Electrical Injuries Robert Primavesi, MDCM, CCFP(EM) Montreal General Hospital McGill University Health Centre Robert Primavesi, MDCM, CCFP(EM) Montreal General Hospital McGill University Health Centre

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

Electrical Injuries Objectives 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.

Top 10 Myths of Electrical Injury *

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

Electrical Injuries Epidemiology 124 deaths in Quebec X additional patients requiring emergency treatment 3-5% of all burn centre admissions Bimodal distribution –Toddlers –Workforce

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

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

Electrical Injuries Factors Determining Severity JOULE’S LAW: Power (watts)= Energy (Joules) time = V x i = i 2 x R

Electrical Injuries Factors Determining Severity Mucous membranes Vascular areas volar arm, inner thigh Wet skin Sweat Bathtub Other skin Sole of foot Heavily calloused palm Skin Resistivity - Ohms/cm

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

Electrical Injury Factors Determining Severity A momentary dose of high voltage electricity is not necessarily fatal. Low voltage is just as likely to kill as high voltage. RK Wright, JH Davis. The investigation of electrical deaths: a report of 220 fatalities. J. Forensic Sci. 1980; 25: Cunningham PA. The need for cardiac monitoring after electrical injury. Medical Journal of Australia. 154(11): 765-6, June 1991.

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

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

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

Electrical Injuries Patterns of Injury Skin Resistivity LeastNerves Blood Mucous membranes Muscle IntermediateDry skin Tendon Fat MostBone

Electrical Injuries Effects of 60 Hz Current 1 mAmpThreshold of perception 5 mAMaximum harmless current 6 mAGround fault interrupter opens 10 mA“Let-go” current 20 mAPossible tetany of resp muscles 100 mAVF threshold 6 ADefibrillation 20 AHousehold circuit breaker opens

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

Electrical Injuries Patterns of Injury James T., Riddick L., Embry J. Cardiac abnormalities demonstrated post-mortem in four cases of accidental electrocution and their potential significance relative to non-fatal electrical injuries of the heart. American Heart Journal. 120: , 1990 Robinson N., Chamberlain D. Electrical injury to the heart may cause long-term damage to conducting tissue: a hypothesis and review of the literature. Int J Cardiol. 53: 273-7, 1996

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

Electrical Injuries Cardiac Monitoring Alexander L. Electrical injuries of the nervous system. J Nerv Ment Dis 1941; 94: Jensen PJ, et. al. Electrical injury causing ventricular arrhythmias. Br heart J 1987; 57: Norquist C., Rosen CL., Adler JN., Rabban JT., Sheridan R. The risk of delayed dysrhythmias after electrical injuries. Acad Emerg Med. 6: 393, 1999

Electrical Injuries Cardiac Monitoring StudyVoltageNo. of patients Initial ECG = Normal Initial ECG = Abnormal Late Arrhythmias Purdue and Hunt Wrobel< Moran and Munster 110 – Kirschmair and Denstl 220 – Fatovitch and Lee Cunningham Kreinke and Kienst > Bailey, et. al.120 and Arrowsmith>

Electrical Injuries Cardiac Monitoring 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.

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

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

Top 10 Myths of Electrical Injury Myth #9 The HYDRO QUEBEC GUIDELINES Provide the Standard of Care for Electrical InjuriesHYDRO QUEBEC GUIDELINES

Electrical Injuries Summary - The Challenges 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 The Future Surveillance electrographique des patients ayant subi une électrisation: Étude prospective multicentrique. Investigateur principal: Benoit Bailey, MD MSc FRCPC 21 sites across Quebec – including RVH, MGH, MCH Primary objectives: 1. determine the prevalence of cardiac arrhythmias in patients on initial ECG 2. determine the prevalence of late arrhythmias in patients who undergo cardiac monitoring

Secondary objectives: – evaluate the importance of electrical injury in Quebec’s EDs – given a normal initial ECG, evaluate if late arrhythmias develop in patients with tetany, current across the heart, or with >1000V – given a normal initial ECG, evaluate if late arrhythmias develop in patients with PMHx of cardiac disease, or decreased skin resistance – evaluate the incidence of cardiac problems in the year following electrical injury

Secondary objectives, cont’d: – accumulate prospectively an experience with applying the Hydro Quebec protocol – determine the utility of measuring CK, CK-MB in predicting ECG abnormalities and the development of late arrhythmias – determine the utility of measuring Troponin in predicting ECG abnormalities and the development of late arrhythmias

Top 10 Myths of Electrical Injury Myth #10 “er” is an Accurate Reflection of Life in the ER

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 Yes No 1 second or more Yes No Yes Cardiac Monitoring 24 hours Touched a voltage source of more than volts Yes No Yes

Electric Shock : What Should You Do? Page 2. Electric Shock : What Should You Do? Page 2. Touched a voltage source of more than volts Cardiac Monitoring 24 hours Has burn marks on his/her skin The current passed through the heart Yes No 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 No BENIGN SHOCK Reassure and discharge Direction Services de Sante Hydro Quebec, 1995