Electrical injury and burn

an introduction to electrical burn for medical students and residents - easy to understand

1. Introduction to Electrical Injury Facebook: Happy Friday Knight

2. Electrical burns: a small part of major burn centers  5-7% Most devastating of thermal injuries on size-to-size basis: involving both skin and deeper tissue Most frequent cause of amputation in burn service

3. PATHOPHYSIOLOGY

4. Exact pathophysiology is unknown Numerous variables cannot be measured when an electrical currents pass through the tissue With high voltage ( ≥1000V), most of injury is thermal and resulting in coagulation necrosis The injury can be explained by Ohm’s Law

5. I = V/R P = I 2 R I = current, in amperes (A) V = potential, in volts (V) R = resistance, in ohms ( Ω ) P = power, in Joules (J)

6. Factors Determining Severity Type of circuit Duration Resistance of tissue Voltage Amperage Pathway of current

7. Type of Circuit Direct (DC) or alternating current (AC) DC: Cause single spasm and throw the victim from the source  increased traumatic blunt injury AC: cause continuous muscle contraction or tetany  no-let-go phenomenon and creating potential for continually increasing severity Occur when both flexor and extensor are stimulated but flexor is stronger making victim unable to let go voluntarily

8. Duration of Contact Longer duration with high-voltage current  greater tissue destruction

9. Tissue Resistance The word entrance and exit  replaced by contact points The higher resistance, the greater transformation electrical injury to thermal injury Least: nerve, blood, mucous membrane, muscle Intermediate: dry skin Most: tendon, fat, bone

10. Tissue Resistance: skin Primary resistor Thick and harden skin = greater resistance Sweating: decrease resistance

11. Voltage Low voltage < 1000V High voltage ≥ 1000V Thailand domestic wiring 220V Higher voltage, higher morbidity

12. Amperage P = I 2 R and I = V/R More amperage, more heat The voltage of source is often known but not for resistance Physical effects vary with different amperage

13. Price TG and Cooper MA. Electrical and lightning injuries: in Rosen’s emergency medicine. Access via PDF

14. Pathway Where the current passes: between the contact points

15. MECHANISMS OF INJURY

16. Primary is burn Secondary: fall or being thrown from electrical source by muscle contractioin 4 types of electrical burn Direct contact: electrothermal heating indirect contact: arc, flame

17. Electrical arc: A current spark between 2 objects differing potential not contact to each other Most destructive indirect injury Usually highly charged source and a ground Temperature of the arc reaches 2500 o C Flame: result from ignition of clothing

18. Heart Most serious: cardiac arrest Dysrhythmia: AF ECG abnormality: non-specific ST-T change Can occur both low and high voltage ECG monitoring is mandatory in patients with ECG abnormality

19. Respiratory May result from: Tetanic contraction of thoracic musculature Injury to respiratory control center of CNS Combined cardiopulmonary arrest secondary to asystole or VF Blunt chest trauma from being thrown

20. Cutaneous Low voltage: small, well-demarcated contact burns High voltage: painless, depressed, yellow-gray, charred craters with central necrosis, or may spare the skin surface but damage deeper tissue

21. Czuczman AD. Electrical injuries: a review for the emergency physician. 2009;11(10):1-21

22. Muscle Coagulation necrosis  becoming edematous and necrotic  Myoglobinuria , rhabdomyolysis, and acute renal failure Compartment syndrome

23. Myoglobinuria Dark urine, mahogany-colored Significant muscle damage with potentially ischemia UA: urine dipstick + ve for blood with few RBC Risk of acute renal failure Elevated CPK

24. Compartment Syndrome High-voltage injury: risk for developing compartment syndrome in first 48 hours Damaged and swelling muscle  increased pressure within fascia CK level: associated with extent of muscle damage

25. Vascular Greatest damage to media layer  delayed aneurysm formation Intima: thrombosis and occlusion Most severe in small muscle branch: tissue necrosis Any vascular injury can cause compartment syndrome

26. Neurologic PNS > CNS in electrical injuries Most common CNS symptom = loss conscious Others: peripheral neuropathy, transient paralysis, spinal cord damage

27. Gastrointestinal injuries Suspected in burn at abdominal wall History of fall, blast, blunt trauma

28. Oral Burn Children who put a power cord in the mouth Labial artery bleeding: occur up to 2 weeks after injury

29. Eye injury: cataracts Auditory system: path of current may be damaged

30. Czuczman AD. Electrical injuries: a review for the emergency physician. 2009;11(10):1-21.

31. Czuczman AD. Electrical injuries: a review for the emergency physician. 2009;11(10):1-21.

32. TREATMENT

33. Prehospital Care Secure the scene Ensure that the power source has been turned off CPR + follow ACLS Protect cervical spine and splint fracture Close burn wound with clean dry dressing

34. ER care Follow ACLS and ATLS Resuscitation Complete lab Remove constricting objects ECG

35. Fluid Resuscitation Parkland formula: only rough starting point In absence of gross myo /hemoglobinuria, goal is to maintain v/s: 0.5 ml/kg/ hr In children: 10% burn: resuscitation Fluid of choice: LRS <2years: 5%DLR Maintenance fluid: 5%DN/2

36. ECG monitoring Czuczman AD. Electrical injuries: a review for the emergency physician. 2009;11(10):1-21.

37. ECG monitoring Duration: 24-48 hours Low voltage + normal ECG: can be discharged Utility of CK-MB: Not reliable due to other muscle injury Use of troponin: insufficient data

38. Treatment of Myoglobinuria Monitoring urine for myoglobin and serum for CPK Maintain a urine output “double” goal rate: 1 – 1.5 ml/kg/ hr Fluid should be NSS 1000 ml + NaHCO 3 50 mEq pH of ABG: > 7.45 Mannitol: 25 g, then 12.5 g/h

39. Compartment Syndrome 4 compartment fasciotomies for lower extremities Anterior and posterior fasciotomies with carpal tunnel release for upper extremities Primary amputations are not generally performed

40. Wound Care Dressing wound with sulfamylon on the thick eschar SSD: for microbial control Biologic dressing on more superficial area Remove necrotic tissue and reevaluate q2-3days Tetanus immunization

41. Pain Management Acute pain: opioids and paracetamol Rehabilitation phase: NSAIDs, antidepressant, massage therapy, cognitive behavioral therapy

42. References ชัยรัตน์ บุรุษพัฒน์. Electrical injuries: principle and management. เวชสารแพทย์ทหารบก .2011;4:207-10. Herndon DN. Total burn care. 4 th ed. China: Elsevier, 2012. Arnoldo B, Klein M, Gibran NS. Practice guidelines for the management of electrical injuries. Journal of burn care and research. 2006;27(4):439-46. Czuczman AD. Electrical injuries: a review for the emergency physician. 2009;11(10):1-21. Fish RM. Electric injury, part II: specific injuries. The journal of emergency medicine. 2000;18(1):27-34.

43. References Price TG and Cooper MA. Electrical and lightning injuries: in Rosen’s emergency medicine. Access via PDF Guidelines for paediatric burn resuscitation