Lightning and Electrical InjuriesPhil Ukrainetz, MD, PGY5 - Nov 21, 2002

Mass Casualty Incident

• You are the G8 medical section officer and you are prepared for all disasters. You are notified that a G8 protest group has just been struck by lightning. There appears to be 30 people affected and 5 appear to be lifeless. How does this change your normal MCI approach?

They get easier….

Mass Casualty Incident

• Normally cardiorespiratory arrests are “START” triaged to blacks/morgue

• In lightning strikes there is a short initial asystole and then the heart resumes beating

• The respiratory arrest however takes longer

• Lightning strike victims then die of secondary hypoxemic induced ventricular fibrillation

Mass Casualty Incident

• Support your arrests first, even if fixed and dilated pupils

• In the absence of arrest lightning strike victims are unlikely to die

• With immediate respiratory support lightning strike victims can have excellent outcomes

Doc, Doc I can’t move!!

• Your 27 year old patient has flaccid paralysis of his lower extremities. Is he for sure paralyzed?

Doc, doc I can’t move!!

What neurologic phenomenon may account for this patients symptoms?

Keraunoparalysis

• Lightning induced sympathetic discharge can cause neurologic and vasomotor instability that can render a patient paralyzed. Recovery is usually within 24 hours

Question?

• A 22 yr old female patient has suffered extensive hand injuries from an AC source. Her ECG is normal but your CKMB fraction is “diagnostic” of an MI. Has she necessarily infarcted?

Answer

• Well described that you get inordinate rises in CKMB with electrical injury

• May get CK rises that contain as much as 25% CKMB (JAMA 255(6):764, 1986)

• Actual MI has been reported but is rare

He bit the cord!

• 2 yr old boy comes in with a oral burn involving the lateral commissure of the mouth as depicted in the following slide. What is your treatment , disposition and follow-up advice?

He bit the cord!

He bit the cord!

• ABC’s

• Tetanus

• Plastics consult: do nothing for a year

• Warn of delayed labial artery bleed when the eschar drops off in 2-4 weeks

Question

• What is the order of increasing resistance of the following tissues?– Bone, fat, muscle, mucous membranes, nervous

tissue, blood vessels, skin

Answer

• Nervous tissue

• Blood vessels

• Mucous membranes

• Muscle

• Skin

• Fat

• Bone

Esoteria continues..

What arbitrary voltage is the cut-off for high and low voltage injury?

Esoteria continues..

• 1000 v is generally recognized as the cut-off

• However amperage, voltage, resistance, type of contact, duration of contact, current pathway and associated injuries need to be assessed regardless of voltage

• E=I2RT

High voltage injury

High voltage injury

High voltage injury

In the code room...

What four mechanisms of injury are you thinking of?

Three classes of injury

• Thermal burns

• Electric current

• Thrown

• “Internal coagulation”

Lineman touches line!

• 37 yr old male o/w healthy. Right hand has nasty entry point and left has an identical exit point as depicted in the following slide. How will you fluid resuscitate this person with approximately 5% thermal burns?

Lineman touches line!

High voltage injury

• Cannot use conventional “Rule of nines”

• Fluid needs will be grossly underestimated• Some data says multiply “Rule of nines by

1.7” (Ann Plast Surg 12:321, 1984)

• Treat as a crush injury

Crush injury management

• Principle of treatment is to avoid myoglobinuric renal failure– Foley output: 1-2 cc/hr/kg– Fluid resuscitation: NS

• If CK up/myoglobinuria:– Alkalinization: 3 amps bicarb in D5W and aim

for urine PH of 7.5 – +/- Mannitol: 0.25 - 0.5 cc/kg

Question?

Why are electrical burns concentrated at distal extremities?

Answer

As the cross sectional diameter of the tissue decreases, more heat is generated and

greater damage occurs

He was gyrating for hours...

• 25 year old male mowing lawn with an electrical mower. On pulling out the cord he received a 10-20 second AC tetanic contraction shock. There are no visible marks on his hand or anywhere on his body but his arm aches. His Mom is quite distressed after observing her son’s dance. What are you going to do?

He was gyrating for hours...

• AC current is three times more dangerous than DC of the same voltage

• AC can produce v. fib at low voltage 50-100 mA

• Repetitive fibrillatory stimulus

• Tetany occurs at muscle stimulations of 40-110 hz (60 Hz is standard household)

He was gyrating for hours...

• If LOC, tetany, wet skin or current flow crosses the heart:– Order a ECG– Cardiac monitoring– Renal function, CK and urine for myoglobin

Question?

• What is Ohm’s law? Why is it important?

Answer

• I = V/R

• Analogy to a river

• The quantity of current through a tissue is often the major determinant of the damage to that tissue

I survived!

• 35 yr old Elvis impersonator, o/w healthy survives a witnessed lightning strike. Besides being visibly shaken he examines perfectly normal. Knowing this is massive DC current how could he survive?

Lightning strikes

• Average DC voltage is massive

• Extremely brief duration of current flow

• Courses over body externally

• Small amount of current may leak internally

Lightning strikes

• Asystole, respiratory arrest, nervous system dysfunction, and spasm of muscles and arteries occur with strikes

• Lightning seldom causes significant burns, tissue destruction or rhabdo

• Remember: QT prolongation, TM rupture and delayed cataracts

Question?

• After a lightning strike a patient is left with a strange feathering pattern along his lateral torso. What is it?

Answer...

• Feathering or Lichtenberg figures is not a burn but a pathognomonic sign of lightning strike. It is not known if it is secondary to electron showers, or current following superficial vasculature or lines of moisture. They typically disappear within 24 hours even in the post-mortem state.

Summary

• AC worse than DC because of tetany

• AC electrical injuries can cause v. fib

• DC injuries tend to be single jolt with blunt trauma and asystole

• Lightning (DC) causes asystole, respiratory arrest but rarely burns or muscle damage

• Electrical injury can cause internal thermal injury that is often underestimated