Shortness Of Breath Case 3

Shortness Of Breath Case 3

A 3-year-old boy is brought to the emergency department with shortness of breath. His parents report that he has had several episodes in which he breathes heavily and turns blue. During these episodes, he is often found squatting, which appears to relieve his symptoms. His parents brought him in today, because the boy lost consciousness. On examination, he is a poorly developed, thin boy who is in acute distress. His skin appears blue, and he has labored breathing with chest retractions A systolic ejection murmur is auscultated at the left third intercostal space. A chest x-ray film shows a smalI, "boot shaped" cardiac silhouette. The boy is admitted to the hospitaI.



Q1
Which of the following is the most likely diagnosis?

/ A. Coarctation of the aorta
/ B. Ebstein's anomaly
/ C. Patent ductus arteriosus
/ D. Tetralogy of Fallot
/ E. Transposition of the great vessels



Q2
A complete blood count is performed, and the hemoglobin is markedly increased. Which of the following substances triggers this erythrocytosis?

/ A. Aidosterone
/ B. Angiotensin ll
/ C. Erythropoietin
/ D. Interleukin 1
/ E. Renin



Q3
While this patient is in the hospital he begins to have fever and headache. On examination, he has numbness of the right side of his face, but no nuchal rigidity. A head CT shows a focal lesion with a hypodense center surrounded by a ring of enhancement. Which of the following is the most likely diagnosis?

/ A. Brain abscess
/ B. Guillain-Barr syndrome
/ C. Meningitis
/ D. Stroke
/ E. Tuberculosis



Q4
A brain biopsy from this patient grows gram-positive cocci in chains. Which of the following is the most appropriate treatment?

/ A. Cefazolin
/ B. Ceftriaxone
/ C. Fiuconazole
/ D. Metronidazole
/ E. Penicillin



Q5
Which of the following sets of changes depict the oxygen partial pressures in the aorta, Ieft ventricle, right atrium, and vena cava of this patient during resting conditions, compared to a healthy individuaI?









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Shotness Of Breath Case 3 Answers

A1
The correct answer is D. Tetralogy of Fallot is a congenital heart anomaly that presents as respiratory distress, cyanosis, clubbing, syncope and sudden death. Historical findings often include reports of "Tet spells," in which the patient is found squatting to relieve respiratory symptoms. Examination findings include a systolic ejection murmur, clubbing, and cyanosis. A characteristic small "boot-shaped" cardiac silhouette is seen on chest x-ray. The anatomic defects of this tetralogy are pulmonary stenosis, overriding aorta, right ventricular hypertrophy, and ventricular septal defect. This anatomic tetralogy results in a right-to-left shunt, and thus a marked decrease in pulmonary blood flow. The severity of symptoms depends on the degree of decrease in pulmonary blood flow. The squatting increases systemic vascular resistance, and decreases the right-left shunt.
Coarctation of the aorta (choice A) is a narrowing of the thoracic aorta. Patients may have headache, epistaxis, and lower extremity claudication. On examination, patients have diminished lower extremity pulses, and a systolic or continuous murmur. This defect may be associated with CHF, aortic dissection, intracranial aneurysmal rupture, and bacterial endocarditis.
Ebstein's anomaly (choice B) is an abnormal tricuspid valve placement that creates an abnormally large right atrium and small right ventricle. The disorder may present with cyanosis, but the clinical presentation may vary. You should suspect Ebstein's anomaly when there is a history of maternal lithium ingestion.
Patient ductus arteriosus (choice C) involves a right to left shunt that may present as acyanotic respiratory distress. It will have a continuous "machinery" murmur.
Transposition of the great vessels (choice E) typically presents as cyanosis and CHF in the neonatal period. An "egg shaped" cardiac contour is seen on chest x-ray films.


A2
The correct answer is C. Erythropoietin is released from the kidney in response to renal hypoxia. This circulates to the red marrow and stimulates erythropoiesis, a process by which erythropoietic stem cells differentiate into red blood cells.
Aldosterone (choice A) is a hormone released from the adrenal cortex in response to angiotensin II. It triggers sodium retention in the renal collecting ducts.
Angiotensin II (choice B) is a hormone created by a series of enzymatic steps. These steps are carried out when the kidney releases renin in response to decreased flow in the area of the renal tubule known as the macula densa.
Interleukin 1 (choice D) is an inflammatory mediator. It has no effect on erythropoiesis.
Renin (choice E) is an enzyme released by the kidney in response to decreased flow in the renal tubule. It initiates a cascade of enzymatic steps to create angiotensin II, which has several vascular, renal, and endocrine effects.


A3
The correct answer is A. Patients with cyanotic heart disease (most commonly tetralogy of Fallot ) may develop a brain abscess. In chronically hypoxic patients, polycythemia with increased blood viscosity leads to poor cerebral capillary flow and reduced tissue oxygenation. This poorly perfused segment acts as a nidus for infection, and as a result, patients with tetralogy of Fallot suffer from brain abscesses. This is a typical presentation for a brain abscess, which may include fever, headache, seizures, nuchal rigidity, papilledema, and focal neurologic defects. The CT findings are also classic for brain abscess.
Guillain-Barre syndrome (choice B) is an acute inflammatory demyelinating polyneuropathy. It typically presents as ascending weakness usually beginning in the legs. It does not present as focal CNS findings.
Meningitis (choice C) would present as headache and fever, but focal findings on neurologic examination and on CT would be unusual. Nuchal rigidity is often present.
Stroke (choice D) would be unusual in this age group. In addition, the focal lesion seen on CT does not describe the findings of stroke. CT findings for stroke vary with the etiology of the stroke, but are typically less well circumscribed and do not display ring enhancement.
Tuberculosis (choice E) could produce a meningitis, which afflicts the very old and very young. It has a long, protracted course as symptoms of fever, headache and nuchal rigidity tend to develop over a two-week course. A focal lesion would not be seen on CT scan.


A4
The correct answer is B. The finding of gram-positive cocci in chains indicates the abscess contains streptococci. An antibiotic must not only be effective against these organisms, it must also penetrate the blood-brain barrier. Ceftriaxone is a third generation cephalosporin that penetrates the BBB. While the effectiveness against gram-positive organisms decreases as one moves from first to second to third generation cephalosporins, unless the medication arrives at the proper site, it cannot be effective.
Cefazolin (choice A) is a first generation cephalosporin. It would kill streptococci, but it would not access the CNS.
Fluconazole (choice C) is an antifungal agent. The culture indicates streptococci. Fungal brain abscess would be unusual in an immunocompetent patient.
Metronidazole (choice D) is an antiparasitic that also has activity against gram-negative organisms. It would be appropriate to use in conjunction with ceftriaxone in an empiric setting. Once the definitive cause is known, discontinuing extraneous antibiotics is appropriate.
Penicillin (choice E) would kill streptococci, but it could not access the CNS in the presence of an intact blood-brain barrier.


A5
The correct answer is C. In Tetralogy of Fallot, the aorta originates from the right ventricle or overrides the septum, and therefore receives blood from both ventricles. This decreases the oxygen tension of aortic blood. Blood flowing through the lungs is still oxygenated normally, causing the oxygen tension of blood in the left ventricle to be normal. Because the oxygen content of the arterial blood is lower than normal, the oxygen tension of the venous blood (and therefore blood in the right atrium) is lower than normal