Pediatric Examination and Board Review (23 page)

CASE 11: A 3-YEAR-OLD GIRL WITH HYPOXIA AND A HISTORY OF HOARSENESS

A 3-year-old girl presents to the emergency department with hypoxia and increased work of breathing. Her family has recently moved and you are seeing her for the first time. She has spastic cerebral palsy and the cognitive development of a 6-month-old. She has had regular health care and her immunizations are up to date. On presentation she clearly has a hoarse voice and a cry that her mother reports has been present since the age of 1 year. The mother also reports that her child drools continually. As a young infant she often “spit up” but that resolved by age 6 months. Other than 2 episodes of “pneumonia,” she has been healthy. Neither episode of pneumonia required hospitalization. Her previous pediatrician had reassured the family that her voice was “normal.”

On physical examination, she is small and appears chronically undernourished. Her heart rate is 120, respiratory rate 42. The temperature is 39°C. The room air oxygen saturation is 84%. The only other significant physical findings are hoarse voice, coarse bilateral breath sounds, and moderate intercostal retractions.

SELECT THE ONE BEST ANSWER

1.
What is the next diagnostic procedure indicated?

(A) a throat culture

(B) CXR

(C) ultrasound of the neck

(D) nasopharyngeal aspirate for viral direct fluorescent antibody tests (DFAs)

(E) a complete blood count

2.
The first therapeutic intervention appropriate for this child is

(A) supplemental oxygen

(B) albuterol nebulizer treatment

(C) IV antibiotics

(D) racemic epinephrine

(E) intubation

3.
The CXR reveals a right lower lobe infiltrate. The appropriate next intervention is

(A) postural drainage

(B) bronchial lavage and culture

(C) IV clindamycin and ceftriaxone

(D) thoracentesis for culture and Gram stain

(E) discharge the patient with a prescription for oral antibiotics

4.
The child deteriorates and requires endotracheal intubation. The best indicator of the need for mechanical ventilation in this patient is

(A) severe increased work of breathing

(B) abnormal blood gas analysis

(C) pulse oximeter reading of 92% on simple face mask oxygen

(D) failure of the child to respond to verbal commands

(E) C and D

5.
Once on mechanical ventilation, the patient’s CXR now reveals infiltrates in all lung fields. Her oxygen requirement has also increased and the ventilator is providing 100% oxygen and a positive endexpiratory pressure (PEEP) of 5 to maintain an O
₂
saturation of 89%. The strategy to improve oxygenation most likely to work is

(A) increase her tidal volume

(B) increase the respiratory rate

(C) increase the PEEP

(D) administer surfactant in her endotracheal tube

(E) place the child on extracorporeal membrane oxygenation (ECMO)

6.
In spite of your best efforts to improve gas exchange on mechanical ventilation, the child continues to worsen. Her arterial blood gas (ABG) on 100% oxygen, PEEP 15, tidal volume 12 mL/kg is pH: 7.29, PCO
₂
: 66, PO
₂
: 55. The blood gas represents a

(A) metabolic alkalosis

(B) metabolic acidosis

(C) respiratory alkalosis

(D) respiratory acidosis

(E) mixed alkalosis

7.
Given the clinical scenario in question 6, your next intervention is

(A) do nothing because the patient is stable

(B) turn the patient prone and see if you can wean the FIO
₂

(C) place prophylactic chest tubes because the risk of pneumothorax is large at a PEEP of 15

(D) perform a bronchoalveolar lavage for the removal of bronchial debris

(E) decrease the ventilator settings

8.
Lung injury from a mechanical ventilator is seen most often in which situation?

(A) the use of a 0.5 FIO
₂

(B) delivery of a tidal volume in excess of 8 mL/kg

(C) the use of 15 cm PEEP

(D) a consistent peak airway pressure of 30 cm H
₂
O

(E) a respiratory rate of 20

9.
If conventional mechanical ventilation fails in acute hypoxic respiratory failure beyond the neonatal period, options include

(A) the oscillator

(B) the Thera vest

(C) the use of bilevel positive airway pressure (BiPAP)

(D) the use of extracorporeal CO
₂
removal

(E) none of the above

10.
Adjuncts to conventional therapy for acute hypoxic respiratory failure include all of the following except

(A) nitric oxide

(B) surfactant

(C) ECMO

(D) heliox

(E) A and D

11.
All cultures in this child are negative. The tracheal aspirate is positive for lipid-laden macrophages, however, leading you to a diagnosis of

(A) aspiration

(B) toxic shock syndrome

(C) viral pneumonia

(D)
Mycoplasma
infection

(E) parainfluenza infection

12.
The history of hoarseness in this child is

(A) not relevant because it is a normal finding

(B) leads you to be more suspicious of aspiration and GERD disease

(C) makes the diagnosis of
Mycoplasma
infection more likely because of its indolent course

(D) is a distinct clinical entity that is most likely unrelated to the more acute event

(E) none of the above

13.
After this child recovers, what, if anything, would be the next appropriate diagnostic test?

(A) a pH probe

(B) nothing because the child has now recovered from a viral illness

(C) a chest CT scan to evaluate for chronic lung disease

(D) a cardiac catheterization to evaluate pulmonary artery pressures

(E) a lower GI series

14.
The residual lung dysfunction following acute hypoxic respiratory failure is

(A) exercise intolerance/reactive airway disease

(B) chronic cough

(C) increased diffusion capacity

(D) sleep-disordered breathing

(E) no residual dysfunction

15.
Untreated GERD can lead to

(A) chronic obstructive lung disease

(B) esophageal dysplasia

(C) vocal cord nodules

(D) B and C

(E) all of the above

ANSWERS

1.
(B)
This child is in respiratory distress. A CXR is the initial procedure that needs to be done. The history illustrates a neurologically disabled child at high risk for reflux and aspiration of oral or GI flora. After the radiograph is performed, it would be reasonable to obtain viral or bacterial studies to determine an infectious etiology.

2.
(A)
Supplemental oxygen should be the first intervention because she has a room air O
₂
saturation of 84%. Additional therapies may be administered after oxygen is started.

3.
(C)
This child presents with a history of hoarseness and respiratory distress followed by respiratory failure, likely caused by aspiration pneumonitis. Antibiotics used to treat this event should cover oral flora including gram-positive and anaerobic organisms. If this child’s respiratory failure progresses and she requires intubation, a bronchial lavage may help in the diagnosis.

4.
(A)
This child progressed to acute hypoxic respiratory insufficiency (AHRF), a complex diagnosis with many etiologies. The best indicator of the need for mechanical ventilation is a marked increase work of breathing. Blood gas analysis can be useful, but the need for mechanical ventilation is largely based on clinical assessment.

5.
(C)
While supported with mechanical ventilation, oxygenation is enhanced or improved by increasing the inspired concentration of oxygen (FIO
₂
), the PEEP, and/or the inspiratory time. Improved ventilation, that is, enhanced removal of CO
₂
, can be accomplished by increases in tidal volume and/or minute ventilation. This is achieved in volume mode ventilation by increasing the tidal volume, and, in pressure mode, increase ventilation by increasing peak inflation pressure. In either mode, the respiratory rate can be increased to enhance minute ventilation and CO
₂
removal.

6.
(D)
The blood gas presented represents a respiratory acidosis but not a profound one. To avoid the complications of mechanical ventilation, one could argue that in significant respiratory disease, permissive hypercapnia, or the acceptance of a modest elevation of PCO
₂
and acidosis (pH ≥ 7.25) is acceptable.

7.
(B)
This child requires 100% oxygen to remain relatively well-saturated in her current state. She is already on significant PEEP, but her inspiratory time could be increased. Additionally, the patient could be turned to the prone position to augment oxygenation and facilitate reduction of FIO
₂
, if that is not possible in the supine position. One hundred percent oxygen is likely to result in oxygen toxicity and is not recommended. Generally, a PAO
₂
higher than 50 mm Hg is acceptable and the FIO
₂
should be reduced. If the patient has a shunt lesion, the inspired FIO
₂
will have a lesser impact on oxygenation. It is likely that an acceptable arterial PAO
₂
could be achieved with less inspired oxygen.