Drowning is defined as a process of experiencing respiratory impairment from submersion/immersion in a liquid medium. To delineate the incident's outcome, this is further divided into descriptive terms such as death, morbidity, and no morbidity. Wet drowning, dry drowning, and near-drowning are no longer accepted terms, although they may still be used when discussing drowning.
Accidental or deliberate exposure to submersion in water or other liquid substances that inhibit the body's ability to oxygenate tissues and organs.
Worldwide, drowning accounts for an estimated 360, 000 deaths annually. This represents 7% of all injury-related fatalities and is the leading cause of death among young males. It is estimated that 4, 000 fatalities occur each year in the United States. Furthermore, it is estimated that for every fatal drowning, four non-fatal drowning victims seek medical care. Fifty percent of those patients require hospital admission and interventions. There are three age-related peaks of victims which include small children (younger than 5), adolescents, and the elderly. Patients may drown in bathtubs, pools, large bodies of water or even rain-filled buckets in the yard. Risk factors for drowning include children and teenagers, residents of southern states, occurring during summer months, concomitant drug or alcohol use, and associated medical problems including dysrhythmias or epilepsy.
When a person suffers from submersion or immersion in a liquid medium, vital tissues may become hypoxic and acidotic which may result in cardiac dysrhythmias (progressing from tachycardia, bradycardia, pulseless electrical activity, and asystole). Aspirated fluid can lead to surfactant washout and dysfunction, increased permeability of the alveolar-capillary membrane, decreased lung compliance, and ventilation/perfusion ratio mismatching. This can result from minor to no respiratory complaints to fulminant non-cardiogenic pulmonary edema, with a clinical picture similar to adult or acute respiratory distress syndrome (ARDS). The highest morbidity and mortality are related to cerebral hypoxia, and management is aimed at reversing hypoxia as quickly as possible. Interestingly, hypothermic exposure with the incident may be tissue protective, although may result in increased occurrence of cardiac dysrhythmias.
Determination of the toxicity of the water that the victim was immersed in (eg salt water versus fresh water) is of little importance in non-fatal drowning. Volume or serum (electrolyte) changes only occur when a significant volume of fluid is aspirated. It is more important to note if the fluid was obviously contaminated (sewage), as those patients are highly prone to pulmonary infection and prophylactic antibiotics may be warranted at presentation. Additionally, current recommendations state that routine use of cervical spine immobilization and imaging is not warranted unless the history or exam suggest that the patient suffered from a traumatic injury.
Someone who is drowning or nearly drowning usually has a history of struggling to breathe after an extended period of water submersion. The skin may appear blue or pale from lack of oxygen in the blood. The patient may be in respiratory distress with apnea or shallow breathing, have an altered level of consciousness, be coughing, fatigued, or have other neurological findings.
Labs and/or imaging studies are not always warranted in well-appearing, normoxic, asymptomatic patients. If obtained, the workup should be directed towards the patient’s history and exam (eg for continued hypoxia a chest x-ray and blood gas may be warranted or for altered mental status a head CT, blood glucose, blood gas, toxicology analysis, ethanol level, and a metabolic panel may be needed). The most common laboratory abnormality noted in these patients is metabolic acidosis secondary to a lactic acidosis. Electrolyte abnormalities are uncommon in non-fatal drowning patients despite the type of fluid in which the patient was immersed.
A chest x-ray is not required in all drowning victims. Moreover, the initial chest x-ray has little correlation with the patient’s clinical course or outcome. However, one should be obtained with continued hypoxia or worsening respiratory symptoms. Patients may develop a non-cardiogenic pulmonary edema/ARDS-type presentation and should be treated accordingly. Routine use of glucocorticoids, diuretics, and empiric antibiotics is not currently recommended. Antibiotics should be withheld until the patient begins to develop infectious signs and/or symptoms. In significantly unstable patients, providers may consider using extracorporeal membrane oxygenation (ECMO) as salvage treatment for refractory hypoxia or hypothermia. Therapeutic hypothermia has also been discussed as being a beneficial treatment adjuvant.
The greatest morbidity and mortality associated with non-fatal drowning is due to tissue hypoxia, specifically cerebral hypoxia, and thus, the greatest priority in the resuscitation process is to address and correct hypoxia quickly. Current recommendations state that rescue breaths should begin as soon as possible, and the breaths should be given with the patient's their chin and airway extended when safe to do so. One recommendation is to start resuscitation with five rescue breaths instead of the usual two and to perform the rescue breaths before performing chest compressions. The Heimlich maneuver is no longer recommended and should be avoided. Hypothermic patients should have their pulse assessed for 30 seconds, as their pulse may be weak, and starting CPR on a heart that has an organized rhythm may trigger life-threatening dysrhythmia. When examining, manipulating, and moving hypothermic patients, it is important to be gentle to prevent inciting a dysrhythmia. Passive and active rewarming methods should be employed to warm the patient’s core temperature.
Initial management of the patient includes delivering oxygen via nasal cannula, non-rebreather, non-invasive positive pressure ventilation, or endotracheal tube. Oxygen should be titrated to maintain oxygen saturation between 92% - 96% and to avoid over oxygenation. Nebulized albuterol may be given for bronchospasm. Cardiac support should be employed. Advanced cardiac life support (ACLS) protocol should be followed if needed. Infusion of crystalloids, and at times vasopressors, may be needed for refractory hypotension.
Patients with mild to no symptoms may be observed in the emergency department for four to eight hours, and if they continue to do well, they may be discharged home with return precautions given. Symptomatic patients may warrant further observation with inpatient admission to the appropriate area (floor vs. intensive care depending on the severity of their symptoms).
It is estimated that more than 85% of drowning cases could be prevented with supervision, swimming instruction, technology, regulation, and public education. Less than six percent of all persons who are rescued by lifeguards need medical attention in the hospital. Education is fundamental to preventing of drowning accidents.