Drowning

Introduction

• Leading cause of injury death in children <15
• Public education has reduced the incidence over the last 40 years
• Drowning (ILCOR)
  • Primary respiratory impairment due to immersion/submersion with liquid-air interface at airway
  • Can live or die

• Incidence
  • Peaks in children <5 (50%)
    • 20% occur in bathtub
  • 15-24yo
    • 25-50% involve alcohol
  • Elderly
  • 5 times as many deaths in boys as girls

Disorders associated with drowning

• Alcohol or other intoxicants
• Syncope (e.g. due to hyperventilation when diving)
• Seizures
• Cardiac e.g. dysrhythmias/IHD
• Dementia
• Intentional 
  • Suicide, homocide, child abuse or neglect, factitious disorder by proxy

Injuries associated with drowning

• Spinal injury
• Hypothermia
• Aspiration
• Respiratory failure, insufficiency or distress
• Electrolyte abnormalities are seldom significant and usually transient unless significant hypoxia, CNS depression, renal injury from haemoglobinuria or myoglobinuria
• Haematological values are usually normal unless massive haemolysis has occurred
• DIC can occur but usually occurs following severe hypoxic insult

Phases

• Voluntary breath holding
• Involuntary laryngospasm from liquid in airway
• Hypoxia/hypercarbia/acidosis
• Active respiratory movements but no gas exchange due to laryngospasm
• Worsening hypoxia means laryngospasm abates  Aspiration
• Surfactant washout
• MODS and death due to tissue hypoxia

Pathophysiology

• Diving reflex not protective
  • Previously thought that diving reflex (bradycardia, apnoea, peripheral vasoconstriction and cerebral shunting of blood flow) was protective during submersion
  • Strongest in infants <6mo and effects decrease with age
  • In adults, vertical immersion (head above) and vertical submersion (head below) activate both the sympathetic and parasympathetic nervous systems and blunt any diving reflex
  • Physiological stress activates sympathetic system
• Reflex inspiratory efforts result in either aspiration or laryngospasm

• Cerebral protection from ice cold water submersion can occur with rapid CNS cooling before significant hypoxic damage
• Those that present with stable CVS with normal neuro function do well
• Those that present with CVS instability and coma do poorly due to hypoxic-ischaemic insult
• 15-20% of patients present between these two extremes and prognostication for them is poor

Salt or fresh

• Aspiration
  • >11mL/kg of body weight is required to alter blood volume
  • >22mL/kg to alter electrolytes
  • Nonfatal victims do not aspirate >4mL/kg

End organ effects

• Pulmonary
  • Hypoxaemia secondary to hypoventilation, aspiration, surfactant washout, ARDS
• Neurological
  • Hypoxaemia and ischaemia with cerebral oedema
• Cardiovascular
  • Arrhythmias secondary to hypoxia/hypothermia OR primary cause of drowning

Treatment

• Pre-hospital
  • Rapid resuscitation
  • C-spine injury is rare (0.5%) unless hx of diving, fall from height or MVA 
  • Only use C-spine precautions if history warrants it – not recommended for all-comers
  • High-flow or PPV O2
  • All patients with drowning amnesia, loss of or depressed consciousness, or an observed period of panoea, as well those who require any period of artificial ventilation must be transported to ED even if asymptomatic at the scene
  • Warm and monitor

• ED Management
  • ABCDE
  • Warm isotonic IV fluids and adjunct warming devices
  • Routine cervical immobilisation and CT of the brain/neck are not necessary unless history suggestive
  • If normothermic on arrival and in arrest, serious thought to discontinuation of resuscitation efforts should be given as recovery without profound neurological compromise is rare

• If GCS >=13 and SpO2 >95% = CAT A (Conn and Modell)
  • Low risk of complications
  • Observe for 4-6 hours NBM
  • If any deterioration, monitored bed and admission
  • If chest clear, SpO2 >95% on RA – can discharge home
  • Lab studies and CXR are unnecessary and not predictive of discharge
  • Advise to return if fever, SOB, mental status changes
• If GCS <13 = CAT B/C
  • Maintain on supplemental O2 and ventilatory support as required
  • If hiflow O2 (40-60% FiO2) cannot maintain PaO2 >60 in adults or >80 in children, intubate and provide PPV
  • CXR and labs 
  • Prophylactic antibiotics show no benefit in aspiration and may be associated with resistant bacteria

• Indications for intubation
  • Signs of neurological deterioration and inability to protect airway
  • T1RF
  • T2RF
• NIV and HFNP can be very helpful
• Prolonged resuscitation efforts are warranted until temp >32
  • More effective if cold water or hypothermia prior to asphyxia suggested
• Initial temperature management
  • Re-warm to 34 degrees for 24 hours

Continued management

• Most patients demonstrate rapid improvement in oxygenation within 24 hours
• Usually haemodynamic recovery occurs over 48 hours but can take up to a week requiring ongoing adrenaline infusion
• Efforts to control cerebral oedema including mannitol, loop diuretics, hypertonic saline, fluid restriction and mechanical hyperventilation have shown no benefit
• Controlled hypothermia, barbiturate ‘coma’, and ICP monitoring do not improve outcomes in paediatric drowning victims

Prognosis

• Extent of required resuscitation is the most objective measure of degree of anoxic or ischaemic insult
• If no CPR at scene or in ED, complete recovery within 48 hours is expected
• A small proportion of those with aspiration may develop ARDS
• Victims requiring bystander CPR at scene have guarded prognosis
  • 20% later die in hospital
  • 5% left with severe HIE
  • Those who show continued neurological, cardiovascular and respiratory improvement after hospital admission do well
• Victims undergoing CPR in ED have poor prognosis
  • >30 minutes CPR in drowning victims indicates severe insult
  • Asystole is a near universal indicator of poor prognosis in adults and children
    • The only caveat to this is drowning in icy water but still very rare to have near-complete neurological recovery
  • Only anecdotal stories of paediatric patients ever recovering without profound neurological recovery

• Submersion time predicts outcome in some studies
  • 85% of good neurological outcome have submersion <6min
  • 7.5% for 6-10 min
  • 5% for 11-59 minutes
  • <1% for >60 minutes
  • >10 minutes is considered a possible cut-off for non-survival
• Water temperature is NOT thought to alter outcome
• Non-reactive pupils and GCS <5 on arrival to ICU are best independent predictors of poor neurological outcome
• 75% of survivors have good neurological outcome

• Orlowski scale – For paediatric drowning
  • Age <3yo
  • Submersion >5 min
  • CPR delayed >10 min
  • Coma on arrival to ED
  • pH <7.1 on arrival
• Score
  • 90% chance of good outcome if <3 of above present
  • 5% recovery if >3 present

• GCS
  • M score of 3 or less at 2-6 hours rarely survive or have severe neurological impairment
  • GCS of 5 = 80% risk of death/severe deficit
  • If improving at 2-6 hours, suggests will do well
  • 1/3 of patients comatose on arrival will die
• Children
  • Comatose on arrival
    • 45% survive with normal brain function
    • 15% survive with severe neurological impairment
    • 40% die

• Large series found:
  • No neurologically intact survivors if submerged >15 minutes (warm or cold water)
  • No survivors of immersion > 60 minutes
  • No survival in children compared to adults (despite commonly held belief)
  • Children <5yo did best in one case-control study
• Poor prognostic factors
  • Submersion >5 minutes (MOST CRITICAL)
  • Resus time >25min
  • Time to effective CPR >10 min
  • GCS <5
  • pH <7.1 on arrival
  • Persistent apnoea and CPR in ED
  • Vt or VF initial rhythm
  • Fixed dilated pupils

• Predictors of poor outcome
  • Scene
    • Immersion >5 minutes (MOST CRITICAL)
    • Delay to CPR >10min
    • No bystander CPR
    • Unwitnessed
    • TIme to first breath
    • Cardiac arrest
    • Identifiable precipitant e.g. AMI
  • ED
    • Asystole
    • CPR >25 minutes
    • Dilated non-reactive pupils at pH <7.0
    • Dilated non-reactive pupils and GCS <5
    • Lactate >4
  • ICU
    • Loss of grey-white by 36 hours
    • Absence of purposeful movements (GCS <5) and absence of brainstem reflexes, pupillary response and spontaneous respiration at 24 hours

Prognosis – Conn and modell

• Performed at 2 hours following initial immersion
• Predicts neurologically intact and guides initial management
• Cat A – Awake
• Cat B – Conscious but obtunded
• Cat C – Comatose
  • C1 – Flexion to pain (decorticate)
  • C2 – Extension to pain (decerebrate)
  • C3 – Flaccid
  • C4 – Arrested

Prevention

• Children <1
  • Parental vigilance during bathing
  • Consider NAI
  • Bath seats give false reassurance
• Preschool
  • Adult supervision with adequate pool fencing could prevent 50-90% of all drownings
• Teen and young adults
  • Avoiding alcohol and illicit drug use
    • 40% of all adult drownings and 75% of boating-related drownings
  • Use personal floatation devices
  • Swimming lessons for young children proven to reduce drownings (no evidence in older groups)
  • Risk reduction education
• Adults
  • Constant monitoring of swimmers with epilepsy
• Elderly
  • Adequate pool fencing and bathtub handrails

Delayed death from drowning

• Causes
  • Brain death from hypoxia
  • ARDS
  • MODS from ischaemic tissues
  • Sepsis from aspiration pneumonia or nosocomial infections

When to terminate resuscitation?

• K >11
• Persistent apnoea and asystole despite 1 hour of post-rescue CPR provided not hypothermic

Last Updated on November 23, 2021 by Andrew Crofton