Chapter 18. Environmental Emergencies

Clinical Summary

Extent of injury depends on the amount of heat, the delivery medium (gas, liquid, solid, or vapor), and the duration of contact. Scald burns are most common in children and the majority of thermal injuries occurring within the home; 60% of pediatric burn patients are male.

Burns can be graded by depth and amount of damage (see Table 18.1).

Emergency Department Treatment and Disposition

All patients should receive analgesics as soon as possible. Minor burns involve <10% body surface area (BSA) and do not involve the airway, hands, face, or genitalia. They can be managed with local wound care in an outpatient setting. The wound should be irrigated with cool saline and patients not allergic to sulfa should apply silver sulfadiazine to burns below the clavicles while bacitracin should be substituted to burns of the head and neck to avoid potential skin discoloration cause by sulfa compounds. A sterile dressing should then be applied and the patient should be provided adequate analgesics and close follow-up.

For significant (>10% BSA) and major (>20% BSA) thermal injuries in patients with preexisting medical conditions, the possibility of multiorgan failure needs to be anticipated and screening labs such as a complete blood count (CBC), electrolytes, glucose, blood urea nitrogen (BUN), creatinine, creatine phosphokinase (CPK), and urinalysis ordered. Any history or signs of significant smoke inhalation (carbonaceous sputum, hoarse voice, or evidence of hypoxia) should prompt a chest radiograph. All patients who were in a fire should have a venous determination of their carboxyhemoglobin (CO-Hgb) concentration. A good pulse oximetry level (>96%) with no visual signs of oral burns and a normal venous CO-Hgb level (<5%) virtually rules out the possibility of inhalation injury. Patients with CO-Hgb levels above baseline should be placed on high-flow oxygen to help dissociate the carbon monoxide (CO) from their hemoglobin. Patients with significant CO-Hgb levels require transfer to a hyperbaric chamber. Hyperbaric oxygen has been shown to decrease the long-term neurologic sequelae associated with CO poisoning and should be employed even if the carboxyhemoglobin level has been returned back to normal with simple high-flow oxygen. Significantly, burned patients should be resuscitated in the emergency department (ED) and transferred to a burn center when possible. (Significant burns are burns that are greater than 10% BSA, >5% third-degree, or involve the hands, face, or genitalia.)

The Parkland formula (4 mL/kg × body weight in kilograms × percentage of BSA burned) is used for calculating the amount of Ringer lactate needed for initial resuscitation for burn shock. Half of this volume should be given in the first 8 hours after the burn occurred and half in the following 16 hours. Treating physicians should remember that this volume is in addition to regular maintenance fluids. A good way to evaluate resuscitation efficacy is to monitor urine output and keep it above 1 mL/kg/h as long as the patient is not in renal failure. Burns are considered traumatic injuries, so any patient with a significant burn should be evaluated by a trauma team. Circumferential burns of an extremity need to be monitored closely and should prompt urgent surgical evaluation should symptoms of compartment syndrome develop.

Electrical burns to the corner of the mouth caused by chewing on an electrified wire deserve special mention. They need to be followed closely as they are prone to delayed bleeding as tissue necrosis can erode into the labial artery 5 to 10 days after the initial injury.

Pearls

1. All burn patients should initially receive supplemental oxygen until it is determined that they do not need it.

2. Children with a large percentage of BSA burned often become hypothermic and need to be kept warm.

3. Children with significant burns need maintenance fluids plus that called for by the Parkland formula for burn shock.

4. Ten percent of burns in children are secondary to abuse.

The authors acknowledge the special contributions of Michael Lucchesi, Ronak Shah, Karen Santucci, M. Douglas Baker, Binita R. Shah, and Lewis Kohl, to prior edition.

Clinical Summary

Cold injuries range from frostnip to frostbite (see Table 18.2). History should focus on exposure temperature, duration, wind velocity, clothing, and underlying comorbidities. Distal areas are always affected first, which usually include fingers, toes, extremities, nose, and ears and even the cornea. Caretakers should focus on vital signs, assessment of the degree of hypothermia, and resuscitation. Retained sensation, normal skin color, and clear fluid within blisters (if present) indicate positive prognosis. Nonblanching cyanotic, firm skin, and dark fluid-filled blisters indicate poor prognosis. Risk factors include extremes of age, homelessness, altered mental status (drug/alcohol use, head trauma), nicotine or other vasoconstrictive drug use, preexistence of peripheral vascular disease, and diabetes.

Emergency Department Treatment and Disposition

Rewarming begins in the field after it is assured that frozen regions will not be re-exposed. Refreezing causes considerably more tissue damage than if the limb was left cold and rewarmed later. Upon ED arrival, stabilize airway, breathing, and circulation (ABCs) including management of hypothermia, cardiac dysrhythmias, intoxication, head injury, and hypoglycemia—all of which could have caused the cold exposure. Remove all restrictive or wet garments, which can cause continued heat loss. Initiate rapid active rewarming of affected areas with immersion in 40°C to 42°C water for 10 to 30 minutes. Analgesia should be provided for reperfusion pain. Clear blisters may be aspirated to remove inflammatory mediators that can worsen tissue destruction but hemorrhagic blisters should be left intact. The affected extremity should be elevated, splinted, and dressed with a dry sterile dressing.

Laboratory studies such as a CBC, electrolytes, CPK, and serum myoglobin values should initially be obtained to identify a baseline and evaluate for rhabdomyolysis. Surgery may be consulted but debridement should never take place until definite demarcation has occurred. Patients should be admitted for observation and supportive care unless frostbite is very superficial and painless.

Pearls

1. Treat hypothermia aggressively as it can lead to malignant arrhythmias.

2. Rewarming should not be initiated if there is a possibility of refreezing.

3. Dry rewarming (such as near an open fire) is uneven, dangerous, and should be avoided if possible.

4. Active rewarming should take place in 40°C to 42° (104°F–108°F) water for 15 to 30 minutes or until thawing is complete.

5. The true extent of frostbite may take up to 6 months to demarcate. Escharotomy/fasciotomy may be indicated in the acute setting.

Clinical Summary

Anaphylaxis is a type I IgE-mediated hypersensitivity reaction caused by mast cell degranulation following antigen exposure in a previously sensitized individual. Anaphylactoid reactions are indistinguishable from true anaphylaxis except that no prior sensitization exists. Two or more organ systems must be involved to make the diagnosis of true anaphylaxis. The most frequent triggers include medications, food, and insect envenomation. Diffuse pruritus, sweating, urticaria, and lip, face, and mouth swelling are often the first signs of anaphylaxis, with hypotension, or even total cardiovascular collapse occurring if not addressed rapidly. Excessive pulmonary secretions and bronchospasm result in wheezing and difficulty breathing. Diarrhea, nausea, and gastrointestinal (GI) upset are also common. About 80% of patients present with a predictable uniphasic course, in which signs and symptoms occur early and respond to therapy. A biphasic pattern can also be seen with a second episode of anaphylaxis occurring up to 8 hours after apparent recovery. Rarely, symptoms persist for days to weeks.

Emergency Department Treatment and Disposition

The antigen must be removed whenever possible, that is, stop the medication infusion or remove the insect’s stinger. A credit card can be used to “flick” the stinger out as tweezers or forceps may actually instill more antigen if the venom sac is compressed. A tourniquet may be applied to delay systemic absorption of the allergen in the case of injection or sting.

All patients should receive an immediate assessment of their ABCs. If there is tongue or pharyngeal edema, establish a secure airway and administer 100% oxygen. Inhaled β2-agonist and anticholinergics (nebulized albuterol and ipratropium respectively) aide breathing by reversing bronchospasm and decreasing pulmonary secretions. Hypotension should be treated initially with an IV crystalloid bolus (20 mL/kg), but pressors may become necessary in the setting of refractory hypotension. Repeat fluid boluses may be administered to compensate for the marked peripheral vasodilation and third-spacing that may accompany anaphylaxis. Parenteral epinephrine is the drug of choice for life-threatening anaphylaxis given subcutaneously or IM and can be repeated every 15 to 20 minutes as needed for persistent symptoms. Patients undergoing previous treatment with β-blocking agents may not respond to epinephrine and may require glucagon to bypass the adrenergic receptor complex. Intravenous aminophylline may also be used in very severe cases although very few patients progress this far. Antihistamines do not reverse end-organ effects or hypotension in patients with anaphylaxis. They block further release of histamine and vasoactive mediators and provide symptomatic relief in anaphylactic reactions accompanied by urticaria and angioedema. A combination of H1- and H2-receptor blocking agents such as diphenhydramine and famotidine, respectively, can be synergistic in effect and should be utilized. Corticosteroids do not play a role in the immediate reversal of anaphylaxis because their onset of action is delayed for 4 to 6 hours. However, they inhibit or lessen biphasic and protracted anaphylactic reactions, including bronchospasm with their anti-inflammatory properties, and should be given in the ED. All patients with moderate to severe reactions requiring resuscitation must be hospitalized and observed for 24 to 48 hours, even in the absence of persistent symptoms.

Patients with milder reactions can be sent home after 6 to 8 hours of observation. Antihistamines and steroids should be prescribed to these patients orally for the next 72 hours. Upon discharge, patients can be referred to an allergist for desensitization immunotherapy. Patient and/or parent education regarding possible future recurrences is important. They must be prepared for severe reactions because a mild reaction at this hospital visit does not guarantee that future episodes will not be life-threatening. Patient with severe reactions should wear a MedicAlert bracelet that indicates precipitating agents if known. Insect exposure should be avoided and patients should be instructed to avoid wearing things that attract insects such as perfumes or bright-colored clothing. Latex-free gloves and catheters should be used with patients allergic to latex. Parents and older children should be provided with a prescription and educated about self-administering epinephrine (eg, EpiPen, EpiPen JR).

Pearls

1. Anaphylaxis is a potentially life-threatening manifestation of an IgE-mediated hypersensitivity reaction involving 2 or more organ systems.

2. Life-threatening features include upper airway obstruction (laryngeal, pharyngeal, and lingual edema) and hypotensive shock due to profound vasodilation and increased vascular permeability.

3. IV fluids and epinephrine are the mainstay of therapy for anaphylaxis regardless of the cause.

Clinical Summary

The brown recluse spider (violin or fiddle back spider; Loxosceles reclusa) is a small orange to reddish brown spider measuring 6 to 12 mm in length that is found in the midwestern and southeastern United States. It can be identified by the classic brown, violin-shaped mark on its dorsal surface. These spiders are not usually aggressive and bite only when threatened.

Initially, bites are red and may be pain-free. Most become firm and heal with little scarring over days or weeks. However, severe and/or systemic envenomations occasionally occur. In these patients, there is localized pain and tissue destruction with systemic symptoms. Depending on the amount of venom delivered, bites may progress over days to weeks to large necrotic defects that may require reconstructive cosmetic surgery to repair. Systemic signs and symptoms include fever and chills, nausea, morbilliform rash formation, arthralgias, and myalgias. Renal failure, hemolysis, thrombocytopenia, disseminated intravascular coagulopathy, and seizures may all occasionally be seen and very rarely may progress to coma or death in small children. The constellation of symptoms classically known as loxoscelism includes necrosis at the bite site, nausea, malaise, fever, hemolysis, and thrombocytopenia.

Emergency Department Treatment and Disposition

ED care can vary from local wound care to intensive care unit (ICU) hospitalization. There are no specific tests to diagnose brown recluse spider envenomation, so definitive diagnosis depends upon identifying the offending arachnid. Patients with systemic symptoms should receive a CBC including platelet count, coagulation profile, serum electrolytes, creatinine, BUN, and urinalysis. A local poison center may be helpful in identifying the species of spider when available.

Brown recluse spider bites typically require local wound cleansing, splinting (for immobilization), tetanus prophylaxis, and pain management. Long-term cosmetic reconstruction may be necessary because the toxin in recluse venom can cause massive local tissue destruction. Some advocate early use of dapsone (leukocyte inhibitor) for these bites but no scientific study has ever proven its efficacy. Patients with systemic manifestations or evidence of a rapidly expanding necrotic lesion should be admitted for observation. If hemolysis is present, maintenance of urine output, urine alkalinization with intravenous (IV) sodium bicarbonate to keep the urine pH >7, and close monitoring of renal function and hematocrit are required. Heat can accelerate tissue destruction and should not be applied. Steroid creams usually do not help and overcutting to extract the venom with a suction device should never be attempted. High-voltage electrotherapy from stun guns has been reported but never shown to be effective in scientific studies. Other home remedies have not been proven useful.

Pearls

1. Monitor patients for evidence of hemolysis, renal failure, or coagulopathy. Smaller children are more likely to develop these systemic manifestations.

2. The shorter the time to the onset of symptoms following a spider bite, the more severe the envenomation is.

Clinical Summary

Widow spiders (hourglass spiders; Latrodectus mactans) range in size from 2.5 to 3.5 cm and have large fangs and a distinct red hourglass-shaped mark on their ventral surface. Envenomations tend to cause local erythema and pain but considerably more systemic effects. Cramping of the back, abdomen, and chest are classic and may become severe enough to require narcotic analgesics. Hemodynamic instability and coagulopathy are also common. Systemic symptoms include nausea and vomiting, hypertension, tachycardia, and diaphoresis. Classic “facies latrodectismica” is characterized by sweating, contortion, and grimacing.

Emergency Department Treatment and Disposition

ED care can range from simple local wound care to hospitalization and antivenom administration. There are no specific tests to diagnose Lactrodectus envenomation, so definitive diagnosis requires identification of the spider. A local poison center may be helpful in identifying the arachnid and locating the appropriate antivenom.

CBC including platelet count, coagulation profile, serum electrolytes, creatinine, BUN, and urinalysis should be obtained. Pain control with nonsteroidal anti-inflammatory drugs (NSAIDs) or even opioids is important because cramping can be severe. Calcium has been used to reduce cramping but has not proven more effective than placebo. Antivenin is indicated in small children for severe envenomations with systemic symptoms and is available as a hyperimmune horse serum, which can be given intramuscularly (IM) or IV. Indications for antivenin include life-threatening hypertension, tachycardia, and respiratory difficulty. Antivenom usually relieves symptoms rapidly though may precipitate anaphylaxis or serum sickness. Hospitalization is recommended for all Latrodectus envenomated pediatric patients.

Pearls

1. The classic red hourglass-shaped mark on their abdomen makes widow spiders easier to identify.

2. The hallmark of black widow spider envenomation is muscle cramping, usually affecting the abdomen, back, and chest.

3. Abdominal pain and rigidity associated nausea and vomiting can mimic acute abdomen.

Clinical Summary

Scorpions, like spiders, are members of the class Arachnida. Of the approximately 1500 venomous species of scorpion found throughout the world, 50 are potentially dangerous to humans, with only one species, Centruroides exilicauda (the bark scorpion), residing in the North America. All scorpions have hard exoskeletons with flat and elongated bodies armed with claws in the front and a whip-like tail in the back. Their tail ends in a bulbous segment known as the telson that contains 2 venom glands and the stinger. Scorpion venom is usually a heterogeneous mixture containing multiple proteins, many of which are neurotoxins that typically activate ion channels such as fast sodium channels. Humans are often stung on the hands or feet as they try to pick up or step on a scorpion. Children frequently manifest worse toxicity because of their small size. Envenomated individuals immediately complain of severe pain at the sting site progressing to local erythema and edema. Systemic symptoms are rare but include nausea, vomiting, hypersalivation, sweating, hyperthermia, anxiety, autonomic instability, myoclonus, and cardiac dysrhythmias. Symptoms typically last 24 to 48 hours although when fatal, death is usually due to cardiogenic shock or pulmonary edema. Pancreatitis is seen in up to 80% of victims of Tityus trinitatis scorpion stings.

Emergency Department Treatment and Disposition

It is important to get a thorough history surrounding the sting and a description of the scorpion if no specimen is available. Initial first aid involves cleaning the wound with soap and water and applying ice to the sting site. ED care is supportive with analgesics plus benzodiazepines for myoclonus and muscle spasms. Tetanus prophylaxis should be checked and updated when indicated. Atropine is typically not needed for excessive oral secretions although it can be used if necessary. Nitroprusside and prazosin have been used to control malignant hypertension. Narcotics and barbiturates should be avoided as they may potentially increase the toxic effects of the venom by an unknown mechanism. Administration of antivenin is recommended in all cases of severe envenomation when available. Observation for 24 hours is prudent for closer monitoring for all envenomated children.

Pearls

1. Contact the American Association of Poison Control Centers (800-222-1222) to be connected to a local poison control center to help take care of a patient envenomated by a scorpion.

2. Antivenom may exist for some scorpion species.

3. All scorpions fluoresce in the dark when exposed to a Woods lamp.

Clinical Summary

Dog bites in children occur disproportionately to the head and face, which is typically closer to a dog’s mouth than adults; male children are twice as likely to suffer dog bites. Most occur from an animal owned by the family or a neighbor. Approximately 5% of dog bites become significantly infected and these are usually polymicrobial in nature. Larger wounds can be easily cleansed and débrided and are paradoxically less likely to become infected than are minor lacerations or puncture wounds, which quickly close over the bacterial inoculum.

Emergency Department Treatment and Disposition

The basic principles of general wound care apply to all dog bites. Radiographs of the injury should be obtained to rule out the presence of foreign bodies, or fracture. Revision of the wound edges may be necessary after injuries are thoroughly cleansed. Because almost all animal bites are contaminated, meticulous wound toilet and copious irrigation are essential. Suturing is controversial. In recent years, the consensus has changed from never suturing such wounds to one of loosely approximating them to obtain the best possible cosmetic appearance without actually closing the wound. Close observation for wound infections is essential in these cases. Tissue adhesives should never be used because it traps bacteria and helps create an anaerobic environment where bacteria can flourish. After wound care, the limb should be immobilized and elevated to reduce swelling. Tetanus should always be updated when indicated and tetanus immune globulin may be needed in unimmunized individuals. Rabies prophylaxis should be considered in an unprovoked attack by a suspicious animal. The patient should be instructed to see a physician in 24 to 48 hours to have his or her wounds reevaluated for signs of infection.

There is no advantage in giving antibiotics to patients who present more than 24 hours after injury with an uninfected dog bite. Conversely, individuals who present with an already infected wound should always receive antibiotics. Amoxicillin plus clavulanic acid is a good single-drug regimen to start until cultures can identify a causative organism(s). A combination of clindamycin plus trimethoprim-sulfamethoxazole is suitable to cover most offending organisms in penicillin-allergic patients.

The effectiveness of antibiotic prophylaxis in fresh bites is less well established. The location of the bite may play a role in choosing to initiate prophylactic antibiotics. Well-vascularized regions like the scalp may be less likely to become infected while hands and other less vascular tissues may not ward off infection as well.

Pearls

1. Dog bites usually have a significant amount of devitalized tissue because of the nature of dog’s flat, crushing teeth, and strong muscles of mastication.

2. Dog bites present a significant potential for morbidity in childhood. Most injuries are minor although fatalities do occur and infections may be commonplace.

3. Bite wound infections are usually polymicrobial in nature.

Clinical Summary

Rabies is an RNA virus transmitted primarily through saliva present in animal bites, although it may be transmitted via direct mucosal exposure, airborne laboratory accidents, and transplantation of tissues harboring undiagnosed rabies. Depending on the inoculum site, rabies virus may take 2 to 12 weeks to become symptomatic. Transmission by airborne virus in bat-filled caves or by human bite have been theorized but never documented.

Initial peripheral infection produces an acute illness with malaise, fever, and headache and progresses to more central symptoms, including anxiety, seizures, dysphagia, and eventually coma, which is invariably fatal within days. The primary cause of death is respiratory arrest. Only a handful of cases are published in the medical literature describing survivors of rabies once neurologic symptoms are present.

Emergency Department Treatment and Disposition

Guidelines for postexposure prophylaxis (PEP) are given in Table 18.3. Rabies PEP requires administration of 2 agents unless there has been previous immunization and a documented adequate rabies antibody titer, in which case rabies immune globulin (RIG) is not required. All others should receive one dose of RIG (20 IU/kg) to provide temporary passive immunity. The Centers for Disease Control and Prevention (CDC) recommends the entire dose be infiltrated into the soft tissues surrounding the bite. If that is impractical, the amount unable to be infiltrated should be injected into a large muscle distant from the injection site of the active vaccine. Active immunization agents such as human diploid cell vaccine (HDCV) or Rab Avert produce longer-acting active immunity to the virus. The development of newer vaccines has markedly reduced the incidence of reactions previously associated with PEP.

The CDC recommends active immunization of previously unvaccinated immunocompetent individuals with 4 doses of HDCV or purified chick embryo cell vaccine (PCECV). Individuals who have already received a full series of PEP or who previously had a documented adequate rabies virus–neutralizing antibody titer should receive 2 doses. Immunocompromised hosts should receive 5 doses. Regardless of weight or age, the dose is 1 mL injected into a large muscle group. Single doses should be administered on days 0, 3, 7, and 14, with day 0 being the day of initial presentation. Immunosuppressed patients should receive a fifth and final dose on day 28.

PCEC (RabAvert) vaccine has been developed for use in patients who develop sensitivity to one of the other vaccines. The entire series must be completed. If there is any patient-related deviation from the schedule, the manufacturer or local poison control center should be contacted for advice on timing of series completion.

Bat exposures deserve special mention, with most human rabies cases diagnosed in the United States being bat variants. Because bat teeth are so small, such bites can go virtually unnoticed. If a patient believes that they could have been bitten by a bat, regardless of the findings on physical examination, rabies PEP should be initiated. Rabies prophylaxis should also be administered to anyone who has an open wound or mucous membrane that could have become contaminated with bat saliva or other potentially infectious material, or who has occupied the same closed space with a bat during a time of altered perception (ie, asleep, intoxication, developmentally immature, mentally impaired), regardless of the findings on physical examination.

Pearls

1. Always consider PEP after animal bites as rabies is almost always fatal after symptoms develop. Exposure to an animal that even might be rabid should lead to consideration of rabies PEP.

2. Postexposure treatment consists of passive immunization with RIG in addition to active immunization.

3. Local health authorities should be consulted when there is doubt about the local rabies status of a particular species of biting animal.

Clinical Summary

It is estimated that 10% to 20% of all animal bite injuries are inflicted by cats, and girls are twice as likely as boys to be bitten. Cat bites are typically puncture wounds and have a high chance of becoming infected and causing osteomyelitis. Approximately 15% to 50% of cat bites become significantly infected, so excellent wound care and close follow-up is essential. Cat bites are usually polymicrobial in nature.

Emergency Department Treatment and Disposition

Basic principles of general wound care apply to cat bites. Radiographs of the site of injury should be obtained to rule out the presence of foreign bodies, or fracture. Revision of the wound edges may be necessary after the injuries are thoroughly cleansed. Cat bites should almost never be sutured or glued closed because they are often narrow, deep puncture wounds that are difficult to irrigate. After wound care, the limb should be immobilized and elevated to prevent swelling. Tetanus should always be updated when indicated and tetanus immune globulin may be administered in unimmunized individuals. Rabies prophylaxis may be considered in an unprovoked attack by a suspicious animal. The patient should be instructed to see a physician in 24 to 48 hours to have his or her wounds reevaluated for infection.

There is no advantage in giving antibiotics to patients who present more than 24 hours after injury with uninfected cat bite wounds. Conversely, individuals who present with an already infected cat bite should always receive antibiotics. Amoxicillin plus clavulanic acid or doxycycline in the penicillin-allergic patient is first-line therapy until cultures can identify a causative organism(s). Prophylactic antibiotics for fresh cat bites are probably indicated. Hand wounds present a special problem with cat bites because 30% or more become infected. Cats have much smaller jaw parts than dogs, so many cat bites occur on the hands and fingers because that is all they can fit in their mouth. Because of the complexity of the tissue planes of the hand and the presence of avascular tendon sheath spaces, there is a high propensity for spread of infection and potential for significant morbidity.

Pearls

1. Cat bite wound infections are usually polymicrobial in nature.

2. Hand wounds tend to become infected more often than those located elsewhere. Considering the complexity of the hand’s structure and the ease with which infection spreads along contaminated tissue planes, function can be easily compromised or destroyed. Thus, every bite of the hand should be considered potentially serious.

Clinical Summary

Human bites are common occurrences in childhood, and of these, 5% require suturing and 5% to 30% will become infected. In children younger than 10 years old, boys are more commonly bitten, while in older children girls are bitten more often. Abrasions account for 66% to 75% of bite injuries. The remainder are evenly distributed between punctures and lacerations. Most are located above the waist.

Infections of human bites are typically polymicrobial. Risk factors for infection include delay in initial care >20 hours, concomitant crush injuries, punctures or deep lacerations, complete wound closure of deep wounds, and larger intraoral bites. Viral infections such as hepatitis B and C, HIV, and herpes may also be transmitted and PEP should be considered when appropriate.

Emergency Department Treatment and Disposition

The general principles of wound management apply. All human bites that break the skin must be considered contaminated, and meticulous wound toilet and copious high-pressure irrigation are essential. Suturing is somewhat controversial as some studies suggest sutured wounds may be more susceptible to infection.

The repair of intraoral bite wounds deserves special mention. The intraoral portion of a through-and-through bite wound to the cheek or lip should be tightly approximated with absorbable sutures. Once closed, a new suture tray should be opened and the external layers of the face can be irrigated and sterilely prepared and then be closed in the regular fashion as if the intraoral rent was not present. Never use saliva-contaminated instruments to suture extraorally.

Contusions and abrasions resulting from human bites generally do not become infected. There also seems to be no advantage in administering antibiotics to patients who present more than 24 hours after injury with uninfected wounds. The utilization of prophylactic antibiotics for fresh human bite wounds is more controversial. Antibiotic prophylaxis should be administered to all deep puncture wounds, sutured full-thickness wounds, full-thickness wounds of the hand, and high impact wounds such as sports- or fight-related wounds that likely contain crushed tissue. Amoxicillin and clavulanic acid are an effective first-line treatment until antibiotic cultures are obtained. Clindamycin is an effective alternative for patients who are allergic to penicillin. Tetanus prophylaxis should be considered in all bite wounds and updated as needed. After wound care, an affected limb should be sterilely dressed, immobilized, and elevated. Appropriate follow-up care (within 36 hours) should also be arranged for these patients.

Pearls

1. All human bites must be managed as contaminated wounds.

2. Infection is the most common type of morbidity associated with human bites. If not aggressively treated, human bite infections can lead to serious permanent dysfunction of the injured area.

3. Always rule out child abuse when a small child presents with a human bite.

Clinical Summary

The corals, sea anemones, and hydroids all have thousands of specialized cells along their tentacles called nematocysts. Each contains a toxin-filled coiled poison dart called a cnidocil. When triggered, the nematocyst rapidly discharges the cnidocil into the target, releasing toxin into the victim.

Coral can be soft or hard. Both can sting but hard corals can also cause abrasions or lacerations. With the exception of fire coral, nematocysts of most corals cannot penetrate human skin. When touched, fire coral causes a painful red local reaction that usually subsides in 15 to 30 minutes. Hydroids cause a mildly painful sting as well. Most sea anemones (class Actinaria) cannot penetrate human skin although there are more poisonous Indo-Pacific varieties that can cause painful stings, rashes, and itching on contact. Systemic envenomations are rare, but in severe cases, evidence of organ damage may be seen. Complications include long-term skin changes such as hyperpigmentation and hypopigmentation and eschar formation. Local reactions to these organisms are common, but allergy to their venom is also a possibility. Full anaphylaxis can be seen in some envenomations by this class of animals.

Emergency Department Treatment and Disposition

Treatment should begin in the field with removal of macroscopic pieces of tentacle. This will prevent further envenomation because nematocysts remain active despite the tentacles being severed from the organism body. No specific antivenom exists against these species, so symptomatic relief is the goal of ED treatment. Rinsing the wound immediately with vinegar may prevent further discharge of nematocysts, but its effectiveness in this group is less clear than with the box jellyfish. Baking soda has been advocated by some to reduce wound pain when applied shortly after the sting. Tetanus status should be assessed and updated as needed. Antihistamines may be used to alleviate itching while topical corticosteroids may also prove effective. More severe skin reactions may require systemic corticosteroids. A 5- to 10-day course of prednisolone is typically adequate. Patients without evidence of a systemic reaction 4 to 6 hours after being stung may be safely discharged home. When evidence of systemic illness exists, the patient should be admitted for 24 hours’ observation to follow the progression of the symptoms. The treating physician may want to contact experts in marine envenomation at Divers Alert Network (DAN: 919-684-9111, 800-446-2671) for any additional information.

Lacerations and abrasions from hard corals should be x-rayed for foreign bodies and cleansed well using high pressure saline irrigation to remove all foreign material. Devitalized tissue can be excised to further prevent infection. Lacerations should not undergo tight primary closure as they are prone to infection; approximation with adhesive strips or delayed closure may be preferred. Antibiotic prophylaxis is not indicated for immunocompetent patients with stings or minor wounds. Dermatology follow-up may be indicated for more severe skin reactions.

Pearls

1. As with all aquatic animals that “sting” you, vinegar may be beneficial to prevent further coral, hydroid, and anemone nematocyst envenomation and it may also denature the venom proteins, thus alleviating symptoms.

2. Treatment is primarily supportive, with antihistamines for itching and analgesics for contusions and painful stings.

3. Simple skin reactions can be treated with topical steroid preparations, whereas worse reactions should receive oral steroids.

Clinical Summary

Although it appears to be a jellyfish, the Portuguese man-of-war is a collection of hydroids in a colony with a float at the top. The long trailing tentacles can measure 10 meters in length and broken tentacles that have washed ashore days later can still sting beachgoers. Box jellyfish (cubozoan jellyfish) are the world’s most dangerous jellyfish. Chironex fleckeri, the Australian box jellyfish, has been linked to at least 70 deaths (mostly in children) that are usually due to cardiovascular collapse. Children are at particular risk, with smaller individuals more likely to suffer a significant envenomation. True jellyfish (scyphozoans) are found worldwide, ranging in size from a few millimeters to 2 meters across.

Jellyfish tentacles contain thousands or even millions of nematocysts that fire toxin-laden cnidocils at high velocity into flesh. Toxins released are a combination of neurotoxins, cardiotoxins, and dermonecrotic substances. Symptoms vary from mild skin irritation to localized pain with redness and itching to life-threatening circulatory collapse. Long-term skin changes, such as hyperpigmentation and hypopigmentation, lichenification, and keloid or eschar formation are common. Severe envenomations, especially by box jellyfish, can lead to full-thickness dermal necrosis and even multiorgan system failure in some cases that may prove fatal.

Emergency Department Treatment and Disposition

Treatment begins in the field with the removal of all tentacles, which may be scraped off with a credit card or paper plate; some recommend covering the area with clean beach sand first. Immediately rinse the wounds with seawater (if the water is known to be free of tentacles). Rinsing the wound with 5% acetic acid (vinegar) prevents further discharge of nematocysts and may inactivate the venom. For box jellyfish envenomation, soak the area for at least 30 minutes in vinegar or place a vinegar-soaked cloth on the wound after tentacle parts have been removed with thick gloves or some sort of tool. Lidocaine may be effective in preventing further nematocyst firing and help with topical pain control. Alcohol, papain, urine, and ammonia have not been proven effective. A box jellyfish antivenin may be available for IV or IM use (sheep-derived immunoglobulin). If antivenin is not available, pressure, and immobilization should be utilized until definitive care is available.

In the ED, monitor cardiovascular status. Treat nonfacial dermonecrotic injuries (essentially chemical burns) with silver sulfadiazine. Cleanse wounds with normal saline after treatment with acetic acid. Tetanus status should be assessed and updated as needed. Mild local reactions may be treated with antihistamines and topical corticosteroids. More severe skin reactions may require systemic corticosteroids. Patients without evidence of systemic reaction 6 hours after being stung may be discharged with good follow-up instructions. Patients with any evidence of systemic illness must be observed closely for at least 8 hours. In the setting of clinical improvement after treatment, discharge may be safe although rebound illness has been reported. Patients with unrelenting signs of systemic envenomation should be admitted for observation. Prophylactic antibiotics are not normally indicated for immunocompetent patients. Dermatology follow-up may prove helpful for more severe skin reactions. Experts in marine envenomation may be sought through local poison control centers or through the Divers Alert Network (DAN: 919-684-9111, 800-446-2671). Burn specialists may be required for management of severe dermal necrosis.

Pearls

1. As with all animals that “sting” you, vinegar should be effective in treating most jellyfish envenomations although lidocaine can be mixed with it for added benefit.

2. Most jellyfish envenomations do not have an antivenom except the Australian Box jellyfish, C fleckeri.

Clinical Summary

Sponges have a matrix-like skeleton of silicon dioxide and calcium carbonate, and can cause injuries in 1 of 3 ways. Their silicate or calcite spicules can penetrate the skin and may be coated with toxin. This can lead to a spicule or irritant dermatitis that may progress to abscess formation around difficult to remove foreign material. They can cause contact dermatitis very much like that from poison ivy. Symptoms from this reaction are similar to those of poison ivy with itching and redness. Desquamation may also occur and erythema multiforme has been reported after such an injury. Finally, they may harbor venomous cnidarians, particularly hydroids. Most symptoms caused by sponges are brief in duration but resolution may take up to a week or more in rare cases. Allergy to sponges has also occasionally been described causing vesiculation, edema, and even urticaria or anaphylaxis.

Emergency Department Treatment and Disposition

Because it is not possible to distinguish which of the 3 mechanisms of injury occurred, treat for all 3, beginning in the field. Rinse the affected area with vinegar, if available. Gently pat the wound dry and apply adhesive tape over the area and slowly remove the tape to remove much of the exposed spicular material. Soak the area again in vinegar for 20 to 30 minutes.

In the ED, wounds should be well irrigated with normal saline. For mild reactions, topical steroids may prevent or reduce secondary inflammation. Tetanus status should be evaluated and updated if necessary. Severe skin reactions may require treatment with a tapering course of oral steroids. Antibiotics should rarely be needed, except where deep tissue penetration or injury has occurred. Urticaria and itching should respond to antihistamine therapy. Dermatologist follow-up is indicated for more severe skin reactions. Experts in marine envenomation may be sought through local poison control centers or through the Divers Alert Network (DAN: 919-684-9111, 800-446-2671).

Pearls

1. Exposed sea sponge spicules can be removed with adhesive tape.

2. Vinegar may help alleviate symptoms caused by sponge envenomation.

Clinical Summary

Echinoderms (starfish and sea urchins) stab with spines that cause penetrating trauma as well as envenomation. Species vary in toxicity although, as with most other toxic marine animals, the most dangerous varieties are found in the Indo-Pacific region.

Injuries from these animals occur when their sharp spines pierce the skin or a joint. When stabbed, venom coating the spines along with the integumentary sheath, seawater, particulate matter, and microorganisms enter the tissues. These spines are quite brittle and often crumble when one tries to remove them, resulting in chronic pain, tattooing, or abscess formation around retained foreign material. Besides the physical injury, envenomation from the poisonous species of echinoderms may occur leading to severe local pain or nonspecific generalized symptoms such as malaise, body aches, neuromuscular weakness, and hypotension. Deaths have been attributed to severe envenomations due to respiratory failure or from overwhelming sepsis if infected retained spines are not removed or treated adequately. The crown-of-thorns starfish has a unique component in its venom that is capable of causing liver injury.

Emergency Department Treatment and Disposition

Treatment should begin in the field. Visible spines should be carefully removed as they fracture easily. Because the toxins from these creatures are usually heat-labile, immersion in hot water (114°F/45.6°C) for 30 to 90 minutes may relieve the pain by denaturing the venom proteins. Foreign bodies must be sought with radiographs and/or sonography. A computed tomographic (CT) scan or magnetic resonance imaging (MRI) may be necessary to find all foreign material embedded in the tissues. All puncture wounds should be aggressively cleansed, although it is usually hard to reach the bottom of the tract. Most echinoderm spines crumble easily and the clinician should try to avoid crushing them during extraction. All foreign material must be removed including the integument sheath when possible. Penetrated joints should be addressed in an operating room (OR) setting. Tetanus should be updated if necessary. Antibiotics such as a quinolone that has activity against marine organisms like Vibrio species are indicated for deep wounds, especially in the hand or foot. Treatment for the envenomation is generally supportive as no antivenin exists for these creatures. Experts in marine envenomation may be sought through local poison control centers or through the Divers Alert Network (DAN: 919-684-9111, 800-446-2671).

Pearls

1. Venom from starfish and sea urchins are usually heat labile, so soak them in the warmest water that the patient can tolerate to denature the proteins and help alleviate symptoms.

2. Seek (and expect) foreign bodies in the skin when stabbed by these creatures as their spines are quite brittle and break easily.

3. No antivenom exists so treatment is supportive.

Clinical Summary

The Scorpaenidae family includes the venomous lionfish, frogfish, scorpionfish, stonefish, and devilfish. Common to this diverse group are the venomous integument-covered spines on their dorsal and ventral fins. The stonefish (Synanceia spp) is by far the most dangerous of these creatures with venom that induces severe localized pain in addition to multiple nonspecific systemic symptoms. Lionfish are frequently kept in aquaria, so are a more common source of envenomation than might be expected.

Clinically, patients envenomated by any of these fishes will complain of intense pain at the injury site surrounded by erythema and swelling. Systemic effects such as nausea and vomiting may be present along with hemolysis, hypotension, and neuromuscular weakness. Death can occur rarely with severe envenomations because of respiratory failure or overwhelming sepsis.

Emergency Department Treatment and Disposition

Treatment should begin in the field. Immersion in hot water (114°F/45.6°C) for 30 to 90 minutes may relieve some of the pain, but narcotic analgesics in liberal doses will likely be required for stonefish injury. Tetanus status should be ascertained and updated when necessary. Foreign bodies must be sought with plain radiography, sonography, CT scan, or even MRI because spines can break off easily. Wounds should be cleansed and débrided aggressively. Penetrated joints should be addressed in an operating room setting. An antibiotic such as a quinolone that has activity against marine organisms is indicated for deep penetrations and wounds that occurred more than 6 to 12 hours before presentation.

ED care is supportive, except in the case of severe stonefish envenomation. Stonefish antivenom is produced by CSL, Ltd. of Australia, from the venom of Synanceja trachynis and may be available for use in the Indo-Pacific region to treat systemic envenomation. Experts in marine envenomation may be sought through local poison control centers or through the Divers Alert Network (DAN: 919-684-9111, 800-446-2671).

Pearls

1. Toxin components of these fish are usually heat labile, so soak them in the warmest water that the patient can tolerate (without burning them) to denature the proteins and help alleviate symptoms.

2. Antivenom is available for stonefish envenomation.

Clinical Summary

Stingrays are cartilaginous fish with a long, sharp barb on their tail used for defense, which is often deployed when they are stepped on or frightened. The barb is coated with venom and covered by an integumentary sheath. As the venom-coated barb is forcefully driven into the tissues, seawater, particulate matter and microorganisms are also dragged in with it. Case reports have documented all kinds of visceral injuries in addition to pneumothoraces and hemothoraces. Most ED visits for stingray injuries are for physical trauma of the lower extremities, although envenomation can lead to systemic symptoms such as nausea, vomiting, diaphoresis, diarrhea, hypotension, neuromuscular weakness, and even respiratory failure in rare cases of severe envenomation. Deaths do occur from stingray injuries but are usually due to penetrating trauma to the chest, neck, or abdomen or from overwhelming sepsis originating from an untreated or undertreated barb wound.

Emergency Department Treatment and Disposition

Treatment should begin in the field. Immersion in hot water (114°F/45.6°C) for 30 to 90 minutes may relieve some pain although any retained barb should be left in place just in case it is tamponading a vascular injury. Because the barb can easily be broken off and left inside the body, radiographs, sonography or even CT scans or MRI should be used to rule out retained barb fragments.

All stingray barb injuries must be treated as if they are life-threatening penetrating stab wounds even when in the lower extremities. Abdominal injuries should be worked up for evidence of visceral injury, and chest trauma should be treated following Advanced Trauma Life Support (ATLS) protocol. Impaled stingray barbs are often difficult to remove if found lodged in the tissues because of their serrated nature and may require a trip to the operating theater if more than shallowly embedded. Tetanus status should be updated when indicated. Wounds must be cleansed and débrided aggressively to remove all foreign material and bits of integument. Penetrated joints should also be addressed in an operating room setting. Antibiotics such as a quinolone that has activity against marine organisms is indicated for deep wounds. Patients should be observed for 6 hours postinjury, after which neurologic involvement is unlikely to occur. Care for envenomation is supportive as no antivenin is available.

Pearls

1. Toxin components are usually heat labile so soak them in the warmest water that the patient can tolerate to denature the proteins and help alleviate symptoms.

2. Treat stingray injuries like any other penetrating trauma before dealing with the envenomation.

3. Retained foreign bodies are likely with stingray injuries. Any number of radiologic modalities can be used to rule them out.

Clinical Summary

Cone shells are small, snail-like mollusks that usually inhabit tropical waters, with the species found in the Indo-Pacific region being the most toxic. They are carnivorous animals that can deliver a highly venomous bite. Cone shell venom is an extremely toxic set of neurotoxins that paralyze its prey. Neurologic impairment may persist from days to weeks, making mechanical ventilation the only bridge to survival in those bitten. Clinically, the patient may initially be asymptomatic, but stinging or sharp pain usually develops at the site. Numbness, pallor, or cyanosis surrounding the wound often follows with paresthesias spreading up the extremity. Perioral numbness, nausea, and vomiting are common early signs of systemic toxicity progressing to cranial nerve dysfunction, muscle paralysis, hypotension, and coma in severe envenomations. Respiratory failure is the usual cause of death in these patients although cardiac failure and cerebral edema have also been reported. Peak activity of venom is within the first 12 hours, but neurologic deficits may persist for days.

Emergency Department Treatment and Disposition

Field management is essential and includes pressure and immobilization, which should begin as soon as possible to prevent the lymphatic spread of toxins. Apply a stack of gauze pads (sterile if available) over the bite and wrap with modest pressure using an elastic bandage. The dressing should be snug, as when wrapping a sprained ankle, but circulation should not be compromised and should be checked frequently. Immobilize the extremity if possible and do not remove the dressing until resuscitative equipment or definitive care is available. Submersion of the wrapped area in hot water for 30 to 90 minutes has been suggested (114°F/45.6°C).

Treatment in the ED is supportive and a ventilator and intubation equipment must be available in case of respiratory failure. Patients without respiratory weakness should be observed for 8 to 12 hours. Tetanus status should be assessed and updated as needed. The wound must be carefully cleansed and explored for foreign bodies; plain films or sonography may reveal a retained object but CT or MRI are more accurate. Antibiotics should be considered for deep injuries, for wounds over joints, and in patients with immune impairment or with significant comorbidities such as diabetes mellitus. Experts in marine envenomation may be sought through local poison control centers or through the Divers Alert Network (DAN: 919-684-9111, 800-446-2671).

Pearls

1. Toxin components of cone shells are usually heat labile, so soak them in the warmest water that the patient can tolerate to denature the proteins and help alleviate symptoms.

2. Cone shell venom is neurotoxic.

3. The pressure/immobilization technique may help stop the spread of venom through the lymphatic system.

Clinical Summary

Blue-ringed octopuses are small (<25 cm) and found throughout the Indo-Pacific living in tide pools and among coral heads and rocks. The octopus produces a highly potent venom that is transmitted through a chitinous beak during a bite. Some believe that other body parts may contain low levels of venom, making these creatures poisonous as well as venomous. The chief component of the venom is a tetrodotoxin-like agent that blocks cellular sodium channels and produces neuromuscular paralysis. Initially the bite may be asymptomatic but numbness or pain at the bite site usually occurs within 30 minutes as does pruritus, erythema, and, occasionally, urticaria. By 30 minutes, facial numbness and weakness typically ensue. Cranial nerve dysfunction is common and voluntary or involuntary muscle paralysis soon follows, culminating in respiratory failure. Hypotension may occur but is not a consistent feature. Peak activity of blue-ringed octopus venom is within the first 12 hours, but neurologic effects may persist for 3 to 4 days.

Emergency Department Treatment and Disposition

Field management is essential. Place a stack of gauze pads over the bite and wrap with a pressure bandage as snugly as possible without compromising circulation. The extremity involved should be immobilized and the dressing kept in place until resuscitative equipment or definitive care is available. The wrapped limb may be submerged in hot water for 30 to 90 minutes.

In the ED, draw baseline labs and provide supportive medical treatment. Laboratory findings are nonspecific although coagulation studies should be performed, as other components of the venom may have anticoagulant properties. Itching and urticaria can be relieved with histamine blockade with an agent such as diphenhydramine, and pain can be addressed with NSAIDs or narcotics if severe. Basic local wound care employing antiseptic preparation followed by copious irrigation should be used in an effort to remove all marine life and bacteria. Tetanus status should be checked and updated as needed. Antibiotics may be considered for deep injuries, for bites over joints, and in patients with immune impairment or with significant comorbidities such as diabetes mellitus. Because respiratory paralysis is common, ventilator support may become necessary, so intubation equipment should be available. Patients without respiratory weakness should be observed for 8 to 12 hours and are unlikely to deteriorate after this period. Experts in marine envenomation may be sought through local poison control centers or through the Divers Alert Network (DAN: 919-684-9111, 800-446-2671).

Pearls

1. Respiratory support is the hallmark of treatment.

2. The pressure/immobilization technique should be utilized prior to hospital arrival.

3. A paralyzed victim may be fully alert.

Clinical Summary

Lightning can injure patients by a direct strike, spread of ground current after a strike, or blunt trauma produced by the explosive force of current discharged to a nearby object. Lightning injuries vary widely from cuts and scrapes, to mild mental disorientation without physical effect, to asystole, or cardiac arrest. Classification of lightning injuries into organ systems affected is common.

Cardiovascular manifestations tend to directly affect the myocardial conduction pathway, and cardiac arrest is the only direct cause of death due to lightning. When lightning strikes cause asystole, spontaneous circulation often returns after early and only brief cardiac pulmonary resuscitation (CPR). Other arrhythmias may also occur. QT prolongation is most common and generally resolves spontaneously within a few weeks to months.

Neurologic effects are among the most frequent nontraumatic sequelae. Altered mental status, which may include confusion or amnesia, is often seen and may compromise the reliability of the history. Patients may also develop acute pain syndromes, paresthesias, temporary paralysis, vertigo, cataracts, and tinnitus. In the most severe cases, anoxic brain injury may occur because of cardiovascular collapse or neurologic respiratory failure.

Dermatologic consequences are generally obvious. Entrance and exit wounds appear similar to traditional electrocution burns and can be quite serious. Diffuse skin burns may also occur because of sweat or rain water being vaporized into steam when a large lightning current passes over the body. Deeper internal burns occur rarely. The phenomenon called Lichtenberg figures or lines are fernlike patterns created on the skin and are considered a pathognomic finding of lightning strikes.

Emergency Department Treatment and Disposition

Evaluate and stabilize ABC and then perform a thorough history and physical examination, after which patients should be observed in a monitored setting. Cervical spine precautions are especially important if there is altered mental status or other signs of neurologic dysfunction. Remove wet clothing to avoid hypothermia and complete a thorough secondary survey. Order plain films of the extremities if there is tenderness or deformity. If the patient’s sensorium is altered or they suffered a loss of consciousness, obtain a noncontrast head CT scan to rule out intracranial bleeding or cerebral contusion. Although no specific laboratory tests are diagnostic of a lightning-injured patient, creatine kinase (CK) and myoglobin levels may help to identify complications such as rhabdomyolysis. The remainder of the workup should follow ATLS guidelines for trauma patients. If cardiac irregularity is present on a screening electrocardiogram, admission is warranted for telemetry monitoring.

Pearls

1. Injuries occur either from a direct strike itself or indirectly from the energy released by the conduction of current to a ground surface.

2. Early CPR is often associated with successful return of spontaneous circulation when lightning causes asystole.

3. No set guidelines exist for the workup of a lightning-injured patient, and clinicians should maintain a high index of suspicion for rhabdomyolysis.

Clinical Presentation

Snake bites are uncommon and have a wide spectrum of presentations depending on the timing of the bite, amount of venom delivered, and species and type of venom. Most snake bites are harmless and are caused by nonpoisonous snakes. The 2 most common classes of venomous snakes are the Elapidae and Viperidae families. Elapids include cobras, mambas, sea snakes and kraits, and the coral snake. In North America, coral snakes have red, yellow, and black bands and bear a close resemblance to King snakes, which are not venomous. Coral and King snakes have a different sequence of colored bands, so that they may be distinguished from one another with the mnemonic “Red on Yellow Kill a Fellow, Red on Black Friend of Jack (or Venom Lack).”

Snakes in the Viperidae family such as rattlesnakes, true vipers, and lanceheads cause bites that often bear typical double puncture marks made by mobile fangs that swing out when biting. These snakes usually have narrow, slit-like pupils and large poison glands located behind their powerful jaws, causing them to exhibit triangular heads that are distinctly separate from their bodies.

Elapid venoms are neurotoxins that cause systemic symptoms including lethargy, weakness, ptosis, aphasia, and, in severe cases, respiratory depression or arrest. Snakes of the Elapidae family have short, fixed fangs and must chew the victim to inject enough venom to be harmful, and thus these bites do not display “typical” double fangs marks. Elapid bites may also manifest symptoms in a delayed fashion (up to hours later) when only small amounts of venom penetrate the skin.

Effects of Viperidae venom are usually rapid and more localized to the bite site with erythema, swelling, and ecchymosis being common. Systemic symptoms may occasionally arise, which can include paresthesias of the tongue, a metallic taste in the mouth, generalized pain, hypotension, and even shock. Up to 30% of venomous snake bites seen are “dry bites” where no toxin was instilled. The volume of venom depends on time since the snake’s last bite, degree of threat perceived by the snake, size of the snake, and size of the victim. Early development of systemic manifestations may signal a significant envenomation, especially if the venom was directly introduced into a vessel.

Emergency Department Treatment and Disposition

Assess and stabilize ABC status first, with special attention to airway compromise or vascular collapse. Perform a complete physical with a full visual examination with the patient wholly undressed. Bulla formation, ecchymosis, petechiae, or muscle fasciculations indicate increased severity of envenomation. Use caution in unconscious patients, ensuring that snake bites are not presumed to be merely puncture wounds.

Obtain plain radiographs of the bite site to rule out bony violation or retained foreign bodies such as broken fangs. Cleanse the affected area with high-pressure irrigation and address pain control. Evaluate for compartment syndrome, which may necessitate fasciotomy. Rarely, snake bite coagulopathy can develop; therefore, baseline coagulation studies should be obtained. Follow CBC closely as thrombocytopenia may also ensue. Check CK levels and electrolytes as rhabdomyolysis may develop.

If the snake can be confirmed to belong to the Crotalin subfamily (rattlesnakes, water moccasins, and copperheads) of the Viperidae, use Crotalin Polyvalent Immune Fab (CroFab) to arrest or reverse symptom progression. The initial dose of CroFab is 4 to 6 vials delivered via IV. If symptoms resolve, give an additional 2 vials every 6 hours for 3 more doses. If the symptoms continue to progress despite being sure that the patient was bitten by a snake of the Crotaline subfamily, give 4 to 6 more vials every hour until symptoms begin to resolve. As with all animal bites, tetanus immunization should be updated when indicated. Antibiotics are often given, although no study has every proven them to be beneficial in preventing wound infections. Any patient discharged must be given close follow-up within 24 to 48 hours for reevaluation of the wound and given detailed discharge instructions describing potential complications.

Pearls

1. Contact the local poison center to assist with snake identification and attempt to determine the type of venom delivered to anticipate its effects and look for an antivenom.

2. Certain venoms can have delayed manifestations, such as compartment syndrome, thrombocytopenia, rhabdomyolysis, and electrolyte disturbances.

3. Offer close follow-up to discharged patients for reevaluation of wounds.

Clinical Summary

Presentation of altitude sickness varies depending on speed of ascent and the individual’s own innate ability to adapt to elevation. Reduced ambient pressure and low oxygen tension at high altitudes are thought to be the cause of tissue injury. Symptoms can be divided into 3 major categories: acute mountain sickness (AMS), high-altitude pulmonary edema (HAPE), and high-altitude cerebral edema (HACE).

AMS usually begins at altitudes >2500 m (8200 ft) as early as 1 hour after ascent, but may develop as late as 2 days after beginning climbing. Patients with AMS appear ill but will have no distinct physical findings. Headache is the most common complaint along with gastrointestinal symptoms such as nausea and vomiting. Constitutional complaints such as weakness, dizziness, and lightheadedness may also be present.

HAPE presents as a cough with thin, clear to yellowish sputum. Other common symptoms include chest tightness or dull pain, but frank shortness of breath with tachypnea may also be present. In severe cases, patients can develop hypoxia.

HACE is considered the most serious and life threatening of high-altitude diseases. It is usually seen in individuals who continue ascent despite early signs of AMS and HAPE. Ataxia is often the first sign and is typically followed by altered mental status. In rare cases, patients can have focal neurologic deficits, such as nerve palsy. Without prompt treatment, further neurologic deterioration to coma and death can occur.

Emergency Department Treatment and Disposition

Descent, even by a small amount, is the treatment for any high-altitude illness; if descent is not an option due to weather or injury, rest at the current altitude may allow acclimatization. Typically, climbers recognize the symptoms and return down to a medical facility. Most will no longer have symptoms and further treatment is rarely indicated.

Regardless of presentation, climbers should be thoroughly evaluated for altitude sickness as well as dehydration or hypothermia. Climbers may take acetazolamide to prevent altitude illness. The recommended prophylactic dosage is 125 to 250 mg taken twice daily beginning 2 to 3 days prior to ascent. Side effects of this drug include paresthesias, urinary frequency, and blurry vision, which can be mistaken for AMS itself. Slow ascent may be more effective in preventing symptom development.

If medical prophylaxis fails and descent is not an option, a portable hyperbaric chamber called a Gamow bag (pronounced gam-off) can be used. Such a device serves as a descent simulator, and is composed of a nylon bag forming a sealed chamber and a manual foot pump to pressurize it. Oxygen can also be concentrated in the chamber for an added benefit. Deployment of this device can simulate a descent of up to 2000 m (6500 ft) and can be accomplished within minutes. Because acclimatization may take up to 24 hours and the device is totally portable, the patient can be transported down to a lower altitude within the Gamow bag where symptoms should not recur when the patient emerges.

Pearls

1. Prophylactic use of acetazolamide can help with acclimatization and avoidance of the development of altitude sickness.

2. Altitude sickness can present with a spectrum of severity, most often affecting the respiratory and neurologic systems.

3. Development of signs/symptoms of altitude sickness should prompt individuals to descend, which is the only definitive treatment for altitude illness.