Emergency medicine

1

Why are children more vulnerable to biologic agents than adults?

• Anatomic and physiologic differences: Thinner dermis, increased surface area–to–volume ratio, smaller relative blood volume, higher minute ventilation

• Developmental considerations: Inability to flee dangerous situations, possible increased risk for posttraumatic stress disorder (PTSD)

• Some vaccines not licensed for children: Anthrax (18 to 65 years), plague (18 to 61 years)

• Vaccines more dangerous in children: Smallpox, yellow fever

• Antibiotics less familiar to pediatricians: Tetracyclines, fluoroquinolones

2

What are the three routes of transmission of anthrax?

• Inhalation: Most feared; can lead to multiorgan hemorrhagic necrosis

• Cutaneous: Inoculated through a wound, causing a black, painless ulcer

• Ingestion: May cause gastrointestinal (GI) or upper respiratory symptoms

Bacillus anthracis , which is a spore-forming gram-positive rod, can survive for extended periods before entering the body, where it will germinate and proliferate ( Fig. 5.1 ).

3

How are the lesions of smallpox distinguished from varicella (chickenpox)?

• Smallpox lesions predominate on the face and extremities (centrifugal), whereas varicella lesions are typically heaviest on the trunk (centripetal).

• Rash of smallpox progresses in similar stages (macules, papules, vesicles, crusting), whereas varicella is seen with multiple crops in differing stages.

• Smallpox rash develops more slowly than varicella rash.

4

How can the presenting symptoms of bubonic plague be differentiated from those of plague resulting from bioterrorism?

Bubonic plague —of “black death” fame—resulted from the bite of fleas, which led to a large, tender, regional adenopathy (the “bubo”) with subsequent hematogenous dissemination, multiorgan involvement, and septicemia. In bioterrorism, the organism Yersinia pestis could be aerosolized, and inhalation would result in presentations more typical of pneumonic plague, with fever, chills, tachypnea, cough, and bloody sputum; lymphadenitis would likely be a later finding.

5

Why should families living near nuclear power plants keep potassium iodide (KI) in their medicine cabinets?

Multiple organizations recommend that families living within 10 miles of a nuclear power plant (or 50 miles in densely populated areas, where evacuations may be more difficult) have KI on hand in the event of a nuclear radiation catastrophe. KI will inhibit the uptake of any released radioactive iodine ( ¹³¹ I) into the thyroid gland. Children are more susceptible than adults to the subsequent development of thyroid cancer if exposed. If KI is administered within 1 hour, 90% of ¹³¹ I is blocked, but after 12 hours, there is little effect. Of note, beyond the 10-mile radius, the major risk for ¹³¹ I exposure is from ingestion of contaminated foodstuffs.

6

Why are children particularly vulnerable to terrorism in the form of explosive and blast attacks?

• Smaller mass results in greater force per unit of body surface from energy released by explosion.

• Children are more susceptible to fractures as a result of incompletely calcified growth plates.

• The chest wall has greater pliability in children, resulting in greater chance of cardiac and pulmonary injury from blast explosives.

7

What categories of agents should be considered in the event of a chemical weapons attack?

• Nerve: Nerve agents are similar to organophosphate insecticides and include cholinesterase inhibitors, such as sarin, soman, and VX. Nerve agents inhibit the action of acetylcholinesterase at cholinergic neural synapses, where acetylcholine then accumulates. These agents are generally colorless, odorless, tasteless, and nonirritating to the skin. Nerve agent vapors are denser than air and tend to accumulate in low-lying areas, putting children at a higher risk than adults for exposure. The agents used in terrorist attacks are inhaled and absorbed through skin and mucous membranes.

• Asphyxiants: Asphyxiants are toxic compounds that inhibit cytochrome oxidase, causing cellular anoxia and lactic acidosis (high anion gap). Hydrogen cyanide, the most commonly known toxicant in this class, is a colorless liquid or gas that smells like bitter almonds. Exposure to hydrogen cyanide produces rapid onset of tachypnea, tachycardia, and flushed skin, followed by nausea, vomiting, confusion, weakness, trembling, seizures, and death.

• Choking and pulmonary agents: Choking agents include chlorine and phosgene. When inhaled, these agents produce massive mucosal irritation and edema, as well as significant damage to lung parenchyma.

• Blistering and vesicant agents: Blistering agents include sulfur mustard and lewisite. Sulfur mustard is an alkylating agent that is highly toxic to rapidly reproducing and poorly differentiated cells; skin, pulmonary parenchyma, and bone marrow are frequently damaged. Lewisite is an arsenical compound that affects skin and eyes immediately on exposure.

8

What should be the practitioner’s initial management when a chemical weapons event occurs?

The single most important first step for treating all chemical exposures is the initial decontamination strategy . Immediate removal of patient clothing can eliminate about 90% of contaminants.

9

What are important historical indicators of possible child abuse?

• Multiple previous hospital visits for injuries

• History of untreated injuries

• Cause of trauma not known or inappropriate for age or activity

• Delay in seeking medical attention

• History incompatible with injury

• Parents unconcerned about injury or more concerned about unrelated minor problem (e.g., cold, headache)

• History of abused siblings

• Changing or inconsistent stories to explain injury

• History of child abuse in either parent as children

• History of prematurity in child

10

What is the most common cause of severe closed head trauma in infants younger than 1 year?

Abusive head trauma. This is the terminology adopted by the American Academy of Pediatrics (AAP) to replace the term shaken baby syndrome . It describes inflicted injury in infants and young children that results either from an impact to the head or violent shaking of the head, or a combination of both mechanisms. The term shaken baby syndrome was changed because it implied a knowledge on the part of the treating clinician of the mechanism of injury that was most often not known. Abusive head trauma is most common in infants < 1 year of age and, compared with accidental head injury, has a much greater mortality rate. Male infants and those from lower socioeconomic groups tend to be at highest risk. Abusive head trauma manifests as subdural hematomas, subarachnoid hemorrhages, and cerebral infarcts. The diagnosis is suggested by the lack of a corroborating mechanism of injury in the face of a symptomatic child or, rarely, a confession by the perpetrator. In many cases, physical examination reveals retinal hemorrhages ( Fig. 5.2 ); other signs of trauma are usually lacking. Diagnosis is confirmed by computed tomography (CT) or magnetic resonance imaging (MRI). If a lumbar puncture is performed, the fluid may be bloody or xanthochromic. The prognosis is grim for an infant who is in a coma from this abuse: 50% die, and nearly half of the survivors have significant neurologic sequelae.

11

Why is the diagnosis of abusive head trauma often overlooked?

When an infant is unconscious with respiratory distress, apnea, and/or seizures, the diagnosis of abusive head trauma should be considered. However, depending on the degree of impact or shaking and the degree of resulting damage, the symptoms can be mild and nonspecific and may mimic symptoms of a viral illness, feeding disorder or dysfunction, or even colic. Victims may have a history of poor feeding, vomiting, lethargy, and/or irritability that may have gone on for days or weeks. Early identification of abusive injuries is critical because of the risk for increased mortality with each recurrent abusive event.

12

What diagnostic tests should be considered if abusive head trauma is suspected?

• Head CT: Good for demonstrating subarachnoid and large extra-axial hemorrhages and mass effect; may be falsely negative, especially early in the presentation

• MRI: Good for diagnosing subdural hemorrhages and intraparenchymal lesions; may miss subarachnoid blood and fractures

• Spinal tap: May yield bloody cerebrospinal fluid

• Skeletal survey: May be normal or may reveal acute or healed rib or other fractures, which are suggestive of abuse

• Complete blood count: May be normal or may show mild to moderate anemia

• Prothrombin time and partial thromboplastin time: May show mild to moderate abnormalities or reveal frank disseminated intravascular coagulation (DIC)

• Amylase: May show an increase, signifying possible pancreatic damage

• Liver function tests: Abnormalities may signify occult liver injury

13

What physical examination findings are indicators of possible child abuse?

• Burns, especially cigarette or immersion burns, on the buttocks or perineum or burns in a stocking-and-glove distribution

• Genital trauma or sexually transmitted infection (STI) in a prepubertal child

• Signs of excessive corporal punishment (welts, belt or cord marks, bites)

• Frenulum lacerations in young infants or tongue bruising (associated with forced feeding)

• Multiple bruises in various stages of resolution

• Bruises in a premobile infant

• Neurologic injury associated with retinal or scleral hemorrhages

• Fractures suggestive of abuse (e.g., skull fractures in infants, metaphyseal fractures, posterior rib fractures, fractures in premobile infants, scapular fractures in infants beyond the immediate newborn period)

14

If physical abuse is suspected, are physicians mandated to photograph physical findings?

No . A good drawing of the physical findings is sufficient. However, if photographs are taken, a card with the patient’s name and date of birth and the photographer’s name and signature must be included in the photograph so that the patient can be clearly identified. In addition, the body part that is being photographed must be clearly identifiable. If abuse is suspected, it is not necessary to obtain parental consent to take photographs.

15

If retinal hemorrhages are noted in a child with seizures, how likely are the seizures to have caused the hemorrhages?

In theory, any seizure may cause retinal hemorrhages through a sudden rise in retinal venous pressure in conjunction with increased central venous and intrathoracic pressure. However, a prospective study of children with seizures who had ophthalmologic evaluation found no evidence of an association of seizures and retinal hemorrhages. Combining their data with some previous studies, the authors determined a prevalence of retinal hemorrhages with a seizure of only about 3 per 10,000—an extremely small likelihood. If retinal hemorrhages are found in a child with seizures, the possibility of nonaccidental injury must be explored.

16

In a suspected victim of child abuse, how common are retinal hemorrhages if neuroimaging reveals no evidence of traumatic brain injury?

Very rare . Research has demonstrated that in the absence of positive neuroimaging, it is unlikely that an ophthalmologic eye examination will reveal clinically significant retinal hemorrhages in suspected child abuse.

17

Which conditions with ecchymoses (bruising) can be mistaken for child abuse?

• Mongolian spots (dermal melanocytosis) are commonly mistaken for bruises, especially when they occur elsewhere than the classic lumbosacral area; unlike bruises, they fade very slowly with time ( Fig. 5.3 ).

  

• Coagulation disorders including hemophilia or von Willebrand disease. In 20% of cases of hemophilia, there is no family history of disease; bruising may be noted in unusual places in response to minor trauma.

• Folk medicine such as the Southeast Asian practices of spoon rubbing (quat sha) or coin rubbing (cao gio) can produce ecchymoses; the practice of cupping (the inversion of a heated cup on the back) produces circular ecchymoses.

• Moxibustion is the Southeast Asian practice of burning an herbal substance on the child’s abdomen to cure disease.

• Clothing dyes, especially from jeans, sometimes mimic bruising; they are easily removed with topical alcohol.

• Vasculitis , particularly Henoch-Schönlein purpura with a purpuric rash most commonly on the buttocks and lower extremities, or idiopathic thrombocytopenic purpura (ITP) may be mistaken for signs of child abuse.

• Vitamin K deficiency

18

How do bruising patterns differ in abused children compared with nonabused children?

Derived at Kosair Children’s Hospital in Louisville, a simple mnemonic “ TEN 4 ,” which assesses body region and age, can be useful in identifying bruises that are of concern for abuse.

TEN stands for To rso, E ar, and N eck and 4 refers to ages (< 4 months or ≤ 4 years). In the context of no confirmed accident in a public setting that would account for bruising, any bruising in an infant < 4 months or bruising in the TEN region of a child ≤ 4 years was highly sensitive and specific for abusive trauma. Another study of 203 children < 3 years of age found bruises were quite uncommon in children not yet walking with support and cautioned that “those who don’t cruise rarely bruise.” In general, the head and face are the most common sites of bruising in abused children. Clustering of bruises may represent defensive injuries, and abusive bruises may carry an imprint of a hand or the looped mark of an extension cord.

19

What screening laboratory tests should be obtained if you suspect nonaccidental abdominal injury?

It is important to remember that pediatric victims of nonaccidental trauma can be symptomatic with signs of hemorrhage or peritonitis, or they may not exhibit overt findings. If you are suspicious of abdominal injury, the workup should include:

• Liver and pancreatic enzyme levels

• Urinalysis

• Contrast-enhancing CT when screening laboratory tests suggest abdominal injury; in all cases of symptomatic injury; and most cases when the physical examination is unreliable because of the patient’s age, presence of distracting injuries, or presence of accompanying head injury.

20

How are fractures dated radiographically in children?

After a fracture, the following will be seen:

• 1 to 7 days: Soft tissue swelling; fat and fascial planes blurred; sharp fracture line

• 7 to 14 days: Periosteal new bone formation as soft callus forms; blurring of fracture line; occurs earlier for infants, later for older children

• 14 to 21 days: More clearly defined (i.e., hard) callus forming as periosteal bone converts to lamellar bone

• 21 to 42 days: Peak of hard callus formation

• ≥ 60 days: Remodeling of bone begins with reshaping of the deformity (up to 1 to 2 years)

If the timing of an injury does not correlate with the dating of a fracture or if fractures are at multiple stages of healing are present, child abuse should be suspected.

21

What fractures are suggestive of child abuse?

All fractures can be the result of child abuse, and a careful history will guide the clinician in the degree of suspicion indicated in each case. In infants and toddlers, physical abuse is the cause of up to 20% of fractures. This is an age group in which suspicion should be high. Some fractures have been shown to have a high specificity for abuse, and these are rib fractures in infants , particularly posteromedially; classic metaphyseal lesions of long bones ; and fractures of the scapula, spinous process, and sternum . Metaphyseal fractures ( Fig. 5.4 ) require shearing forces not usually produced in accidental trauma, with an increased likelihood of mechanisms that involve shaking with limbs flailing, twisting, and jerking. The presence of multiple fractures, fractures of different ages and/or stages of healing, and complex skull fractures also have a good degree of specificity for abuse.

22

How certain can a clinician be in attributing a femur fracture in a nonambulatory child to nonaccidental trauma?

Femur fractures in the nonambulatory child are most often the result of nonaccidental trauma. However, there are exceptions to this “rule.” Certain femur fractures in young children may be accidental:

• A short fall to the knee may produce a torus or impacted transverse fracture of the distal femoral metaphysis.

• Children playing in a stationary activity center, like an Exersaucer, may sustain an oblique distal femur metaphyseal fracture.

• Falls down a stairway in a nonambulatory child can sometimes cause one leg to become twisted underneath the child, resulting in a spiral femoral fracture.

23

What is the purpose of the skeletal survey?

Skeletal injuries, particularly multiple healed lesions, are strong indicators of a pattern of abuse. The skeletal survey is a radiologic evaluation of multiple bones in the body to:

• Reveal fractures of additional bones (new or healing) other than the fractured bones already known to the clinician

• Reveal fractures (new or healing) in a child suspected of abuse manifesting in ways other than fractures.

24

What constitutes a skeletal survey?

The skeletal survey is a multiple-imaging series that includes x-ray views of the following:

• Appendicular skeleton: Humeri, forearms, hands, femurs, lower legs, and feet

• Axial skeleton: Thorax, pelvis, entire spine and head CT

The series can include anywhere between 19 and 30 x-rays. “Body grams” (studies that encompass the entire child in one or two exposures) are not thought to be of sufficient sensitivity to be useful.

25

Up to what age should a skeletal survey be ordered?

If physical abuse is suspected, the AAP recommends a mandatory study in children up to the age of 2 years. The yield diminishes after that age and is of little value after the age of 5 years.

26

What is the value of a follow-up skeletal survey?

Both the AAP and the American College of Radiology recommend follow-up skeletal surveys about 2 to 3 weeks after the initial study if the first was abnormal or equivocal or when abuse is suspected on clinical grounds despite a normal first study. The follow-up skeletal survey can demonstrate a previously missed occult fracture by the presence of new callus formation. The yield can be substantial, with studies demonstrating new findings ranging from 14% to 61%. Because of the additional radiation, research is also addressing the applicability of more limited views on the follow-up study.

27

Can an initial skeletal survey be limited with fewer x-rays to reduce radiation exposure?

Not yet, but there is considerable debate. Views of the spine and pelvis have the lowest yield in revealing fractures, and they require the largest amounts of radiation. Some researchers believe these views could be eliminated without missing cases of abuse. They advocate for a stepwise approach to imaging that would protocolize a “core” skeletal survey, without lateral spine and pelvis, but would encourage inclusion of these views if clinically indicated. The complicating factor is that fractures of the spine and pelvis are highly specific for abuse when they are found. Some researchers believe it would be dangerous to eliminate these views from the initial skeletal survey.

28

In addition to child abuse, what conditions must you consider as a cause of multiple unexplained long bone fractures in a young child?

• Osteogenesis imperfecta (OI) is a rare congenital disorder that presents with bone fragility. In addition to frequent fractures, patients with this disorder often present with the following:

  • Blue sclera

  • Ligamentous laxity

  • Osteopenia

  • Wormian skull bones (additional isolated sutural lines on skull x-ray)

  • Dentinogenesis imperfecta

  • Family history of OI (although not always because new cases can result from de novo mutations)

  • Hearing loss

• Vitamin D deficiency–associated rickets

• Scurvy

• Copper deficiency

29

When are burn injuries suspicious for child abuse?

Burn injuries account for about 5% of cases of physical abuse. As with other injuries, the description of the incident causing the burn should be consistent with the child’s development and the extent and degree of the burn observed. The following types are suspicious for abuse:

• Immersion burns: Sharply demarcated lines on the hands and feet (stocking-and-glove distribution), buttocks, and perineum, with a uniform depth of burn; the immersion of a child in a hot bath is a classic example

• Geographic burns: Burns, usually of second or third degree, in a distinct pattern, such as circular cigarette burns or steam iron burns

• Splash burns: Pattern with droplet marks projecting away from the most involved area; splash marks on the back of the body usually require another person and may or may not be accidental

30

How do you recognize fabricated child abuse?

This form of child abuse, previously called Munchausen syndrome by proxy, now goes by various names, including pediatric condition falsification, abuse by pediatric condition falsification, caregiver-fabricated illness in a child, medical child abuse, or factitious disorder imposed on another. Adult caregivers (most commonly the patient’s mother) inflict illness on a child or falsify symptoms to obtain medical care for a child. Features include the following:

• Recurrent episodes of a confusing medical picture

• Multiple diagnostic evaluations at different medical centers (“doctor shopping”)

• Unsupportive marital relationship, often with maternal isolation

• Compliant, cooperative, and overinvolved mother

• Higher level of parental medical knowledge

• Parental history of extensive medical treatment or illness

• Conditions resolve with surveillance of the child in the hospital

• Findings correlate with the presence of the parent

31

How often is sexual abuse committed by an individual known previously by the child or adolescent?

Between 75% and 80% of the time. Relatives are the perpetrators in about one-third of cases.

32

In the case of suspected prepubertal sexual abuse, how critical is it to perform the physical examination immediately on presentation of the child to a medical facility?

If no exchange of bodily fluids has occurred and the child is not presenting with a medical emergency, such as vaginal bleeding, it is not necessary to perform a medical examination immediately in the office or emergency department (ED) setting. In fact, it is preferential to refer the child to a setting staffed by medical personnel familiar with the sexual abuse examination, such as a pediatric ED or a child advocacy center. If exchange of bodily fluids has occurred, then the timing of the examination is more critical. Guidelines vary from state to state, with recommendations that forensic evidence be collected from 24 hours to 96 hours after an assault.

33

After the documentation of history and a careful physical examination, what evidence should be collected in cases of suspected sexual abuse in a prepubertal female?

Because STIs are not common in prepubertal children evaluated for abuse, culturing all sites (vaginal, rectal, and oral) for all organisms is not recommended if the child is not symptomatic. Each case should be treated individually. However, here are some considerations:

• Whether the child was penetrated, either vaginally or anally

• Whether the abuser was a stranger

• Whether the abuser is known to have an STI or be at risk

• Whether the child has a sibling or other relative in the household with an STI

• Whether the child has signs or symptoms of an STI

• Whether the child has already been diagnosed with a previous STI

If the decision is made to collect specimens from a prepubertal child, the AAP recommends the use of a nucleic acid amplification test (NAAT) for detection of infection with Chlamydia trachomatis and Neisseria gonorrhoeae . Culture-based tests for these organisms are highly insensitive. However, it should be noted that the Food and Drug Administration (FDA) has not approved the use of the NAAT for cultures of the rectum and throat in pediatric patients.

34

After the documentation of history and a careful physical examination, what evidence should be collected in cases of suspected sexual abuse in a postpubertal female?

• Pregnancy test, if postmenarchal

• Evidence of sexual contact, including two to three swabbed specimens from each area of assault for the following substances: sperm (motile and nonmotile), acid phosphatase (secreted by the prostate; component of seminal plasma), P ₃₀ (prostate glycoprotein present in seminal fluid), blood group antigens

• NAAT for STIs from all three sites

• Evidence to document perpetrator: foreign material on clothing, suspected nonpatient hairs; DNA testing (controversial)

35

After the initial ED evaluation for sexual assault, what kind of follow-up care should the ED physician offer?

• Human immunodeficiency virus (HIV) follow-up counseling with infectious disease or HIV specialist in 3 to 5 days

• Follow-up gynecologic examination at 1 to 2 weeks

• Repeat serologic tests for syphilis and HIV in 6 weeks, 3 months, and 6 months

• Psychiatric counseling

36

If a child who is not sexually active is diagnosed with an infection caused by an STI-associated organism, how likely is sexual abuse the reason for acquisition?

See Table 5.1 .

37

Is the size of the hymenal opening an important finding in the diagnosis of sexual abuse?

The hymenal opening is measured with a child in the supine, frog-leg position, and various studies have attempted to determine a size that most likely correlates with sexual abuse. The upper limit of normal had ranged from 4 to 8 mm, but variations in technique, positioning, and relative relaxation of the patient have rendered such measurements generally unhelpful and nondiagnostic . A more important part of the examination is inspection of the posterior hymen and surrounding tissues. Typically, a posterior rim of hymen measuring at least 1 mm is present unless there has been trauma. Complete transaction of the hymen leaves a permanent gap or defect. A full-thickness transaction through the posterior hymen (best visualized in the knee–chest position) is thought to be reliable evidence of trauma. Other variations of hymenal shape or size must be interpreted with caution because there is considerable overlap among abused and nonabused girls.

38

What is the most common finding of the physical examination of a child who has been sexually abused?

A normal physical examination is the most common physical finding, which is why in the absence of vaginal bleeding or other medical emergency, the physical examination should be deferred to an experienced medical examiner in a pediatric ED or a child advocacy center. It is crucial to know that a normal examination does not rule out sexual abuse.

39

What are the date-rape drugs?

Date-rape drugs are substances that render a patient incapable of saying “no” or asserting herself or himself, which makes it easier for a perpetrator to commit rape. The term typically applies to three drugs— flunitrazepam ( Rohypnol ), γ -hydroxybutyrate ( GHB ), and ketamine hydrochloride —which go by a variety of street names. The effects of these drugs, including somnolence, muscle relaxation, and profound sedation and amnesia—are enhanced by the concurrent use of alcohol.

40

How can you tell whether a patient has been given a date-rape drug?

Most of these drugs can be detected in blood and/or urine. However, because they are metabolized very quickly, it is important to screen early in your evaluation of the patient. For example, Rohypnol can be detected in blood for 24 hours and in urine up to 48 hours, GHB in urine only for up to 12 hours after ingestion, and ketamine in urine for up to 72 hours. None of these drugs is included in routine drug screen panels.

41

How do freshwater and saltwater drownings differ?

Fresh water injures the lung primarily by disrupting surfactant, thereby leading to alveolar collapse. Damage to the alveolar membranes leads to the transudation of fluid into the air spaces and pulmonary edema. Salt water pulls fluid into the air spaces directly by creating a strong osmotic gradient, and the accumulated water washes away surfactant, thereby leading to alveolar collapse. Both types result in abnormal surfactant function and increased capillary endothelial permeability. Patients develop ventilation-perfusion mismatch and hypoxemia, which may require aggressive mechanical support. Ultimately, management for either freshwater or saltwater drowning is the same.

42

How is the duration of submersion predictive of outcomes in drownings?

Risk for death or severe neurologic impairment after hospital discharge increases with duration of submersion as follows:

• 0 to 5 minutes: 10%

• 6 to 10 minutes: 56%

• 11 to 25 minutes: 88%

• > 25 minutes: nearly 100%

Signs of brainstem injury are also predictive of death or severe neurologic sequelae.

43

What cardiovascular changes occur as body temperature falls?

• 31°C to 32°C: Elevated heart rate, cardiac output, and blood pressure; peripheral vasoconstriction and increased central vascular volume; normal electrocardiogram (ECG)

• 28°C to 31°C: Diminished heart rate, cardiac output, and blood pressure; ECG irregularities include premature ventricular contractions (PVCs), supraventricular dysrhythmias, atrial fibrillation, and T-wave inversion

• < 28°C: Severe myocardial irritability; ventricular fibrillation, usually refractory to electrical defibrillation; often absent pulse or blood pressure; J waves on ECG

44

What are the physiologic consequences of externally warming a severely hypothermic patient too rapidly?

• Core temperature “after-drop”: The body temperature drops because external rewarming causes peripheral vasodilation and the return of cold venous blood to the core.

• Hypotension: Peripheral vasodilation increases total vascular space, thereby causing a drop in blood pressure.

• Acidosis: Lactic acid returns from the periphery, thereby resulting in rewarming acidosis.

• Dysrhythmias: Rewarming alters acid–base and electrolyte status in the setting of an irritable myocardium.

45

What are acceptable rewarming methods for the hypothermic child?

For patients with mild hypothermia (32 ° C to 35 ° C), passive rewarming by removing cold clothing and placing the patient in a warm, dry environment with blankets is generally sufficient. Active external rewarming involves the use of heating blankets, hot-water bottles, and overhead warmers and can also be used for patients with acute hypothermia in the 32 ° C to 35 ° C range. Active external rewarming should not be used for chronic hypothermia (> 24 hours). More aggressive core rewarming techniques should be considered for patients with temperatures lower than 32 ° C. These techniques include gastric or colonic irrigation with warm fluids, peritoneal dialysis, pleural lavage, and extracorporeal blood rewarming with partial bypass. Intravenous and other fluids should be heated to 43 ° C. Patients should be given warmed, humidified oxygen by facemask or endotracheal tube (ETT).

46

What organ systems are affected in patients suffering from heat stroke?

Heat stroke is a medical emergency of multisystem dysfunction that includes a very high body temperature (usually > 41.5°C). The systems that are affected include the following:

• Central nervous system (CNS): confusion, seizures, and loss of consciousness

• Cardiovascular: hypotension as a result of volume depletion, peripheral vasodilation, and myocardial dysfunction

• Renal: acute tubular necrosis and renal failure, with marked electrolyte abnormalities

• Hepatocellular: injury and dysfunction

• Heme: abnormal hemostasis, often with signs of DIC

• Muscle: rhabdomyolysis

47

How quickly can temperature rise inside an enclosed automobile?

The greatest rise in temperature in a closed vehicle occurs within the first 15 to 30 minutes. Leaving the window slightly open (“cracking the window”) does not affect the rapid temperature elevation. In one observational study, the internal temperature of an automobile increased by ≈ 40°F compared with outside temperatures. Heat stroke is a significant cause of death in children who are left unattended in motor vehicles.

48

What are characteristics of heat stroke?

Heat stroke occurs when the body temperature exceeds 104°F, resulting in thermoregulatory collapse and accompanied by central nervous system (CNS) dysfunction. Symptoms include dizziness, disorientation, agitation, confusion, sluggishness, seizure, hot dry skin that is flushed but not sweaty, loss of consciousness, rapid heartbeat, and hallucinations. A core body temperature of 107°F or greater can be lethal because cells are damaged and internal organs begin to shut down.

49

Why are children more vulnerable to effects of external temperature changes?

Children’s thermoregulatory systems are not as efficient as an adult’s, and their body temperatures warm at a rate three to five times faster than an adult’s.

50

What are the signs and symptoms of significant upper airway heat exposure in a patient who has been in a house fire?

• Carbonaceous sputum

• Singed nasal hairs

• Facial burns

• Respiratory distress

One should not rely on the presence of respiratory distress as an indicator for prompt endotracheal intubation. The first three signs listed represent significant heat exposure to the airway, and progressive swelling can rapidly progress to upper airway obstruction.

51

What are the signs and symptoms of impending respiratory failure as a result of mucosal injury and edema from heat exposure during a house fire?

• Hoarseness

• Stridor

• Increasing respiratory distress

• Drooling and difficulty swallowing

An ETT should be emergently considered for patients with these signs and symptoms. Upper airway mucosal swelling may make intubation difficult, and the most experienced physician should perform this intervention.

52

Which laboratory studies are needed for patients with suspected carbon monoxide (CO) poisoning?

• Blood carboxyhemoglobin (COHb) level

  • 0% to 1%: Normal (smokers may have up to 5% to 10%)

  • 10% to 30%: Headache, exercise-induced dyspnea, confusion

  • 30% to 50%: Severe headache, nausea, vomiting, increased heart rate and respirations, visual disturbances, memory loss, ataxia

  • 50% to 70%: Convulsions, coma, severe cardiorespiratory compromise

  • 70%: Usually fatal

• Hemoglobin level: To evaluate correctable anemia

• Arterial pH: To detect acidosis

• Urinalysis for myoglobin: With CO poisoning, patients are susceptible to tissue and muscle breakdown with possible acute renal failure resulting from the renal deposition of myoglobin.

53

What are the key aspects of treatment for CO poisoning in children?

• Treatment includes 100% oxygen through a nonrebreather mask until the COHb level falls to 5%. The half-life of COHb is 5 to 6 hours if the patient is breathing room air (at sea level). The half-life of COHb is reduced to 1 to 1.5 hours if the patient is breathing 100% oxygen (at sea level). The half-life of COHb is reduced to under 1 hour with hyperbaric oxygen therapy.

• Refer for use of hyperbaric oxygen for the following conditions: a history of coma, seizure, or abnormal mental status at the scene or in the ED; persistent metabolic acidosis; neonate; pregnancy (the fetus is more vulnerable to hypoxic effects of CO); or the COHb level is more than 25%, even if the patient is neurologically intact.

54

Why is CO such a deadly toxin?

• CO is odorless and invisible and can overwhelm a patient without warning.

• CO is ubiquitous as a product of partial combustion (car exhaust emissions, household heating equipment, burning charcoal).

• In the absence of a clear history, early CO intoxication is often misdiagnosed as a flulike illness.

55

What is the pathophysiology of CO poisoning?

• CO develops a nearly irreversible bond with hemoglobin (with an affinity 200 to 300 times that of oxygen) that shifts the oxyhemoglobin dissociation curve to the left and changes its shape from sigmoidal to hyperbolic (with greatly diminished O ₂ tissue release).

• CO develops a strong bond with other heme-containing proteins , particularly in the mitochondria, thereby leading to metabolic acidosis and cellular dysfunction (especially in cardiac and CNS tissues).

56

What other serious exposure risk should one consider when managing a patient suffering from carbon monoxide poisoning?

One of the most important considerations in managing a CO-poisoned patient is concomitant cyanide (CN) poisoning. In CO-exposed patients with persistent acidosis and high lactate levels, one should seriously consider CN poisoning and treat accordingly. Supplemental oxygen therapy is not adequate. If CN poisoning is suspected, treat the patient with sodium thiosulfate.

57

What are the different degrees of burn injuries?

See Table 5.2 .

58

How does the “rule of nines” apply in children?

The “rule of nines” is a tool used to estimate the extent of burns in adults. For example, in adults, the entire arm is 9% of the total body surface area (TBSA), the front of the leg is another 9% of the TBSA, and so on. The resulting estimate of the extent of burns is particularly helpful for calculating fluid requirements. Correction for age is necessary with this formula because of differing body proportions. Therefore, for children, use the surface of a patient’s palm, which represents about 1% of TBSA, as the tool for estimating the percentage of the TBSA affected by the burn ( Fig. 5.5 ).

59

Which burn injuries are indications for hospitalization?

• Partial-thickness burns covering > 10% of the TBSA

• Full-thickness burns covering > 2% of the TBSA

• Significant burns involving the hands, feet, face, joints, or perineum

• Burns resulting from suspected child abuse

• Electrical burns

• Circumferential burns (which may predispose the patient to vascular compromise)

• Explosion, inhalation, or chemical burns (in which other organ trauma may be involved)

• Significant burns in children < 2 years

60

Why are alkali burns worse than acid burns in the eye?

Alkali burns are caused by lye (e.g., Drano, Liquid-Plumr), lime, or ammonia, in addition to other agents; they are characterized by liquefaction necrosis. They are worse than acid burns because the damage is ongoing. When spilled in the eye, acid is quickly buffered by tissue and limited in penetration by precipitated proteins; coagulation necrosis results, which is usually limited to the area of contact. Alkali, however, has a more rapid and deeper advancement, thereby causing progressive damage at the cellular level by combining with membrane lipids. This underscores the importance of extensive irrigation of the burned eye, particularly in cases of alkali burns.

61

How do the injuries produced by lightning and high-voltage wires differ?

• Lightning: Consists of direct current of extremely high voltage (200,000 to 2,000,000,000 volts) delivered over milliseconds. Lightning exposure causes massive electrical countershock with asystole, respiratory arrest, and minimal tissue damage.

• High-voltage wires: Deliver alternating current of lower voltage (rarely exceeding 70,000 volts) over a longer period. High-voltage exposure causes ventricular fibrillation and deep tissue injury. The resultant muscle necrosis can lead to substantial myoglobin release and renal failure.

62

In electrical injury, is alternating or direct current more hazardous?

At low voltages (e.g., those found in household electrical devices), alternating current is more dangerous than direct current. Exposure to alternating current can provoke tetanic muscle contractions so that the victim who has grasped an electrical source is unable to let go, thereby prolonging the exposure and producing greater tissue injury. Direct current or high-voltage alternating current typically causes a single forceful muscular contraction that will push or throw the victim away from the source.

63

What agents are the most common causes of anaphylaxis seen in U.S. emergency rooms?

Food . Peanuts , tree nuts (e.g., almonds, hazelnuts), and seafood head the list and are twice as common as bee stings as a trigger. Severe reactions occur 1 to 2 hours after exposure. Anaphylaxis may occur without a skin reaction, so a high index of suspicion is needed in a child with unexplained sudden bronchospasm, laryngospasm, severe GI symptoms, or poor responsiveness. In some adolescents, certain foods (e.g., wheat, celery, shellfish), if ingested within 4 hours of exercise, can lead to food-dependent, exercise-induced anaphylaxis. Risk factors for fatal anaphylactic reactions include a history of asthma, delayed diagnosis, and delayed administration of epinephrine.

64

What are important considerations when treating frostbite in children?

• Rewarm the affected area in water with a temperature of 37°C to 43°C (99°F to 109°F) for 20 minutes.

• Never attempt to rewarm if there is risk for refreezing.

• Rubbing the affected area may cause further damage to tissue.

65

Are there any indications for chest compression–only cardiopulmonary resuscitation (CPR) in children?

When trained medical personnel are present, such as with in-hospital arrests, simultaneous performance of chest compressions and ventilation is recommended for children and adults. However, new American Heart Association (AHA) guidelines encourage chest compressions alone for out-of-hospital arrest in adults if one or more lay rescuers are reluctant to perform mouth-to-mouth ventilation. However, compression-only CPR is not recommended for children . Ventilation remains vital for infants and children, as most arrests originate from a noncardiac nature with progressive tissue hypoxia and acidosis occurring due to respiratory failure or shock.

66

What common problems are identified in CPR done by professionals?

• Chest compressions are often too fast. Compressions should be done at a rate of 100 to 120 compressions per minute.

• Chest compression depth, which should be at least one-third of the depth of the child’s chest, is often inadequately shallow, particularly when administered to younger children.

• Chest wall decompression (the relaxation phase) is often insufficient. Allow for full recoil.

• Ventilation rates are often excessive.