Drowning

Dr. Kevin Kuo's Presentation on Drowning

Definition

  • Significant confusion in the literature with many different terms being used (Drowning, near-drowning, wet drowning, dry drowning, secondary drowning, etc)
  • Utstein consensus definition (Circulation, 2002): Process resulting in primary respiratory impairment from submersion/immersion in a liquid medium. 
  • Hence, medicine has abandoned terms such as near drowning, secondary drowning, wet drowning, etc.

Epidemiology

  • Low/middle income countries account for 90% of fatalities
  • Drowning is the leading cause of accidental death in children <5 years in locations where pools/beaches more accessible
  • Males, african americans, children 1-5, southern states, low socioeconomic status all associated with higher rates of drowning
  • In the US, approximately 4000 deaths/yr (~400,000 deaths/yr worldwide)
  • Overall drowning rates are decreasing over time
WHO Data re: US Drowning Related Mortality by Location (2017)

  • Location of drowning varies by age: Toddlers (bathtub, pool), Adolescents (natural bodies of water, risk taking behavior)
  • Prevention remains key (pool gates combined with adequate adult supervision. Estimates that up to 86% of drowning deaths for children <18yrs might be preventable using these measures.

Pathophysiology

  • Panic, abnormal breathing, breath holding, air hunger, struggle to stay above water
  • Hyopthermia, shivering, increased oxygen consumption
  • Reflex inspiratory effort +/- laryngospasm
  • Hypoxemia leading to hypoxic ischemic injury and eventual multiple organ dysfunction syndrome
  • Surfactant washout with impaired pulmonary compliance
  • VQ mismatch and intrapulmonary shunting 
  • Hypotension (secondary to cold diuresis as blood moves to core, body senses increased volume status and decreases ADH production)- can also develop afterdrop (drop in blood pressure due to warming of extremities with subsequent reversal of peripheral vasoconstriction as well as drop in core body temperature)
  • Below 30C, shivering stops and heart rate and BP fall.
  • Salt water vs. Fresh water: Not thought to be important. Initially thought that salt water would lead to pulmonary edema via osmotic effect and conversely, fresh water would lead to volume overload/hemodilution. However, >11 cc/kg aspiration is needed for blood volume changes to occur and >22 cc/kg for electrolyte changes to occur. Usual aspiration in drowning is only 3-4 cc/kg.
  • Hypothermia: Initially thought to be potentially neuroprotective. However, hypothermia is usually a sign of prolonged submersion and multiple retrospective analyses have failed to demonstrate a protective effect of hypothermia. This may be different in very profound hypothermia

Treatment

  • Pre-Hospital Setting:
    • Remove from water
    • Rescue breaths
    • CPR if no response to 2 rescue breaths (hypothermic patient may have sinus bradycardia and barely palpable pulses so AHA recc is for 1 minute pulse check for these patients)
    • No evidence to support use of Heimlich manuever
    • Despite common concern for C-spine injury, extremely rare (0.5%) and when it does occur, is associated with obvious signs of injury and a concerning mechanism (i.e. dive into shallow water, MVC)
  • Hospital Setting:
    • Intubation/mechanical ventilation if impaired neurological status and/or respiratory failuure/impending respiratory failure
    • Steroids: No evidence for their use
    • Surfactant: While biologically plausible, no evidence for efficacy
    • Prophylactic antibiotics: Not recommended unless grossly contaminated water
    • Seizure prophylaxis: If using, consider keppra/fosphenytoin to avoid sedative effects
    • Neuromuscular blockade: If needed for respiratory failure but generally try to avoid to allow for neurological examination
    • Mechanical ventilation strategies: Similar to standard ALI/ARDS management including targeting Vt ~ 6cc/kg, plateau pressures <30 cmH20. One caveat may be in the setting of presumed anoxic brain injury/cerebral edema- may not want to tolerate permissive hypercapnea in this setting due to risk of raising intracranial pressure
    • ECLS: No definitive evidence although has been used many times to support patients with refractory cardiopulmonary failure due to drowning. Overall 51% survival based on ESLO registry review of 246 patients. 
    • ICP management: Avoid hypoxemia, hyper/hypo ventilation, hyperthermia, hyper/hypoglycemia, seizures. HOB 30 degrees, sedation, neck midline, C-collar not too tight, +/- Hyepertonic saline and mannitol.
    • Temperature management: Rewarm to 32-36 (THAPCA did not reveal differences between therapeutic hypothermia and normothermia). Rate of no more than approximately 1C/hr. Remove wet clothing. Can use passive external (blankets), active external (warm blankets/air), or active internal (Warm O2, warm fluids, pleural/peritoneal lavage, warm ECLS). Beware of afterdrop (cool peripheral vasoconstricted blood vasodilates with external warming of extremities, leading to hypotension and drop in core body temperature)

Concern for "Dry Drowning"

  • Confusion in lay literature/social media re: "Dry Drowning" (i.e. children having a small choking event in the pool and then dying days later). However, based on the literature, all patients who will exhibit symptoms have done so within 7 hours (Noonan L, Pediatrics 1996). Based on this observation, if the patient is asymptomatic 8 hours after the initial concerning event, they can be safely discharged home. Those that are symptomatic or within the 8 hour window should be admitted/observed, respectively. 

Concern in lay press and social media re: "Dry Drowning." USA Today 2017


Prognosis

  • Risk factors for poor outcomes include:
    • Duration of submersion >5 minutes (most critical factor)
    • Time to effective basic life support >10 minutes
    • Resuscitation duration >25 minutes
    • Age >14
    • Initial GCS <5
    • Persistent apnea and CPR requirement in ED
    • Initial pH <7.1
    • Lack of purposeful movements at 24 hours
Predictors of good outcome in drowning. (Quan L et al, Resuscitation 2014)