1. A 23-year-old man with a known peanut allergy presents to your emergency department complaining of 20 minutes of shortness of breath and pruritus that began when he was eating at a Thai restaurant. While en route to the hospital he noticed swelling of his lips and eyes. Physical examination reveals a patient in mild distress, with diffuse urticaria and mild facial angioedema, without obvious intraoral involvement. Mild wheezing is also present. He is afebrile, with stable vital signs; oxygen saturation is 97% on room air. Which of the following drugs is the first-line treatment for this clinical scenario?
A. Antihistamines (H₁ and H₂ blockers)
B. Corticosteroids
C. Epinephrine (Adrenalin), 0.01 mg/kg (maximum, 0.5 mg) by intramuscular injection
D. Nebulized albuterol (AccuNeb, Proventil)

2. You are evaluating an 8-year-old child with abdominal pain for possible appendicitis. Laboratory testing shows a white blood cell (WBC) count of 7.9 x 109/L. You are wondering whether to pursue the diagnosis further, when your attending physician remarks that the absence of leukocytosis has a negative predictive value (NPV) of 62% for appendicitis. Based on this information, what would you conclude?
A. The probability of not having appendicitis is 62% in the absence of leukocytosis
B. Approximately 62% of patients without appendicitis will not have leukocytosis
C. The positive predictive value for leukocytosis is 38%
D. You need to review your evidence-based medicine

3. An 18-year-old woman presents to your clinic with 3 days? duration of lower abdominal pain and vaginal discharge. She is in mild distress and has a temperature of 99.8?F. Physical examination reveals bilateral lower quadrant tenderness, with guarding but no rebound. Pelvic examination reveals bilateral adnexal tenderness, a friable cervix with thick yellow discharge, and significant cervical motion tenderness. Which of the following treatment regimens would NOT be appropriate?
A. Ceftriaxone (Rocephin), 125 mg intramuscularly plus oral doxycycline (eg, Adoxa, Doryx, Vibra-Tabs), 100 mg twice daily for 14 days
B. Ceftriaxone, 125 mg intramuscularly plus oral azithromycin (Zithromax), 1 g
C. Oral levofloxacin (Levaquin), 500 mg once daily with/without oral metronidazole (Flagyl), 500 mg twice daily for 14 days
D. Oral ofloxacin (Floxin), 400 mg once daily with/ without oral metronidazole, 500 mg twice daily for 14 days

4. A 24-year-old man with known severe hemophilia, type A, walks into the emergency department after having been in a motorcycle crash. He was not wearing a helmet. He experienced a 10-minute loss of consciousness and vomited twice at the scene. Currently he complains only of a mild headache. The patient is hemodynamically stable and has a small cephalohematoma. Physical examination reveals no focal neurologic deficit. What would be the next appropriate step in management?
A. Head computed tomography (CT) without contrast
B. After 6 hours of observation in the emergency department, discharge home if asymptomatic
C. Intravenous (IV) infusion of factor VIII, 50 U/kg
D. IV infusion of factor VIII, 25 U/kg

5. You are called to manage a 70-year-old woman in cardiac arrest. She has coronary artery disease and collapsed 3 minutes ago. Upon arrival, cardiopulmonary resuscitation is in progress, and bag-mask ventilation is being used. The presenting rhythm is asystole, and 1 mg IV epinephrine has been administered. Which of the following interventions would NOT be appropriate?
A. Transcutaneous pacing
B. IV vasopressin (Pitressin), 40 U
C. IV epinephrine (Adrenalin), 1 mg
D. Orotracheal intubation

6. A 56-year-old man with hypertension and renal insufficiency presents with 1 week?s duration of pain and swelling of his right ankle and left knee. He had a similar episode 2 years ago. The review of systems is negative for antecedent trauma, fever, or dysuria. Physical examination reveals a swollen, warm right ankle, with decreased range of motion but no overlying erythema. Which of the following statements is NOT true?
A. The condition is polyarticular in 40% of cases
B. Point of insertion for arthrocentesis of the ankle should be at the sulcus between the medial malleolus and anterior tibial tendon
C. A joint aspirate will show negatively birefringent crystals
D. Acute treatment includes nonsteroidal antiinflammatory drugs (NSAIDs), steroids, colchicine, and allopurinol

7. A 41-year-old man is brought to the emergency department after sustaining a high-speed front-end motor vehicle collision. He is complaining of upper back pain and an inability to move his legs. Physical examination shows the patient has no motor strength in his legs but normal strength in his arms. He cannot feel pain up to the level of his nipples. His position sense in the legs remains intact. What is the diagnosis?
A. Central cord syndrome
B. Brown-S?quard?s syndrome
C. Anterior cord syndrome
D. Transverse myelitis

8. A 7-year-old girl returns to the emergency department for a wound recheck. Two days earlier she underwent incision and drainage of a superficial leg abscess and was given empiric therapy with cephalexin (Biocef, Keflex). The mother says that the pain, swelling, and erythema are nearly resolved. Wound culture obtained at incision and drainage grew methicillin-resistant Staphylococcus aureus (MRSA). The patient is an otherwise healthy child with no previous hospital visits. Which of the following statements about this clinical scenario is true?
A. The antibiotic regimen should be switched to a drug with intrinsic MRSA coverage
B. MRSA is a relatively infrequent etiologic pathogen in community-acquired skin infections
C. This patient?s MRSA isolate is genetically different from hospital-associated MRSA
D. The patient is at risk for the development of severe pneumonia

9. A healthy 45-year-old woman presents to your clinic at the Mount Everest base camp (altitude, 5500 m). She arrived at the camp 8 hours ago and is complaining of headache associated with nausea, vomiting, and general malaise. She appears fatigued, but her physical examination findings, including neurologic and pulmonary evaluations, are normal. Which of the following therapies is NOT indicated?
A. Oral analgesics
B. Immediate descent
C. Acetazolamide
D. Dexamethasone (Decadron)

10. A 19-year-old man presents with a Colles? fracture after falling while playing basketball. Except for being treated for an upper respiratory tract infection, he has no significant medical history. While being sedated with ketamine for fracture reduction, the patient becomes stridulous. Which of the following statements is true?
A. The patient should be emergently intubated
B. The reversal agent should be administered
C. Age older than 16 years is a contraindication to using ketamine for procedural sedation
D. Common adverse effects of ketamine therapy include hypersalivation, nystagmus, random limb movements

11. A 3-year-old boy is brought to the emergency department by emergency medical services (EMS) after he was found to be unresponsive at his grandmother?s home. The grandmother reports finding near the child an empty plastic bag, in which she used to keep her blood pressure (BP) medications. The child is hypotensive, bradycardic, apneic, and has pinpoint pupils. After securing an airway, which of the following therapies may be beneficial?
A. Cardioversion
B. High-dose insulin
C. Glucagon (GlucaGen)
D. Naloxone HCl (Narcan)

12. What characteristics differentiate a simple febrile seizure from a generalized tonic-clonic seizure?
A. Only tonic-clonic seizures show generalized slowing on electroencephalography
B. Only generalized tonic-clonic seizures are associated with a postictal period
C. Typically there is a family history of tonic-clonic seizures
D. Only tonic-clonic seizures involve both hemispheres of the brain

13. A 9-year-old boy with a history of spina bifida, hydrocephalus, and a ventriculoperitoneal shunt that was placed 2 years ago is brought to the emergency department because of 1 week of intermittent nausea and vomiting and worsening headaches. The mother reports no history of fever but says she has been unable to depress the shunt?s chamber. A brain CT shows significantly narrowed ventricles compared with the child?s baseline scan. The boy is crying and holding his head in pain. What immediate therapy may provide some relief?
A. Tapping the shunt to release pressure
B. Placing the child in the Trendelenburg position
C. IV hydration
D. IV antibiotics

14. A 58-year-old construction worker was working outside when he was bitten by a pygmy rattlesnake just below the thumb. In the emergency department, you note fang marks, erythema, and swelling up to the elbow. The patient feels nauseous. What is the most appropriate management?
A. Emergent fasciotomy
B. Broad-spectrum antibiotics for cellulitis
C. 10 vials of crotalidae polyvalent immune fab (CroFab)
D. Observation in the emergency department for 8 to 12 hours; if the symptoms worsen, administer antivenom

15. A 92-year-old man with congestive heart failure (CHF) is brought to the emergency department by EMS after a syncopal episode. He has had 2 days of nausea, vomiting, and abdominal pain without diarrhea. His medications include digoxin (Digitek, Lanoxin), insulin, and furosemide (Lasix). His blood glucose level in the field was 118 mg/dL. Vital signs include: BP, 112/56 mm Hg; pulse, 53 beats/min (irregular on monitor); respirations, 24 breaths/min; oxygen saturation, 92% on room air. Laboratory test results show: sodium, 135 mmol/L; potassium, 7.5 mmol/L; chloride, 109 mmol/L; bicarbonate, 25 mmol/L; blood urea nitrogen (BUN), 10 mg/dL; creatinine, 1.4 mg/dL. Electrocardiography (ECG) demonstrates a narrow-complex tachycardia. What is the appropriate management?
A. Synchronized cardioversion
B. Calcium gluconate to treat the elevated potassium level
C. Digoxin immune fab (Digibind, DigiFab) for presumed digoxin toxicity
D. Magnesium sulfate therapy for the supraventricular tachycardia

16. A 65-year-old man comes to the emergency department because he has been passing bright red blood from his rectum for the last few days. He also complains of 2 days of chest pain and shortness of breath. His medical history includes aortic valve replacement 10 years ago. He reports that he used to be able to hear a click at times but has not heard it in the past few days. Physical examination shows he is hypotensive, and there are no metallic sounds, crackles, or chest wall tenderness. Rectal examination is positive for a small amount of gross blood. The patient tells you he stopped taking his warfarin sodium (Coumadin, Jantoven) when he began bleeding. What is the next step in management?
A. Transfuse 2 units of packed red blood cells for the rectal bleeding
B. Administer 40 mg furosemide to treat his CHF exacerbation
C. Call the cardiothoracic surgeon and begin anticoagulation; this patient has thromboembolic disease
D. Admit him to the hospital to rule out myocardial infarction (MI)

17. A 4-year-old girl presents with nausea, vomiting, and watery diarrhea of 3 days? duration. The mother reports she has been acting increasingly fussy, and her urine output has decreased. On physical examination you note an ill-appearing child with a capillary refill time of more than 2 seconds and an absence of tears. How would you categorize the degree of dehydration?
A. Minimal
B. Mild
C. Moderate
D. Severe

18. A 67-year-old man is brought into the emergency department after a witnessed episode of cardiac arrest in a casino. EMS personnel report that security staff on the scene were able to shock the patient out of ventricular fibrillation within 10 minutes using an automated external defibrillator. The patient is still unresponsive but has a pulse and is tachycardic, with a heart rate of 110 to 119 beats/min. What therapy has been reported in the past few years to protect against ischemic brain injury?
A. Mild hypothermia
B. Amiodarone HCl (Cordarone, Pacerone)
C. Lidocaine (Xylocaine) infusion
D. Warmed IV fluids

19. A 72-year-old man with a medical history of hypertension, atrial fibrillation, and CHF is brought to the emergency department with slurred speech, right-sided facial drooping, and an inability to use his right arm. The patient is afebrile, with BP, 215/110 mm Hg; pulse, 72 beats/min; respirations, 18 breaths/min; and oxygen saturation, 99% on room air. He is able to follow your commands and answer some of your questions appropriately. He can grip your fingers with his right hand with moderate strength. Which of the following factors would be a contraindication to the use of thrombolytic agents for the treatment of his ischemic stroke?
A. Age
B. BP 168/86 mm Hg after administering 20 mg of labetalol HCl (Trandate)
C. History of atrial fibrillation
D. Onset of symptoms 2 hours earlier
E. None of the above

20. A 48-year-old man is brought to the emergency department after passing out at home. He had been arguing with his wife when he suddenly collapsed. ECG shows sinus rhythm, with a corrected QT (QTc) interval of 500 ms. What other ECG sign would indicate that this patient is at high risk for cardiac events?
A. T-wave alternans
B. U wave
C. Peaked T waves
D. Osborne waves

ANSWERS
1?C. Anaphylaxis can be defined as an acute reaction to a likely antigen with multisystem involvement. Symptoms and signs include pruritus, urticaria, angioedema, bronchospasm, nausea, vomiting, hypotension, and/or syncope. The treatment of choice is the intramuscular administration of epinephrine, which results in more rapid and higher peak blood levels than subcutaneous administration. Several doses may be required. For cases of severe hypotension and/or cardiac arrest, IV epinephrine should be used. Antihistamines and albuterol have demonstrated efficacy in anaphylaxis but are considered second-line therapy. Corticosteroids remain a mainstay of therapy and are believed to protect against biphasic reactions, despite a lack of supportive evidence from placebo-controlled trials.

Source
Sampson HA, Munoz-Furlong A, Campbell RL, et al. Second symposium on the definition and management of anaphylaxis: summary report?second National Institute of Allergy and Infectious Disease/Food Allergy and Anaphylaxis Network Symposium. Ann Emerg Med. 2006;47: 373-380.

2?A. The NPV is the probability of a true negative (absence of appendicitis) given a negative test result (no leukocytosis). The probability of a negative test result given the absence of disease (option B) describes the specificity of the test, whereas 38% is the false-negative rate (1 ? NPV). The positive predictive value cannot be derived from the information given.

3?B. The clinical scenario is consistent with mild pelvic inflammatory disease (PID), which implies infection of the upper genital tract, including endometritis; salpingitis; tuboovarian abscess; and, in its most severe form, peritonitis. Common etiologic agents include Neisseria gonorrhea and Chlamydia trachomatis, but PID is increasingly recognized as a polymicrobial infection with other isolates, including anaerobes, coliforms, and genital mycoplasma. Initiation of therapy in the clinic is based on clinical findings, not culture results; thus empiric treatment should provide a broad spectrum of coverage. Although considered appropriate treatment for simple mucopurulent cervicitis, the combination of ceftriaxone and azithromycin offers inadequate coverage when upper genital tract infection is suspected.

Source
McCormack WM. Pelvic inflammatory disease. N Engl J Med. 1994; 330:115-119.

4?C. The patient has a head injury with a history (ie, loss of consciousness and vomiting) that mandates CT of the brain to rule out intracranial lesions. The possibility of intracranial bleeding in patients with hemophilia, however, requires immediate infusion of factor VIII and should not be delayed for CT. Intracranial injury in hemophiliac patients requires replacement of factor VIII to a desired activity of 100%. Since 1 U/kg of factor VIII raises activity by 2%, this patient requires 50 U/kg. Observation in the emergency department without therapy would not be indicated, given this patient?s risk for intracranial injury.

Source
Janz TJ, Hamilton GC. Disorders of hemostasis. In: Marx J, Hockberger R, Walls R, eds. Rosen?s Emergency Medicine: Concepts and Clinical Practice. 5th ed. Vol 2. St Louis, Mo: Mosby; 2002: 1697.

5?A. In December 2005 the American Heart Association published updated guidelines for cardiopulmonary resuscitation. Based on a retrospective study that showed increases in the return of spontaneous circulation in patients with asystole, vasopressin, 40 U by IV administration or intraosseous cannulation, may be given in place of the first or second epinephrine dose. Pacing is no longer recommended for asystolic arrest but may be used as an adjunct in symptomatic bradycardia. The patient in this scenario should have an advanced airway (eg, endotracheal tube) placed.

Source
ECC Committee, Subcommittees and Task Forces of the American Heart Association. 2005 American Heart Association guidelines for cardiopulmonary resuscitation and emergency cardiovascular care. Circulation. 2005;112(suppl):IV1-IV203.

6?D. This case illustrates the classic picture of acute gouty arthritis. Common risk factors include male gender, hypertension, renal insufficiency, alcohol consumption, and a diet high in purine. Diagnosis relies on examination of the joint aspirate. Synovial fluid will show crystals exhibiting negative birefringence. There are usually less than 50,000 inflammatory cells (WBCs), and Gram?s stain and culture findings are negative. Colchicine, steroids, and NSAIDs are the mainstay of emergency department treatment. Uric acid?lowering agents, such as allopurinol, are contraindicated, because they prolong the duration of acute gouty attacks.

7?C. The patient is exhibiting an anterior cord syndrome, which is associated with flexion injuries that cause spinal cord contusions, impingement by bony fragments, or compression of or thrombosis to the anterior spinal artery. Central spinal cord syndromes refer to hyperextension injuries that cause weakness in the extremities with variable loss of bladder control and are frequently seen in elderly patients. Brown-S?quard?s syndrome is associated with penetrating trauma that causes hemisection of the spinal cord and resultant ipsilateral paralysis, loss of dorsal column function, and contralateral loss of pain and temperature sensation. Transverse myelitis is not associated with trauma but is usually an idiopathic or postinfectious inflammatory condition that results in motor and sensory loss.

8?C. Community-acquired MRSA is an emerging pathogen in skin infections among patients presenting to the emergency department. In a recent emergency department surveillance study, community-acquired MRSA was cultured from more than 50% of infected sites. Genetic studies have shown that community-acquired MRSA contains a different gene coding for methicillin resistance than hospital-acquired MRSA. Community-acquired MRSA is typically sensitive to a variety of oral antibiotics, including trimethoprim/ sulfamethoxazole (Bactrim, Septra), clindamycin (Cleocin), and doxycycline (eg, Adoxa, Doryx, Vibra-Tabs). In this scenario the patient is improving; thus it is unnecessary to change the antibiotic regimen. Clinical cure in this patient is likely related to the surgical drainage of the infection. Although community-acquired MRSA also causes severe necrotizing pneumonia, there is no evidence that it arises in patients with skin infections.

Source
Frazee BW, Lynn J, Charlebois EE, et al. High prevalence of methicillin-resistant Staphylococcus aureus in emergency department skin and soft tissue infections. Ann Emerg Med. 2005;45:311-320.

9?B. Acute mountain sickness is the mildest form in the continuum of altitude illnesses that includes high-altitude pulmonary edema and high-altitude cerebral edema. Criteria for diagnosis include headache and at least 1 of the following symptoms: anorexia, insomnia, vomiting, or lassitude in the setting of recent arrival at high altitudes (>2500 m). Mild cases may respond to symptomatic treatment with oral analgesics alone. Acetazolamide (a carbonic anhydrase inhibitor) and dexamethasone have been shown to decrease the severity and duration of acute mountain sickness symptoms. Although a patient with symptoms of acute mountain sickness should not ascend, descent is only required in cases that have progressed to high-altitude pulmonary edema or high-altitude cerebral edema.

Source
Rodway GW, Hoffman LA, Sanders MH. High-altitude?related disorders?part I: pathophysiology, differential diagnosis, and treatment. Heart Lung. 2003;32:353-359.

10?D. The patient is experiencing laryngospasm, a rare complication of ketamine. Initially, the airway of the patient should be repositioned. If he remains stridulous, ventilations should be assisted with a bag-valve mask, which is usually all that is needed. Only a minority of patients will require intubation. Laryngospasm usually occurs when the gag reflex is activated by either instrumentation or salivation. Risk factors for laryngospasm include age 3 to 12 months, concurrent upper respiratory tract infection, and an underlying lung disease. Ketamine is safe for both healthy adults and children but should not be used in infants less than 3 months of age or adults with an underlying cardiac disease. No reversal agent exists for ketamine.

Source
Green SM, Krauss B. Clinical practice guideline for emergency department ketamine dissociative sedation in children. Ann Emerg Med. 2004;44:460-471.

11?D. Clonidine is a central alpha-adrenergic agonist used to reduce BP and slow the heart rate by decreasing sympathetic stimulation. Clonidine toxicity is manifested by altered mental status, hypotension, bradycardia, miosis, and respiratory depression. Many times, supportive therapies for clonidine toxicity, such as gastric lavage, whole-bowel irrigation, and IV fluid administration are effective. Vasopressors and alpha agonists may be required to raise BP and heart rate. Naloxone has been shown to improve the mental status of adults and children who have ingested toxic amounts. The American Academy of Pediatrics recommends a dose of 0.1 mg/kg for children up to 5 years old or those who weigh less than 20 kg. For children 5 years and older or those who weigh 20 kg or more, the minimum dose is 2 mg. Although the patient is hypotensive, he is bradycardic, and cardioversion will not help. High-dose insulin is used for calcium channel blocker toxicity and glucagon for beta-blocker toxicity. Although these antihypertensive agents can certainly cause hypotension and bradycardia, they will not produce the miosis and respiratory depression seen in this case.

Sources
Niemann JT, Getzug T, Murphy W. Reversal of clonidine toxicity by naloxone. Ann Emerg Med. 1986;15:1229-1231.

Horowitz R, Mazor SS, Aks SE, et al. Accidental clonidine patch ingestion in a child. Am J Ther. 2005;12:272-274.

American Academy of Pediatrics. Drugs for pediatric emergencies. Pediatrics. 1998;101:e13.

12?A. Only tonic-clonic seizures show generalized slowing on electroencephalography. Febrile seizures are the most common type of seizures in children and are considered ?simple? when they are generalized, last less than 15 minutes, are associated with a rapid rise in temperature, and do not recur within 24 hours. A postictal period can occur, but the child typically recovers completely. Age is the primary determinant of febrile seizure recurrence. For children who are younger than 12 months at the time of their first febrile seizure, the risk of recurrence is about 50%. For children who are older than 12 months when they have a first febrile seizure, the risk of recurrence is 30%. Children who have a second febrile seizure have a 50% chance of having at least 1 more recurrence.

Sources
Hirtz D, Berg A, Bettis D, et al. Practice parameter: treatment of the child with a first unprovoked seizure: report of the Quality Standards Subcommittee of the American Academy of Neurology and the Practice Committee of the Child Neurology Society. Neurology. 2003;60: 166-175.

American Academy of Pediatrics. Practice parameter: long-term treatment of the child with simple febrile seizures. Pediatrics. 1999; 103:1307-1309.

13?B. This patient has signs and symptoms of slit ventricle syndrome, which involves the overdrainage of cerebrospinal fluid because of obstruction of the shunt system by occluding tissue. As intracranial pressure rises, the occluding tissue is pushed away from the orifice, resulting in the intermittent occurrence of headache, nausea, vomiting, and mental status changes. Progressive cerebral compliance may lead to ventricular collapse and result in a true neurologic emergency. Slit ventricle syndrome is seen in about 5% of patients with shunts. Newer shunt systems can contain antisiphon devices that provide some protection. Manifestations of slit ventricle syndrome are relieved by lying down or being in the Trendelenburg position and are worsened by standing. Although tapping the shunt and IV hydration would probably provide some relief, placing the patient in the Trendelenburg position would offer the most rapid relief. Most shunt infections occur within the first 6 months of placement, making IV antibiotics unnecessary in this patient.

Sources
Pagane J, Ladde J. Complications of central nervous system devices. In: Tintinalli JE, Kelen GD, Stapczynski JS, eds. Tintinalli?s Emergency Medicine: A Comprehensive Study Guide. 6th ed. New York, NY: McGraw-Hill; 2004:1437-1441.

Pudenz RH, Foltz EL. Hydrocephalus: overdrainage by ventricular shunts. A review and recommendations. Surg Neurol. 1991;35: 200-212.

14?C. Rattlesnakes are pit vipers and are part of the Crotalidae subfamily of Viperidae that includes rattlesnakes, such as pygmy rattlesnakes and massa?saugas, copperheads, and water moccasins. Pit vipers have heat-sensing pits just below the eye midway to their nostril and 2 fangs that fold against the roof of the mouth. These characteristics distinguish the pit viper from the neurotoxic coral snake of the Elapidae family. Crotalidae venom is an enzyme mixture that can cause local tissue injury as well as systemic signs and symptoms from vascular damage, hemolysis, and fibrinolysis. Antivenom is the mainstay of therapy and should be given immediately to any patient with progressing signs and symptoms, such as worsening of the local injury, systemic manifestations of hypotension or altered mental status, and laboratory abnormalities. Severe envenomation can result in compartment syndrome; antivenom is the first line of therapy for this condition. Fasciotomy can save the limbs after antivenom failure, but its benefit as first-line therapy continues to be debated.

Sources
Dart RC, Daly FFS. Reptile bites. In: Tintinalli JE, Kelen GD, Stapczynski JS, eds. Tintinalli?s Emergency Medicine: A Comprehensive Study Guide. 6th ed. New York, NY: McGraw-Hill; 2004: 1200-1205.

Gold BS, Barish RA, Dart RC, et al. Resolution of compartment syndrome after rattlesnake envenomation utilizing non-invasive measures. J Emerg Med. 2003;24:285-288.

15?C. Digoxin is a cardiac glycoside used to treat CHF as a result of its inotropic effects and ability to increase automaticity and shorten repolarization intervals of the atria and ventricles. Such events occur because of increased cellular calcium during systole and the inhibition of sodium and potassium transport into the cell. Therefore, use of calcium to treat hyperkalemia can be disastrous if intracellular hypercalcemia already exists. Cardioversion for tachydysrhythmia has been associated with the development of lethal ventricular tachydysrhythmia. Although this patient could benefit from the administration of magnesium if he was hypomagnesemic, digoxin-specific fab is the standard of care for life-threatening digoxin toxicity.

Sources
Hack JB, Lewin NA. Cardiac glycosides. In: Goldfrank LR, Flaumenbaum NE, Lewis NA, et al, eds. Goldfrank?s Toxicologic Emergencies. 7th ed. New York, NY: McGraw-Hill; 2002:725-733.

Williamson KM, Thrasher KA, Fulton KB, et al. Digoxin toxicity: an evaluation in current clinical practice. Arch Intern Med. 1998;158: 2444-2449.

16?C. The cardiothoracic surgeon should be called to begin anticoagulation therapy, since this patient has thromboembolic disease. Artificial mechanical and bioprosthetic or tissue valves are implanted in more than 60,000 patients in the United States annually. All mechanical prostheses have a metallic closure sound. Complications of prosthetic valves include structural failure, infective endocarditis, and thromboembolic events. Because this patient stopped taking his anticoagulation, he is at increased risk for a thromboembolic event. Patients with mechanical valves usually require lifelong anticoagulation, with a target international normalized ratio of 2.5 to 3.5. Signs and symptoms of a thrombosed valve include sudden hypotension, loss of the metallic closure sound, and CHF.

Sources
Dunmire SM. Infective endocarditis and valvular heart disease. In: Marx J, Hockberger R, Walls R, eds. Rosen?s Emergency Medicine: Concepts and Clinical Practice. 5th ed. Vol 2. St Louis, Mo: Mosby; 2002:1149-1157.

Vongpatanasin W, Hillis, LD, Lange RA. Prosthetic heart valves. N Engl J Med. 1996;335:407-416.

17?C. Dehydration in children is typically categorized as mild (<5%), moderate (5%-9%), or severe (10%) based on signs and symptoms, including dryness of mucous membranes, skin turgor, general appearance, mental status, abnormal vital signs, and capillary refill time. Pertinent laboratory values include urine volume and specific gravity and BUN and pH status. It has been shown, however, that 4 findings can clinically indicate the level of dehydration: general appearance, dry mucous membranes, capillary refill time, and absent tears. The presence of 3 or more of these findings predicts moderate dehydration.

Sources
Gorelick MH, Shaw KN, Murphy KO. Validity and reliability of clinical signs in the diagnosis of dehydration in children. Pediatrics. 1997;99: e6.

Barkin RM, Ward DG. Infectious diarrheal disease and dehydration. In: Marx J, Hockberger R, Walls R, eds. Rosen?s Emergency Medicine: Concepts and Clinical Practice. 5th ed. Vol 3. St Louis, Mo: Mosby; 2002:2315-2326.

18?A. The Advanced Life Support Task Force of the International Liaison Committee on Resuscitation recommends that unconscious patients with spontaneous circulation after out-of-hospital cardiac arrest should be cooled to 32?C to 34?C for 12 to 24 hours when the initial rhythm was ventricular fibrillation. Mild hypothermia may also help patients with other rhythms or in-hospital arrests. Studies have shown that patients treated with mild hypothermia after cardiac arrest caused by ventricular fibrillation have higher rates of neurologic recovery.

Sources

ECC Committee, Subcommittees and Task Forces of the American Heart Association. 2005 American Heart Association guidelines for cardiopulmonary resuscitation and emergency cardiovascular care. Circulation. 2005;112(suppl):IV1-IV203.

The Hypothermia after Cardiac Arrest Study Group. Mild therapeutic hypothermia to improve the neurologic outcome after cardiac arrest. N Engl J Med. 2002;346:549-556.

Nolan JP, Morley PT, Vanden Hoek TL, et al. Therapeutic hypothermia after cardiac arrest. An advisory statement by the Advanced Life Support Task Force of the International Liaison Committee on Resuscitation. Circulation. 2003;108:118-121.

19?E. Treatment of an ischemic stroke with thrombolytic agents is indicated in patients whose symptom onset was within 3 hours, who have no evidence of bleeding or early infarct, and who have acute neurologic findings. Advanced age is not a contraindication, but age under 18 years is. BP of more than 185/110 mm Hg refractory to treatment is a contraindication; a BP of 168/86 mm Hg after appropriate pharmacotherapy (option B) would not be a contraindication.

Source
Adams H, Adams R, Del Zoppo G, et al. Guidelines for the early management of patients with ischemic stroke 2005: guidelines update: a scientific statement from the American Heart Association/ American Stroke Association. Stroke. 2005;36:916-923.

20?A. This patient has a long QT interval. The upper limit of the normal QTc is 460 ms for women and 440 ms for men. T-wave alternans, an alternation in the polarity and amplitude of the T wave, is associated with an increased risk of adverse cardiac events. The U wave is associated with hypokalemia. Peaked T waves can indicate MI or hyperkalemia. Osborne waves (J waves) are usually seen in hypothermia.

Sources
Meyer JS, Mehdirad A, Salem BI, et al. Sudden arrhythmia death syndrome: importance of the long QT syndrome. Am Fam Physician. 2003;68:483-488.

Zareba W, Moss AJ, le Cessie S, et al. T wave alternans in idiopathic long QT syndrome. J Am Coll Cardiol. 1994;23:1541-1546.