Introduction
Man has suffered death and injury from drowning since the beginning of time. According to the Bible, the most of the earth's civilization perished in the great floods during the time of Noah. Pharaoh and his army drowned in the Red Sea after after Moses and his followers had crossed the parted waters. Drowning and near drowning continue to be a serious health problem even into the 21st century.

Definition
Drowning is defined as: 'death within 24 hours after submersion in a fluid media'. The media is more often than not water but it can be any liquid. Near drowning can be defined as: 'any patient that survives an immersion incident'. Other terms exist such as immersion syndrome, and immersion injury. They are often used to describe a plethora of signs/symptoms that the patient may or may not have related to a drowning or submersion injury.

The Problem
In the United States more than 7,000 people die from drowning each year. Drowning is one of the top 5 leading causes of trauma death and is the #2 killer of children.

Age distribution is bimodal: drowning mainly effects two age groups: young children (toddler age) and the 15-24 year old group.

Causes
The pediatric patient typically drowns at a residence. Infants/toddlers often drown in bathtubs, pails or toilets. Often this can be linked to a lapse in adult supervision. Some of these incidents may involve neglect or abuse. Look for other injuries on the child and observe the parents closely. Make sure and notify the receiving facility of your suspicion. The preschool age child frequently drowns in a pool or spa. These incidents may also involve a lapse in adult supervision. Many of these spas and pools have no physical barriers (covers, fences, etc.) The adolescent and young adult age group typically drowns in rivers, lakes, ponds, or oceans. Many of these patients are involved in boating and/or diving incidents/mishaps. Upwards of 40-50% of these patients are under the influence of alcohol or drugs. In both age groups males are overwhelmingly more likely to suffer an immersion event.

Pathophysiology
The most critical problem of any drowning or immersion episode is hypoxemia and ultimately asphyxiation. The target organs are the lungs and pulmonary system. Hypoxemia initially results from gasping and attempting to breathe while submerged, leading to aspiration of the fluid media or laryngospasm. As the patient becomes more hypoxic, anoxia ensues, subsequently leading to CNS/cerebral cell death and cardiac arrest from asphyxiation.

Victims that aspirate water are referred to as having a "wet drowning". The vast majority of victims aspirate freshwater. Freshwater is less concentrated than plasma (hypotonic) and through osmosis moves into the patient's bloodstream. Though rare, this can lead to hypervolemia and serious electrolyte imbalances. Freshwater damages lung tissue, alters surfactant and leads to difficulty in ventilation and oxygenation. Saltwater drowning is less common. Saltwater is more concentrated (hypertonic) and through osmosis tends to stay in the pulmonary system but will even draw fluid from the bloodstream into the lungs. Both freshwater and saltwater drowning are treated essentially the same and have the main issue: hypoxemia and its effects on the body.

Anywhere from 10-20% of patients do not aspirate but have a laryngospasm until cardiac arrest occurs. This phenomenon is known as "dry drowning" i.e.: the patient does not aspirate any of the fluid media.

Presentation
EMS providers must be able to quickly assess and ascertain what led up to the drowning or submersion event. For example, did the patient have a seizure and fall into the water? Was there some other medical or traumatic reason for the event? Think about whether the drowning is a primary or secondary event. Are there witnesses that know what happened? Medic Alert tags or other identification or medical history that is relevant?

Essential information to assess and report about the scene includes:

• Submersion time
• Associated trauma
• Drug or alcohol ingestion
• Type of water
• Amount of water contamination
• Water temperature
• Attempted rescue maneuvers

At what point during the drowning sequence the patient is removed from the water largely drives the clinical presentation. Some patients may appear in full cardiopulmonary arrest other patients may be either symptomatic or asymptomatic. An asymptomatic patient is just that; asymptomatic. However, symptoms or serious complications may occur up to 72 hours after the incident. Here is an 'EMS Providers Rule of Thumb' to follow: Any patient with a history of a significant immersion incident should be transported to a definitive care facility for evaluation and observation. Be especially careful with children and the elderly. The margin for error is narrow here and you must have a high index of suspicion for occult hypoxia/injury.

Patients that are symptomatic may have an alteration in their airway, breathing, circulation or neurological status. If the patient has any alteration in any of the above parameters they are considered symptomatic. Assess for:

• Cough
   
• Dyspnea
   
• Wheezing
   
• Hypothermia
   
• Bradycardia or tachycardia
   
• Vomiting and/or diarrhea
   
• Anxiety
   
• Altered levels of consciousness

The patient in cardiopulmonary arrest will most likely present in asystole (>50%) or ventricular tachycardia, ventricular fibrillation and bradycardia. These patients should be aggressively resuscitated. The victim may also be hypothermic which negatively influences the patient's outcome.

It goes without saying that patients with rigor mortis, lividity, no CNS function and cardiopulmonary arrest do not need to be resuscitated. (Be sure to follow your local guidelines for presumption of death.)

Treatment Considerations

Again, hypoxia is the culprit and should be treated aggressively. Overall treatment is supportive. Maintaining a patent airway, maximizing oxygenation/ventilation, hemodynamic support, and maintaining normothermia are your treatment goals. Success or failure of initial basic life support provided at the scene by EMS is very influential on the patient's outcome.

Your first action is to make sure the scene is safe and secure. The scene of a child that has drowned or has been critically injured will most often be chaotic to say the least. Emotions are often running high. Remember you will most likely encounter these patients in a residence. Teens and young adults will most likely be in an outdoor recreational type setting; alcohol or drugs may be involved. A good policy is to have law enforcement on hand or even be the first ones into the area. Be careful!

Hopefully the victim will be out of the water. Again, be careful. Water rescue is best left to experts. Many drowning victims can drown or disable their would be rescuers. A good rule of thumb is "Reach, Throw, Row and Go". If you have to make a rescue attempt initially try reaching for the victim with a long stick or pole, then throwing something to them, (flotation device, rope, etc) then rowing to them (either a boat, a surfboard, or raft). The last thing is to go into the water to get them. This can be very dangerous; without the proper training you could become a victim yourself!

The patient should be removed from the water with full spinal precautions. If the patient is apneic or breathing ineffectively ventilations can be started in the water. If the patient does not have a pulse you'll need to start chest compressions as soon as you can get the patient on a firm surface.

Airway/Spinal Immobilization: After the patient is rescued from the water, the next step is to establish an airway with simultaneous immobilization of the cervical spine if spinal trauma is possible. The airway may be obstructed with water, emesis, etc. Clear the airway and secure it in the easiest most efficacious way. Endotracheal intubation should be considered in anyone with an unsecured airway, extreme respiratory distress or altered mental status (GCS <8). Patients that have an intact airway and can ventilate themselves adequately should have 100% oxygen applied.

Breathing: Assessing breathing/ventilation is next. Look for presence or absence of breathing and evaluate if the breathing is adequate. If the patient is not breathing begin ventilations with 100% oxygen and a bag-valve-mask immediately. Listen to lung sounds and observe for respiratory distress. Remember that higher pressures may be required for ventilation, due to the poor lung compliance resulting from aspiration of water or pulmonary edema.

Circulation: The next step is circulation. Note presence or absence of a pulse; begin compressions for pulseless patients. Compare/contrast central pulses with peripheral pulses, note color, and capillary refill. For hypovolemic patients fluid resuscitation may be indicated using an isotonic crystalloid (20 mL/kg) such as normal saline. Cardiac dysrhythmias should be treated according to ACLS/PALS guidelines. However, if the patient is severely hypothermic (<86F) only one round of drugs should be given. Support blood pressure with pressors or fluid boluses according to your local EMS protocols.

Disability/Neurological: Note the patient's level of consciousness, pupil size/reactivity, and movement of extremities. Obtain a Glasgow Coma Score and Revised Trauma Score for a useful baseline neurological assessment that you and the Emergency Department staff can compare to. At this time you should also consider or give D50W or naloxone to patients with altered mental status. Children, diabetics, and the elderly are at risk for hypoglycemia. Adolescents and young adults may have been using illicit drugs.

Further Treatment/Management: After securing the ABC's decide upon your transportation mode and destination. If the patient is critically injured you might consider air medical transport or transport to a tertiary care center. The critically injured child is best handled in a tertiary care center. Adults with underlying medical problems, hypothermia, or concurrent injuries should be transported to a Level 1 Center also. The rest of the treatment algorithim consists of a detailed head to toe exam, obtaining a good history, and continued reassessment. Pulse oximetry, use of an end-tidal CO2 device for the intubated patient and continuous cardiac monitoring will be helpful tools to evaluate clinical signs.

Special Concerns

Hypothermia/Thermoregulation: Heat loss in the drowning victim is by conduction; i.e. the transfer of heat by direct contact with the water. Water conducts body heat away up to 26 times faster than air of the same temperature. Hypothermia is a real concern for drowning victims, especially in cold water drownings. A full discussion of cold water drowning, care, special considerations, and outcome are beyond the scope of this article.
Pediatric patients are at a higher risk for heat loss due to a higher body surface to body mass ration than in adult patients. Hypothermic patients should be handled with care. All wet clothes should be removed; the patient dried, warmed IV fluids and warmed oxygen (if available) should be used.

Aggressive rewarming is best initiated in the receiving facility. Outcomes differ from age group to age group and are dependent upon water temperature, immersion time, response to prehospital care, and water quality. Younger children tend to do better; this is thought to be due to the mammalian diving reflex. This mechanism shunts blood to the heart and brain thus prolonging survival. It is thought to be initiated by cold water touching the face.

Cervical Spine Injury: Of the two age groups the teen/young adult are vastly more prone to C-spine injury. Most of these injuries are burst type fractures resulting in quadriplegia or paraplegia. Most victims have a high impact with the water such as with a diving incident, fall or MCA. Many of these patients are under the influence of drugs or alcohol.

Should all drowning patients be immobilized? Watson, et al did a retrospective study of 2,244 patients that had a submersion incident. Of the 2,244 eleven (0.5%) had C-spine injuries. All 11 were submerged in open bodies of water, had clinical signs of serious injury and had a history of diving, MCA, or a fall from a height. No C-spine injuries occurred in low impact submersions. The authors postulate that routine C-spine immobilization is not warranted solely on the basis of a history of submersion.

Be careful, if in doubt, immobilize the patient. Follow your own agency's guidelines and/or protocols.

Concurrent Injuries
Drowning victims may also have other injuries. They could be victims of assault, abuse, an MCA, etc. Don't get "tunneled in" on the drowning mechanism. If the patient is hypotensive suspect blood loss. Look for other injuries. Observe for possible closed head injuries or abdominal trauma.

No Transports: Patients that have an immersion incident or near drowning experience may appear asymptomatic. They may even refuse EMS transport. Be very careful; symptoms may occur as much as 72 hours later. The safest thing is to transport the patient. Don't let yourself be fooled by a "normal" presentation. Be especially careful with patients that have underlying medical problems. Be a patient advocate and strongly suggest transport to an appropriate facility.

Prevention
Many of these incidents are preventable with good education of parents and children. Enclosures around pools, spas, etc. along with swimming lessons go a long way. Education of teens on the dangers of alcohol and open water could be efficacious.

Conclusion
Approach each patient in a concise and orderly way. Remember the epidemiology of this injury and the age patterns. The problem is hypoxemia, aggressively treat hypoxia and be on the lookout for occult injury. Hypothermia, concurrent injuries also need to be on your mind. As we head into the summer the incidence of drowning rises. Be aware and be at your best.

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References:
 

1. Policy Statement, Drowning in Children, American Academy of Pediatrics, August 1999
2. Consumer Product Safety Commission, Water Safety, September 1999
3. Norris, Robert MD, Submersion Injury, emedicine.com , July 1999
4. Dickison, Ann, Near Drowning Wilderness Medicine Newsletter, Spring 1999
5. Campbell, Ernest, Immersion Hypothermia, Dive Medicine, April 1999
6. Pediatric BTLS, BTLS International, 2002