Drownings Present as Hypoxic Events

 

 
 
 

Andrew Schmidt, DO, MPH, | Bryan Bledsoe, DO, FACEP, FAAEM, EMT-P | Justin Sempsrott, MD, | Seth C. Hawkins, MD, FACEP, FAAEM, FAWM | From the July 2012 Issue | Friday, June 29, 2012


Learning Objectives

>> Identify the difference between the terms "drowning," "immersion" and "submersion.
>> Learn the pathophysiology involved for drowning victims.
>> List methods of preventing drowning incidents.

Key Terms
Atelectasis: Collapse of the alveoli, which prevents the exchange of carbon dioxide and oxygen by the blood.
Laryngospasm: A sudden, temporary closure of the larynx.
Pneumocyte: Specialized cells in the alveoli in the lungs.

Drowning is defined as the process of experiencing primary respiratory impairment from submersion/immersion in a liquid medium. Drowning is the 10th leading cause of unintentional injury death for people of all ages in the U.S., but it disproportionally affects children. It’s the most common cause of deaths by unintentional injury for 1–4 years olds and the second most common cause of unintentional injury deaths for 5–9 year olds.1 Worldwide, the problem is much worse, with nearly 1% of all deaths occurring from drowning.2 Drowning remains a significant public health problem and something most EMS providers will encounter at some point in their career. 

History
Humans have always been both intrigued by and fearful of drowning. The fresh drowning victim was an enigma: They looked relatively well but were dead. In some instances, a drowning victim would survive despite apparent death. Because of this, strategies were devised in the 17th century to try and resuscitate victims of drowning. In that era, the strategy was to expel water from the body by various methods, such as hanging the victim upside down or shaking them. One practice was to place the victim in a barrel, open the barrel on both ends and whirl it around to stimulate the vital organs.  

In Paris, in the late 17th century, a rescue model for drowning victims was developed and used. Ultimately, this desire to save drowning victims became the model for subsequent first-aid care and education. In fact, some have argued that attempts to resuscitate drowning victims led to the establishment of EMS and emergency medicine as we know it today.3 Interestingly, the face on the famous Resusci Anne manikin, developed by Åsmund S. Laerdal, was based on a death mask from an unidentified girl who drowned in Paris, in the River Seine, in the 1880s.4  

Despite a longtime human interest in drowning, however, the pathophysiology of the drowning process is still somewhat misunderstood by many. However, we’ve learned a great deal about the pathophysiology of drowning during the past 40 years.

Pathophysiology
At the most fundamental level, fatal drowning is death from asphyxia. However, the unique characteristics of the fluid in which the patient is submerged (e.g., temperature, cleanliness and ease of access for rescuers) contribute to the amount of time that the patient is hypoxic, and have a bearing on subsequent outcome. The pathophysiology of drowning is now better understood. 

The process of drowning begins when the victim’s airway is submerged below the surface of the water. While above the water, a child will typically struggle for only 20 seconds before they become submerged. In contrast, an adult will struggle for approximately 60 seconds before they become submerged. The drowning process begins when the patient’s airway is below the water. Initially, there’s breath holding, and a small amount of water (typically less than 30 mL or 2 tablespoons) may enter the lungs if the patient gasps. During the struggle and the early part of unconsciousness, there’s reflex swallowing as the body attempts to clear the oropharynx of water. Even if water enters the lungs during this period, it’s typically only a small amount (2–4 mL/kg).  

It was previously believed that as many as 30% of drowning patients had some degree of laryngospasm, but we now understand this to be much lower (7–10%). In reality, there’s probably no such thing as a “dry drowning.”6 Ultimately, as the victim’s oxygen levels fall and carbon dioxide levels rise, the brainstem will stimulate involuntary breathing, and then water enters the lungs.  

Unconsciousness typically occurs within four to six minutes of submersion. In the past, a patient who asphyxiated from laryngospasm or didn’t involuntarily gasp prior to asphyxiation was termed a “dry drowning.” The more typical course described above was called a “wet drowning.” As discussed later, these terms have little use and are no longer recommended in the medical discussion of drowning.
The water that enters the lungs, regardless of the type, can wash away surfactant, leading to atelectasis (collapse of the alveoli). Aspirated water is also directly toxic to the pneumocytes (cells that make up the alveoli), thus causing bronchoconstriction, inflammation and hypoxic vasoconstriction. In the past, it was common to differentiate drowning types based on the type of water involved (e.g., salt, chlorine or fresh water). However, this was based on K9 studies for which the dogs had as much as 22 mL/kg of water instilled into their lungs, resulting in electrolyte and other abnormalities. The amount that actually enters the lungs in human drowning is significantly less than this (2–4 mL/kg).7 Thus, all drowning patients are initially treated the same (with the rare exception of drowning in industrial chemicals or sewage).  

Although there’s some injury to the lungs during the drowning process, the final common pathway of all morbidity and mortality is hypoxia with resultant anoxic brain injury. Despite the presence of non-sterile water, salt or chlorine, the lungs typically recover, and emergency treatment should therefore be directed at interrupting the drowning process by providing oxygenation and ventilation as quickly as possible. 

Terminology Changes
Now that the pathophysiology of drowning is better understood, terminology related to drowning has been standardized. Archaic terms such as “near drowning,” “dry drowning,” “wet drowning,” “secondary drowning” and “passive drowning” have been abandoned.8 Accepted terms include the following:
Drowning: Drowning is the process of experiencing respiratory impairment from submersion/immersion in a liquid medium, thus preventing the victim from breathing air. The victim may live or die after this process, but whatever the outcome, they’ve involved in a drowning incident.
Immersion: Immersion means to be covered in water. Usually at least the face and airway are immersed for drowning to occur.
Submersion: Submersion means the entire body, including the airway, is under water.

Treatment
As in all conditions, the primary assessment is key to treatment. You should determine whether the airway is patent, whether respirations are present and whether there’s a pulse. All these physiological functions are interrelated. Simple mechanical techniques, such as a modified jaw-thrust, are usually adequate for opening the airway, which may be obstructed by foam or water. When assessing breathing, look for the presence of cough, the presence of foam from the mouth or nose and presence or absence of rales.  

Assess circulation by presence or absence of a carotid or radial pulse. A study of more than 41,000 lifeguard rescues in Rio de Janeiro, serves as the most extensive guideline to date on the treatment of drowning patients.6 Minimally symptomatic patients with just a cough and no foam at the mouth or nose can usually be released at the scene with instructions to watch for any signs of respiratory difficulty during the next 24 hours. All patients with respiratory symptoms (e.g., dyspnea, foam or rales) require high-concentration oxygen and transport. 

It’s important to understand the differences in treatment priorities in drowning when compared with standard emergency medical care. In the typical medical cardiac arrest, the patient has suffered a cardiovascular event (e.g., heart attack, stroke or arrhythmia). In contrast, the drowning victim has suffered a hypoxic event (similar to most pediatric cardiac arrests). Thus, the 2010 American Heart Association Guidelines for circulation, airway, breathing (CAB) should be modified for drowning victims. Granted, some drownings may be due to a cardiac event, but those cases are generally uncommon.9 Thus, it’s prudent to follow the airway, breathing and circulation (ABC) assessment model in drowning victims. 

The best chance for the successful resuscitation of a drowning patient is to administer oxygen and ventilate as soon as possible. The first person to encounter the patient is often a bystander, first responder (e.g., lifeguard or law enforcement) or EMS provider. Those personnel should be able to provide immediate BLS. Lifeguards and water rescue-trained personnel can take this a step further and start rescue breathing and initiate resuscitation while in the water, all of which contribute to improved outcomes.10  

One complicating factor in the treatment of a drowning patient is the presence of copious amounts of foam in the upper airway. It was previously thought that this fluid was coming from the lungs, but it’s now recognized that much of it comes from the stomach. Ancient and outdated drowning treatments were directed at “draining” the water from the lungs either through the Heimlich maneuver or inverting the patient. All attempts to suction or clear this foam from the airway only delay much-needed oxygenation and go against most dogma of airway management—the patient is dying from cerebral anoxia and not foam in the upper airways. Thus, prehospital providers should focus on oxygenating and ventilating the patient and not on aggressive suctioning. Of course, if cardiac arrest is present, CPR should be initiated and necessary ALS measures provided.  

Water is almost always cooler than the patient, and nearly all drowning patients will have some degree of hypothermia—even in warm weather. Remember to warm all your patients, especially if they’re in full arrest. The phrase “they are not dead until they are warm and dead” comes from drowning resuscitation.

Special Considerations
There are several special considerations in the treatment of drowning victims.

  • >> Patient positioning: Many drowning resuscitations begin along sloped riverbanks, beaches, boat ramps or other uneven terrain. When positioning the patient, you do not want to place them along the slope in such a way that blood will collect at the feet or at the head. Rather, you want to position them perpendicular to the slope, which is typically parallel to the water (see photo this page).
  • >> CPR in the water: In the case of patients still immersed in the water in cardiac arrest, the patient should be rapidly extricated to a hard surface (e.g., boat or land) prior to initiation of CPR. For prolonged extrications, intermittent rescue breathing may be appropriate. Full CPR in the water, however, even with commercially available floating devices, is rarely effective and delays the most important intervention to a drowning patient in cardiac arrest—effective CPR and oxygenation.
  • >> AED usage: As detailed earlier, most drownings are due to hypoxia, and ventricular fibrillation (v fib) is uncommon. However, if v fib or ventricular tachycardia without a pulse is encountered, defibrillation may be indicated. It’s important to remember that water is a good conductor of electricity, and rescuers and bystanders can be injured.11
  • >> Spinal immobilization: The incidence of trauma in submersion injury victims is low (excluding diving, boating and surfing injuries).11 However, some spinal cord injuries occur in or near water, and it’s often unclear whether an unconscious drowning victim has sustained a C-spine injury. Routine C-spine immobilization isn’t necessary, but EMS workers should provide needed immobilization based on protocols or index of suspicion if there’s a concern.
  • >> Transport: Transport may not always be required for drowning victims. Every day, lifeguards rescue, treat and safely release drowning victims. Submersion victims who are asymptomatic, normal and don’t have a cough can be treated and released after a period of monitoring them and educating them on the signs and symptoms of respiratory distress that should prompt a visit to emergency department (ED) (e.g., shortness of breath, wheezing, severe cough and unusual behavior). All other victims should be transported. Submersion victims with post-mortem changes (e.g., rigor mortis, livor mortis or dependent lividity) shouldn’t be transported and declared dead on scene. Most guidelines call for termination of resuscitation after 25 minutes of CPR (after the patient is warmed to 94° F) or if the patient has been submerged for greater than 60 minutes. This should be done in accordance with local resources and protocols. 

Prevention
Research has shown the following groups have the highest risk for drowning:

  • >> Children: Children ages 1–4 have the highest drowning rates in the U.S. In 2007, among children 1–4 years old who died from an unintentional injury, almost 30% died from drowning.1 Fatal drowning remains the second-leading cause of unintentional injury-related death for children ages 1–14 years.
  • >> Males: Nearly 80% of all drowning victims are males.
  • >> African American: The rate of fatal drownings in African Americans is 1.3 times that of whites. The fatal drowning rate of African American children ages 5–14 is 3.1 times that of white children in the same age range.
  • >> American Indians and Alaskan Natives: The rate of fatal drownings in American Indians and African Natives is 1.7 times that of their white counterparts. For American Indian and Alaskan Native children, the fatal drowning rate is 2.3 times higher than for white children.12
  • In addition to age, gender and ethnicity, other factors are associated with an increased incidence of drowning.
  • >> Lack of supervision and barriers: All children, regardless of swimming ability, should be supervised by a lifeguard or another adult capable of rescue swimming. In the household, it’s important to closely supervise young children when they’re in the water, whether it’s a pool or bathtub. But when children aren’t supposed to be in the water, supervision alone isn’t enough to keep them safe. Also, remember that children can fall into buckets containing water and drown. Homes should be periodically inspected for risks and barriers.  

Such barriers as pool fencing should be used to help prevent young children from gaining access to the pool area without caregivers’ awareness. There’s an 83% reduction in the risk of childhood drowning with a four-sided isolation pool fence, compared with three-sided, property-line fencing. Among children ages 1–4 years old, most drownings occur in residential swimming pools. Most young children who drowned in pools were last seen in the home, had been out of sight less than five minutes and were in the care of one or both parents at the time.

  • >> Natural water settings (e.g., lakes, rivers or the ocean): The percentage of drownings in natural water settings increases with age. When a location was known, 65% of drownings among those 15 years and older occurred in natural water settings.
  • >> Lack of life jacket use in recreational boating: In 2009, the U.S. Coast Guard received reports for 4,730 boating incidents; 3,358 boaters were reported injured, and 736 died. Among those who drowned, nine out of 10 weren’t wearing life jackets. Most boating fatalities that occurred during 2008 (72%) were caused by drowning, with 90% of victims not wearing life jackets; the remainder were due to trauma, hypothermia, carbon monoxide poisoning or other causes.
  • >> Alcohol use: Alcohol use is involved in up to half of adolescent and adult deaths associated with water recreation and about one in five reported boating fatalities. Alcohol influences balance, coordination and judgment; its effects are heightened by sun exposure and heat.
  • >> Seizure disorders: For persons with seizure disorders, drowning is the most common cause of unintentional injury death, with the bathtub as the site of highest drowning risk.13
  • As with many injuries and illnesses encountered in EMS, prevention is often the most effective strategy for reducing death and disability. This is especially true with drowning. EMS and the fire service should take a proactive strategy in drowning prevention by developing and implementing local prevention programs. Many programs have already been developed by the American Red Cross and similar organizations and are available. 

Proactive prevention strategies include the following:

  • >> Public education: Public education can be an effective strategy in drowning prevention. Parents and caregivers need to be advised that they should never—even for a moment—leave small children alone or in the care of another young child while in bathtubs, pools, spas, wading pools or near irrigation ditches or other open standing water.14 An encounter with an EMS system or a hospital ED, even if unrelated to drowning, is often a “teachable moment” when parents are more receptive to education about minimizing drowning risks.15 Public events and community meetings are often a good time to provide education about drowning prevention (see photo, p. 68). Drowning prevention strategies shouldn’t be limited to childhood prevention.
  • >> Swimming instruction: Learning to swim is one of the best tools for drowning prevention. The American Academy of Pediatrics recommends that, after the age of 5, all children should learn how to swim.16 Recent research, also by the American Academy of Pediatrics, has indicated that formal swimming lessons can reduce the incidence in drowning for patients ages 1–4 years.17 Fortunately, pediatric drowning prevention strategies seem to be working because pediatric drowning deaths have declined between 1993 and 2008.18
  • >> Surveillance: Inspection of private pools can play a significant role in drowning prevention. EMS personnel can inspect high-risk factors around pools and make recommendations to the owners. Such factors include fencing and gating, the absence of necessary rescue equipment (e.g., floats and ropes), pool drainage systems, toys and objects that look like toys, and pool alarms. In homes with children, particular attention must be paid to access points to the pool area from the house and yard, and all locks must be childproof. It’s often prudent for parents to have an alarm system for the pool. These devices detect surface waves or subsurface disturbances and activate an alarm. Also, don’t forget the risk of pool drains. The pumps that power waterflow through pools and spas are powerful and create a significant amount of suction that can entrap hair or body parts. This is especially true in pools and spas with a single drain. Modern pool technology calls for multiple drains to reduce this risk (see photo, p. 72).19–20 

Summary
The past 40–50 years of research and experience have given us improved knowledge of the pathophysiology and treatment of drowning injuries. Still, an all-too-common event, the morbidity and mortality of drowning can be mitigated by prevention, recognition and target treatment. Old terms, such as “near drowning” and “secondary drowning,” are confusing and misleading, and use of these terms should be abandoned.21  

Most importantly, EMS personnel should understand that drowning is a hypoxic event resulting from submersion in a liquid. Most BLS and ALS strategies are designed to treat cardiac causes of respiratory and cardiac arrests (with recent change to a CAB algorithm). Drowning, however, is initially a purely hypoxic event and should be treated as such with ventilation and oxygenation (with an ABC algorithm). EMS and the fire service, because of their presence in the community, are uniquely positioned to play a major role in drowning prevention and treatment. JEMS

References
1. Centers for Disease Control and Prevention. (2009). 10 Leading Causes of Injury Death by Age Group Highlight Unintentional Injury Deaths, United States 2009. In Centers for Disease Control and Prevention. Retrieved Apr. 11, 2012, from www.cdc.gov/Injury/wisqars/pdf/Leading_Causes_injury_Deaths_Age_GRoup_Hi....
2. World Health Organization. (2004). The Global Burden of Disease: 2004 Update. In World Health Organization. Retrieved Apr. 11, 2012, from www.who.int/healthinfo/global_burden_disease/GBD_report_2004update_full.pdf.
3. Marinozzi S, Bertazzoni G, Gazzaniga V. (2012). Medical Instructions of the XVIII Century to Resuscitate the Apparently Dead: Rescuing the Drowned to Define the Origins of the Emergency Medicine, Emergency Medicine—An International Perspective. In InTech. Retrieved Apr. 11, 2012, from www.intechopen.com/books/emergency-medicine-an-international-perspective....
4. Laerdal Medical. (n.d.) The Girl from the River Seine. In Laerdal Medical. Retrieved Apr. 11, 2012, from www.laerdal.com/us/docid/1117082/The-Girl-from-the-River-Seine.
5. Layon AJ, Modell JH. Drowning: Update 2009. Anesthesiology. 2009;110(6):1,390–1,401.
6. Orlowski JP, Szpilman D. Drowning. Rescue, resuscitation, and reanimation. Pediatr Clin North Am. 2001;48(3):627–646.
7. Oehmichen M, Hennig R, Meissner C. Near-drowning and clinical laboratory changes. Leg Med (Tokyo). 2008;10(1):1–5
8. Idris AH, Berg RA, Bierens J, et al. Recommended guidelines for uniform reporting of data from drowning: the “Utstein style.” Circulation. 2003;108(20):2,565–2,574.
9. Denoble PJ, Caruso JL, Dear Gde L, et al. Common causes of open-circuit recreational diving fatalities. Undersea Hyperb Med. 2008;35(6):393–406.
10. Youn CS, Choi SP, Yim HW, et al. Out-of-hospital cardiac arrest due to drowning: An Utstein Style report of 10 years of experience from St. Mary’s Hospital. Resuscitation. 2009;80(7):778–783.
11. Lyster T, Jorgenson D, Morgan C. The safe use of automated external defibrillators in a wet environment. Prehosp Emereg Care. 2003;7(3):307–311.
12. Cushing TA, Hawkins SC, Sempsrott J, et al: Wilderness Medicine Sixth edition. Elsevier: Philadelphia, 2012.
13. Hwang V, Shofer FS, Durbin DR, et al. Prevalence of traumatic injuries in drowning and near drowning in children and adolescents. Arch Pediatr Adolesc Med. 2003;157(1):50–53.
14. Centers for Disease Control and Prevention. (May 30, 2012). Unintentional Drowning: Get the Facts. In Centers for Disease Control and Prevention. Retrieved Apr. 11, 2012, from www.cdc.gov/HomeandRecreationalSafety/Water-Safety/waterinjuries-factshe....
15. American Academy of Pediatrics Committee on Injury, Violence, and Poison Prevention. Prevention of drowning. Pediatrics. 2010;126(1):178–185.
16. Quan L, Bennett E, Cummings P, et al. Do parents value drowning prevention information at discharge from the emergency department? Ann Emerg Med. 2001;37(4):382–385.
17. Brenner RA, Saluja G, Smith GS. Swimming lessons, swimming ability, and the risk of drowning. Inj Control Saf Promot. 2003;10(4):211–216.
18. Brenner RA, Taneja GS, Haynie DL, et al. Association between swimming lessons and drowning in childhood: A case-control study. Arch Pediatr Adolesc Med. 2009;163(3):203–210.
19. Bowman SM, Aitken ME, Robbins JM, et al. Trends in U.S. pediatric drowning hospitalizations, 1993–2008. Pediatrics. 2012;129(2):275–281.
20. Modell JH. Prevention of needless deaths from drowning. South Med J. 2010;103(7):650–653.
21. Szpilman D, Bierens JJ, Handley AJ, et al. Drowning. N Engl J Med. 2012;366(22):2,102–2,110.



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Related Topics: Patient Care, Airway and Respiratory, submersion, resuscitation, pediatric drowning, immersion, drowning, Bryan Bledsoe, AHA, ABCs, Jems Features

 

Andrew Schmidt, DO, MPH,is a second-year emergency medicine resident at the University of Florida College of Medicine-Jacksonville and co-founder of Lifeguards Without Borders. He can be contacted at Andrew@lifeguardswithoutborders.org.

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Bryan Bledsoe, DO, FACEP, FAAEM, EMT-PDr. Bledsoe is an emergency physician and Professor of Emergency Medicine and Director of the EMS fellowship at the University of Nevada School of Medicine in Las Vegas. He is the author of numerous EMS textbooks and articles.

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Justin Sempsrott, MD,is a third-year emergency medicine resident at the University of Nevada School of Medicine and co-founder and chief executive officer of Lifeguards Without Borders. He can be contacted at Justin@lifeguardswithoutborders.org.

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Seth C. Hawkins, MD, FACEP, FAAEM, FAWM

is an emergency physician and EMS medical director in North Carolina. He’s the founder of the Appalachian Center for Wilderness Medicine and the Carolina Wilderness EMS Externship, as well as a board member of Lifeguards Without Borders. He is the former assistant medical director of the Burke (N.C.) EMS Special Operations Team. He's also the former EMS coordinator for Blue Ridge HealthCare in Morganton, N.C., and fomer assistant professor at the Emergency Care Program at Western Carolina University. He can be reached at hawk@aya.yale.edu.

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