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Near Drowning

Drowning is the leading cause of death of young children. Near drowning again demonstrates that toddlers and adolescents share many things in common. Near drowning has two bi-modal peaks during those age ranges. Even in the young children, the 2-5-year-old there is a very impressive male to female predominance. Four times as many boys as little girls end up drowning. In the adolescents it’s very often high risk behavior that results in drownings.

What’s the pathophysiology of near drowning? It’s really an anoxic ischemic injury that is preceded typically with anoxia being the primary event, as the patient is unable to ventilate. It’s hard to breathe when you are under water. If you are getting no oxygen, your heart and brain don’t do so well. You may have ischemic injury to all of the organs in the body, although most will recover and not be the cause of ongoing morbidity or mortality. Aspiration of water, 80-90% of patients have some aspiration of water, although it is typically relatively low volumes. All of the studies … many of the animal studies looking at things like near drowning do things like infuse 40 ml/kg in a dog’s tracheas. Drownings typically involve much much smaller volumes.

Pulmonary; you have acute hypoxemia. You may develop a severe ARDS. The ARDS will actually end up being the cause of death in some patients with immersion events. The most common cause of death is the neurologic event.

Cardiac; initially you get the sequelae of the anoxia and ischemia with asystole being by far the most common rhythm. You may transiently have some ventricular fibrillation or tachycardia and you are going to have poor cardiac function. Once you get someone resuscitated, if you are able to get their heart back beating again, the primary cardiac dysfunction is unlikely to be the cause of their demise.

Liver and kidney problems, although they may be transient, are rarely a major long term problem.

Hypothermia; there is a difference between dying and getting cold and getting cold and dying. If they fish somebody out of a swimming pool who has been there overnight and they bring them into the emergency room, they are not surprisingly going to be cold. It doesn’t mean that they’ve had a cold water drowning and that they are going to be fine. When people talk about cold water drownings they refer to cold, cold water. Like falling through the ice.

Near drowning therapy is kind of boring to talk about. There is nothing magic about resuscitation a near drowning victim. Advanced cardiac life support; treat their dysrhythmias, treat their asystole. If they are cold you should warm them up. If they are 25 degrees because they have been dead over night, you are not going to be able to warm them up because they’ve been dead.

Supportive care. They should be observed, with a significant immersion event, at least eight hours. ICP monitoring has not been shown to alter outcome in anoxic ischemic events, such as near drowning, and is not advocated and not carried out at most institutions.

Prognosis; well, not surprisingly, the longer you have been under water and the longer you have been dead, the more likely you are to stay dead. So if you have been underwater for a long time you don’t do so well. If it’s taken resuscitation a long time to get your heart going, you don’t do so well. If you are still apneic by the time you get to the emergency department, you don’t do so well. If you are still pulseless, despite ACLS coming into the emergency department, you don’t do so well. People who are going to do well from near drowning typically have relatively rapid neurologic improvement. Even though they got CPR at the scene, you see them six or eight hours later and they are reaching for their endotracheal tubes and trying to pull it out. In the absence of neurologic improvement over the first day, their outcome is relatively dismal. The degree of metabolic acidosis, in some studies, has been shown to be a helpful predictor in outcome.

Environmental exposures. We see environmental exposures very rarely in the ICU. The Board questions almost always have one of these topics reflected; heat stroke, smoke inhalation, or carbon monoxide poisoning.

Heat stroke; heat stroke basically refers to a very high temperature, oftentimes as high as 106 or 107 degrees, where bad things begin to happen to the enzymes in your body. How does this happen? Well, you can have increased heat generation either from pyrogens generating a fever, exercise if you go out to run a marathon across Death Valley, not surprisingly your body temperature rises. Or if you have hypothalamic disregulation problems. Some children with severe neurologic injuries don’t have good hypothalamic regulation and they don’t regulate their temperature well. So they have increased generation of heat.