The Child with an Electrical Injury or Drowning

Question 1

What determines the risk of cardiac arrest in electrical injury?

Answer 1

RISK OF CARDIAC ARREST

ELECTRICAL INJURY

• Size of the current
  
  • usually occurs in the home - low currents and voltage, few need hospitalisation
  • high mortality + severe tissue damage if from high power / voltage external sources e.g.
    
    • railway
    • high tension cables
    • lightning strike - massive direct current of short duration depolarises the myocardium and causes immediate asystole
  • AC can cause cardiac arrest at lower voltage than DC (alternating and direct current)
  • water decreases resistance of the skin and increases the amount of current that flows through the body
• Duration of exposure

Question 2

Describe how increasing current changes the pathophysiology of electrical injury and the differing effects seen.

Answer 2

PATHOPHYSIOLOGY

ELECTRICAL INJURY

INCREASING CURRENT

• > 10 mA: Tetanic contractions of muscles, child may not be able to let go of electrical source
• 50 mA: tetanic contraction diaphragm + IC muscles –> resp arrest until current disconnected –> hypoxia –> cardiac arrest
• > 100 mA - 50 A: primary cardiac arrest
• 50 A - several 100 A: prolonged resp + cardiac arrest + severe burns

Question 3

How does electrical resistance affect the pathophysiology of electrical injury?

Answer 3

ELECTRICAL INJURY

PATHOPHYSIOLOGY

RESISTANCE

• current follows the path of least resistance through tissues
• tissue fluid < blood < muscle < nerve < fat < skin < bone
• water decreases skin resistance allowing more current to flow through the body
• electrocution generates heat which causes tissue damage
• most damage - nerves, blood vessels, skin
• damaged tissues swell
• swelling of muscle can cause crush or compartment syndrome - FASCIOTOMY

Question 4

How does high voltage affect the pathophysiology of electrical injury?

Answer 4

PATHOPHYSIOLOGY

HIGH VOLTAGE

ELECTRICAL INJURY

• e.g. lighting, railways, high-tension cables
• high voltage can cause
  
  • high current and severe tissue damage OR
  • FLASH BURNS/ ARCING –> severe superficial burns, no damage to deeper structures

Question 5

Describe the management of electrical injury.

Answer 5

ELECTRICAL INJURY

MANAGEMENT

• FIRST PRIORITY
  
  • DISCONNECT ELECTRICAL CURRENT !
  • NB high voltage sources can discharge through several cm’s of air
• PRIMARY SURVEY AND RESUS
  
  • A
    
    • Immobilise C-spine as appropriate
    • Open and secure airway (esp if facial injuries)
  • E
    
    • determine entry and exit point of current + => possible internal injuries
• SECONDARY SURVEY AND EMERGENCY Mx
  
  • associated injuries are common
    
    • falls
    • thrown from the source
    • burns from the current or burning clothes
      
      • oedema
      • fluid loss
    • fractures, luxations, muscle tearing (from tetanic contractions)
    • myoglobinuria
      
      • after sig. muscle damage
      • aim UO > 2 ml/ kg/ hr
      • mannitol (diuretics)
      • fluids
      • sodium bicarbonate to alkalinise the urine - helps excretion
• STABILISATION AND TRANSFER TO DEFINITIVE CARE
  
  • consider transfer to burns centre

Question 6

Define Drowning.

Answer 6

DROWNING:

A PROCESS RESULTING IN…

PRIMARY RESP IMPAIRMENT…

FROM SUMERSION/ IMMERSION IN A LIQUID MEDIUM.

Question 7

Describe the pathophysiology of drowning.

Answer 7

PATHOPHYSIOLOGY

DROWNING

• submersion
• diving reflex
  
  • –> bradycardia
  • –> apnoea
• hypoxia
• acidosis
  
  • –> tachycardia
  • –> rise in BP
• breakpoint (20 secs - 5 mins later)
• breathing
• fluid inhaled
• touches the glottis
• laryngospasm
• subsides
• fluid aspirated into lungs
  
  • –> alveolitis
  • –> pulm. oedema
• severe hypoxia
• LOC
• +/- bradycardia / dysrrhythmias (VF rare)

Question 8

What are the main problems arising from drowning that require treatment?

Answer 8

DROWNING

THERAPY FOR: B H x 3 I

• Bradycardia/ dysrrhythmias
• Hypoxia (main cause of death)
• Hypothermia
  
  • Submersion injuries
  • Infants and children more at risk due to large body surface: weight ratio
  • protective against neurological sequelae of hypoxia + ischaemia
  • BUT can cause
    
    • dysrrhythmias (life threatening)
    • coagulation disorders
    • susceptibility to infections
• Hypovolaemia
• Injury esp. spinal
  
  • common in older children
  • often overlooked
  • C-spine injury
    
    • always suspect if mechanism of drowning unclear
    • rare - 0.5% overall, more rare if < 5 yo
    • RTA, diving accidents

Question 9

How does the type of water involved in drowning affect the clinical course?

Answer 9

DROWNING

TYPE OF WATER

• Saltwater or freshwater
  
  • does not predict clinical course
  • same Mx
• Severely contaminated water
  
  • infections (unusual org’s)
• Contaminated with petroleum products e.g. soap, shampoo
  
  • ARDS

Question 10

Describe the primary survey and resuscitation of drowning.

Answer 10

DROWNING

PRIMARY SURVEY AND RESUS

<> ABCDEFG

• FIRST PRIORITY
  
  • remove victim from water w/o risk to the rescuer
  • rescue in a vertical position - venous pooling + CV collapse
  • do NOT delay the rescue for horizontal rescue/ C-spine immobilisation in water
• EARLY BLS
  
  • standard algorithm even in hypothermia
  • Rescue breaths in the water - mouth over nose
  • pulses can be difficult to feel - start compressions if doubt
  • if using AED - DRY THE SKIN FIRST!
• ALS - slight modifications in HYPOTHERMIA
  
  • ​ (See E)
• A
  
  • Immobilise C-spine
  • high risk of aspiration - swallowed water
  • RSI + ETT
  • –> OGT/ NGT
• B
  
  • I+V
  • aim sats 94 - 98%
  • O2 + PEEP
  • BEWARE
    
    • observe for at least 8 hrs
    • 4-6 hrs later resp deterioration (delay)
• E - HYPOTHERMIA
  
  • core temp (rectal/ oesophageal)
  • NB therapeutic hypothermia 32- 34 degrees for at least 24 hrs in children who remain comatose improves neurological outcome
  • Prevent further cooling (initially) - adversely affects resus attempts
    
    • arrythmias
    • VF may be refractory below 30 degrees
  • Changes to ALS in HYPOTHERMIA
    
    • < 30 DEGREES
      
      • limit defibrillation to 3 shocks
      • do NOT give antiarrhythmic/ inotropic drugs
      • IF unsuccessful quickly warm above 30 degrees then re-attempt defibrillation
    • 30 - 25 degrees
      
      • 2 x dose interval for resus drugs
    • Continue
      
      • until T at least 32 degrees OR
      • cannot be raised despite active measures
    • Intubate if necessary - benefit > small risk of pptating malignant arrythmias
  • REWARMING
    
    • SLOW - 0.25 - 0.5 degrees/ hour
    • reduces haemodynamic instability due to vasodilatation (most hypothermic children are hypovolaemic, fast rewarming - vasodilation - hypotension)
    • continuous monitoring of BP
    • treat hypotension with fluids
    • avoid overfilling/ pulm oedema
  • Rewarming strategies
    
    • External (> 30 degrees)
      
      • remove cold, wet clothing
      • blankets + heating blankets
      • warm air system
      • infrared radiant lamp
    • Core (< 30 degrees)
      
      • Warm
        
        • IV fluids (39 degrees)
        • Ventilator gases (42 degrees)
      • Lavage
        
        • gastric/ bladder (normal saline at 42 degrees)
        • peritoneal (potassium-free dialysate, 42 degrees, 20 ml/kg, 15 min cycles)
        • pleural
        • pericardial
      • Endovascular warming
      • Extracorporeal blood rewarming
        
        • ECMO / Bypass
        • best in circulatory arrest

Question 11

Describe the secondary survey of drowning.

Answer 11

DROWNING

SECONDARY SURVEY

• HEAD TO TOE
• Looking for injuries that occured before immersion incl. spinal
• Consider ingestion of alcohol/ drugs esp. older children
• Ix
  
  • Bloods
    
    • Baseline incl. U+E
    • Clotting
    • GAS + GLUCOSE
  • MICRO
    
    • BCx
    • Aspirate culture
  • Radiology
    
    • CXR
    • C-spine imaging if appropriate
  • ECG

Question 12

Describe the emergency management and stabilisation of drowning.

Answer 12

DROWNING

EMERGENCY Mx & STABILISATION

• D
  
  • brain is most vulnerable to hypoxia
  • cerebral impairment before cardiac after submersion
  • raised ICP
    
    • post hypoxic injury
    • aggressive Rx does not improve prognosis
  • keep normoglycaemic - important for neuro outcome
• E
  
  • prophylactic ABx not helpful
  • give if water severely contaminated - Pseudomonas aeruginosa & Aspergillus
  • fever in first 24 hrs not usually due to infection - develops later
  • IVAB e.g. cefotaxime + repeat sputum/ BCx
• Indications for admission to ITU
  
  • respiratory insufficiency
  • haemodynamic instability
  • hypothermia
• NO - barbiturates, calcium channel blockers, surfactants, steroids, free radical scavengers
• Search for the precipitating cause of drowning - esp channelopathy e.g. long QT syndrome

Question 13

What are the prognostic indicators in drowning?

Answer 13

DROWNING

PROGNOSTIC INDICATORS

THE RIVER IS GONNA BE COLD

• Temperature - CORE - low
  
  • hypoxic brain damage is reduced when the brain cools before the heart stops
  • Improved prognosis - protects vital organs
    
    • pre-existing hypothermia
    • rapid cooling after submersion
  • Increased survival
    
    • < 33 on arrival
    • < 10 water
  • more pronounced in small children (larger surface area: WT ratio)
• Respiratory effort - time to
  
  • Good prognosis - w/1 3 mins of starting BLS
    
    • Little - no chance of survival - no resp effort after 40 mins of full CPR - unless resp depressed by
      
      • hypothermia
      • medication
      • alcohol
• Immersion time
  
  • v. small chance of intact neurological recovery/ survival - > 10 mins submersion
• Gas - poor prognosis if:
  
  • pH < 7.1 despite Rx
  • pO2 < 8 despite Rx
• BLS - time to
  
  • poor prognosis - delay of > 10 mins
  • starting BLS at the scene greatly improves survival
• Coma - persistent
  
  • GCS < 5 - BAD

NB - duration of resuscitation efforts is not prognostic

DISCONTINUATION OF RESUS:

• in hospital - only after consideration of prognostic indicators
• out of hospital - DO NOT discontinue resuscitation out of hospital UNLESS CLEAR EVIDENCE OF FUTILITY e.g.
  
  • major trauma
  • rigor mortis

Question 14

What is the outcome of drowning?

Answer 14

OUTCOME OF DROWNING

• BLS at the scene
  
  • YES - 70% survival
  • NO - 40% survival, even with maximal Tx
• Survival after in hospital CPR
  
  • 70% - complete recovery
  • 25% - mild neuro deficit
  • 5% - severely disable, persistent vegetative state