remon exam

97. A 3.5-kg term male delivered by uncomplicated vaginal delivery has a normal physical examination. On the day of discharge the mother tells you that an older sibling has just broken out with chicken pox. Which of the following is true?

• (A) All newborns are very susceptible to varicella upon exposure.

• (B) This infant is likely already infected because of the maternal exposure to the sick sibling.

• (C) Varicella immune globulin should be administered to all infants in this situation.

• (D) If the mother had varicella in the past, the infant is likely protected with passively acquired antibody from the mother.

• (E) The infant will not develop a typical varicella infection, but will likely develop varicella zoster.

Answer explanation

(D) Varicella infections in the newborn are frequently life threatening. If the mother has had varicella in the past, her IgG antibody to varicella crosses the placenta and protects the infant for weeks after delivery. Certainly, infants who face exposure without maternal antibody protection acquire the infection at a high rate with serious morbidity, mainly from varicella pneumonia. Varicella immune globulin is useful in preventing acquisition of infection in susceptible infants. Infants are considered susceptible if maternal onset of varicella is 5 days or less before delivery. Varicella immune globulin is not indicated if the mother has zoster

25. A 6-year-old boy is proud to show off the first tooth he lost but his mother is concerned because the tooth was one of his canines and a permanent tooth seems to be erupting in this area. Which of the following best describes the correct sequence for eruption of permanent teeth?

• (A) central incisors, first premolars, canines, second molars

• (B) first molars, central incisors, canines, first premolars

• (C) central incisors, lateral incisors, canines, first molars

• (D) first molars, lateral incisors, canines, first premolars

• (E) lateral incisors, first molars, canines, first premolars

Answer explanation

(C) Growth of the midface and lower face in children occurs gradually. Loss of the deciduous (baby) teeth is a more dramatic sign of maturation, beginning at around 6 years of age, after eruption of the first molars. Replacement with adult teeth occurs at a rate of about 4 per year. The mandibular, then maxillary central incisors are replaced at the same time or just following the eruption of the first molars at around 6–7 years of age. After this, the lateral incisors erupt, at around 7–8 years of age. The adult canines replace the baby teeth at around 9–11 years of age, and next to erupt are the first premolars and then the second premolars. The second molars erupt at around 12 years of age but the third molars (wisdom teeth) do not erupt until 17–21 years of age.

16. At a 2-month well child visit, a mother states her family has a history of cow milk protein allergies and wonders if soy formula would be better for her baby. Which of the following statements regarding soy formula is correct?

• (A) Infants fed exclusively with soy formula display growth comparable to infants fed cow milk protein formula.

• (B) The protein in soy formulas is essentially nonallergenic, and clinically significant soy protein hypersensitivity is extremely rare.

• (C) Soy formula is most useful in children with well-documented, severe, gastrointestinal allergic reactions to cow milk protein.

• (D) Soy formula should not be used by patients with a family history of celiac disease.

• (E) Infants fed soy formula should receive supplemental dietary calcium.

Answer explanation

(A) Soy protein based commercial infant formulas presently available provide adequate nutrition (including calcium), and infants fed these formulas exhibit normal growth. Soy formulas often are prescribed for infants with personal or family history of allergy in the hope of avoiding the development of milk-protein allergy. Unfortunately, severe gastrointestinal allergic reactions to soy protein in infants are well recognized and are not rare. For this reason, soy formula is not recommended for infants or children already demonstrating significant gastrointestinal hypersensitivity to cow Feeding and Nutrition milk protein. These patients are best prescribed a protein hydrolysate formula. Soy-based formulas are not recommended for premature infants.

18. A 15-kg toddler with group A coxsackievirus infection is refusing to drink. His serum potassium is normal. For maintenance of intravenous fluids, what concentration of KCl should be added?

• (A) 5 meq KCl/L

• (B) 10 meq KCl/L

• (C) 25 meq KCl/L

• (D) 40 meq KCl/L

• (E) 50 meq KCl/L

Answer explanation

(C) Potassium requirement generally is calculated at 2–2.5 meq KCl/kg/day. For this 15 kg child that would be 30–37 meq KCl/day. Using the Holliday-Segar method, the child’s maintenance fluid requirement is 1250 cc/day; 30 meq KCl/1.250 L = 24 meq KCl/L, or approximately 25 meq KCl/L.

11. An 8-year-old child presents to the emergency department with a 3-day history of fever and new altered mental status. Her parents report that they have been camping several times and she has sustained a lot of mosquito bites. Mosquitoes are recognized as vectors in the transmission of encephalitis of which of the following viruses?

• (A) arbovirus

• (B) coxsackievirus

• (C) enterovirus

• (D) influenza virus

• (E) mumps virus

Answer explanation

(A) Mumps virus, enterovirus, coxsackievirus, and influenza virus are spread primarily by direct contact (eg, respiratory droplets, hands) and not through an arthropod vector. Anumber of viruses, notably the arboviruses, are spread by mosquito vectors, as well as ticks and sandflies. Examples in North America include eastern and western equine encephalitis, St. Louis encephalitis, and LaCrosse and West Nile encephalitis

10. A 4-year-old child is brought to the urgent care by parents who were concerned because the child suddenly developed unusual posture and movements. Examination reveals an alert child who holds the head in a tilted position and has uncontrolled, writhing movements of the hands and arms. The examination is otherwise normal. When questioned regarding medications at home, parents state they do have routine cold medicine, acetaminophen, and some kind of antiemetic medication in an unlocked medicine cabinet. At this time you should do which of the following?

• (A) perform a head computerized tomography (CT) scan

• (B) perform a lumbar puncture

• (C) obtain an electroencephalogram

• (D) administer naloxone intravenously

• (E) administer diphenhydramine intravenously

Answer explanation

(E) The child described has developed extrapyramidal symptoms typical of phenothiazine toxicity. These findings may occur with therapeutic as well as excessive dosage and are common in children. Akinesia, trismus, opisthotonos, torticollis, chorea, dystonia, and oculogyric crises may be seen. These symptoms usually respond dramatically to intravenous diphenhydramine (Benadryl) or benztropine mesylate (Cogentin), although relapses are frequent. The clinical picture is so classic that it can be suspected even in the absence of a history of ingestion. Aside from managing this ingestion and screening for other medications this child may have ingested, you must work with these parents to prevent future episodes of ingestion.

66. A 7-year-old unimmunized child presents with fever and vesicular rash. You notice about 300 lesions, some of which were crusted. You suspect varicella infection. Which of the following is a TRUE statement about varicella?

• (A) It has an incubation period of 5–7 days.

• (B) The rash is confluent, centrifugal, and pustular.

• (C) It is associated with Koplik spots.

• (D) There is a high risk of shingles

• (E) It can cause visceral dissemination in the immunocompromised host.

Answer explanation

(E) The rash of varicella follows an incubation period of 10–21 days. There is the onset of a very pruritic rash, with crops of lesions that begin as papules and progress to vesicles and finally crusted scabs. Typically, all three stages of skin lesions are identified on clinical examination. Fever usually is mild to moderate. While a generally self-limited and benign course is noted, severe disease may occur occasionally in the otherwise healthy host, especially adolescents and adults. A progressive and severe disease with visceral dissemination is seen in 30%–50% of children with lymphoproliferative malignancies, solid tumors, or posttransplantation with the development of hepatitis, encephalitis, and pneumonia. Fatal disease has also been reported in those treated with highdose corticosteroids and in those with other defects of T-cell function.

Which of the following sets of blood gas values is most compatible with acute aspirin poisoning in a 16-month-old child?

• (A) pH 7.60, PCO2 40, HCO3 40

• (B) pH 7.5, PCO2 40, HCO3 30

• (C) pH 7.25, PCO2 20, HCO3 8

• (D) pH 7.20, PCO2 45, HCO3 20

• (E) pH 7.00, PCO2 35, HCO3 8

Answer explanation

(C) Aspirin poisoning results in a mixed disturbance of metabolic acidosis and respiratory alkalosis. In adolescents and adults, the predominant early abnormality usually is the respiratory alkalosis. Before the age of 2 years, however, metabolic acidosis is the predominant process and the net change in arterial pH generally is a decrease.

7. A 4-year-old with a history of renal failure, encopresis, and asthma is brought to the emergency room because of lethargy and difficulty breathing. She has been taking her usual breathing treatment and has not had any respiratory symptoms or fevers. She had recently been severely constipated and her parents have been administering multiple enemas to try to help her stool with no result. Which of the following is the most likely cause of her lethargy and respiratory distress?

• (A) hyperphosphatemia secondary to enemas

• (B) albuterol overdose

• (C) sepsis

• (D) asthma exacerbation

• (E) anaphylaxis

Answer explanation

(A) A Pediatric Fleet Enema is a hypertonic solution with high levels of phosphate. If these enemas are retained or are given in quick succession, there is a chance of inducing hyperphosphatemia, especially in conjunction with renal failure, although this can happen even without renal insufficiency. Hyperphosphatemia often manifests with the signs of an induced hypocalcemia—which are lethargy, tetany, and occasionally seizures. An albuterol overdose would most likely present as tachycardia, sweating, and tachypnea (B). Sepsis would likely present with fever, hypotension, and tachycardia (C). An asthma exacerbation would present with tachypnea and wheezing (D). Anaphylaxis would present with hypotension, wheezing, hives, and difficulty breathing (E).

24. The patient remains febrile and has worsening abdominal pain despite 72 hours of antibiotic therapy. At this time what is the best next step?

• (A) continue therapy at the scheduled doses

• (B) add diphenhydramine for a potential drug reaction

• (C) consult gynecology for imaging and drainage of a possible tubo-ovarian abscess

• (D) repeat blood cultures and obtain a C-reactive protein to help monitor response to therapy

• (E) consult infectious disease for evaluation of the possibility of methicillin-resistant S aureus infection

Answer explanation

(C) Complications of PID including chronic pelvic pain, perihepatitis, ectopic pregnancies, infertility, and tubo-ovarian abscess should be worsening signs and symptoms despite appropriate antimicrobial therapy. These are suggestive of tubo-ovarian abscess. Consultation with a gynecologist and diagnostic imaging (usually ultrasound) is appropriate at this time. A C-reactive protein to monitor therapy is not needed when the clinical picture clearly suggests lack of response to therapy. Methicillinresistant S aureus is an uncommon cause of PID.