Environmental Medical Hazards

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DYPMCMedicine Department

Electrical InjuriesElectrical 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 InjuriesObjectives

Electrical InjuriesObjectives

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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 InjuryMyth #1

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5X additional patients requiring emergency treatment

3-5% of all burn centre admissions

Bimodal distributionToddlers, Electricians

Electrical InjuriesEpidemiology

Electrical InjuriesEpidemiology

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• Voltage Is the Most Important Determinant of Injury


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1. V = voltage

2. i = current

3. R = resistance

Electrical InjuriesFactors Determining Severity


OHM’S LAW: i = V / R

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JOULE’S LAW:

Power (watts) = Energy (Joules) time= V x i= i2 x R

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Skin Resistivity - Ohms/cm2

100300 - 10 000

1 200 - 1 5002 500

10 000 - 40 000100 000 - 200 000

1 000 000 - 2 000 000

Mucous membranesVascular areas

• volar arm, inner thighWet skin

• Sweat• Bathtub

Other skinSole of footHeavily calloused palm

Electrical Injuries Factors Determining Severity

Electrical Injuries Factors Determining Severity

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• High Voltage Is More Likely to Kill Than Low Voltage


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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 InjuryFactors Determining Severity

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The Extent of the Surface Burn Determines the Severity of Injury


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• Direct contact– Direct tissue heating

– Contact burns (entry and exit)

– Thermal burns

Electrical InjuriesPatterns of Injury


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The Pathway the Electrical Current Takes Through the Victim Predicts the Pattern of Injuries


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Skin Resistivity

Least Nerves

Blood

Mucous membranes

Muscle

Intermediate Dry skin

Tendon

Fat

Most Bone



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1 mAmp Threshold of perception5 mA Maximum harmless current6 mA Ground fault interrupter opens10 mA “Let-go” current20 mA Possible tetany of resp muscles100 mA VF threshold6 A Defibrillation20 A Household circuit breaker

opens

Electrical InjuriesEffects of 60 Hz Current

Electrical InjuriesEffects 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


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All Patients With Electrical Injury Require 24 Hours of Cardiac Monitoring


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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 InjuriesCardiac 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


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PregnancyFetal monitoring is

mandatory for pregnant patients

Oral commisure burns Cataracts Delayed neuro-

psychological sequelae



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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 InjuriesSummary - The Challenges

Electrical InjuriesSummary - The Challenges

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Electric Shock: What Should You Do?

Electric Shock: What Should You Do?The victim:

Felt the currentpass throughhis/her body

The currentpassed through

the heart

Was held by thesource of the

electric current

Lostconsciousness

YesNo

No

No1 secondor more

Yes

No

Yes

Cardiac Monitoring24 hours

Touched a voltagesource of morethan 1 000 volts

Yes

No

Yes


Page 2.


Page 2.Touched a voltage

source of morethan 1 000 volts

Cardiac Monitoring24 hours

Has burn markson his/her

skin

The currentpassed through

the heart

Yes

No

Yes

Yes

Evaluate and treat burns (surgical evaluation,

look for myogolbinuria, etc.)

No

Was thrown fromthe source

Evaluate trauma

No

Is pregnantEvaluate fetal

activity

No

Yes

YesNo

BENIGN SHOCKReassure and discharge

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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 strokeThermoregulatory failure in association with a warm environment Malignant hyperthermiaHyperthermic and systemic response to halothane and other inhalational anesthetics in patients with genetic abnormality Neuroleptic malignant syndrome


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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.


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Clinical Findings Laboratory Findings Treatment Prevention

Heat disorders

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GeneralAbdomen, CVS, CNSKidney, 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, infectionKidney 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°Ca core temperature >41.5°Can uncontrolled increase in body temperature de- spite a normal hypothalamic temperature settingan elevated temperature that normalizes with anti- pyretic therapytemperature >40.0°C, rigidity, and autonomic dysregulation

Q1---Hyperthermia is defined as

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Immediate therapy should include

intravenous dantrolene sodiumacetaminophenexternal cooling devicesA and CA, B, and C

Q-2 A patient in the intensive care unit develops a temperature of 40.8°C, profoundly rigid tone, and hemody- namic shock 2 min after a succinylcholine infusion is started.

Environmental Medical Hazards

Health & Medicine

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