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)
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