The immediate physiologic response to drowning is breath-holding. After breath-holding, involuntary laryngospasm can occur with entry of fluid into the oropharynx and larynx. At this point, oxygen stores are depleted quickly leading to hypoxia as well as hypercarbia and acidosis. Alternatively, if laryngospasm does not occur, the drowning individual will quickly begin gasping for air and reflexively coughing with entrainment of water into the airways. Thus, drowning results from asphyxiation (with or without aspiration of water). Initial management of cardiac arrest in the drowning victim is to restore ventilation through rescue breathing. This differs from cardiopulmonary resuscitation in a patient with cardiac arrest due to other causes where CPR begins with immediate and uninterrupted chest compressions. In the drowning victim, two rescue breaths should be delivered to produce chest rise. If the patient does not respond, the rescuer should begin high-quality chest compressions and continue CPR according to BLS protocols, with 2 minutes of CPR and a 30:2 compression-to-ventilation ratio.
Updated definition 2020:
Drowning is defined as “the process of experiencing respiratory impairment from submersion /immersion in liquid.” Of note, any submersion incident without respiratory impairment is considered a water rescue, not a drowning. The clinical picture and outcome of a drowning depends on the extent of fluid aspiration into the airways leading to hypoxia and cardiac arrest, which in turn, evolves into irreversible neurologic damage. After submersion, an individual initially expels water from their mouth and nose voluntarily, followed by a breath hold. After more than a minute, involuntary inspiratory efforts cause water inhalation and coughing. This is followed by laryngospasm, which ceases with the development of progressive brain hypoxia. Water aspiration leads to pulmonary edema with impaired gas exchange, in part due to the dilution of surfactant. Systemic hypoxia causes the deterioration of cardiac function – initially, the victim will be tachycardic which progresses to bradycardia, pulseless electrical activity, then asystole. Generally, irreversible damage to the heart and brain will occur within a few minutes. However, in patients with concomitant hypothermia, in rare circumstances, cardiac and neurologic cooling can afford extended protection and the improved possibility of recovery after prolonged immersion.
The American Heart Association guidelines recommend removing the drowned victim from the water as quickly possible, followed by initial resuscitation efforts. If CPR is required, rescue breaths should be included to refill the alveoli with oxygen and air, as the cardiac arrest is secondary to hypoxia. If the rescuer is alone, it is recommended they perform five cycles of CPR (about two minutes) before leaving the victim to activate emergency medical response. In victims with obvious signs of injury, alcohol intoxication, or a history of diving into shallow injury. Once victims are transported to a hospital, initial care should focus on securing a definitive airway, improving oxygenation, supporting circulation, gastric tube insertion, and rewarming. Bronchodilator therapy may be helpful in the prevention of bronchoconstriction and helping clear water from alveoli, but there is no evidence for the use of glucocorticoids in drowned victims.
- Szpilman D, Bierens JJ, Handley AJ, Orlowski JP. Drowning. N Engl J Med. 2012 May 31;366(22):2102-10. PubMed Link
- ACLS Drowning Resource Link
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