nitrogen’s effect on cerebral function
– Diver may act intoxicated and take risks that he
ordinarily would not take.
– Martini effect
 Feels like you have had one martini for every 33 feet of depth
descended

High-Altitude Illness
• Decrease in atmospheric pressure
• When ascending to high altitudes, you must do so
gradually to allow body to acclimate.
• Failure to allow acclimation to hypoxic
environment of higher altitude may result in
illness.
• Quickly bring patient to lower altitude.

High-Altitude Illness (2 of 5)
• Acute mountain sickness
– Person ascends to altitude of 2,000 meters (6,600 feet)
too rapidly.
– Mild signs and symptoms
 Lightheadedness
 Mild shortness of breath
 Weakness
 Headache
 Nausea and vomiting

• Acute mountain sickness (continued)
– Severe signs and symptoms
 Profound weakness
 Severe vomiting
 Significant shortness of breath
 Altered mental status
– Ensure adequacy of airway, breathing, circulation.
– Bring patient to lower altitude.

• High-altitude pulmonary edema (HAPE)
– Noncardiogenic pulmonary edema; occurs at altitudes
of 2,500 meters (8,200 feet) or greater
– Tachycardia
– Shortness of breath
– Rales, coughing
– Weakness
– Coma, death

• High-altitude cerebral edema (HACE)
– Increase of fluid in brain leading to increase in
intracranial pressure
 Lack of coordination
 Decreased level of responsiveness
 Seizure
 Headache
 Vomiting
 Coma

Lightning Injuries (1 of 4)
• Voltage
– Measurement of energy within electric circuit at given
point
• Current
– Flow of electric charge through conductive material
– Current referenced by unit of measure called amperes

• Voltage and current of lightning extraordinarily
high—in excess of 1,000,000 volts with 200,000
amperes of current
• Direct strike
– Lightning hits victim first, before making contact with
any other object
• Contact strike
– Lightning hits object with which patient is in contact

• Side flash strike
– Lightning hits object and then jumps to victim who is
located nearby
• Ground current strike
– Lightning energizes ground, affecting people standing
in area of strike
• Be alert for associated traumatic injuries.

– Ensure scene is safe.
– Lightning strike affects many body systems.
– Energy produced by lightning strike causes injury along
its path through body.
– Management supportive; treatment of burn injuries,
musculoskeletal injuries, spine injuries, cardiac arrest.
• What are some signs and symptoms of lightning
strikes?

Chapter Summary (1 of 2)
• People can become victims of the environment in
many different ways.
• Injuries can be minor, but can be life threatening;
especially true for pediatric and geriatric
populations.
• Respect the environment.
• Ensure you are prepared for conditions to which
you will be exposed.

Chapter Summary (2 of 2)
• As an Advanced EMT, you are not immune to
injury or illness.
• Always take precautionary measures.
• Your goal is to identify environmental cause of
illness or injury.
• Manage patient’s condition appropriately; prevent
deterioration; provide transport.

Alexander ch41 lecture

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