electricity and heat related

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DYPMC
Medicine Department
Electrical Injuries

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To identify the important complications of
electrical injuries.
To expose the pitfalls in diagnosis.
To explore the management.
Electrical Injuries
Goals

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Define the population at risk.
Determine the factors predicting the severity of
injury.
Differentiate between high-voltage and low-
voltage injuries.
Recognize which patients require admission or
referral.
Decide which patients need cardiac monitoring.
Electrical Injuries
Objectives

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 Extent of injury determined by type, amount
,duration and pathway of electric current
 Clinical findings alone are unreliable, hence
resuscitation MUST be attempted without
presuming death
 Skin findings are misleading and are not indicative
of deeper injury
Essentials of Electrical Injury

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• Electrical Injuries Are Uncommon
Top 10 Myths of Electrical Injury
Myth #1

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5X additional patients
requiring emergency
treatment
3-5% of all burn centre
admissions
Bimodal distribution
Toddlers, Electricians
Electrical Injuries
Epidemiology

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• Voltage Is the Most Important Determinant
of Injury
Top 10 Myths of Electrical Injury
Myth #2

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1. V = voltage
2. i = current
3. R = resistance
Electrical Injuries
Factors Determining Severity
OHM’S LAW: i = V / R

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Electrical Injuries
Factors Determining Severity
JOULE’S LAW:
Power (watts) = Energy (Joules)
time
= V x i
= i2
x R

10. 10
Skin Resistivity - Ohms/cm
2
100
300 - 10 000
1 200 - 1 500
2 500
10 000 - 40 000
100 000 - 200 000
1 000 000 - 2 000 000
Mucous membranes
Vascular areas
• volar arm, inner thigh
Wet skin
• Sweat
• Bathtub
Other skin
Sole of foot
Heavily calloused palm
Electrical Injuries
Factors Determining Severity

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• High Voltage Is More Likely to Kill
Than Low Voltage
Top 10 Myths of Electrical Injury
Myth #3

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 A momentary dose of
high voltage electricity is
not necessarily fatal.
 Low voltage is just as
likely to kill as high
voltage.
Electrical Injury
Factors Determining Severity

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The Extent of the Surface
Burn Determines the
Severity of Injury
Top 10 Myths of Electrical Injury
Myth #4

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• Direct contact
– Direct tissue heating
– Contact burns (entry and
exit)
– Thermal burns
Electrical Injuries
Patterns of Injury

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The Pathway the Electrical Current
Takes Through the Victim Predicts the
Pattern of Injuries
Top 10 Myths of Electrical Injury
Myth #5

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Skin Resistivity
Least Nerves
Blood
Mucous membranes
Muscle
Intermediate Dry skin
Tendon
Fat
Most Bone
Electrical Injuries
Patterns of Injury

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1 mAmp Threshold of perception
5 mA Maximum harmless current
6 mA Ground fault interrupter opens
10 mA “Let-go” current
20 mA Possible tetany of resp muscles
100 mA VF threshold
6 A Defibrillation
20 A Household circuit breaker opens
Electrical Injuries
Effects of 60 Hz Current

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 Electricity Kills by Causing Myocardial
Damage
 CK and/or Troponin Are Good Markers for
Myocardial Damage in Electrical Injury
Top 10 Myths of Electrical Injury
Myth #6

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All Patients With Electrical Injury
Require 24 Hours of Cardiac Monitoring
Top 10 Myths of Electrical Injury
Myth #7

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• Cardiac monitoring is not justified in
ASYMPTOMATIC patients,
• Or, in patients with only CUTANEOUS burns,
• Who had a normal ECG after a 120 v or 240 v
injury.
Electrical Injuries
Cardiac Monitoring

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ALL Patients Who Are Asymptomatic
and Who Have a Normal ECG After a
120V or 240V Injury Can Be Safely
Discharged From the ED
Top 10 Myths of Electrical Injury
Myth #8

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 Pregnancy
Fetal monitoring is
mandatory for pregnant
patients
 Oral commisure burns
 Cataracts
 Delayed neuro-
psychological sequelae
Electrical Injuries
Patterns of Injury

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Electrical injuries involve multiple body systems.
Entry and exit wounds fail to reflect the true
extent of underlying tissue damage.
Electrical current may cause injuries distant from
its apparent pathway through the victim.
Controversies exist regarding indications for
admission and cardiac monitoring following low
voltage injuries.
Electrical Injuries
Summary - The Challenges

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Electric Shock:
What Should You Do?The victim:
Felt the current
pass through
his/her body
The current
passed through
the heart
Was held by the
source of the
electric current
Lost
consciousness
YesNo
No
No
1 second
or more
Yes
No
Yes
Cardiac Monitoring
24 hours
Touched a voltage
source of more
than 1 000 volts
YesNo
Yes

25. Electric Shock:
What Should You Do?
Page 2.
Touched a voltage
source of more
than 1 000 volts
Cardiac Monitoring
24 hours
Has burn marks
on his/her
skin
The current
passed through
the heart
Yes
No
Yes
Yes
Evaluate and treat burns
(surgical evaluation,
look for myogolbinuria, etc.)
No
Was thrown from
the source
Evaluate trauma
No
Is pregnant
Evaluate fetal
activity
No
Yes
YesNo
BENIGN SHOCK
Reassure and discharge
25

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 Hyperthermia results from body’s inability to
maintain normal temperature through heat loss
Heat Disorders

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An unchanged setting of the hypothalamic set
point in conjunction with an uncontrolled increase
in body temperature that exceeds the body’s
ability to lose heat
Hyperthermia

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An elevation of normal body temperature in
conjunction with an increase in the hypothalamic
set point
Heat Disorders-Fever

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Spectrum of diseases-
 Heat syncope /collapse
 Heat cramps
 Heat exhaustion
 Heat Stroke
Essentials of Heat disorders

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Heat stroke
Thermoregulatory failure in association with a warm
environment
 Malignant hyperthermia
Hyperthermic and systemic response to halothane and other
inhalational anesthetics in patients with genetic abnormality
 Neuroleptic malignant syndrome
Essentials of Heat disorders

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Syndrome of hyperthermia, autonomic
dysregulation, and extra pyramidal side effects caused by
neuroleptic agents (e.g., haloperidol)
Hyperpyrexia-Temperature >41.5 C (>106.7 F)
Can occur with severe infections, but more commonly
occurs with central nervous system (CNS) haemorrhages
or hyperthermia
Heat stroke

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 Salt tablets are not recommended without medical supervision
 Whole Body cooling methods to be instituted early for rapid
cooling
 Avoid shivering during cooling---too much cold
 Know different methods of cooling and their judicious use
according to severity of heat disorder.
Essentials of Heat disorders

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 Clinical Findings
 Laboratory Findings
 Treatment
 Prevention
Heat disorders

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General
Abdomen, CVS, CNS
Kidney, Liver, MOF
Heat disorders
Clinical symptoms/signs

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 All patients irrespective of severity of
manifestations for monitoring/observations
 Vitals, Cardiac rhythm, ARDS, infection
Kidney parameters, LFT, hypoglycemia, seizures
When to admit to hospital

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 Multi organ failure-
 CK> 1000
 Metabolic acidosis
 High liver enzymes
Prognosis
Mortality high

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a core temperature >40.0 C
a core temperature >41.5 C
an uncontrolled increase in body temperature de- spite a
normal hypothalamic temperature setting
an elevated temperature that normalizes with anti- pyretic
therapy
temperature >40.0 C, rigidity, and autonomic dys-
regulation
Q1---Hyperthermia is defined as

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Immediate therapy should include
intravenous dantrolene sodium
acetaminophen
external cooling devices
A and C
A, B, and C
Q-2 A patient in the intensive care unit develops a temper- ature of
40.8 C, profoundly rigid tone, and hemody- namic shock 2 min after a
succinylcholine infusion is started.