Drowning and Near Drowning

• 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 from suffocation by submersion.
• Secondary drowning is a non-specific 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. 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, suddenly 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.¹ Prolonged hypoxia can lead to CNS and renal damage.

In addition haemolysis occasionally occurs after fresh water near drowning. Fresh water drowning can be much faster than salt water 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 fresh and salt water drowning are unimportant in terms of management.

Worldwide, drowning is the 4th commonest injury after road traffic accidents, self-inflicted injuries and violence. It is more common than war deaths. It is the 2nd or 3rd 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.²

This depends on age. In children under 1 year unattended buckets of water and the bath account for most cases of drowning. Between 1 and 5 years unattended swimming pools³ 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 4 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.⁴ 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.⁵

• 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
• Vomiting
• Likelihood of associated trauma, other precipitants (arrhythmia, MI, seizure, NAI, etc).

• Temperature, pulse oximetry
• Cardiac rhythm
• Respiratory pattern
• Look for evidence of pulmonary oedema
• Head or neck injuries
• Intra-abdominal and thoracic injuries also possible (if water entered from a height)⁶
• 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.⁶
• Radiology: CXR, also C-Spine and possibly CT head if indicated.

This will involve several important modalities of treatment.⁶

• Instigate or continue resuscitation as required. Intubate if unconscious.⁶
• Oxygen
• Treat hypothermia, hypoglycaemia, seizures, hypovolaemia, hypotension if occur.
• If awake and alert, observe for at least 6 hours. Pulmonary oedema may develop late (usually develops within 4 hours).⁶
• Otherwise may need: continuous positive airway pressure (CPAP), intubation & mechanical ventilation with high positive end expiratory pressure (PEEP), or even extracorporeal membrane oxygenation (ECMO) for severe pulmonary oedema.⁷
• NG 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. Should be given if fever develops or 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.⁶

Do not be too eager to abandon resuscitation as hopeless, especially with coexistent hypothermia. Even very profound hypothermia with asystole can be treated by cardiopulmonary bypass.⁸ Children, especially, can have remarkably good recovery after prolonged resuscitation with no neurological problems but 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.⁹

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.^10,11,12 However no single system is comprehensive and there are pitfalls in the methodologies used.¹³One example is the Orlowski Scale for paediatric drowning and near drowning.
Criteria:

• Age less than 3 years
• Submersion for longer than 5 minutes
• CPR delayed for more than10 minutes after rescue
• Coma on arrival in A&E
• pH<7.10 on arrival in A&E

If 1 or 2 criteria are present, then 90% achieve a good recovery
If 3 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.⁶
• In warm water immersion, those who were not doing well at 24 hours have a poor neurological outcome.¹⁴

• Fences around swimming pools.³ 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%), cobathing (39%), the use of infant bath seats (17%), and coexistent medical disorders predisposing the infant or child to the drowning episode (17%).¹⁵