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Drowning

Drowning is the process of experiencing respiratory impairment from submersion or immersion in a liquid (regardless of outcome).

Definitions related to drowning:

  • Submersion - the act of being completely covered by a liquid

  • Immersion - being partly covered by a liquid (in medical terms this usually includes the face)

  • Previously, the term “near drowning” was used to indicate patients that survived for > 24 hours following a drowning event. Whilst this term is still commonly used, it has been replaced by the term “non-fatal drowning”

The Problem

In Australia this is a big problem. It is the second most common cause of accidental death in children in Australia.

  • Boys : girls 5:1

  • Highest incidence in 0 - 4 years old

  • Most urban drownings occur in private swimming pools; around 20% occur in bathtubs

  • Alcohol is a big risk factor in teenagers

  • Always consider the possibility of non-accidental injury in children

Pathophysiology

Patients panic, struggle, breath hold and eventually either aspirate or go into laryngospasm.

It was previously thought that patients may undergo “wet drowning” or “dry drowning” as follows:

  • “Wet Drowning” - due to aspiration of water into the lungs (85% of cases)

  • “Dry Drowning” - hypoxia due to laryngospasm (15% of cases)

However, more recent autopsy studies of drownings have shown at least some level of increased fluid in the lungs in over 98% of victims, suggesting that aspiration occurs in almost all cases.

Most deaths in hospital are due to hypoxic brain injury, rather than from pulmonary oedema or lung injury from the initial drowning incident.

Assessment

Historically if available it is useful to know:

  • Length of submersion

  • Type of water, contamination and water temperature

  • Other associated trauma (e.g. fall, boating accident, diving in shallow water)

  • Other factors involved such as alcohol and drugs

  • Underlying conditions such as epilepsy

  • Prehospital care provided, including vital signs and GCS on arrival of EMS

Investigations

  • ECG
  • CXR (looking for pulmonary oedema)
  • CT brain (if focal neurological signs or significant head trauma)
  • Other as indicated by clinical picture, e.g. skeletal survey in suspected NAI

Management

Treat as a trauma - primary survey, ABCDE approach and immediate resuscitation in systems.

The same principles apply whether wet or dry drowning, and for salt and fresh water submersions.

  • Call for help early - senior ED doctor

  • Airway - ensure airway is clear of fluid or debris e.g. sand, vomit; protection if necessary

  • Breathing - immediate respiratory support is important in the initial resuscitation (compression only CPR should not be used in drowning victims).

    • High flow oxygen

    • Non-invasive ventilation (CPAP) has been shown to improve oxygenation (PEEP 10 cm water)

    • Endotracheal intubation if reduced LOC or hypoxia with supplemental oxygen and CPAP

  • Circulation - if arrested, usually initial rhythm is asystole or PEA - follow usual ALS pathway

    • IV fluids often needed to correct hypovolaemia

  • Disability - institute neuroprotective measures to minimise further brain injury

    • Avoid hypoxia, maintain normoglycaemia, prevent hyperthermia, treat seizures
    • No evidence that steroids have a neuro-protective effect

  • Exposure - in cooler climates, drowning is often associated with hypothermia

    • Rewarming measures may be required, especially if core temp is < 35°C

Other considerations

  • C spine immobilisation - protect the cervical spine if trauma is suspected

    • Spinal injuries occur in < 0.5% of drowning victims, however be suspicious if history of trauma such as diving into shallow water or boating accident

  • Use of antibiotics - no evidence that prophylactic antibiotics should be given, unless liquid was contaminated (e.g. containing raw sewage)

Disposition

If awake with no ABC problem can be safely discharged after a period of 6 hours of observation in the ED (to ensure hypoxia +/- pulmonary oedema don’t develop).

Prognostic Factors

No single clinical score accurately predicts which patients will survive post a drowning event. Some studies show correlation between submersion time and survival – other factors include water temperature, time to CPR and time to first spontaneous respiratory effort.

The Orlowski scale is commonly used to predict outcomes post drowning - based upon the following features:

  • Age < 3 yrs
  • Estimated submersion > 5 minutes
  • No attempted resuscitation in first 10 minutes after rescue
  • Coma on arrival in ED
  • Metabolic acidosis on arrival in ED with pH < 7.1

It is predicted that there is a 90% chance of good recovery if < 3 of these are present and a 5% chance of recovery if > 3 are present.

Further Reference and Resources