Unusual Resucitation situations: Environmental Emergencies

When an environmental emergency progresses to respiratory and/or cardiac arrest, standard treatment is less likely to succeed. This article reviews assessment and treatment for unusual resuscitation situations resulting from the environmental emergencies of lightning injury, drowning and severe hypothermia.

Lightning Injuries

Lightning is wildly unpredictable in where it strikes and the severity of injuries it causes. It is the second leading weather-related cause of fatalities in the United States. An average of 67 fatalities per year are reported, but many researchers believe deaths and injuries are underreported because lightning is often not recognized as the cause of death or injury.

The energy of a lightning strike super- heats the surrounding air to as much as 50,000º F in a few millionths of a second. A lightning bolt can generate between 100 million and one billion volts of electricity. Lightning’s electrical energy can disrupt the body’s electrical communication pathways, especially in the heart and brain. The superheated air at the strike location is at extremely high pressure, creating a shock wave that expands outward for 10 m before becoming an ordinary sound wave. It can cause blunt trauma to the patient from the concussive force.

According to lightning injury expert MaryAnn Cooper, MD, lightning injuries range from trivial to fatal and are categorized as either immediate or delayed. Immediate injuries like cardiac arrest are instantaneous and unpredictable. The prognosis for patients with severe injuries is poor. Delayed injuries, which are a result of neurological insult to the brain after lightning strike, might not present until hours or days later.

Cardiopulmonary arrest is the only immediate cause of death for lightning-strike victims. The electrical effect of lightning sends the heart into ventricular standstill, or asystole, and paralyzes the brain’s respiratory center, incapacitating them and putting the patient into respiratory and cardiac arrest.

Respiratory arrest persists longer than cardiac arrest. Heart automaticity, the heart’s own electrical system, reorganizes contractions quickly. At this point, the heart is pumping but is not being supplied with oxygen.

As respiratory arrest continues, the heart becomes hypoxic, leading to arrhythmias and, ultimately, the return of cardiac arrest. Immediate basic and advanced cardiac life support skills can prevent hypoxia-related cardiac arrest.

Before we discuss assessment and treatment of lightning-related cardiac arrest, it is important to dispel myths about lightning strikes that may perpetuate improper actions that delay treatment and put rescuers at risk.

A common myth says, “If it is not raining, I am safe.” In fact, lightning can strike 10–15 miles from the storm, with clear blue sky overhead.

Lightning can also strike the same place twice. If an area or object was hit once, there is a chance it will be hit again.

Another myth that causes considerable delays in treatment is that lightning-strike victims carry an electrical charge. In fact, it is safe to immediately touch the patient and provide treatment.

Evacuating the patient is your highest priority. According to Ron Holle of the National Severe Storms Laboratory, “It is relatively unusual for victims to have major fractures that would cause paralysis or major bleeding complications unless they have suffered a fall or been thrown a distance. As a result, rescuers need to choose whether evacuation from high-risk areas to an area of lesser risk is warranted, and they should not be afraid to move the victim rapidly if necessary. Rescuers are cautioned to minimize their exposure to lightning as much as possible.”

An open garage or picnic shelter is not sufficient shelter. Rapidly move the patient to a fully enclosed structure or a vehicle with closed windows. Although spinal cord injuries from lightning strikes are rare, provide spinal stabilization for any patient who is unconscious, has fallen from a height or was thrown by the lightning strike.

Lightning has the potential to affect multiple patients, like picnickers gathered under a park shelter or a golfing foursome waiting out a storm under the same tree. For multiple victims, use reverse triage—start by attempting to resuscitate the dead. Since the only cause of death is cardiopulmonary arrest, a patient who is awake, breathing and/or has a pulse generally has a good outcome.

Treatment of Lightning Injuries

If a patient is not breathing and/or has no pulse, follow BLS or ALS protocols. Begin CPR, and if available, use an AED and shock when indicated. Monitor the patient for changes in pulse and breathing. After 20 minutes of sustained cardiac arrest from a lightning strike, return of spontaneous pulse is unlikely, but continue resuscitation efforts based on local protocols.

In addition to treating life threats, paramedics should establish IV access if the patient has unstable vitals, is not awake or is disoriented. If the patient is hypotensive, administer normal saline or lactated Ringer’s following local protocols. Regardless of patient condition, obtain a 12-lead ECG. Indications for antiarrhythmic medications and pressor agents are the same as for myocardial infarction. Being a victim of a lightning strike is not a contraindication for medications you might administer for pain, cardiac problems or rapid sequence intubation. Treat dysrhythmias with standard ALS protocols and agents.

If the patient is successfully resuscitated, gather other assessment information during transport. The patient may have other injuries, which, if they worsen, could precipitate a decline in consciousness, respiratory distress or arrest, and cardiac arrest. If lightning has flashed over the victim, there might be little evidence of external injuries. Do a thorough head-to-toe physical exam to look, listen and feel for injuries. Use serial sets of vital signs to monitor stability of the respiratory and circulatory systems and the potential for shock.

Drowning

Drowning is the second unusual environmental emergency resuscitation situation. Shortly after submersion and the cessation of breathing, pulmonary damage and cellular hypoxia create a cascade of negative consequences. In just a few minutes, cardiac arrest occurs and the likelihood of survival decreases with each passing minute. Drowning is defined as death from asphyxia while submerged or within 24 hours of submersion. Near-drowning is surviving 24 hours or more after the submersion event.

The number of U.S. drowning deaths per year is estimated at around 4,000. Drowning deaths by age peak in two areas: toddlers ages 1–4 and adolescent males. Toddler fatalities are likely to occur due to poor swimming skills and lack of supervision. Adolescent males are likely to drown in lakes, ponds, pools or rivers. They are often the victims of their penchant for risk-taking behavior combined with drugs and alcohol.

Factors that cause a patient to become submerged include exhaustion, lack of swimming skills, trauma, seizure and intoxication.

After victims lose consciousness under water, they reflexively attempt to breathe. Drowning happens when the victim attempts to breathe and aspirates water (wet drowning) or has a laryngospasm (dry drowning). In a dry drowning, laryngospasm—reflexive closing of the larynx— stops the passage of water and air into the lungs. Laryngospasm accounts for about 10% of drownings.

In wet drowning, water, debris, emesis and microorganisms flow freely down the trachea and into the lungs. The influx of water damages alveolar surfactant, which collapses the alveoli. Surfactant is what gives alveoli their structure and surface area for oxygen and carbon dioxide diffusion.

Wet or dry, the patient suffocates, becomes hypoxic, and brain damage ensues.

Many factors combine to affect drowning survival. The primary factor is likely to be the cause of submersion. Survival will be complicated if the cause of submersion was hypothermia, trauma, seizure or intoxication. Age has also been shown to be a factor in survival. Generally, young, healthy children submerged for a short duration in cold water have a better chance of survival than others.

It is unlikely that an EMS provider will witness the submersion. Rather, EMS is called when the patient is discovered. Most submersions are unwitnessed, and the time under water is difficult to pinpoint; however, an attempt should be made to do so. If the patient has been under water for less than one hour, begin treatment. The chance for resuscitation, let alone normal CNS function, is dismal if submersion is greater than one hour, and resuscitation should not be attempted. If the time of submersion is unknown, examine for signs like skin slippage and animal predation.

Cold water near-drowning refers to the water temperature, not the patient’s core temperature. Cold water is defined as water below 70ºF (21ºC). If the patient is hypothermic, the point of rewarming is to improve the likely effectiveness of defibrillation. Although the chance of survival is better in cold water submersion, its effect on drowning is not well understood, and the incidence of survival is still low. Nonetheless, our treatment focuses on cardiopulmonary arrest.

Both fresh water and saltwater, through different mechanisms, disrupt the gas exchange process at the alveolar level. Obviously, if the victim is not rescued, water salinity has no relevance for treatment. There is conjecture about salinity affecting the potential for successful resuscitation, but it is not nearly as important as other factors.

Successful resuscitation is complicated by significant hypotension, ventricular dysrhythmias and asystole from hypoxic heart tissue, neurological injury and metabolic acidosis. All of these complications are the result of decreased blood oxygen during submersion. Hypoxia, at the cellular level, leads to a shift of fluid out of the blood vessels and into other fluid compartments, resulting in hypotension. Severity of the neurological injury from hypoxia is the largest factor in resuscitation and long-term survival.

Treatment of Drowning Victims

The spectrum of injuries from submersion varies from trivial to cardiac arrest. Accordingly, concern for the patient and urgency of treatment vary with the symptoms. For the awake and breathing patient, document incident history and patient’s medical history, which may reveal the underlying cause of submersion; complete a physical exam, measure vital signs and treat what you find with what you have. Cardiac arrest patients require urgent and aggressive treatment.

Rapid on-scene BLS and ALS care is key to successful resuscitation. If the patient is in cardiopulmonary arrest, all efforts should be focused on controlling, providing and/or regaining an open airway, breathing and circulation. The first step is to remove the patient from the water. If it does not delay rescue, maintain the patient in a horizontal position during extrication and begin rescue breathing while in the water. Chest compressions are useless in the water, on a floating backboard or in the bottom of an inflatable raft. They are only effective when the patient is on a hard surface. If the patient has an unknown or positive mechanism of injury for the spine, such as a diving injury or boating accident, protect the c-spine during extrication and resuscitation.

Open the airway using the jaw thrust or head tilt, chin lift. A wet-drowning patient may have aspirated debris blocking the airway. If that is the case, use normal methods to clear the airway. It is often thought that abdominal thrusts or backslaps are necessary to clear water from the airway; however, this is not effective, since water flows with gravity to the lowest spot. Water does not lodge in the airway like a piece of food might. Abdominal thrusts to remove water are futile and only result in delaying rescue breathing and chest compressions.

For cold-water drowning situations, assess pulse and respirations for 60 seconds. If there is no pulse and respirations, begin CPR immediately. Deliver high-flow supplemental oxygen by bag-valve mask as soon as possible.

Expect the patient to vomit. In addition to aspirated water, the patient may have swallowed water and debris. Be prepared to roll the patient to the lateral position and suction the oropharynx.

Identify and treat arrhythmias. Apply an AED as soon as it is available. If the AED identifies ventricular fibrillation or ventricular tachycardia, follow prompts to deliver shocks as indicated, reassess breathing and pulse, and resume CPR.

Paramedics should utilize 12-lead ECG monitoring and defibrillation. Possible arrhythmias include ventricular tachycardia, ventricular fibrillation, bradycardia and asystole. Follow ACLS protocols to treat and monitor arrhythmias. If local protocols allow, insert a nasogastric tube to drain swallowed water and debris that might be causing gastric distention.

Any patient who was submerged (head under water) and lost consciousness needs physician evaluation, even if they are successfully resuscitated and have regained consciousness. The prognosis is good for patients who are awake by the time they arrive at the hospital. If CPR is still in progress when the patient arrives at the hospital, the chance for survival is poor. If they are resuscitated at the hospital, there is a greater than 50% chance of long-term neurological side effects from submersion hypoxia.

Hypothermia

Hypothermia is the result of excessive heat loss, inadequate heat production or both. Hypothermia onset can be fast or slow. An example of acute onset is an ice fisherman who falls through the ice, reducing his body temperature very quickly. An example of delayed onset is a cross-country skier who cools gradually during a day of extended activity, inadequate calorie intake and steady environmental exposure. Chronic hypothermia is more typical of geriatric patients who cannot afford to comfortably heat their homes, and their bodies gradually cool over days or weeks. This is often exacerbated by underlying illness and medications that affect heat production and retention. Any onset of hypothermia, if untreated, can progress to cardiopulmonary arrest.

Hypothermia is either mild or severe. Patient symptoms are used to assess the type. A mild hypothermia patient is awake, shivering uncontrollably, and has a core body temperature between 93º–95º F. The patient may show some alteration in mental status—anxiety, confusion or lethargy—and deterioration of fine motor skills. The “umbles”—mumbling, fumbling, bumbling, stumbling—is an easy way to describe the mildly hypothermic patient. Your treatment is preventing further heat loss and aggressive rewarming so the patient does not progress to severe hypothermia.

With severe hypothermia, the patient is no longer shivering and has lost consciousness. Vital signs become barely detectable to undetectable. Severe hypothermia patients need to be handled very gently, as the heart is highly susceptible to ventricular fibrillation from any disturbance or body movement. Even gentle movement could initiate v-fib. Potentially, a patient with a present but unassessable pulse could die from a fatal arrhythmia due to rough handling before treatment is even initiated. Treatment is based on core rewarming.

Assessment of severe hypothermia first requires an environment that could lead to severe hypothermia, which can range from a bitter cold winter day to a cool wet summer day, or a poorly heated home. The severe hypothermia patient is not awake and vital signs will be difficult to assess. Breathing may be infrequent—as little as twice per minute—and very shallow. Check for pulse and respirations for at least 60 seconds. Also check for other signs of circulation, such as movement or coughing.

Treatment of Hypothermia Victims

If the patient has no pulse and/or breathing, deliver three minutes of ventilations, which may increase previously undetectable cardiac activity. After three minutes, recheck for pulse before assuming there is no cardiac activity.

Assessing core temperature is difficult. Rectal temperature trails actual core temperature in the cooling and rewarming process. Off-the-shelf digital thermometers do not read temperatures in the range of severe hypothermia. In cold-weather climates, paramedics may be specifically trained and authorized to use esophageal probe thermometers, which are the preferred way to gauge core temperature. Regardless of the measurement method, environmental exposure coupled with other exam findings can help assess severe hypothermia. Temperature trending shows the patient’s response to rewarming and resuscitation efforts.

Treatment of the severe hypothermia patient includes preventing further heat loss, core rewarming, avoiding rough handling and initiating resuscitation in the field. Regardless of prehospital treatment, the patient needs emergency department evaluation and treatment. Rewarming can continue en route, but do not delay transport to do so in the field.

Your first priority is to stop further heat loss. Move the patient to a warm environment, remove any wet or frozen clothing, dry the patient and cover with insulating layers. Chemical heat packs placed inside the packaging will help prevent further heat loss by keeping the packaging warm, but they are ineffective for warming the patient. Do not allow heat packs to contact the patient’s skin.

In some situations, patients may need to be packaged and transported to a waiting ambulance. For effective patient packaging, wrap the patient in multiple layers of dry, high-loft insulation with a wind- and water-resistant outer layer. Leave the face uncovered for airway monitoring. Preplace blood pressure equipment, stethoscope and thermometer probe for vital signs monitoring. During evacuation to an ambulance, minimize the need to open the packaging and expose the patient to the environment.

Severe hypothermia patients need to be rewarmed from the inside out, which is difficult in prehospital care, but treatment can begin en route to the hospital. The state of Alaska’s Cold Injuries Guidelines recommend oxygen and fluids. Warm fluids to at least the patient’s core temperature, or 104º–108º F if fluid warming is available. Hypothermia patients are typically volume-depleted. A 250 ml bolus of normal saline is preferred. Keep the line open with a saline lock, or decrease to keep open. Boluses are preferred because fluid temperature is more easily controlled. Additional fluid boluses can be given as needed to moderate underlying tachycardia.

Deliver warm, humidified, high-flow oxygen via bag-valve mask. Warm O2 to no more than 108º F (42º C). If humidification is not possible, continue to deliver O2 that is at least warmed to the patient’s core temperature. Reduce ventilations to six per minute. Avoiding hyperventilation reduces the risk of v-fib in the cold heart.

Increase the ambient environmental air temperature (inside ambulance, helicopter, treatment room) to at least 80º F (27º C).

Indications for securing the airway and using a defibrillator are the same as in a normothermic patient, with a few alterations. Before intubating or inserting a Combitube, ventilate the patient for at least three minutes. If an AED or defibrillator is available, apply to the patient as you would to a normothermic patient. According to Alaska’s Cold Injuries Guidelines, give up to three shocks as indicated by the machine. If the patient’s core temperature is above 86º F (30º C) or is unknown, treat the patient as if normothermic. If core temperature is below 86º F, discontinue use of the AED after the initial three shocks or until the patient’s core temperature is above 86º F.

Severe hypothermia depresses cardiac function so profoundly that pulse and respirations cannot be assessed. An AED that does not display a rhythm will only tell you if a shock is indicated. It will not tell you if there is no pulse or a rhythm other than v-fib or v-tach. If the pulse cannot be assessed and the heart rhythm is unknown, contact medical control about starting CPR; if a pulse is present, CPR could precipitate v-fib. Alaska’s Cold Injuries Guidelines direct you to begin CPR if a hospital is not reachable within three hours. For lower transport times, continue to ventilate and rewarm the patient. If the cardiac rhythm is asystole, do not attempt defibrillation.

Severe hypothermia patients metabolize medications inefficiently and poorly. Furthermore, even when given at therapeutic doses, medications can become toxic when the patient is rewarmed because of poor metabolism. Consult with medical control before delivering any medications when the patient’s core temperature is below 86º F.

Finally, you have often heard the saying, “hypothermia patients are not dead until they are warm and dead,” but this is less widely accepted than in the past. After 60 minutes of sustained rewarming and resuscitation attempts, if there is no spontaneous return of pulse and breathing, consult with medical control about terminating resuscitative efforts. Factors that are likely to influence the chance of survival include the patient’s core temperature at the start of treatment, length of time below normal body temperature, time it takes to reach a core temp greater than 86º F and the patient’s underlying health. Time is of the essence. Any interventions in the prehospital phase must aid rewarming. Do not allow prolonged on-scene attempts at intubation or IV access to delay transport. ?

Bibliography

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