oPatientPlus articles are written by UK doctors and are based on research evidence, UK and European Guidelines. They are designed for health professionals to use, so you may find the language more technical than the condition leaflets.
- Drowning is death within 24 hours from suffocation by submersion in a liquid, normally fresh water or sea water.
- Near drowning is survival for more than 24 hours (even if temporary) from suffocation by submersion.
- Secondary drowning is a nonspecific term for death after 24 hours from complications of submersion.
- Immersion syndrome is sudden cardiac arrest on cold immersion. It may be vagal response coupled with vasoconstriction.
- Recovery syncope is syncope immediately following removal from cold water. It may be due to cold diuresis and loss of external water pressure, leading to reduced central perfusion.
After an initial gasp, with possible aspiration, or a period of breath holding, apnoea eventually exceeds breaking point and stimulates hyperventilation, causing aspiration and a variable degree of laryngospasm. This leads to hypoxia and resultant acidosis, and the patient eventually loses consciousness and develops cardiac arrest. In 85% of cases, asphyxia leads to relaxation of the airway before inspiratory efforts have ceased, and the lungs fill with water. This is called wet drowning. In the remainder, laryngospasm is maintained and this is called dry drowning. In young children, sudden immersion in cold water (<10°C) can stimulate the protective diving reflex and produce apnoea, bradycardia, and preferential shunting of blood to the coronary and cerebral circulation, which may improve the victim's chances of survival.
Pulmonary oedema is a common insult. Surfactant loss occurs, producing areas of atelectasis and exudate can flood the alveoli. Further fluid shifts into the alveoli as pulmonary vessels constrict in response to the hypoxia and intravascular pressures rise. This may take minutes to days to develop but results in marked V/Q mismatching. In addition, foreign body aspiration, laryngospasm or bronchospasm may worsen the hypoxia.
Hypothermia, if it occurs, leads to a slowing of the metabolic rate but respiration is slowed even more so and hypoxia and hypercapnia develop. Prolonged hypoxia can lead to CNS and renal damage.
In addition, haemolysis occasionally occurs after freshwater near drowning. Freshwater drowning can be much faster than saltwater drowning. Salt water has a higher osmolarity than plasma and tends to draw water out of the erythrocytes. Fresh water is hypotonic; water is drawn into erythrocytes that swell and burst releasing potassium. This induces hyperkalaemia that can stop the heart. Experimentally observed differences between freshwater and saltwater drowning are unimportant in terms of management.
Worldwide, drowning is the fourth most common injury after road traffic accidents, self-inflicted injuries and violence. It is more common than war deaths. It is the second or third most common cause of accidental death in children in the UK, Australia and the USA. Incidence peaks for toddlers and teenage boys. The latter are the risk-taking group. It is also a common form of suicide.
This depends on age. In children under one year, unattended buckets of water and the bath account for most cases of drowning. Between one and five years, unattended swimming pools account for most cases of drowning.
Alcohol use, water sports and unsupervised swimming, particularly in open water, are risk factors in adults.
In very cold water, hypothermia is a very potent aggravating factor that will rapidly inhibit the ability to swim. If a person falls into water at about 4°C, as in the North Sea in winter or the Arctic Ocean, rescuers have approximately four minutes to rescue the person from drowning. Cold can be a significant contributory factor to deaths in water, even with the temperature well above 4°C. In general terms, water below 15°C is more likely to be associated with hypothermia. However, other factors such as age, body fat and activity will affect the speed at which hypothermia develops.
If a victim is in water and not breathing, resuscitation should be started by the rescuer whilst still in the water, as this improves outcome.
- Start Basic Life Support at the scene.
- Remember the cervical spine may be injured.
Note the following:
- Mechanism and duration of submersion.
- Type and temperature of water.
- Time to institution of CPR.
- Time to first spontaneous breath.
- Time to return of spontaneous cardiac output.
- Likelihood of associated trauma, other precipitants (arrhythmia, myocardial infarction, seizure, nonaccidental injury, etc.).
- Temperature, pulse oximetry.
- Cardiac rhythm.
- Respiratory pattern.
- Look for evidence of pulmonary oedema.
- Head or neck injuries.
- Intra-abdominal and thoracic injuries are also possible (if water entered from a height).
- Neurological status.
- ECG: note rate, rhythm, evidence of ischaemia, J waves of hypothermia.
- Bloods: ABG, electrolytes, renal function, glucose, osmolarity, alcohol level, FBC, LFTs, coagulation screen, blood cultures.
- Radiology: CXR, also C-Spine and possibly head CT scan if indicated.
This will involve several important modalities of treatment.
- Instigate or continue resuscitation as required. Intubate if unconscious.
- Treat hypothermia, hypoglycaemia, seizures, hypovolaemia, and hypotension, if they occur.
- If the patient is awake and alert, observe for at least 6 hours. Pulmonary oedema may develop late (it usually develops within four hours).
- Otherwise, the following may be needed: continuous positive airway pressure (CPAP), intubation and mechanical ventilation with high positive end expiratory pressure (PEEP), or even extracorporeal membrane oxygenation (ECMO) for severe pulmonary oedema.
- Nasogastric tube +/- urinary catheter.
- Artificial surfactant, hyperbaric oxygen and inhaled nitrous oxide therapies are all of unproven value.
- Dialysis for renal failure.
- Prophylactic antibiotics are unproven. They should be given if fever develops or there is grossly contaminated aspirated water, and then targeted towards the likely pathogens. Pneumonia can be a major problem and even a fatal complication, and atypical organisms are an important consideration.
Do not be too eager to abandon resuscitation as hopeless, especially with co-existent hypothermia. Even very profound hypothermia with asystole can be treated by cardiopulmonary bypass. Children, especially, can have remarkably good recovery after prolonged resuscitation, with no neurological problems; however, the outcome is variable. It is not possible to predict at an early stage who will have good outcome and so aggressive resuscitation should be given to all.
There are many possible complications:
- Cardiac (cardiac arrest, bradycardia, myocardial infarction).
- Pulmonary (pulmonary oedema, pneumonia).
- Neurological (stroke, cerebral hypoxia, cerebral oedema).
- Renal (renal failure).
- Haematological (haemolysis).
- Metabolic (hyperkalaemia, acidosis).
- Infective (pneumonia, septicaemia).
Many have investigated and reported on outcome and possible predictors. However, no single system is comprehensive and there are pitfalls in the methodologies used.
One example is the Orlowski Scale for paediatric drowning and near drowning.
- Age less than three years.
- Submersion for longer than five minutes.
- CPR delayed for more than ten minutes after rescue.
- Coma on arrival in A&E.
- pH <7.10 on arrival in A&E.
If one or two criteria are present, then 90% achieve a good recovery.
If three or more criteria are present, only 5% recover.
Generally, the intuitive view stands: the shorter the submersion time and the shorter the delay to CPR, the better the outcome.
- Prognosis is ultimately related directly to the duration and magnitude of hypoxia.
- The most significant impact on morbidity and mortality occurs before arrival at hospital.
- Poor survival is associated with the need for continued cardiopulmonary resuscitation efforts in hospital (35-60% die in the emergency department and 60-100% have long-term neurological sequelae).
- The neuroprotective effects of cold water drowning are poorly understood. Neuroprotective effects seem to occur only if the hypothermia occurs at the time of submersion (and if very rapid cooling occurs in water with a temperature of less than 5°C).
- Even with hypothermia, intact survival of comatose patients is still quite uncommon. However, there are some remarkable case histories where, even after over an hour of submersion and with initially no vital signs (rectal temperature 13.7°C), full recovery has been achieved.
- In warm water immersion, those who were not doing well at 24 hours have a poor neurological outcome.
- Fences around swimming pools. This is a legal requirement in some countries.
- Teach children to swim.
- Adult supervision of children swimming.
- Wearing of life jackets in water sports, including yachting, water skiing and jet skiing.
- Alcohol and swimming do not mix.
Even good swimmers should not swim alone as, if they develop cramp or have any other trouble, there is no one to raise the alarm. Rivers can be treacherous, with eddies and reeds. Alcoholic intoxication is a major risk. Those who go swimming alone after a night of drinking are at very high risk. Night-time and intoxication also increase the risk of diving into shallow water, producing head or neck injuries.
Infants and small children may drown in the bath. The most significant factor is inadequate supervision. A study from Canada found that contributory factors were inadequate adult supervision (89%), co-bathing (39%), the use of infant bath seats (17%), and co-existent medical disorders predisposing the infant or child to the drowning episode (17%).
Further reading & references
- Datta A, Tipton M; Respiratory responses to cold water immersion: neural pathways, interactions, and clinical consequences awake and asleep.; J Appl Physiol. 2006 Jun;100(6):2057-64.
- Wirthwein DP, Barnard JJ, Prahlow JA; Suicide by drowning: a 20-year review.; J Forensic Sci. 2002 Jan;47(1):131-6.
- Stevenson MR, Rimajova M, Edgecombe D, et al; Childhood drowning: barriers surrounding private swimming pools.; Pediatrics. 2003 Feb;111(2):E115-9.
- Brooks CJ, Howard KA, Neifer SK; How much did cold shock and swimming failure contribute to drowning deaths in the fishing industry in British Columbia 1976-2002?; Occup Med (Lond). 2005 Sep;55(6):459-62. Epub 2005 May 4.
- Szpilman D, Soares M; In-water resuscitation--is it worthwhile?; Resuscitation. 2004 Oct;63(1):25-31.
- Harries M; Near Drowning (Review) BMJ 2003; 327:1336-1338
- Thalmann M, Trampitsch E, Haberfellner N, et al; Resuscitation in near drowning with extracorporeal membrane oxygenation.; Ann Thorac Surg. 2001 Aug;72(2):607-8.
- Giesbrecht GG, Hayward JS; Problems and complications with cold-water rescue.; Wilderness Environ Med. 2006 Spring;17(1):26-30.
- Plubrukarn R, Tamsamran S; Predicting outcome in pediatric near-drowning.; J Med Assoc Thai. 2003 Aug;86 Suppl 3:S501-9.
- Zuckerman GB, Gregory PM, Santos-Damiani SM; Predictors of death and neurologic impairment in pediatric submersion injuries. The Pediatric Risk of Mortality Score. Arch Pediatr Adolesc Med. 1998 Feb;152(2):134-40.
- Habib DM, Tecklenburg FW, Webb SA, et al; Prediction of childhood drowning and near-drowning morbidity and mortality. Pediatr Emerg Care. 1996 Aug;12(4):255-8.
- Oakes DD, Sherck JP, Maloney JR, et al; Prognosis and management of victims of near-drowning. J Trauma. 1982 Jul;22(7):544-9.
- Dueker CW; Immersion in fresh water and survival. Chest. 2004 Dec;126(6):2027-8; author reply 2028-9.
- Bratton SL, Jardine DS, Morray JP; Serial neurologic examinations after near drowning and outcome.; Arch Pediatr Adolesc Med. 1994 Feb;148(2):167-70.
- Somers GR, Chiasson DA, Smith CR; Pediatric drowning: a 20-year review of autopsied cases: III. Bathtub drownings.; Am J Forensic Med Pathol. 2006 Jun;27(2):113-6.
Disclaimer: This article is for information only and should not be used for the diagnosis or treatment of medical conditions. EMIS has used all reasonable care in compiling the information but make no warranty as to its accuracy. Consult a doctor or other health care professional for diagnosis and treatment of medical conditions. For details see our conditions.
Dr Adrian Bonsall
Dr Richard Draper