Pediatric Examination and Board Review Read Free

pulmonary artery hypertension or ductal-dependent cardiac lesions when planning for closure of the patent ductus arteriosus.
    3. (D ) The presence of a small patent ductus arteriosus is unlikely to lead to significant left-to-right shunting or volume overloading and therefore does not place the child at risk for development of heart failure. There is about a 5% incidence of spontaneous closure of a small patent ductus arteriosus, and thus immediate surgery is usually not required in that situation. Recent review of subacute bacterial endocarditis has suggested that the lifelong risk for bacterial endarteritis with the presence of a patent ductus arteriosus is extremely low. Therefore, current guidelines do not recommend antibiotic prophylaxis for this condition.
    4. (B) In this situation, a large patent ductus arteriosus has allowed significant left-to-right shunting resulting in pulmonary edema, shortness of breath, and left ventricular volume overload. The treatment options at this point include administration of indomethacin in an attempt to close the patent ductus arteriosus. Indomethacin is effective in approximately 80% of cases; however, its effectiveness decreases if administered after 2 weeks of age. Other treatment options for closure of a hemodynamically significant ductus arteriosus include surgery or transcatheter device closure. Both can be performed safely and effectively with minimal morbidity and mortality. Administration of oxygen to the patient with congestive heart failure because of a large leftto-right shunt would be detrimental in that it may decrease pulmonary vascular resistance and increase the degree of left-to-right shunting, exacerbating the symptoms of heart failure. The same is true for administration of nitric oxide in this situation. Administration of phenylephrine would cause an increase in systemic vascular resistance and result in a greater degree of left-to-right shunting.
    5. (A) The etiology of shock in the neonate includes the following:
• hypoglycemia
• asphyxia
• sepsis
• intracranial bleeding
• arrhythmias including tachyarrhythmias and bradycardias
• cardiogenic shock because of left-sided obstructive lesions
• myocarditis
    The least likely explanation of shock in this baby is asphyxia because there is no history of perinatal asphyxia or distress based on the birth history.
    6. (B) Cardiogenic shock may be the first presentation in the neonate with congenital heart disease. Specific heart lesions causing left ventricular outflow tract obstruction may present in this manner. These lesions include critical aortic stenosis, hypoplastic left heart syndrome, and coarctation of the aorta. A patent ductus arteriosus allows for blood to bypass left-sided obstructions thus maintaining adequate cardiac output. With closure of the ductus, cardiac output is diminished. The neonate with cardiogenic shock from ductal-dependent lesions often presents at 1-2 weeks of age with shock related to the spontaneous closure of the ductus arteriosus.
    7. (D) An echocardiogram would be the most useful test in this situation to determine if there is a ductaldependent cardiac lesion. It is also useful to detect primary myocardial dysfunction related to other causes of shock.
    8. (A) The acute therapy for shock as a result of ductal-dependent cardiac lesions is infusion of prostaglandin E 1 in hopes of reestablishing patency of the ductus arteriosus.
    9. (E) The other acute management strategies for shock in the neonate include inotropic support with dopamine or epinephrine, ventilatory support in cases of respiratory compromise, oxygen supplementation, and correction of metabolic abnormalities such as acidosis, hypokalemia, and hypocalcemia.
    10. (E) Cyanosis can be divided into 2 clinical categories: central or peripheral. Central cyanosis is a result of a decrease in the oxygen saturation of blood supplying the body. Peripheral cyanosis is a benign finding caused by increased oxygen extraction