Electrical Injuries/Burns Case-Based Presentation 5 February, 2009

When is electricity not your friend?

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• 45 year-old man encountered in an alley behind an apartment building after a passer-by heard a loud “bang.” • EMS notes: patient found in tree alongside powerline, next to 20-foot metal ladder (fallen over).

• Pair of shoes noted to be hanging from line by their laces.

• 2 blocks from hospital: rapid transport.

Initial assessment

• Paitent initially GCS E3 V3 M5 per EMS.

• Now in full c-spine (sort of) with GCS E2 V2 M5.

– VS: HR 120 reg, BP 110/50, RR 30, SpO2 92% on high-flow O2 by NRM.

– Attempt by ER doc to examine patient elicits movement of head and all extremities as pt struggles against tape and straps.

– Right hand is mangled beyond recognition.

What are the mechanisms of electrical injury?

• Direct and indirect.

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1. What are the mechanisms of electrical injury (direct and indirect)?

4 causes of damage:

• 1) direct effect of current on body tissues, leading to asystole, ventricular fibrillation, or apnea; • 2) blunt mechanical injury from electrocution, resulting in muscle contraction or falling; • 3)conversion of electrical energy to thermal energy, resulting in burns; and • 4) electroporation

• Electroporation: defined as the creation of pores in cell membranes by means of electrical current • disrupts cell membranes and leads to cell death without clinically significant heating

Electrocution

• Direct – 1 0 determinant of damage caused by direct effects of electricity is the amount of current flowing through the body – other factors include voltage, resistance, type of current, current pathway, and duration of contact with an electrical source

High or Low

• Electrical shocks of 1000 V or more are classified as high voltage • household electricity has 110 to 230 V, and high-tension power lines are more than 100000 V. Lightning strikes are can produce 10 million V or more • High-voltage electrical shocks are expected to result in more severe injury per time of exposure

Burns

• 4 groups: electrothermal burns, arc burns, flame burns, and lightning injuries.

• Electrothermal burns are the classic injury pattern and create a skin entrance and exit wound • High voltage can cause much more damage to deeper tissues than to skin

Respiratory

• Respiratory arrest may result – Multiple reasons Noemie will elaborate on later • lung damage is rarely seen but blunt trauma may be present if falls

Cardiovascular

• Arrhythmias – Sudden cardiac death due to ventricular fibrillation is more common with low-voltage AC, – asystole is more frequent with electric shocks from DC or high-voltage AC – fatal arrhythmias are more likely by horizontal current flow (hand to hand); – current passing in vertically(from head to foot) more commonly causes myocardial tissue damage

• 10% to 46% of survivors experience other arrythmias • most common arrhythmias are sinus tach and PVCs, but V tach and afib have been reported • nonspecific ST–T-wave abnormalities are common and usually resolve spontaneously

• Conduction Abnormalities – Sinus brady and high-degree AV block have been reported.

– Electrical injury caused by AC seems to have a predilection for the SA and AVnodes

Musculoskeletal

• Bone has the highest electrical resistance and experiences the most severe electrothermal injuries, including periosteal burns, destruction of bone matrix, and osteonecrosis • Forceful tetanic contractions or falls can cause fractures and large-joint dislocation

• Electrothermal injury of the musculature may manifest as edema formation and tissue necrosis and may lead to the compartment syndrome and rhabdomyolysis

Neurologic

• can damage the central and peripheral nervous system • Loss of consciousness, generalized weakness, autonomic dysfunction, respiratory depression, and memory problems are frequent manifestations • Don’t forget about blunt trauma

• Keraunoparalysis is a specific form of reversible, transient paralysis that is associated with sensory disturbances and peripheral vasoconstriction and is seen in some patients following lightning injury

Lightning Strikes

• 150 to 300 deaths annually in the USA • causes cardiac and respiratory arrest, resulting in a 25% to 30% mortality rate • Lots of volts but short time • according to Joule’s law, the amount of energy delivered may be less than with other high-voltage electrical injuries because of the short exposure

• rarely sustain extensive tissue destruction or large cutaneous burns; • cardiac arrest is usually asystole, with frequent spontaneous restoration of a rhythm • respiratory arrest is often prolonged, and without vent support, apnea results in hypoxia-induced vfib

• Lichtenberg figures are pathognomonic skin manifestations in persons struck by lightning

What are the most common causes of electrical injury?

• 1000 people die of exposure to electricity annually in the USA • age distribution of patients who are electrocuted is bimodal; the first peak occurring in children younger than 6 yrs, and the second occurs in persons in young adulthood

• In children usually occurs at home associated with electrical and extension cords (in about 60–70%) and with wall outlets (another 10–15%) • Most deaths in adults due to electrocution are work related (5–6% of all workers’ deaths) • Miners and construction workers account for most of these cases, with rates of 1.8 to 2.0 deaths per 100 000 workers

• Yoan • Noemie

Evaluation of Our Patient

• Paramedics report that he was initially not moving much beyond shallow respirations. – (protective when slung over a branch 15 feet above asphalt) • However, his overall LOC has deteriorated somewhat.

• His clothes are cut off, revealing extensive burnt skin from the remains of his right hand, along his arm, involving his torso and left thigh.

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Airway Issues

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Breathing

• How might his initial assessment (on scene) have been clouded by his electrical injury?

– What are the effects of electrocution on skeletal and respiratory muscles?

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“Keraunoparalysis”

• 2dary to massive catecholamine release • Typically after lightening injury • Clinical manifestation – Paraplegia/quadriplegia – Autonomic instability • Hypertension • Peripheral vasospasm • Mydriasis and anisocoria • Resolves within a few hours Critical Care Clinics 1999;15(2)

Respiratory failure

• Usually no specific injury from the electric current to the lung or airways • Causes of respiratory arrest: – Blunt trauma – Injury to the respiratory control center as a result of electrical current through the brain – Spinal cord injury C4 to C8 (hand-to-hand) leads to indefinite refractory state of the NMJ • Tetanic contraction  suffocate

Skeletal system

• Current: – DC: causes single muscle contraction – AC: causes repetitive tetanic muscle contraction  prolonged electrical exposure • Muscle: – Tissue necrosis – Can lead to compartment syndrome and rhabdo

Skeletal System

• Bone has the highest resistance  highest electrothermal injuries – Periosteal burns – Osteonecrosis – Long bone fractures from muscle contraction

Initial management goals

In the field:

– Provide a safe environment; disconnect electricity if necessary.

– ABCs – Arrhythmia management as per ACLS guidelines.

• may also cause fixed dilated pupils due to autonomic effects; do not cease resusc.

– Immobilize C-spine and splint other fractures prior to transfer.

In the E.R.

– Aggressive fluid resusc. for significant electrical injury through large bore IV.

– Less fluid usually required for lightning injury.

– Complete Hx, including nature of electrical contact, voltage, duration of contact, and any resulting fall have obvious implications.

– Complete Px looking for associated (esp. spinal cord) injuries, as well as entry, exit wounds, and blunt thoracic and abdominal trauma.

After initial resuscitation:

– Most common complication is cardiac arrhythmia. Although most run a benign course, particularly with transthoracic injuries, cardiac monitoring for up to 24 hours is appropriate.

– R/O spinal cord, C-spine injury with appropriate imaging.

• Keep this in mind in event of impaired motor function.

• Serial evaluation of liver, pancreatic,and renal function for traumatic and anoxic/ischemic injury (in case of cardio-respiratory arrest), supplemented by appropriate imaging studies (e.g., CT or abd. U/S) as necessary.

• CT scan of the head is indicated in all severe cases of lightning injury, of injuries due to a fall, and if there are persistent abnormal findings in the neurologic examination.

• Evaluation of the limbs for compartment syndrome that may require fasciotomy (rare in lightning injury).

• Nutritional support due to increased energy expenditures.

• Ophthalmologic and otoscopic evaluation (injury common in cases of lightning injury).

Fluid resuscitation

• Any concerns about crystalloid volume?

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Fluid Management

• Traditional formulas use %BSA

How do you estimate BSA in Electrical Injuries

• Often see superficial burns – Rule of 9’s, but not the full story • Not able to asses internal burns along path of electricity • Often extensive internal organ injury • Third spacing is often significant and ongoing

So how do you decide how much fluid to give?

•

Titrate to normal urine output (0.5 cc/kg/hr)

• How much is too much?

–

Klein et al.

• 5ml/ % BSA = increased pneumonia + death – Compartment syndromes • Abdominal • Extremity • Ocular Physicians tend to over resus follow BP, unwilling to decrease when good U/O

Which fluid to give?

• Crystalloid • Hypertonic saline – Increased risk of renal failure • Colloid – No benefit over crystalloid, may increase ARDS • Mannitol • Bicarb

Fluid Resuscitation

– In high voltage injury, risk of rhabdo is high.

– Maintain u/o 70-100 cc/h until clear of pigment, then 50 cc/h.

– Alkaline diuresis with intravenous sodium bicarbonate may improve clearance of myoglobin.

– Osmotic diuresis with mannitol can be tried in patients who have increased pigment. – If compartment syndrome has been excluded, early amputation may be necessary when there is persistent myoglobinuria. – The fluid requirement is approximately 1.7 times the calculated fluid requirement for the percentage of body surface area burnt by standard formulas. – Because of large fluid shifts, close monitoring of electrolytes is also necessary with replacement as needed.

Later, in ICU

• His spine imaging is clear.

• Seen by plastics, who plan to take him to OR within 24 hours.

• VS after volume resus: – HR 110, BP 115/65, RR 18 on PSV FiO2 .35

– U/O approx 1 cc/kg/hr – Requiring MS and midaz to allow for ventilation.

– Admission labs come back…

• 7.20/30/90/18 • CBC: Hb 110 • ‘lytes: K + 4.8

– PAG: 18 • Lactate: 6 • Cr: 95 • CK: 500

Labs

Exam

• GCS 3, sedated/ventilated.

• HR 110 BP 100/50 RR 24 SpO 2 FiO 2 0.4. Afebrile.

98% on • Right arm is more swollen and tense than it was downstairs.

• Peripheral pulse no longer palpable.

What is the cause of his lactic acidosis? DDx?

• Marios

Question 6: What is the cause of his lactic acidosis? What can be done about it?

Differential for lactic acidosis

Compartment syndrome in electrical injuries

• Small vessels do not dissipate heat from electrical current as efficiently as larger vessels, and undergo coagulative necrosis • The electrical current may also cause direct injury to the muscle fibers • These factors lead to myonecrosis and swelling which can then cause a compartment syndrome with secondary ischemic injury.

Prevention of compartment syndrome: “when in doubt…”

• Surgeons historically advocated early surgical exploration with fasciotomy and debridement within the first 24h.

• Theorized to prevent secondary tissue loss from massive edema and compartment syndrome • This was followed by serial debridement of necrotic tissue until the wound was suitable for closure with skin grafts.

Prevention of compartment syndrome: being more selective

Mann R.,et al. Is immediate decompression of high voltage electrical injuries to the upper extremity always necessary? J Trauma. 1996 Apr;40(4):584-7

Prevention of compartment syndrome: guidelines

• Recent guidelines from the American Burn Association recommend that surgical decompression (fasciotomy +/- carpal tunnel release) be performed in the setting of: 1. Progressive neurological dysfunction 2. Vascular compromise 3. Increased compartment pressure ( > 30 mmHg) 4. Clinical deterioration from suspected myonecrosis Arnoldo B. et al. Practice guidelines for the management of electrical injuries. J Burn Care Res. 2006 Jul-Aug;27(4):439-47.

That was close

• Plastics whisks him to the OR, where R upper arm fasciotomy and amputation of his hand are performed.

• Returns to ICU with essentially normal ABG and HR 88, BP120/60 unsupported.

Day 2 in ICU

• Darn it! The dietician is away!

• Enteral feeding had been held due to the whirlwind of activity as above, but now we’re at “GI” in rounds, and there’s a pregnant pause… – Any particular feeding strategy for this gentleman?

Any particular feeding strategy?

• Burn pts are among the most hypermetabolic in the ICU • The extent of open wound area can be used to estimate energy requirements for burn patients Hill, Bruns Patient 2005

Trigger of physical, hormonal, metabolic and inflammatory response Hill, Bruns Patient 2005

Caloric estimation

• Indirect calorimetry – Individualize requirement – Prevents over/under feeding – Modality of choice to estimate caloric need Hill, Burns Patient 2005

•  Amino acids needed for tissue repair – Acute phase protein production – Cellular immunity – Gluconeogenesis – Recommend 2 to 3 gm/kg Hill, Burns Patient 2005

Specialty formulas ?

When to start?

• Start feeding as early as possible • Avoid catheter associated morbidity and depression of gut function • Consult a dietician near you… Burns,2007;33:14-24

Does someone need to know about this?

• At sign-out rounds, you notice that his urine output has been trailing off since morning, and is now 10 cc/hr.

• It looks… not normal.

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Afternoon Labs

• Cr 180 • CK 30,000 – 500 at admission, then • 1,000 10 hours ago.

What is the most likely cause of his oliguria? What can be done about it?

Rhabdomyolysis and myoglobinuria

• Rare in lightning strikes and low-voltage injuries.

• Lowest voltage that caused myoglobinuria in a 26 year retrospective review in Boston (N=211), was 600 volts (2 cases involving subway rails) • Risk factors associated with myoglobinuria were: – High voltage (> 1000 V) – Pre-hospital cardiac arrest – Full thickness burns – Compartment syndrome Rosen CL, et al. Early predictors of myoglobinuria and acute renal failure following electrical injury. The Journal of Emergency Medicine. 1999;17(5): 783-789

Treatment of rhabdomyolysis

1. Early aggressive fluid resuscitation with saline • Shown to minimize the risk of ARF when started within 6h of admission • Various authors suggest target urine-outputs from 70 to 300 cc/h 2. No clear evidence for urine alkalinization or mannitol but… ? Benefit in pts with CK elevations > 30 000

GRAY BARS: NaHCO3/Mannitol BLACK BARS: No NaHCO3/Mannitol Brown CV, et. Preventing renal failure in patients with rhabdomyolysis: do bicarbonate and mannitol make a difference? J Trauma. 2004 Jun;56(6):1191-6.Click here to read

Treatment of rhabdomyolysis

• Dialysis may be necessary in cases where forced diuresis fails. • Persistent myoglobinuria should prompt surgical exploration for necrotic tissue

Marios rhabdo

7 days later

• The electrocuted patient is transferred out of ICU, to be followed by nephrology re: dialysis. • He vows never to go near power lines again.

• The news is on in the lounge as you walk by…

Welcome to Edmo…Vancouver

This is news centre 4’s 6:00 report for February 3, 2009.

• “Our lead story is of a young man who was just taken to hospital after being Tasered by police. • Eyewintesses state the man was apparently sleeping in his car, and when he did not respond to verbal requests to wake up and move, he was shot with a Taser. • The man has just been taken to hospital, but with us is police spokesperson---”

• The 35 year-old man is now in the trauma bay, and the ER physician is concerned about medically clearing the patient before he can be further evaluated by police.

– A freezer bag of coke and a pistol were found in his jacket pocket.

– CCU has refused to see him, and suggested a monitored bed in ICU for admission.

– VS: HR 130, sinus tach. BP 140/50. RR 28. SpO2 98% on oxygen to the left cheek by nasal prongs.

• Neuro: GCS E 4 V 4 M6. Moving all extremities.

Does someone need to know about this?

• HR 120 – 100 • 80 – 60 » 40 QuickTime™ and a TIF F ( Uncompressed) decompressor are needed to see this picture.

• Monitor beeps. Continuously.

How can electrical injuries cause cardiac arrest?

• What conditions contribute to the risk of cardiac arrest in patients with electrical injuries?

Cardiac injury

• Pathway: – Horizontal pathways: • Hand-to-hand • High potential for fatal arrhythmias – Vertical pathways: • Are at higher risk for myocardial tissue damage

Arrhythmia

• Up to half of electrical shock survivors experience some form of arrhythmia • Can have delayed arrhythmia up to 12 hours post electrical injury • Common Arrhythmia: – Sinus tach – PVC – Afib – VT

Conduction abnormalities

• Sinus and AV node especially vulnerable to AC current – ?RCA being close to the chest wall  vasospasm – Can have permanent heart block

Myocardial Injury

• Thermal injury of the myocardium results in patchy band necrosis • Coronary spasm leading to ischemia • Myocardial contusion • Secondary hypoperfusion from shock • ECG: Non specific ST changes that resolve spontaneously • CK-MB elevation, not helpful in determining injury

Cardiac monitoring

• Prolonged monitoring required if: – History of arrest or loss of consciousness – Cardiac arrhythmia in the field/ER – Abnormal ECG on admission – Admission for extent of burn or age of pt • Monitor for ~24hours Critical Care Clinics, 1999;15(2)

• Yoan

Should we just call it?

Are these things safe?

• Yoan successfully resuscitated the patient. – The cops breathe a sigh of relief.

• The patient’s family arrives, seven shades of pissed… • “Are these things supposed to be safe?!?” they demand.

Uhhh…

• No.

• The taser is a weapon.

• Weapons are not safe.

• These particular weapons are not carefully regulated with regard to delivered electrical current.

– Approx 18 amps/ 50,000 volts

Alternatives?

• Annals of Internal medicine 1987 Jan 16 (1) 3-8.

• Compared Taser to industry standard… 0.38 Special QuickTime™ and a TIFF (Uncompressed) decompressor are needed to see this picture.

• Predictable result.

Discussion…