NARD Diving MedicineDiving MD

Drownings

Preventing drowning accidents is one of the number one reasons dive teams are established. Drowning is the second leading cause of accidental death, averaging approximately 8000 deaths per year in the United States alone. Near drowning accidents are estimated at 500 to 600 times more common than drownings. A victim drowns when they are suffocated by water. The highest incidence of drownings is in children less than 5 years of age, (40%) with the greatest number, being about two years odds. The next group is young adults between 15 and 24 years of age. The elderly also experience high drowning rates. Mortality is 3 to 4 times greater for males than females. Half of all drownings occur between May and June and then in August.

Not all victims found in water are drowning victims, although many rescuers wrongly assume it. Their root cause of being in the water may be trauma, or medical in origin. Because of this there are predictable predisposing factors associated with drownings and near drownings. These are:

Predisposing Factors Associated with Drownings and Near Drownings
  • Alcohol Abuse
  • Drug Intoxication
  • Trauma with head and neck being most common.
  • Barotrauma
  • Syncope secondary to a medical condition (MI, Seizures, diabetes, cerebrovascular accident, arrhythmias, etc.)

The history should exclude all other possible causes of hypoxia; however it is essential to also exclude entities that may have predisposed the victim to the drowning episode. Always be sure to get a good history of what happened and when.

Closed head injury should be suspected in any near drowning victim who is unconscious or demonstrates changing mental status. This is because many near drownings are secondary to head trauma, therefore, unless it can be proved otherwise, it must be assumed. Always assume that head or neck trauma has occurred. Altered mental status may be due to hypoxia, cerebral edema, or they may be due to a contributing injury or condition, e.g., trauma, drugs or alcohol, air embolism. The victim may present completely normal and then start to deteriorate. A postictal state may indicate that submersion was secondary to a seizure.

Barotrauma is associated with SCUBA diving with the worst cases being air embolism or CNS Bends. Any SCUBA diver who is a near drowning victim and exhibiting CNS depression should be assumed to have one of these. The near drowning is not his major problem but secondary to it. Hyperbaric recompression therapy must be started as soon as possible.

People under the influence of drugs, particularly those with a sedative effect, are at an increased risk of drowning. Alcohol abuse while engaging in water activities predisposes a person to drowning; 40% of drowning deaths were alcohol related. Los Angeles lifeguards stated 70% of near drowning victims had been drinking.

Keep in mind drownings of children may be secondary to child abuse.

When we look at drowning we find there are two types. First is a WET DROWNING, in which water fills the lungs, stopping gas exchange. The second, and more common is a DRY DROWNING, occurring when the entrance of water causes a laryngospasm occluding the airway bringing about suffocation. The person of most concern to the rescue diver is the victim of a NEAR DROWNING. A near drowning victim is the person who is saved. Near drowning victims may become SECONDARY DROWNING victims, which is death occurring after an initial recovery, for this reason every near drowning victim must be evaluated at a hospital.

Most drownings follow the same course of events no matter how the victim got in the water. Once the victim starts to submerge, water enters the nose and mouth. This results in coughing, gasping for air, and most victims swallow a large amount of water. Once water enters the larynx, the body's defense against foreign objects entering the trachea sets off a laryngospasm, sealing the upper airway. The laryngospasm has now obstructed the air flow to the lungs and the victim loses consciousness due to hypoxemia. If the victim is not removed from the water at this time, asphyxia will result in a relaxing of the laryngeal muscles, and water can fill up the lungs.

How any water entering effects the body is dependent on if the victim was in salt water or fresh. The result can be hypotonicity from fresh water, or hypertonicity from salt water, based on the amount of fluid aspirated. Knowing this makes it possible to predict possible tissue response. However, the amount of water aspirated is the variable that cannot be determined, but in most cases when the victim is found unconscious in the water, it is about one third the total amount of fluid the lungs can hold.

Osmosis states that water will cross a semipermeable membrane from a solution of lower concentration to one of higher. Because of this fresh water is rapidly absorbed into the blood, but salt water draws plasma into the alveoli. From this it can be concluded that the salt water victim will have a greater amount of hypoxia, due to the reduction in the number of working alveoli.

In fresh water, victim's blood, may be diluted causing blood chemistry to be changed, sometimes leading to cardiac dysrhythmias. Freshwater is hypotonic meaning it has a lower osmotic pressure than blood, so it is drawn out of the lung into the blood. This fluid passing into the blood dilutes it (hemodilution) and causes hypervolemia (increase in blood volume). Saltwater is hypertonic meaning it has a higher osmotic pressure than the blood, drawing it into the lung tissue. This causes hypovolemia (low blood volume) and hemoconcentration (increase in RBC) due to the plasma being drawn into the lung. This makes IV fluid therapy more interesting.

Victims of either type of drowning will have decreased hemoglobin but for different reasons. Freshwater in the blood causes a situation known as hemolysis. This is the destruction of the RBC with the liberation of the hemoglobin which diffuses into the surrounding fluid. When this occurs the body is unable to retain the hemoglobin which is lost through the kidneys imparting a red color to the urine (hemoglobinuria). Saltwater causes the RBC to change from their normally smooth round shape into a shrunken, knobbed, starry shape preventing the bonding of oxygen with the cell called CRENATION.

Differences Between Freshwater & Saltwater
FRESHWATER SALTWATER
Hypotonic Hypertonic
Hypervolemia Hypovolemia
Hemodilution Hemoconcentration
Hemolysis Crenation of RBC

Although these differences can be studied, most victims do not aspirate enough fluid to cause life-threatening changes in the blood or electrolyte concentrations.

To the rescuer, whether the victim is in fresh or salt water is of little consequence, both are basically treated the same. A wide variety of crisis may be present, including cardiac arrest, hypothermia, severe respiratory distress, arterial gas embolism, major trauma, C-spine injury, or there may be no symptoms at all. When first reaching the victim establish if breathing, even while still in the water. Once the victim is removed from the water clear the airway and start ventilation. Remember that drowning victims are also victims of an obstructed airway due to water. The water can be removed easily and the Heimlich maneuver is not necessary. However, if artificial respirations fail then it should be done on the grounds that foreign matter may have been missed.

Initial management is the most crucial determinant of survival of the victim. Late therapy is often of limited value. The efforts of rescue personnel to provide quick and effective early resuscitation is seen as more crucial than sophisticated ICU efforts latter on. This is because the longer the victim is hypoxic the greater the damage to tissue. Immediate attention must be paid to airway control for reversal of hypoxemia, maintenance of circulation and correction of acidosis. Treatment should not be withheld due to prolonged submersion time. Consideration must be given to any precipitating condition and associated injuries.

Almost all drowning victims swallow water, and occluding the esophagus not only prevents aspiration, it also can help endotracheal intubation. Insertion of an ESOPHAGEAL GASTRIC TUBE AIRWAY (EGTA) as soon as possible can help protect the airway prior to ENDOTRACHEAL INTUBATION. The EGTA is preferred over the ESOPHAGEAL OBTURATOR AIRWAY (EOA) because it allows for evacuation of the stomach prior to removal. The use of EGTA's and EOA's in the field has been a point of controversy but when used on drowning victims it can make difference.

After securing the airway give the victim positive pressure ventilation at 100% oxygen. Even the conscious near drowning victim should be given oxygen by demand valve. Remember that in both cases RBCs may be reduced so the victim will be, or may become hypoxic. Attempts to suction the lungs of aspirated water at the scene is potentially dangerous and most times useless.

Once the victim is receiving oxygen, an IV lifeline should be started with cardiac monitoring. The IV solutions are the same for freshwater and saltwater, Lactated Ringer's or normal saline, TKO or to blood pressure. However some physiologist believe that for the freshwater victim, he may already have too much fluid so he needs a TKO IV such as dextrose in water. Saltwater victims are similar to trauma victims and may need a volume expander use lactated ringers, or normal saline and titrate to blood pressure. This is a debatable issue and under study.

After the airway is secure, a nasogastric tube should be inserted to decompress the stomach.

In an arrest associated with drowning studies show most victims develop metabolic acidosis first and may require bicarbonate initially, unlike the normal arrest victim. Given at 1mEq/kg bicarbonate IV push as soon as the IV line has been started, and then follow standard ACLS protocol. This is a judgement call based on time the victim has not been breathing. American Heart Association ACLS Textbook states that "The safety or efficacy of sodium bicarbonate in the near drowning victim is unknown; routine use of this agent for the near drowning victim is not recommended."

For ventricular fibrillation, defibrillation should be attempted but in the severe hypothermic victim (core temperature 28oC or less) it will not be successful until the core temperature has been raised.

Facilitate management to reduce agitation and activity and to maximize ventilatory control. Elevation of head to at least 30 degrees if vital signs stable and spinal injury has been ruled out.

If pulmonary edema or cerebral edema is suspected, give Mannitol 0.25 to 0.5 g/kg IV slowly over 10 to 15 minutes, every 3 to 4 hours, as needed, with a maximum dose of 1g/kg/dose, or Furosemide 1mg/kg IV every 2 hours as indicated.

NEVER GIVE UP ON A DROWNING VICTIM! This includes all drowning victims, not just the cold water victims, but remember that the colder the water the greater the chance of recovery as bottom time increases. Prompt and effective resuscitation at the scene is the crucial factor in a victim's chance of survival.

Any victim that has documented submersion, cyanosis, apnea, or requiring resuscitation should be admitted and observed at a hospital for at least 24 hours, no matter how good they appear. Delayed onset of serious pulmonary and neurologic symptoms has been documented occurring several hours post incident. Some studies show that all salt water victims that meets the above criteria will show respiratory distress within four hours if it is going to develop, so that no more than a four to six hour observation period is necessary.

Victims that have a questionable history or who had been submerged for a brief period should be observed for four to six hours. If no signs, symptoms, or laboratory abnormalities develop, the patient may be discharged from the ER.

Every near drowning victim needs to be evaluated at a hospital, especially the salt water victim who has a higher likelihood of developing pneumonia, and pulmonary edema. Remember that any saltwater in the lung will draw fluid into it, so 12 to 24 hours later the victim may die due to hypoxia. Aspirated water may contain sand, mud, algae, chemicals, or microorganisms capable of causing secondary problems. Even victims who state that they are all right must be transported and given 100% oxygen all the way to the hospital. The only way to determine amount of fluid in the lung is by x-ray.

Even if a victim of near drowning presents fully conscious, a sudden cerebral edema may develop in the first 24 hours. This cerebral edema is due to the hypoxic injury that occurs with a near drowning that leads to acidosis of the brain. After circulation is restored, edema often develops. This resulting edema further compromises tissue perfusion thereby intensifying brain damage.

In a near drowning the main organs involved are the lungs, with both delayed and initial pulmonary problems dominating the clinical course. Chest radiography of near drowning victims show that abnormalities may occur immediately or as late as 24 hours post-immersion. These findings range from patchy infiltrates to diffuse, dense infiltrates secondary to aspiration pneumonia and/or pulmonary edema. For this reason an initial chest x-ray is obtained as a base line and a 4, 12 and 24 hour chest x-ray for comparison is made to note any progression. Studies show that 80% of all children who are near drowning victims have abnormal chest x-rays.

Hypothermia starts as soon as any person enters the water. The rate of heat loss in water is 32 times faster than in air. In a drowning this cooling may be exacerbated by aspiration or swallowing. However, hypothermia has a protective effect to organs especially the brain. This protection comes from the slowing down of metabolism, but this reduction is only substantial at 32 C and below. At 20 C the body's oxygen consumption is approximately 24% of normal. This protective effect is significant when the hypothermic state came before significant hypoxemia. The rescue team should get the water temperature or an estimate there of, since hypothermia influences prognosis. Recoveries have been reported after prolonged cold water submersion (<10 C). At least 28 cases of intact CNS after submersion of 15 minutes have been reported. The longest documented submersion with an intact neurologic outcome is 66 minutes. The victim's core temperature was 19 C. A key point to remember in every drowning victim is, they are not dead, until they are warm and dead.

Hypothermia can occur following immersion in water of any temperature. Unconsciousness can occur within minutes in water that is 10 C. At a core temperature of 28 C, the basal metabolic rate is 50% normal, the heart is prone to dysrhythmias and spontaneous ventricular fibrillation. Blood pressure begins to drop at 25 C and at 22 C, cerebral activity stops.

Respirations of the near drowning victim are rapid due to a response to hypoxia, acidosis, and hypercapnia, the primary disorders of near drowning. As a rescuer never assume that the victim is hyperventilating due to an anxiety or fear of the accident and withhold oxygen or worse, have him breathe in a paper bag. A continuous cough may indicate pulmonary injury due to aspiration.

Any abnormal respiratory sounds may reflect aspiration, pulmonary edema or atelectasis. Keep in mind that aspiration of salt water draws fluid into the alveoli whereas fresh water destroys surfactant resulting is pulmonary shunting and atelectasis.

The skin may be cyanotic reflecting the hypoxia and/or hypothermia. This cyanosis is easily reversible if due to these. However if due to aspiration the result is from ventilation perfusion mismatch and/or shunting of blood to the heart and brain due to a hypometabolic state. The rescuer should always gauge the degree of cyanosis and note if it is decreasing or increasing. Try to determine skin color prior to arrival. Keep in mind that decreasing cyanosis is a sign of improvement, while increasing indicates rapid deterioration of the victim.

Pallor reflects peripheral vasoconstriction secondary to cold exposure and should not be confused with cyanosis. If the rescuer cannot tell the difference between pallor and cyanosis, treat as cyanosis. Cold skin is a reflection of peripheral vasoconstriction.

For transport the EMS should have good definitive management with positive airway control by endotracheal intubation if artificial respirations are required. If the victim is complicated with the Bends or air embolus, the transfer to the ER should be by air if possible. Remind the flight crew that patient should not be taken above 1000 feet to avoid exacerbation of diving maladies.

Vomiting occurs frequently and is secondary to gastric irritation from ingested water. There may also be abdominal distention due to large amounts of water swallowed during immersion.

A near drowning is a multi system disorder with the lungs as the primary target organ and hypoxemia the major adverse effect. The victim will present with manifestation of hypoxemia, acidosis, hypoperfusion, respiratory distress, and CNS anoxia. Complications of near drowning are respiratory arrest, disseminated intravascular coagulation, coma, postimmersion respiratory syndrome, neurologic sequella, and multi system failure. Prevention, through education and improved safety measures, should be the goal of every rescue team. Help promote water safety and knowledge of CPR and resuscitation techniques.

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