Pediatric Examination and Board Review (28 page)

3.
Of the following choices, the most appropriate antibiotic regimen for this child is

(A) ampicillin and ceftriaxone

(B) ceftriaxone and vancomycin

(C) amoxicillin and azithromycin

(D) ceftazidime and gentamicin

(E) oxacillin and ceftazidime

4.
A large pleural effusion is identified and aspirated from the right hemithorax. Which of the following is indicative of an empyema?

(A) a pH 7.0, glucose 20 mg/dL, total protein 4 g/dL, WBC 20,000/mm
³
, LDH more than 1000 U/L

(B) a pH 7.2, glucose 80 mg/dL, total protein 4 g/dL, WBC 1000/mm
³
, LDH 585 U/L

(C) a pH 7.3, glucose 60 mg/dL, total protein 4 g/dL, WBC 500/mm
³
, LDH 348 U/L

(D) a pH 7.2, glucose 80 mg/dL, total protein 4 g/dL, WBC 5000/mm
³
, LDH 475 U/L

(E) none of the above

5.
If an empyema is identified, the appropriate intervention is

(A) instillation of antibiotics into the pleural space

(B) daily thoracentesis for 7 days

(C) video-assisted thoracoscopy (VAT) and decortication

(D) instillation of chlorhexidine into the pleural space

(E) close observation as an outpatient

6.
If, after removal of the effusion, it is apparent that there is a 2-cm lung abscess, the appropriate therapy would be

(A) urgent surgical drainage

(B) elective surgical drainage after antibiotic treatment for 5 days

(C) prolonged parenteral antibiotics

(D) interventional radiology-directed drainage of the abscess

(E) A and C

7.
How often is a bacterial pneumonia accompanied by a pleural effusion?

(A) less than 20%

(B) 20-30%

(C) 35-50%

(D) 55-75%

(E) more than 75%

8.
Which of the following statements is true?

(A) all patients with a parapneumonic effusion require hospitalization

(B) all pleural effusions require thoracoscopy for resolution

(C) all parapneumonic effusions, if cultured, will be positive for pathogens

(D) all parapneumonic effusions require surgical intervention

(E) small parapneumonic effusions are generally clinically inconsequential and resolve without surgical intervention

9.
In this case, the comorbidity that most needs to be considered is

(A) HIV

(B) sickle cell disease

(C) congestive heart failure

(D) hepatitis A

(E) none of the above

10.
Which pathogen on this list is the most likely to be implicated in this 16-month-old with a lung abscess?

(A)
Chlamydia trachomatis

(B)
Moraxella catarrhalis

(C)
Staphylococcus aureus

(D)
Mycoplasma pneumoniae

(E)
Klebsiella pneumoniae

11.
In the neonate, the most common pathogens associated with bacterial pneumonia among the choices here are

(A) group B streptococcus and
Escherichia coli

(B)
H influenzae
and
Listeria monocytogenes

(C)
L monocytogenes
and group D streptococcus

(D) group D streptococcus and group B streptococcus

(E)
Chlamydia trachomatis

12.
In the school-age child, the most likely pathogen in bacterial pneumonia with parapneumonic effusion is

(A)
Chlamydia trachomatis

(B)
Staphylococcus aureus

(C)
Streptococcus pneumoniae

(D)
Neisseria meningitidis

(E)
H influenzae

13.
In the perioperative period after cardiac surgery, a pleural effusion sometimes occurs. Among these patients, chylothorax may occur. A chylothorax would be most characterized by

(A) pH 7.1, protein 4 g/dL, glucose 25 mg/dL, WBC 2,000/mm
³
, triglycerides: 86 mg/dL

(B) pH 7.3, protein 4 g/dL, glucose 75 mg/dL, WBC 5,000/mm
³
, triglycerides: 345 mg/dL

(C) pH 7.2, protein 3 g/dL, glucose 85 mg/dL, WBC 200/mm
³
, triglycerides: 67 mg/dL

(D) pH 7.4, protein 3 g/dL, glucose 210 mg/dL, WBC 30/mm
³
, triglycerides: 95 mg/dL

(E) none of the above

14.
A pleural effusion in the child that suggests malignancy is characterized by

(A) a pH lower than 7.1

(B) a serum glucose less than 40 mg/dL

(C) a blood triglyceride level higher than 500 mg/dL

(D) the presence of atypical white cells

(E) all of the above

15.
Malignant pleural effusion is most often seen in the child in

(A) rhabdomyosarcoma

(B) neuroblastoma

(C) hepatoblastoma

(D) lymphoma

(E) medulloblastoma

ANSWERS

1.
(C)
Although a decubitus film may be obtained, an ultrasound of the right hemithorax and aspiration of the fluid for diagnostic purposes should ideally precede the administration of antibiotics. However, if the child’s clinical condition is rapidly deteriorating, stabilization of the child’s condition and administration of appropriate antibiotics before thoracentesis should proceed without delay.

2.
(A)
This case represents an example of bacterial pneumonia with an associated pleural effusion. In the emergency department the most appropriate intervention is attention to the airway, adequacy of respiratory effort, and circulation. The child is desaturating on room air and should receive supplemental oxygen. After the patient is stabilized with oxygen and a CXR is acquired, an IV line should be placed and appropriate antibiotics given. Ideally, an ultrasound with aspiration of pleural fluid should be attempted in the stable child before antibiotics.

3.
(B)
Selection of appropriate antibiotics for this particular patient should include coverage for
S aureus
and
S pneumoniae
, as well as consideration of less likely gram-negative pathogens. Community-associated methicillin-resistant
S aureus
(CA-MRSA) may present with a profound, rapidly progressive, necrotizing pneumonia, so consideration should be given to an IV antibiotic that targets MRSA. Therefore, the best initial choice of antibiotics in this child would be ceftriaxone and vancomycin.

4.
(A)
The presence of the pleural effusion in this child demands a diagnostic procedure. It is imperative that fluid from this effusion be obtained for diagnostic and therapeutic purposes. The pleural space is a potential space defined in its boundaries by the parietal and visceral pleurae. The parietal pleura cover the inner aspect of the chest wall and the diaphragm; the visceral pleura is strongly adherent to the surface of the lung tissue itself. A thin film of liquid separates these 2 spaces and creates the potential space where fluid may accumulate in a number of pathologic states. In the child with an effusion, diagnostic aspiration and evaluation of pleural fluid are important and will provide information that will inform further therapy.

Pleural fluid can be classified in several ways. Typically, one distinguishes among a transudate, an exudate, and an empyema. An alternative categorization of the fluid findings is a distinction between a simple parapneumonic effusion, a complex parapneumonic effusion, and an empyema. A third schema classifies the parapneumonic effusion into a simple exudative phase, a fibrin proliferative phase, and a stage of organization. The distinction between transudate, exudate, and empyema depends on chemical analysis of the pleural fluid. Pleural fluid that has a fluid-to-serum LDH ratio more than 0.6, a pH 7.3-7.4, and a pleural fluid protein concentration more than 3 g/dL should be considered an exudate. Most transudates have a total protein concentrations less than 3 g/dL and have a pH higher than 7.4. Although a positive pleural fluid culture defines an empyema, the clinician must often decide about empyema when the culture is negative. Because of the efficient clearance of organisms from the pleural space and the natural bacteriostatic host defense mechanisms of the pleural space, the pleural fluid culture may be negative even when there are organisms identified on the gram stain. Prior antimicrobial therapy may also influence the culture results.

5.
(C)
For the child with a large parapneumonic effusion or an empyema accompanied by mediastinal shift, the management includes drainage of that fluid. Should an empyema be defined by either chemistry or the presence of organisms, VAT and decortication early in the patient’s course is recommended and may abbreviate the hospital stay. Another management strategy for a complicated parapneumonic effusion is the instillation of fibrinolytics into the pleural space if VAT cannot be done.

6.
(C)
Most children with lung abscess respond to a prolonged course of IV antibiotic therapy; surgical intervention is rarely required. Typically the CXR reveals an air fluid level in the diseased lung field. A CT scan may be necessary to further delineate the size of the abscess and its relationship to the tracheobronchial tree. Rarely the abscess needs to be drained either surgically or by interventional radiology. Drainage may complicate the disease process because there is a risk for crosscontamination of unaffected pulmonary tissue as well as contamination of the pleural space at the time of surgery.

7.
(C)
Pleural effusion is a common event associated with at least 40% of bacterial pneumonias. Generally, the effusions are uncomplicated and small. The presence of an effusion more than 10 mm in width should be aspirated for diagnostic purposes. If the fluid is compatible with an empyema on microscopic examination and by chemical analysis, drainage is indicated.

8.
(E)
The case described a child with a complicated parapneumonic effusion and lung abscess. However, in the setting of a simple parapneumonic effusion, the effusion usually resolves with treatment of the underlying pneumonia. If there is a complex parapneumonic effusion that is loculated, causes mediastinal shift, or if an empyema is present, more aggressive drainage of the pleural space is recommended.

9.
(B)
In general, the clinical manifestations of pneumonia in children include fever, cough, and tachypnea. Although additional signs of respiratory distress such as nasal flaring, accessory muscle use, grunting, and desaturation may be present, a respiratory rate of more than 50 breaths per minute at rest has a relatively high sensitivity of predicting a pneumonic process in an otherwise healthy-appearing infant. Auscultatory findings associated with pneumonia include bronchial breath sounds, rales, rhonchi, wheezes, and diminution in breath sounds.