Drowning

Drowning and near drowning is a fascinating area. As a dinghy sailor, I regularly teach about drowning on our first aid courses, but as we sail on top of the water and not in the water, I've still never seen it! If you get a chance to watch the Cold Water Casualty video, it is well worth a watch. The Royal Yachting Association has a good summary about cold shock, hypothermia and drowning. The RNLI provides some UK statistics. Drowning is specifically mentioned in the cardiac arrest competencies, and in HAP11 Environmental emergencies (an adult competency).

WHO provides us a statistical summary about drowning, and Update in Anaesthesia provides a very thorough overview as does BMJ best practice, LITFL, EP monthly and the AHA.

There is an e-learning module on drowning here and here. Unless you are a Paramedic you're unlikely to have access to the former, and there are so many alternative resources out there I wouldn't subscribe. Enlighten me has an excellent CEMPedia article on drowning  and an adult case.


Statistics
Drowning is the process of experiencing respiratory impairment from submersion/immersion in liquid. In 2000, there were 409,272 deaths from unintentional drowning worldwide, decreasing slightly in 2004 to an estimated 388 000. 150 people drown in the UK coast every year - and 80% of these are male. Drowning is the second highest cause of death from injury, after road traffic injuries.

Young children are at risk as they are unaware of the dangers and less able to escape from water once submerged.

Things Drowning Causes
There are four main problems drowning causes:

• Hypothermia and Cold Water Shock
  Not everyone drowns in warm water! Hypothermia causes its own special problems. The most relevant problem is that blood gets diverted in to the core of the body - causing chilly blood outside, and warm blood inside. When you start to mix the warm and chilly blood, the body gets a bit confused - and arrhythmias can occur.
  Cold shock can happen at any water temperature below fifteen degrees - the average UK water temperature is twelve degrees.
• Associated injuries
  Remember to think about what people injured when they drowned themselves - neck and c-spine injuries are common.
  Awareness of injuries will be low because of natural adrenaline, and vasoconstriction in the extremities.
• Water aspiration
  As you hit the water, before the diving reflex is triggered, you get a gasp reflex (as you do when you first get in a really cold swimming pool!). If you enter turbulant water, as waves crash overhead you are even more likely to inhale some water. Aspiration of even small amounts of water significantly impairs gas exchange. The water dilutes and inactivates surfactant, so alveoli are prone to collapse. The water can also cause direct lung injury.
• Post rescue Collapse
  Loss of hydrostatic pressure of water on the body results in loss of peripheral resistance and venous pooling. Patients should be extricated from the water in a horizontal position.
• Post Drowning Infection
  Some people contract infections after drowning. Swamp water might cause fungal infection (aspergillosis)- so think about it in your poorly patients. Stagnant water with rat urine may cause Weil's disease (Leptospirosis). There are many case reports (1 2 3) about pneumonia after drowning - but there is still no evidence for prophylactic antibiotics.

Investigations
- ABG if significant history of submersion as saturations may not be reliable.
- CXR
- ECG - look closely for a prolonged QTc.
- Core temperature measurement
- Electrolytes and BM
- Blood culture in patients with significant aspiration

Treatment

• ABCD approach
• For children, no modifications to the resuscitation sequence are recommended.
• If intubation needed, ventilate using an ARDS protocol. 
• Observe for  at least six hours.
• After discharge, written discharge advice is well received by families. 
• There is no evidence to support giving prophylactic antibiotics on discharge.