USMLE Forum Archives - USMLE Step 2 CK - Peds 7
Peds 7
TheOne - 11-26-06 19:03
A female infant was born at 32 weeks gestational age following a spontaneous vaginal delivery. The mother had regular prenatal care with negative serologies. Labor lasted 14 hours, and nitrous oxide was used for pain control. Apgar scores were 7 and 8 at 1 and 5 minutes, respectively, because of poor respiratory effort and decreased tone. She is transferred to the neonatal intensive care unit, where vitals are monitored continuously and
nasal continuous positive airway pressure (CPAP) is begun. Periodic changes in breathing were noted, with absent respiration of 22 seconds' duration with each episode. Apneic episodes are associated with a heart rate of 90/min and a PaO2 of 65. Heart rate returns to 150/min, and PaO2 to 96, between episodes. The patient's temperature is 36.8 C (98.2 F), respiratory rate is 62/min, blood pressure is 85/55 mm Hg, and birth weight is 1630 g. Physical
exam and routine laboratory results are otherwise normal. Which of the following is the most appropriate pharmacotherapy for this infant's apnea?
A. Bicarbonate
B. Dextrose
C. Epinephrine
D. Naloxone
E. Theophylline
F. Phenobarbitol
TheOne - 11-26-06 19:03
A female infant was born at 32 weeks gestational age following a spontaneous vaginal delivery. The mother had regular prenatal care with negative serologies. Labor lasted 14 hours, and nitrous oxide was used for pain control. Apgar scores were 7 and 8 at 1 and 5 minutes, respectively, because of poor respiratory effort and decreased tone. She is transferred to the neonatal intensive care unit, where vitals are monitored continuously and
nasal continuous positive airway pressure (CPAP) is begun. Periodic changes in breathing were noted, with absent respiration of 22 seconds' duration with each episode. Apneic episodes are associated with a heart rate of 90/min and a PaO2 of 65. Heart rate returns to 150/min, and PaO2 to 96, between episodes. The patient's temperature is 36.8 C (98.2 F), respiratory rate is 62/min, blood pressure is 85/55 mm Hg, and birth weight is 1630 g. Physical
exam and routine laboratory results are otherwise normal. Which of the following is the most appropriate pharmacotherapy for this infant's apnea?
A. Bicarbonate
B. Dextrose
C. Epinephrine
D. Naloxone
E. Theophylline
F. Phenobarbitol
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#3
Re: Peds 7 Brainlab - 12-03-06 11:33 There is some evidence that nitrous oxide affects the opiate system. Therefore the answer D may be correct.
#4
Re: Peds 7
TheOne - 12-03-06 16:55 The correct answer is E. This child has apnea of prematurity (AOP), a common problem that affects premature infants and, to a lesser degree, term infants. Apnea is the cessation of air flow/exchange for >20 seconds and is often associated with bradycardia and hypoxemia, as seen in this case. It occurs in approximately 50% of infants born at 30 to 31 weeks' gestation and appears to be due to immaturity of the infant's neurologic and respiratory systems. The first-line pharmacologic agents of choice for the management of AOP are methylxanthines (caffeine and theophylline) which act to stimulate respiratory neurons. AOP usually resolves by the time the infant is 34 to 36 weeks gestational age.
Bicarbonate (choice A) may be used to correct documented acidosis. Because routine laboratory tests are within normal limits, bicarbonate is not indicated.
Dextrose (choice B) is used for the correction of hypoglycemia, which can occur in premature infants. However, hypoglycemia typically does not manifest as apnea. Furthermore, the normal laboratory panel does not reveal hypoglycemia.
Epinephrine (choice C) is used in neonatal resuscitation when the heart rate stays below 80/min despite effective ventilation with 100% oxygen and chest compressions for at least 30 seconds. It is not the appropriate management for the bradycardia found in AOP.
Naloxone (choice D) is used as an antidote to opiates overdose. It has no place in the management of AOP.
Phenobarbitol (choice F) would increase the respiratory depression in this case, it also has no place in the management of this condition.
#6
Re: Peds 7 bingousmle - 07-18-10 06:23 this is a good question.. could figure out the correct answer only by ruling out other choices.. and that a correlation exists between nitric oxide and theophylline
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