Drowning is a process resulting in primary respiratory impairment from submersion /immersion in a liquid medium.2
A liquid/air interface at the entrance to the airway prevents the victim from breathing air. The victim may live or die after this process.2
Case: A 15 yr old was playing with his brother outside by a dam. Their mother was unaware of the childrens’ location for 10 minutes. The alarm was raised by the brother. The teenager was found by his mother face down in the water, blue and apnoiec. She gave rescue breaths, and the boy started to breath spontaneously.
On arrival of the HEMS team, the boy is cold and smells of vomitus. His saturations are in the 80s and he is agitated with a GCS 5/15. His pupils are large and minimally reactive to light.
He receives IO access and an RSI for airway and neurological protection. During his transfer to a trauma centre, his observations steadily improved. His made a rapid recovery in the ICU and he was discharged neurologically intact.
Challenge: How do we optimise the drowning victim’s chances of a full neurological recovery?
Pathophysiology: From the point at which the airway lies below the surface of the liquid, the victim voluntarily holds his or her breath. Breathholding is usually followed by an involuntary period of laryngospasm secondary to the presence of liquid in the oropharynx or larynx.3 The victim then becomes hypercarbic, hypoxemic, and acidotic.
During this time the victim will frequently swallow large quantities of water. As the victim’s arterial oxygen tension drops further, laryngospasm abates, and the victim actively breathes liquid. Surfactant washout, pulmonary hypertension, and shunting also contribute to development of hypoxaemia.4
Modern day sirens or the antidote?
Learning Points: The most important and detrimental consequence of drowning is hypoxia. Oxygenation, ventilation, and perfusion should be restored as rapidly as possible. Ideally this should be initiated by the first responder.4
The reported incidence of cervical spine injury in drowning victims is low (0.009%).5 Unnecessary cervical spine immobilization could impede initiation of adequate oxygenation. Routine stabilization of the cervical spine in the absence of circumstances that suggest a spinal injury is not recommended in the AHA guidelines.6
In a 10-year study in Australia, 66% of victims who received rescue breathing and 86% of those who required compressions and ventilations, vomited.7 So have the suction at the ready and be prepared to roll the patient if necessary.
V/Q mismatch, reduced compliance and acidosis lead to reduced O2 delivery and anoxic brain injury. This is the leading cause of death or morbidity in drowning victims.
Many of the other sequelae are actually related to the hypothermia that often accompanies drowning. Water that is <10°C has pronounced cardiovascular effects, including increased blood pressure and ectopic tachyarrhythmias. Please see a future blog for more on this topic….
Summary: Like our trusted HEMS team in the above scenario, doing the simple things well, can lead to a favourable outcome.
3. Miller, R. D., 2000. Ed. Anesthesia. 5th ed. Philadelphia, Pa: Churchill Livingstone: 1416–1417.
“Periculum in mora”