With urban and rural swiftwater rescues from flooding or other misadventures; backyard pools of all shapes, sizes and depths; inebriated persons in roadside puddles; and even toddlers upending themselves in buckets, the chances of a rescue team having to deal with a wet victim are very high. While the 'time immersed' does impact survival, the initial treatment of an immersion incident will have a significant impact on the eventual recovery of the survivor.
If the mechanism of injury involves alcohol or other intoxicants, high-powered personal watercraft (PWC), a diving accident or a fall of more than 10 meters, complications should be expected from significant trauma to the head, face, spine or other portions of the anatomy. Another source of secondary trauma is from whitewater incidents, where the victim may be ejected from a canoe, raft or kayak.
THE DROWNING PROCESS
In the mid 1990s, the World Health Organization and World Bank sponsored a study on the Global Burden of Disease, which found that drowning was a much underappreciated cause of death worldwide.1 The first World Conference on Drowning, held in Amsterdam in 2002, developed a new definition of drowning to simplify reporting of injuries and deaths due to immersion. The expectation is that, by replacing many of the other terms and definitions currently associated with drowning, a more comprehensive and useful Utstein-type database can be developed.2 Public health organizations can then use the data to improve prevention efforts. While most injury reporting will be the province of hospital emergency departments, Utstein-style data reporting may be required for EMS divisions of public service districts. A number of primary and supplemental criteria have been identified, including:
- Precipitating event
- Degree and duration of immersion/submersion
- Time to first resuscitation efforts (duration of untreated cardiac arrest)
- Initial response to treatment
- Adequacy and type of ventilation
- Measurement and production of blood flow during chest compressions (demonstrated by palpable pulses in the field), and the definition of return of spontaneous circulation
- Patient condition on arrival at the emergency department.
Other criteria are also included.3 It is hoped that improved reporting of standardized information will help improve the prevention and treatment of immersion victims in the future.
Overall, the U.S. reported 1.93 drowning deaths per 100,000 people for all age groups in 1995, with almost 3,600 unintentional deaths in 2005.4,5 Additionally, there were 14 ED visits and four hospitalizations per death, with the concomitant burden on EMS and ED services. Of these, 25% of victims were under age 15. However, an important point to consider is that the majority of victims suffer no significant injury and often do not seek treatment, leading to significant underreporting of the problem. Improved standards of living and education can make marked improvements in the rates of death, as demonstrated by the Netherlands. The Dutch went from 14.4 deaths per 100,000 person-years in 1900 to only 0.6 deaths per 100,000 in 2000 with a combination of improved swimming instruction and general education. This compares to the current 14.2 deaths per 100,000 person-years in Africa.6 EMS agencies, in conjunction with local swimming pools and the Coast Guard Auxiliary, can improve the survival rate by helping sponsor swimming lessons, especially for lower-income families.
Like so many other causes of death or disability, extremes of age make a significant difference. When considering infants and young toddlers (age birth to 30 months), the major risk areas are bathtubs, toilets and water buckets where the infant is not supervised. Most of us are familiar with the warnings that have been printed on five-gallon buckets for years, because, like toilets, a toddler can upend into a bucket and not be able to get out without assistance. Another consideration in toddlers is the suspicion of child abuse, including Munchausen's by proxy,7 even with an apparently clear-cut explanation for the lack of supervision.8
With older toddlers and children (ages 1–12 years), drowning is actually the second leading cause of unintentional death, accounting for almost 30% of all deaths and following only trauma as a cause.4 Children under age 4 are most at risk, due to their activity levels and ability to escape notice at the drop of a hat. Preschoolers are at very high risk from home pools, even wading pools, as they are big enough to handle unlocked gate latches or doors intended to separate them from the attractive pool. Most of the time that kids this age are on 'open water' (lakes, rivers, etc.), there is a fair chance they will be equipped with water-safety devices and effective supervision. Drown-proofing techniques and swimming lessons are an effective way to help prevent injury and death starting at or about age 5, but are of limited utility before that age.9 Because of the 'attractive hazard' factor, many municipalities have enacted zoning, fencing or other restrictions on pools, sometimes requiring secured fences for pools as shallow as 36 inches. Pool covers, floating alarms and even video cameras in the pool area will not substitute for appropriate fences with locked gates and proper adult supervision in preventing death and injuries in children this age range.11
There is a dip in mortality and morbidity between ages 10 to 15 or so, as the children are now old enough to understand some of the dangers of being around water and to appreciate swimming lessons, and have not started the social competition of typical teens. Starting at age 15 up to around age 24, a second peak of risk is noted, as the kids have become more independent, have unsupervised access to vehicles, and suffer from peer pressure unbalanced by caution. High-risk areas for the 'teens and tweens' include lakes, rivers and other bodies of open water, and are often associated with small boats and personal watercraft.4 Additionally, alcohol or drugs are frequently involved, even if everyone in the party is under age 19.11 Those older than 19 usually have friends who can supply alcohol, while teens 18 and younger are less likely to have that kind of access. This was the reasoning behind increasing the legal drinking age to 21 some years ago. In certain areas, drowning injuries have been associated with gang activities, including initiations or punishment, or with fraternity-style hazing. A fair percentage of teen drowning victims may be suicides.4
From about age 25 through 45 there are fewer deaths, but this starts to increase after age 45. Most episodes are still associated with open water like lakes and rivers, and with watercraft. Frequently, there is significant alcohol involvement. Parkinsonism or other mobility impairment or cognitive dysfunction may also contribute to the increasing mortality and morbidity.8
Generally, there are four males for every female involved in drowning incidents. Much of this difference may be due to increased risk-taking of young males as a result of the phenomenon of 'acute testosterone poisoning.' Interestingly enough, there is some evidence that females who drown may have a lower survival rate than males in a similar situation, but this needs to be confirmed by further research. If boats are involved, the risks are even higher for males, as around 12 males are injured or killed in watercraft incidents for every female involved.8 Approximately 90% of all boating-related deaths are a result of submersion, not direct trauma from a boating collision. As with many other conditions requiring an EMS response, warm water drowning victims who are pulseless and apneic have a very poor recovery prognosis.
Other risk factors are many and varied. Alterations of consciousness are obviously important, including the previously mentioned intoxicants (drugs and alcohol), seizure activity, stroke, myocardial events, hypoglycemia and other syncope. Whitewater recreation, including tubing, rafting, canoeing and kayaking, as well as ocean surfing and kayaking, carry the additional risk of significant trauma in addition to submersion. River and surf rip current effects are often underappreciated, but significantly contribute to both the trauma and submersion problems. Scuba diving is generally regulated because of its set of increased risk factors, which may be reduced considerably by proper training. These include panic (especially induced by equipment failure or cloudy water), exhaustion, hypothermia, barotraumas (either descending or ascending) and nitrogen narcosis. Marine envenomations can be problematic in warm, shallow, salt-water environments, but are less of a factor in freshwater situations. Skin-diving (breath-holding type) is considered 'safer' because there is no use of pressurized air to support long periods under water, and thus is less regulated. However, breath-holding diving has two unique risk factors not seen in scuba: deep water and shallow water blackout.8
ANATOMY, PHYSIOLOGY AND PATHOPHYSIOLOGY
There are a number of anatomic and physiologic factors to consider in drowning victims. Glottal locking is perhaps the most common case in survivors, where fluid in the posterior oropharnyx or across the vocal folds causes a protective spasm of the folds that prevents aspiration. Most of these people come up for air coughing and sputtering, and do not require further emergency intervention. So-called 'dry drowning' is involved in only about 15% of deaths.4
As the victim remains submerged, hypoxia and hypercarbia increase, suppressing consciousness and causing the vocal folds to relax and fluid to pass into the lungs, either passively or by aspiration if there is a remaining breathing drive. This 'wet drowning' is the cause of the other 85% of drowning deaths.
Impairment of gas exchange, either from the locked glottis or fluid in the lungs, will result in the same kind of blood gas changes seen in any other cause of apnea. These include hypoxemia, which in turn causes most non-trauma neurological damage;4 an initial hypercapnea that increases the breathing drive; a terminal hypercapnea, which leads to full loss of consciousness; and loss of any other protective reflexes (including struggles to swim to the surface).
As previously noted, breath-holding diving has additional risks known as deep and shallow water blackouts. Deep water blackout (DWB) is a hypoxic syncope that may be seen during ascent from a deep (over 10 meters/33 feet) free dive, possibly due to decrease in partial pressure of oxygen as pressure decreases, as well as activity-related hypoxia. Because of the pressure changes, this often occurs near or at the surface. It may even occur after the victim reaches the surface and tries to breathe. DWB often results in significant aspiration, because the victim will involuntarily attempt ventilation while still submerged.
A different type of hypoxic blackout occurs when someone tries to swim a long distance under water. This 'shallow water blackout' generally involves depths less than 2 meters (6.5 feet) and is related to activity-induced absolute hypoxia following deliberate hyperventilation as often practiced in long-distance underwater free swimming. This is because unconsciousness from hypoxia occurs before hypercapnia increases to the point of forcing ventilation attempt.8
We have long considered water tonicity a significant cause of morbidity and ultimate mortality, and we still divide immersion into fresh (less than 0.2%/2000 ppm), 'natural salt water' (3.5%/35,000 ppm salinity), and 'salt-water pools' (0.2–0.6%/2000–6000 ppm salinity).12 Recent research has shown that most of the time, even with 'wet drowning,' not enough fluid enters the lungs to cause electrolyte problems from the water itself.13 While impairment of gas exchange can result from as little as 1–3 ml/kg,4,8 normal body functions clear the excess fluid over the space of a couple of days, allowing for the return of normal pulmonary function.14 Similar research has shown that ingestion is more of a risk than aspiration, especially in pediatric cases, as a larger relative volume is usually involved. Even in small-volume aspiration (1–2 ml/kg), surfactant washout, especially in salt water, may occur, worsening acute respiratory distress syndrome (ARDS). This has caused at least one reported child death here in the U.S.15 In moderate volume ingestion (11 ml/kg), mild changes in fluid balance may be noted, but it takes a large-volume ingestion (22 ml/kg) to show significant electrolyte changes. As always, water will move down the concentration gradient (e.g., fresh water moves toward the blood and salt water draws water into the lungs).
However, while aspiration of clean water is a relatively small problem, aspiration of various types of pollution, including chemicals, biologicals (such as sewage or warm, stagnant water) or gastric contents, can cause major problems in survivors. EMS treatment is no different than with clean water, as virtually all of these problems will occur after admission to the ICU; however, rescue personnel may require further personal protective gear (or rapid decontamination) for protection from the pollution.
Some of the best rescue stories over the years have involved interesting changes produced by immersion in cold water, especially in young children. This has been associated with the poorly understood 'mammalian diving reflex,' which provides a protective shutdown of neurologic function during sudden immersion in cold (&llt;20°C) water. Hypothermia is common, and "not dead until warm and dead" is still the gold standard in the ED. However, recent research has shown that leaving the pulseless patient cold and wet during transport to the ED is worth consideration, as there is a growing body of evidence for the positive effects of hypothermia.4,13 This must be done in accordance with local medical control guidelines.
Trauma considerations are always part of the response to a submersion injury.4,8 These include, but are not limited to: spinal cord injuries from diving into shallow water, ejection from personal watercraft or during whitewater activities, crush injuries from ejection into whitewater or from personal watercraft, lacerations from propellers or broken glass/torn metal, and impaled objects from whitewater or personal watercraft incidents. Persons who fall or jump from high bridges (over 10 meters) are also at high risk for blunt and spinal trauma. Rare (but highly publicized) incidents have involved entrapment against suction grids with dramatic injuries.16 Protective covers for pool drains are now required, but some older, private pools may not have been retrofitted.17
Victim presentation on EMS's arrival will vary dramatically, depending on the situation. A victim from a local swimming pool or patrolled lake swimming area, where policy may require EMS activation any time a lifeguard has hauled a sputtering victim from the water, may not require transportation, but does require a good evaluation before accepting refusal of transportation. Hypothermic victims with moderate symptoms after a raft overturns during a slow river trip will require moderate support with warming and oxygen, but will often be able to be released from the ED after treatment. Incidents in unpatrolled swimming areas on a lake or river, or from whitewater incidents where the victims have been ejected into fast-moving water, may result in severe symptoms, where the patient requires significant support with intubation and ventilation and will spend time in the ICU after stabilization in the ED. Lethal situations, where the victim is pulseless and apneic on arrival of the EMS squad and the incident involves warm (>20°C) water, are often associated with small children and home swimming pools or solo fishermen. In warm-water incidents, the recovery rate of pulseless victims is as dismal as with unobserved cardiac arrest.4,8
As with any EMS response, scene safety is paramount, because an injured or entrapped rescuer is just another victim. Various training programs provide appropriate training for rescue and other EMS personnel, and departments with known water hazards beyond backyard pools are encouraged to provide that training to responding personnel.18,19 Situations again vary from simple, shallow pools to the flat waters of a calm pond or lake, with the most challenging rescues occurring in the fast water of floods and wilderness whitewater streams or rivers.20 Rescue/recovery diver training, available from the Professional Association of Diving Instructors (PADI) and the National Association of Underwater Instructors (NAUI),21 as well as other sources of advanced scuba instruction, is useful for flat-water situations (slow currents as found in lakes, bays and larger, slow-moving rivers). Swiftwater rescue training is available from sources like the International Rescue Instructor's Association and Rescue 3 International, among others.22 Just as water entry techniques require training, rescue boat operators should also be trained, as there are significant hazards that even experienced 'flat water' boaters do not appreciate.23 If there is a significant search area to be covered, then coordination of air assets, primarily helicopters, is essential to reduce the time to find survivors. Just as structural entry firefighting requires intensive, realistic team training for personal safety, swiftwater rescue requires the same.
Trained and qualified personnel directly involved in the rescue who might end up in the water should have available and be wearing protective equipment (as a minimum, protective technical rescue headgear; gloves; a wet, dry or other exposure suit to prevent rescuer hypothermia; and an appropriate personal flotation device).24 Class I and II PFDs are designed for use in rough water and will inherently turn an unresponsive victim face up. Class III PFDs are the most common type in use on the water, as they are required for recreational boating and are used by the USCG Auxiliary. Some Type III PFDs are 'speed-rated' for use by water skiers and PWC users. Type IV PFDs are 'throwable,' such as ring or horseshoe-style devices. Type V buoyant work vests, often used by waterborne workers (tugboat deck hands or bridge workers) are less desirable, as they have no inherent face-up capability. They do, however, provide good 'workability.' Other appropriate equipment as required by the situation, common sense and unit operating procedures should be available and used.25
The use of typical bunker firefighting gear, including traditional 'beaver tail' helmets, during water rescue is dangerous if the rescuer ends up in the water. The bunker gear quickly saturates, causing a critical loss of buoyancy and hindering swimming. The projections on the helmet (as opposed to the relatively smooth rim of technical rescue helmets) tend to catch in the current and on underwater obstructions, potentially forcing the rescuer's head under water. Both of these problems will endanger the rescuer and should be discouraged. It cannot be emphasized enough that swiftwater rescue is more dangerous to firefighters than structural entry! Personal protective equipment designed to protect a firefighter in structural entry situations makes work even more dangerous to the firefighter attempting a water rescue!
The use of 'short-haul' techniques with dangling ropes/slings from an aircraft, or even rescuers/victims hanging from the helicopter's skids rather than full hoist operations, are advocated here. While this works best with careful coordination of rescuers and benefits from proper training of the air crews, it can be effective, as demonstrated by the ad hoc efforts surrounding the crash of Air Florida Flight 90 into the Potomac River on Jan. 13, 1982, where all of the survivors were extracted by this method under conditions that were nothing short of devastating.26
The old Red Cross/Boy Scout lifesaving adage of 'reach, throw, row, then go' was updated based on research conducted by the late Jim Segerstrom to include: talk, reach, wade, throw, helo, row, go, tow. This is a reminder that rescuer safety should include: talking the victim down from a panicked state to allow him to self-rescue; reaching for the victim with an appropriate pole, extension ladder or other device; throwing a lifeline with a ring or other buoyancy device attached; wading into shallow water to assist the victim in the last stages of rescue or to allow thrown devices to reach him; coordinating a helicopter rescue; using a boat or other rescue craft; and only going into the water as a last resort.15 Scene safety and the use of low- to high-risk rescue techniques cannot be emphasized too much.
Rescue craft should be of an appropriate size (ranging from a simple surfboard to the Coast Guard's 47-ft-long self-righting lifeboats), be kept in good condition, and manned by appropriately trained personnel. Certain types of personal watercraft are now accepted as 'rescue watercraft' and are being used to good effect in open water areas, such as beaches on large lakes, bays and the seashore.27 It is not a good idea to strap a patient already secured in a rescue basket to the deck of the boat, as the boat may founder, with tragic results. Numerous other incidents, most involving either swiftwater or floodwater rescues, have occurred due to lack of proper training or equipment. Again, a rescuer who becomes a victim simply complicates the situation. Some way, such as a flush fantail (no transom at the aft end of the craft), is needed to simplify getting both the victim and the rescuers on the boat.
Like most trauma, immersion injuries are situations where good EMT-Basic skills really do save lives and can reduce severe disabilities. No matter what type of immersion, the field treatment is initially the same:
- Open the airway (with appropriate C-spine precautions)
- Start ventilation with supplemental oxygen
- Provide compressions to restore circulation, if needed
- Apply and utilize an automatic external defibrillator, if available and allowed under local protocols, taking appropriate precautions due to the wet patient and deck
- Provide rapid transport to a higher level of care for victims not rapidly responding to basic techniques.
Due to the frequency of hidden cervical spine injuries in unconscious immersion victims, use appropriate cervical spine precautions while the airway is cleared and ventilation started. Various methods of spinal packaging have been used over the years, including floating backboards (wood or plastic), Stokes baskets with attached flotation collars, or a Sked28 with a flotation collar. The Sked is a proprietary, flexible rescue device that improves on the vertical and horizontal extrication abilities of both the Stokes rescue basket and the military's Vietnam-era litter, semi-ridged jungle extraction. All are capable of being lifted out of the water by various methods, and, when properly applied, all provide at least some spinal protection, as well as ease the handling of limp, unresponsive victims.
Further basic care will involve shallow suctioning to remove fluids, finger sweeps for visualizing obstructing objects in the posterior pharynx, oral or nasal pharyngeal airways, and use of supraglottic airway techniques as allowed by local protocol. Adequate ventilation remains the gold standard as with any situation involving apnea but not pulselessness. Ventilations should be started while the victim is still in water, but compressions can wait until a solid surface is available and the patient has had a better evaluation,8,13 as compressions are potentially hazardous if the patient is severely hypothermic and pulseless but not in ventricular fibrillation or asystole.29 It should be noted that the Heimlich maneuver is of little use, as there generally is no solid food bolus to be expelled. Again, leaving a pulseless victim hypothermic is worth considering for the protective effect on the nervous system.30
An AED may be of use, especially around pools or other patrolled swimming areas where there is a significant likelihood that the victim was recovered soon after immersion, and, while pulseless, is not yet severely hypothermic. Defibrillation is not particularly effective if the patient is severely hypothermic, hypoxic or acidotic. Recent research is showing that, in warm, pulseless patients, there may be an advantage in providing uninterrupted chest compressions without ventilations while preparing to use the AED if the patient is already out of the water and on a firm surface. Take appropriate precautions for rescuer safety when using any electrical device on a wet patient in a wet environment.
ALS techniques (including invasive airways, medications and intravenous fluids) should not delay transport from the field to the emergency department. If the victim has a history of heart problems and was quickly recovered from immersion, full ALS may be of some utility. The exception is in the delivery of continuous positive airway pressure (CPAP) or positive end expiratory pressure (PEEP), depending on the victim's spontaneous respirations, or the lack thereof, and local protocols. As far back as 1996, a small case report study showed that CPAP delivered using a nasal mask improved oxygenation in breathing drowning survivors.31
Because of the increased utilization of remote water recreational areas (river rafting, boating, etc.), ground access may be limited and transport by water, especially if the rescue craft has to work against a current, is often slow. In addition to the search and rescue aspects described previously, helicopter EMS may have significant value, if an appropriate landing zone can be established near the rescue site. Some HEMS units do not include hoist capability (U.S. military medical and Coast Guard helicopters all have hoist capability, as do some of the larger public safety operators). If available, it can significantly reduce transport time of badly injured survivors.32
Careful attention to scene safety, immediate institution of EMS basic care and rapid transport to definitive care of the immersion victim is vital to improve the ultimate outcome of drowning survivors. ALS care, while important in a few instances, should not delay transport in most cases.
Acknowledgements: Thanks to Gene Gandy, JD, LP, and Chris Johnson, BHS, NREMT-P (ret.), for their advice and comments. The rescue segment is dedicated to the memory of Jim Segerstrom (1946–2007), a founder of Rescue 3 International and educator of swiftwater rescue for many years.
1. Van Beeck EF, Branche CM, et al. A new definition of drowning: Towards documentation and prevention of a global public health problem. Bulletin of the World Health Organization WHO:83 (11) November 2005.
4. Shepard SM. Drowning. http://emedicine.medscape.com/article/772753-overview.
6. WHO, ibid.
7. Mason JD. Munchausen's Syndrome by Proxy. http://emedicine.medscape.com/article/806735-overview.
8. Verive M. Near Drowning. http://emedicine.medscape.com/article/908677-overview.
9. American Academy of Pediatrics. Prevention of drowning in infants, children and adolescents. http://www.guideline.gov/summary/summary.aspx?doc_id=4255&nbr=003255&string=drowning+AND+pediatrics Aug 2003, accessed June 27, 2009.
11. Gulliver P, Begg G. Usual water-related behavior and near-drowning incidents in young adults. Australian and New Zealand Journal of Public Health 29(3):238–244, 2005.
12. http://phoenix.about.com/cs/wet/a/saltpool01.htm, accessed Nov 12 2008.
13. Circulation 2005, part 10.3. http://circ.ahajournals.org/cgi/content/full/112/24_suppl/IV-133.
14. Jenkinson SG, George RB. Serial pulmonary function studies in survivors of near drowning. Chest 77(6)777–80, Jun 1980.
15. Personal communication with Chris Johnson, BHS, NREMT-P (ret.).
18. Organizations mentioned in this section are for illustration and initial points of contact. Prospective rescue units should evaluate course offerings and obtain appropriate instruction for their situation and needs.
19. http://en.wikipedia.org/wiki/Swiftwater_rescue quoting NFPA 1670 Standard on Operations and Training for Technical Rescue.
24. Maloney ES. Chapman's Piloting & Seamanship, pp. 90–97, Hearst Books, 65th Ed, 2006. Also see USCG information at http://www.uscgboating.org/safety/fedreqs/equ_pfd.htm.
25. www.uscg.mil/d13/diraux/docs/dirauxnotes/200408.pdf. Includes information on the USCG requirements for Personal Protective Equipment beginning on page 3.
29. Harris M. Near Drowning, Clinical Review. Br Med J 327:1336–1338, 2003.
30. Bernard SA, et al. Treatment of comatose survivors of out-of-hospital cardiac arrest with induced hypothermia. N Engl J Med 346:557–563, 2002.
31. Dottorini M, et al. Nasal continuous positive airway pressure in the treatment of near-drowning in fresh water. Chest 110:1122–1124, 1996.
32. Personal experience with UH-1H/V helicopters in the 4th Platoon, 507th Medical Company (air ambulance) from 1980–83, as well as knowledge of operations involving UH/MH/SH-60 Blackhawk series helicopters. The shots of a U.S. Army MEDEVAC UH-1 drowning in the opening sequences of Rescue 911 were shots of our sister platoon (3/507th, based at Fort Hood, TX) during the flooding in Central Texas in 1982. Both aircraft used the Western Gear high-speed hoist at least through 1991. U.S. Air Force, Navy and Coast Guard helicopters often have fixed hoists mounted outside of the right side cargo door. A training manual can be found at www.helirescueconsult.com/PDFs/training.pdf.
Charles Krin is a retired family and emergency medicine physician with over 30 years' experience in the field. He was called up in support of Desert Storm in 1991, where he provided medical care while assigned at Ft. Hood, TX. He later participated in the local response to Hurricanes Opal, Katrina and Rita while practicing in Louisiana.