Q1 :
A 2-week-old infant presents to the emergency department with a 1-day history of decreased
feeding, pallor, diaphoresis, and increasing somnolence. He was born at term, and the delivery
was uncomplicated. On physical examination, his heart rate is 190 beats/min, his respiratory
rate is 80 breaths/min, his blood pressure is 50/30 mm Hg, and his extremities are cool and pale
with poor pulses. You place the infant on a cardiorespiratory monitor and begin your
assessment and management.
Of the following, the MOST appropriate pair of tests to consider in this child is
A. complete blood count and bone scan
B. electrocardiography and echocardiography
C. electroencephalography and head ultrasonography
D. lumbar puncture and head computed tomography scan
E. serum electrolytes and chest computed tomography scan
The Answer :
B
Explanation :
The child described in the vignette is in shock and has clinical signs and symptoms of
diminished systemic perfusion. His heart rate is elevated to increase cardiac output (cardiac
output = heart rate x stroke volume). Shock has several causes in the neonate, including
hypovolemia, sepsis, and metabolic and cardiogenic dysfunction. Differentiating these causes
upon presentation in the neonate can be difficult.
Although it is appropriate for the infant described in the vignette to receive empiric broadspectrum
antibiotics against the most likely infectious organisms in this age group, performing a
lumbar puncture may compromise the infant’s cardiorespiratory status further and is
contraindicated. Because the findings in this infant are most consistent with cardiogenic shock,
an electocardiogram and echocardiogram should be obtained as soon as possible. These tests
can be performed at the bedsides of even the most critically ill infants.
There is no reason to perform computed tomography scan, bone scan, or electrocephalography in this infant. Although a complete blood count and electrolytes should be measured, it is unlikely that these test will aid
in the immediate management of the infant described in this vignette.
In the first few weeks after birth, cardiogenic shock often is due to cardiac anomalies.
Congenital heart lesions that may lead to such a dramatic presentation include those that require
ductal patency for the maintenance of systemic blood flow.
Among these are :
critical aortic stenosis
aortic coarctation
interruption of the aortic arch
hypoplastic left heart syndrome.
In each of these left heart obstructive lesions, persistence of the fetal shunting pattern through
the ductus arteriosus from the pulmonary artery to the aorta provides the necessary blood flow
to the aorta to maintain end-organ and cellular perfusion.
As the ductus arteriosus begins to close in the hours and days after delivery, the volume of blood delivered to the systemic circulation diminishes in patients who have severe left heart obstruction.
Although the ductus arteriosus closes by the fourth postnatal day in approximately 90% of neonates, in some infants, closure does not occur for several weeks.
Therefore, left heart obstructive lesions should be considered in any neonate who presents with congestive failure and shock, and administration of prostaglandin E to establish or maintain ductal patency should be considered.
Head ultrasonography may be important in determining this child’s prognosis afterstabilization, but it cannot aid in diagnosis and acute management.
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Q2 :
You are evaluating an 8-week-old infant whose birthweight was 1,000 g and who was delivered
at 30 weeks’ gestation. He experienced early respiratory distress and sepsis, but now these
problems have resolved, and he recently progressed from parenteral nutrition to full enteral
feedings.
Of the following, the feeding that will provide the BEST mineral content to ensure healthy bone
development for this infant is
A. cow milk-based infant formula
B. human milk
C. premature formula
D. protein hydrolysate formula
E. soy protein-based formula
Answer :
C
Explanation :
The optimal source of nutrition for the infant in the vignette should provide sufficient energy
substrate (carbohydrate and lipid) and protein to facilitate growth and development as well as the
necessary minerals and vitamins to help make up for delayed bone mineralization. Term infant
cow milk-based formula lacks sufficient calories, protein, Ca++, P, and other trace minerals and
vitamins, as does unsupplemented human milk. Term formulas and human milk require
supplementation with a fortifier to meet these goals.
Formulas designed specifically for preterm infants contain higher caloric density; more
readily absorbed lipids; greater protein content; and enriched Ca++, P, and other minerals and
vitamins. They provide the best mineral content to ensure healthy bone development in VLBW
preterm infants and generally do so by the time the infant attains a postconceptive age of 44
weeks. Protein hydrolysate formulas and soy protein-based formulas deliver suboptimal energy,
protein, minerals, and vitamins to VLBW preterm infants and should be used only for a specific
indication for a limited period of time.
------------------------------
Q 3 :
A 4-week-old infant who was born at term without any complications ate well and gained weight for the first 3 weeks after birth. Over the last week, however, his mother reports that he appears hungry but fatigues with feeding and now takes twice as long to complete his feeding as he did 1 week ago. He also breathes fast during his feedings and stops frequently to "catch his breath." Of the following, the MOST likely explanation for the symptoms in this infant is
A. aspiration syndrome
B. congestive heart failure
C. gastroesophageal reflux disease
D. inborn error of metabolism
E. pneumonia
Q 3 :
A 4-week-old infant who was born at term without any complications ate well and gained weight for the first 3 weeks after birth. Over the last week, however, his mother reports that he appears hungry but fatigues with feeding and now takes twice as long to complete his feeding as he did 1 week ago. He also breathes fast during his feedings and stops frequently to "catch his breath." Of the following, the MOST likely explanation for the symptoms in this infant is
A. aspiration syndrome
B. congestive heart failure
C. gastroesophageal reflux disease
D. inborn error of metabolism
E. pneumonia
Answer :
B
The symptoms described for the child in the vignette are typical of progressive congestive heart failure (CHF).
The "hunger" described by the mother suggests that the problem results from the infant's inability to take enough calories for satiation and growth. Such so-called poor feeding is due to his inability to generate a prolonged suck while maintaining nasal breathing because of the tachypnea that is caused by pulmonary congestion. Thus, the infant seems to stop sucking and "catch his breath."
Decreased caloric intake coupled with increased caloric expenditure caused by tachypnea and tachycardia makes it difficult for the infant to gain weight. Indeed, weight loss is common in infants who have CHF.
CHF is a clinical syndrome that reflects the inability of the myocardium to meet the metabolic requirements of the body, including those for growth.
CHF results from excessive workload imposed on the cardiac muscle that usually is caused by the structural defects. The cardiac defects may impose an excessive volume load on the left ventricle (eg, large ventricular septal defect, atrioventricular septal defect), an excessive pressure load on the ventricle (eg, aortic stenosis), or a combination of volume and pressure load (eg, ventricular septal defect with coarctation).
Less commonly, CHF may be caused by an intrinsic alteration in myocardial performance, which could result from an inflammatory or an infectious process that directly affects the myocardium and depresses its contractile function.
Aspiration syndrome typically is an acute event resulting from the passage of gastrointestinal contents (including food) into the lungs. The symptoms usually are acute and not associated with poor feeding in spite of hunger.
Similarly, gastrointestinal reflux presents more acutely with signs of discomfort that might include arching during feedings.
Pneumonia is associated with other signs of infection, including tachypnea when at rest, fever, or change in
behavior.
Inborn errors of metabolism, although less common, are important to consider in the neonate and infant who is not feeding well. Most commonly, they are associated with symptoms that are present both at rest and during feeding as well as other systemic signs.
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Q4 :
You are examining a 3-week-old preterm infant who was born at 26 weeks’ gestation and is receiving continuous positive airway pressure (CPAP) respiratory support. He has had increasing episodes of apnea and bradycardia over the past 12 hours. On physical examination, his temperature is 37.0°C, heart rate is 150 beats/min, and respiratory rate is 50 breaths/min on CPAP pressure support of 6 mm Hg with an FiO2 0.35. The infant has a flat and soft anterior fontanelle, moist mucous membranes, normal heart and lung sounds, and benign findings on abdominal examination. His extremities are mildly warm, and his left knee is swollen without noticeable erythema. Range of motion of the left knee is mildly decreased compared with the right. A clean and dry dressing covers a peripherally inserted central venous catheter in the right arm. The white blood cell count is 9.0x103/mcL (9.0x109/L), with 55%polymorphonuclear leukocytes, 10% band forms, 30% lymphocytes, and 5% monocytes.
Cerebrospinal fluid evaluation reveals 15 white blood cells/mm3 with 80% lymphocytes, 10% polymorphonuclear leukocytes, and 10% monocytes; protein of 70 mg/dL; and glucose of 60 mg/dL. Urinalysis yields normal results. Blood, cerebrospinal fluid, and urine specimens have been sent for cultures. A magnetic resonance imaging study reveals increased signal in the left knee. You order broad-spectrum intravenous antibiotics.
Of the following, the next BEST step is
A. arthrocentesis of the left knee
B. bone scan of the left knee
C. radiograph of the left knee
D. removal of the central venous catheter
E. ultrasonography of the left knee
Answer :
A
The preterm infant described in the vignette has hematogenously acquired infective osteoarthritis, most likely caused by Staphylococcus aureus. Arthrocentesis of the knee and cultures of fluid and bone would assist in establishing the diagnosis.
The unique neonatal anatomy allows spread of bacteria from the metaphyseal bone through the transphyseal vessels into the epiphysis and the adjacent joint.
Therefore, unlike most infections in older children, neonatal disease involves both the bone and joint contiguously.
The most common clinical presentation of infective osteoarthritis is an occult bacteremia that
leads to inoculation of bone, and multiple sites can be involved in up to 50% of cases.
The femur and tibia are the most commonly infected bones (80%), and adjacent arthritis is common.
The clinical findings, especially in preterm infants, can be subtle.
Infants may be irritable, with mild swelling of the affected area and decreased movement of the limb.
Marked limb swelling and erythema may be absent.
The infants can be afebrile and have normal vital signs.
Serum inflammatory markers (C-reactive protein, erythrocyte sedimentation rate) may not be markedly elevated and are not specific.
Less often, infants can present with overt sepsis that involves bacteremia and focal limb abnormality that is not the most prominent symptom.
Rarely, infection can result from penetrating trauma from instrumentation or procedures (eg, catheters, heel stick).
Plain radiography is important for evaluating for fracture, but destructive bony changes from infection will not be apparent until at least 10 days after the onset of symptoms.
The sensitivity of magnetic resonance imaging (MRI) for detecting changes consistent with osteomyelitis approaches 100%.
Bone scans in neonates can be nondiagnostic.
Ultrasonography of the knee in a preterm neonate may not reveal a significant effusion and is of little utility in the patient described in the vignette, in whom changes already are evident on MRI.
Removal of the central venous catheter may be warranted if blood cultures reveal a pathogen but is unnecessary if they are negative.
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Q 5:
During the 1-week health supervision visit, a mother who is exclusively breastfeeding asks about vitamin and iron supplementation for her healthy term infant. She explains that her previous child, who was born at 30 weeks’ gestation, was discharged with an oral iron supplement and vitamins.
Of the following, the MOST appropriate oral supplement to initiate for this infant at this visit is
A. calcium
B. folic acid
C. iron
D. vitamin D
E. vitamin K
Answer :
D
The most appropriate oral supplement to initiate at 1 week of age for an exclusively breastfeeding term infant is vitamin D.
In 2008, new guidelines from the American Academy of Pediatrics recommended that breastfed and partially breastfed infants be supplemented with 400 IU of vitamin D daily within days of birth.
Exclusive breastfeeding without adequate sun exposure or vitamin D supplementation is a risk factor for
vitamin D deficiency and rickets.
The term infant has adequate calcium stores, in contrast to the preterm infant, who is born
during the period when 80% of calcium, phosphorus, and magnesium are accrued. The term
infant also has adequate folate stores.
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Q 6:
A 2-hour-old full-term newborn infant is noted by the nursing staff to be having episodes of cyanosis and apnea. Per nursery protocol they place an oxygen saturation monitor on him. When they attempted to feed him, his oxygen levels drop into the 60s. When he is stimulated and cries, his oxygen levels increase into the 90s. Which of the following is the most important next step to quickly establish the diagnosis?
a. Ventilation perfusion scan
b. Echocardiogram
c. Hemoglobin electrophoresis
d. Passage of catheter into nose
e. Bronchoscopic evaluation of palate and larynx
D
Choanal atresia
Most neonates are obligate nose breathers and cannot breathe adequately through their mouths. Infants with choanal atresia have increased breathing difficulty during feeding and sleeping and improved respirations when crying.
A variety of temporizing measures to maintain an open airway have been used, including oropharyngeal airways, positioning, tongue fixation, and endotracheal intubation, but surgical correction with placement of nasal tubes is most effective.
The diagnosis can be made by failure to pass a catheter through the nose to the pharynx or by checking for fog developing on a cold metal instrument placed under each nares
Q 7:
A
1-week-old term female infant suddenly develops melena. The mother is healthy,
and the pregnancy was normal. Delivery was attended by her family at home, but
it was uncomplicated. The infant is breastfeeding. Hemoglobin is 6.7 g/dL (67
g/L), white blood cell count is 13,000/cu mm (13 x 109/L), and platelets are
599 x 103/cu mm (599 x 109/L). Of
the following, the MOST likely cause of the bleeding is:
A. factor
VIII deficiency hemophilia
B. factor
IX deficiency hemophilia
C. necrotizing
enterocolitis
D. rectal
fissure
E. vitamin
K deficiency
Answer :
E
Answer :
A
Answer :
E
Home
birth is associated with many clinical problems, including vitamin K
deficiency. The vitamin often is not
administered with home births.
The
pathophysiology responsible for hemorrhagic disease of the newborn is complex.
Vitamin K is required to activate the procoagulant factors II, VII, IX, and X
as well as proteins C and S, all of which are synthesized in the liver.
Neonatal
hepatic immaturity impairs the synthesis of these factors and limits the
effectiveness of vitamin K.
Inefficient transplacental transfer of vitamin K
also may be a contributing factor.
Delayed colonization of the gut by bacteria
(which become an endogenous source of vitamin K) is another factor that occurs
with delayed feeding, breastfeeding, vomiting, severe diarrhea, and the use of
antibiotics (including those that are present in human milk).
All of these
factors contribute to vitamin K deficiency, low levels of vitamin K-dependent
factors, and when severe enough, clinical hemorrhagic disease of the newborn.
Classic
vitamin K deficiency can present with melena, large cephalohematomas,
intracranial hemorrhage, and bleeding from the umbilical stump, injection
sites, and after circumcision.
Bleeding occurs most commonly from the second to
seventh days of life in healthy, breastfed, and often term infants who have not
received prophylactic vitamin K.
It occurs rarely in formula-fed infants
because of the supplemental vitamin K in those products.
Laboratory
evaluation :
In vitamin K deficiency, the prothrombin time (PT) and
partial thromboplastin time (PTT) are more prolonged than usual for a neonate,
the vitamin K-dependent factors (factors II, VII, IX, and X and proteins C and
S) are decreased, and non-vitamin K-dependent factors (factors V, VIII, and
fibrinogen) and platelet counts are normal.
D Dx :
Bleeding
in the neonate has many other etiologies.
If thrombocytopenia accompanies a
prolonged PT and PTT, disseminated intravascular coagulation is likely.
Factor
VIII and IX deficiency hemophilia will cause prolongation of the PTT but not
the PT.
Liver disease prolongs the PT and PTT and decreases vitamin K-dependent
factors, but factor V and fibrinogen also are decreased. Hepatic function is
abnormal in contrast to the normal-for-age function seen in vitamin K
deficiency.
Disorders such as necrotizing enterocolitis and rectal fissures can
result in gastrointestinal bleeding in the absence of coagulopathy. However,
rectal fissures do not cause melena, and necrotizing enterocolitis rarely
occurs in healthy term infants.
Prophylactic
vitamin K is used widely to prevent hemorrhagic disease of the newborn.
Treatment of clinical hemorrhagic
disease of the newborn necessitates frequent doses of subcutaneous or
intravenous vitamin K1; intramuscular administration should be avoided.
Improvement will occur within 24 hours with vitamin K1 alone, but plasma should
be used to treat infants who are experiencing serious bleeding.
-------------------------------------------
Q 8:
Answer :
C
Most patients who have DiGeorge syndrome are
found to have partial monosomy for the proximal long arm of chromosome 22 due
to microdeletion of 22q11.2. This microdeletion can be detected by fluorescent
in situ hybridization (FISH) using a molecular probe specific for the region.
-----------------------------------
Q 9:
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Q 8:
A
newborn female has a cardiac murmur. Before the cardiologist arrives to
evaluate her, she has a seizure. Results of laboratory testing include a serum
calcium level of 5.0 mg/dL (1.25 mmol/L). Subsequently, echocardiography
reveals an aortic arch anomaly.
Of
the following, the MOST appropriate test to obtain now is:
A. brainstem
auditory evoked responses
B. electroencephalography
C. fluorescent
in situ hybridization analysis of chromosome 22
D. peripheral
blood chromosome analysis
E. thyroid
function testing
Answer :
C
The
infant described in the vignette has a number of features of DiGeorge syndrome.
DiGeorge syndrome results from abnormal cervical neural crest migration into
the derivatives of the third and fourth pharyngeal arches and pouches during
early embryogenesis.
The pattern of malformations includes hypoplasia or
aplasia of the thymus and parathyroid glands and structural abnormalities of
the great vessels. The defects lead to the classic clinical manifestations of
deficient cellular immunity due to T-cell dysfunction, causing increased
susceptibility to infection; hypocalcemia due to absent parathyroid hormone,
resulting in hypocalcemic seizures; and aortic arch abnormalities. Some
affected infants also have facial dysmorphic features, which can include
hypertelorism, short palpebral fissures, short philtrum, micrognathia, and ear
abnormalities.
-----------------------------------
Q 9:
A
2-day-old boy has biphasic stridor that worsens with agitation. He has
intermittent desaturations with bradycardia and a weak cry. Blood pressure is
80/60 mm Hg, and pulse rate is 112 beats/min.
Of
the following, the MOST likely etiology of this child's condition is:
A. congenital
subglottic stenosis
B. cystic
fibrosis
C. hypoplastic
left heart
D. innominate
artery compression
E. tracheoesophageal
fistula
Answer :
A
Stridor
is produced by rapid, turbulent flow of air through a narrow segment of the
airway. Biphasic stridor suggests an anatomic location at the glottic or
subglottic level. Inspiratory stridor typically is produced by an obstruction
above the vocal cords; expiratory stridor is produced by an intrathoracic site
of obstruction.
Cystic
fibrosis often presents with meconium ileus at birth and the development of
chronic cough, respiratory distress, and failure to thrive later in life.
Stridor is uncommon.
Patients who have hypoplastic left heart syndrome do not
have obvious stridor; rather, they present with signs of cyanosis and
hypoperfusion. Signs of congestive failure usually appear within the first few
days or weeks of life.
Tracheoesophageal fistula presents with excessive oral
secretions, choking, coughing, and cyanosis when feeding is attempted.
Tracheomalacia may cause expiratory stridor, but biphasic stridor is uncommon.
Innominate artery compression, although usually mild and asymptomatic, may
cause expiratory stridor, cough, and recurrent pneumonias. Respiratory distress
is uncommon.
----------------------------------------------------
Q 10:
Q 10:
A
newborn female has an open neural tube defect, low-set ears, ventricular septal
defect, and rib and vertebral column malformations.
Of
the following, the MOST likely maternal condition that was present during this
pregnancy is:
A. alcoholism
B. diabetes
mellitus
C. hypothyroidism
D. iodine
deficiency
E. syphilis
Answer :
B
Maternal
diabetes mellitus can have profound effects on the development and health of
the fetus. The severity of the maternal disease and the subsequent fetal
effects can vary considerably. Because the maternal diabetic state can be
present from the time of conception, early prenatal effects can result in
malformations, growth deficiency, and stillbirth.
There is a threefold increase
in malformations among offspring of diabetic mothers; the incidence is
correlated with the severity and level of control of the maternal illness. The
most common defects involve the heart, central nervous system, kidneys, and
skeleton, as described for the infant in the vignette.
Of the cardiac defects,
ventricular septal defect, transposition of the great vessels, and dextrocardia
are most common. Central nervous system defects can range from anencephaly or holoprosencephaly to spina bifida and
hydrocephalus. Malformations of the lower spine also occur and are termed the
caudal regression syndrome.
The spine may be segmented defectively or terminate
in the sacral or lumbar region, resulting in abnormal neurologic function below
the level of the defect. Rib defects also may be seen. Although many types of
malformations can occur in infants of diabetic mothers, holoprosencephaly and
the caudal regression syndrome are characteristic.
Fetal
alcohol syndrome is characterized by prenatal growth deficiency,
microcephaly, and cardiac defects. Neural tube and vertebral column defects are
not common features.
Maternal hypothyroidism has little effect on the fetus,
which produces its own thyroid hormone; women who have untreated hypothyroidism
have been reported to give birth to normal offspring.
Maternal iodine
deficiency can cause fetal deficiency of the mineral, which results in goiter, signs of cretinism, retarded bone growth, constipation, umbilical
hernia, and mottling in the newborn. Prompt treatment with iodine is necessary
to prevent mental retardation.
Maternal syphilis can affect the fetal skin,
mucous membranes, liver, central nervous system, and bones. Cardiac anomalies
and open neural tube defects are not common features.
------------------------------
Q 11:
Of
the following, the MOST accurate statement about energy expenditure of a
preterm infant is that:
A. a
thermoneutral environment is effective in minimizing energy expenditure
B. diet-induced
thermogenesis is higher with continuous than with intermittent feeding
C. metabolic
cost of growth is higher with deposition of fat than with synthesis of protein
D. physical
activity is the major component of total energy expenditure
E. resting
metabolic rate decreases with advancing postnatal age
ANSWER :
A
The
preterm neonate’s energy expenditure can be minimized by keeping the infant in
a thermoneutral environment.
The thermoneutral environment is a range of
ambient temperatures within which the metabolic rate of the infant is minimal
and the infant can maintain a normal body temperature without any regulatory
changes in metabolic heat production or evaporative heat loss. The
thermoneutral range varies with gestational age. In an unclothed resting adult,
the lower limit of the thermoneutral range is 78.8°F to 82.4°F (26°C to 28°C)
in an environment of 50% relative humidity and still air. Under similar
conditions, the lower limit of the thermoneutral range is 89.6°F (32°C) or
higher in a naked term neonate and 95°F (35°C) or higher in a naked preterm
neonate.
Diet-induced
thermogenesis, also known as specific dynamic action, thermic effect of food,
or postprandial thermogenesis, is the increase in metabolic rate that follows
food intake. It represents the energy consumption necessary for digestion,
absorption, and assimilation of nutrients. The magnitude of increase in energy
expenditure following the ingestion of nutrients is estimated to vary between
4% and 30% in both term and preterm neonates. Diet-induced thermogenesis is
lower with continuous than with intermittent enteral feeding.
Metabolic
cost of growth represents the energy required for the formation of new tissue,
and it varies with the composition of the synthesized tissue. The cost of
depositing absorbed dietary fat into adipose tissue is much less than that of
synthesizing new protein. The overall metabolic cost of growth in neonates is
estimated at approximately 4.4 kcal/g of weight gain.
Energy
expenditure increases with physical activity, but because neonates sleep 80% to
90% of the time, physical activity is a small component of their energy
expenditure compared with that of adults. It is estimated that physical
activity contributes to only about 10% of the total energy expenditure in
preterm neonates.
Resting
metabolic rate increases steadily from birth in both term and preterm neonates.
The resting metabolic rate in term neonates is estimated at approximately 40
kcal/kg per day at 3 days of postnatal age, increasing to approximately 60
kcal/kg per day at 3 months of postnatal age. A similar but smaller increase in
resting metabolic rate is observed in preterm neonates.
-----------------------------
Q 12 :
-----------------------------
Q 12 :
A
pregnant woman is diagnosed as having active pulmonary tuberculosis at the time
of delivery. She is placed on appropriate chemotherapy after delivering a
healthy-appearing term infant.
Of
the following, the MOST appropriate management of the infant includes
separation from the mother:
A. for
1 month
B. until
the infant begins isoniazid
C. until
the infant receives bacillus Calmette-Guerin (BCG) vaccine
D. until
the infant undergoes skin testing
E. until
the mother is no longer contagious
Answer :
B
Q 13 :
Answer :
A
Strictures (Figure 20B) are the most common
long-term gastrointestinal complication of NEC, occurring in 10% to 35% of
survivors.
-----
Q 14
Answer :
D
Pulmonary hemorrhage is a potential complication of surfactant treatment.
Answer
C
Answer
A
Answer :
B
the
maternal infection. Although protecting the infant from infection is of
paramount importance, separation from the mother should be avoided when
possible. Recommendations of the American Academy of Pediatrics’ Committee on
Infectious Diseases are determined by the type of maternal infection and
include:
If the mother has a positive skin test, normal findings on chest
radiography, and is asymptomatic, no separation is required. The newborn needs
no special evaluation or therapy. Because a positive skin test result could be
a marker of an unrecognized case of contagious tuberculosis within the
household, other household members should have a skin tests and further
evaluation.
If the mother’s radiograph is abnormal, the mother and infant should be
separated until the mother has been evaluated and, if tuberculosis is found,
until the mother is receiving appropriate antituberculosis therapy. Other
household members should have skin testing and further evaluation.
If the mother’s chest radiograph is abnormal but not typical of
tuberculosis and the history, physical examination findings, and sputum smear
indicate no evidence of tuberculosis, the infant can be assumed to be at low
risk for Mycobacterium tuberculosis infection and need not be separated from
the mother. The mother and infant should receive follow-up care. Other
household members should have skin testing and further evaluation.
If the mother has clinical or radiographic evidence of possibly
contagious tuberculosis, the case should be reported immediately to the local
health department so that all household members can be investigated within
several days. All contacts should have skin testing, a chest radiograph, and a
physical examination. Women who have only pulmonary tuberculosis are not likely
to infect the fetus, but they may infect their infant after delivery.
Congenital tuberculosis is rare, but in utero infections can follow maternal M
tuberculosis bacillemia. The infant should be evaluated for congenital
tuberculosis and tested for human immunodeficiency virus infection. If a
newborn is suspected of having congenital tuberculosis, a skin test, chest
radiograph, lumbar puncture, and appropriate cultures should be obtained
promptly. The skin test result usually is negative in newborns who have
congenital or perinatally acquired infection. Hence, regardless of the skin
test results, the infant should be treated promptly with isoniazid, rifampin,
pyrazinamide, and streptomycin or kanamycin. The placenta should be examined
histologically and cultured for M tuberculosis. The mother should be evaluated for
the presence of pulmonary or extrapulmonary (including uterine) tuberculosis.
If findings on the maternal physical examination or chest radiograph support
the diagnosis of tuberculosis, the newborn should be treated with regimens
recommended for tuberculous meningitis, excluding corticosteroids. If
meningitis is confirmed, corticosteroids should be administered. Drug
susceptibilities of the organism recovered from the mother, infant, or both
should be determined. If the infant is receiving isoniazid, separation is not
necessary. Other household members should have skin testing and further
evaluation.
If congenital tuberculosis is excluded, isoniazid is administered until
the infant is 3 or 4 months of age, at which time the skin test should be
repeated. If the skin test result is positive, the infant should be reassessed
for tuberculosis. If disease is not present, isoniazid should be continued for
at least 9 months. If the purified protein derivative test is negative and the
mother and other household contacts who have tuberculosis have good adherence
and response to treatment and are no longer contagious, isoniazid may be
discontinued. The infant should be evaluated at monthly intervals during
treatment.
If the mother has disease due to multiple drug-resistant M tuberculosis
or adheres poorly to treatment and directly observed therapy is not possible,
the infant should be separated from the ill mother and bacillus Calmette-Guérin
(BCG) immunization considered for the infant. Because the response to BCG in
infants may be delayed and inadequate for prevention of tuberculosis, directly
observed therapy for the mother and infant is preferred.
M
tuberculosis usually is spread via airborne transmission, with inhalation of
droplet nuclei produced by an adult or adolescent who has contagious, cavitary,
pulmonary tuberculosis. The duration of contagiousness of an adult receiving
effective treatment depends on drug susceptibilities of the organism, the
number of organisms in sputum, and the frequency of cough. Although
contagiousness usually lasts only a few weeks after initiation of effective
drug therapy, it may extend further, especially when the patient does not
adhere to medical therapy or is infected with a resistant strain. If the sputum
is negative for organisms on three smears and coughing has ceased, the person
is considered noncontagious. Children younger than 12 years of age who have
primary pulmonary tuberculosis usually are not contagious because their
pulmonary lesions are small, cough is minimal or nonexistent, and there is
little or no expulsion of bacilli.
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Q 13 :
A
700 g infant presents with abdominal distension, excessive gastric residuals,
and bloody stools. Physical examination reveals lethargy, poor perfusion, and
recurrent apnea. Abdominal examination reveals tenderness, guarding, and
erythema. You suspect necrotizing enterocolitis (NEC).
Of
the following, the MOST accurate statement about NEC is that:
A. age
at onset is inversely related to gestational age at birth
B. it
is more common among critically ill than convalescing neonates
C. pneumatosis
intestinalis is the earliest radiographic sign
D. strictures
that occur as a late complication appear most frequently in the ileum
E. the
incidence is higher among Caucasian than African-American infants
Answer :
A
The
age of onset of necrotizing enterocolitis (NEC) is inversely related to
gestational age at birth.
The
earliest radiographic sign of NEC is generalized bowel distension. Other
nonspecific findings on abdominal radiographs include bowel wall thickening and
the presence of intraperitoneal fluid. Pneumatosis intestinalis represents gas in the bowel wall and usually confirms the diagnosis of NEC.
Pneumatosis intestinalis can extend into the portal venous
circulation and be visible as linear branching lucencies overlying the liver.
Portal venous gas usually is associated with severe disease.
-----
Q 14
An
800 g newborn whose estimated gestational age is 26 weeks is experiencing
respiratory distress. Maternal history is significant for spontaneous preterm
labor, rupture of membranes for fewer than 2 hours, and precipitous vaginal
delivery. Chest radiography shows diffuse haziness with a reticulogranular
pattern. You begin administration of surfactant by intratracheal instillation
as well as mechanical ventilation.
Of
the following, surfactant treatment is MOST likely to increase the incidence of:
A. bronchopulmonary
dysplasia
B. intraventricular
hemorrhage
C. pneumothorax
D. pulmonary
hemorrhage
E. retinopathy
of prematurity
Answer :
D
Pulmonary hemorrhage is a potential complication of surfactant treatment.
Both
prophylactic and rescue administration of surfactant have been shown to
decrease the incidence of pneumothorax and other pulmonary air leaks.
The
improvement in cardiopulmonary stability and oxygenation induced by surfactant
therapy may protect preterm infants from nonpulmonary complications, including
retinopathy of prematurity (ROP).
------------------------------
Q15 :
------------------------------
Q15 :
A
newborn has hepatosplenomegaly, purpuric rash, jaundice, thrombocytopenia, and
microcephaly. Computed tomography of the head demonstrates cerebral
calcifications.
Of
the following, the MOST appropriate diagnostic testing for this infant includes:
A. maternal
human immunodeficiency virus serology
B. serologic
testing of mother and infant for cytomegalovirus
C. serologic
testing of mother and infant for Toxoplasma
D. VDRL
on infant and maternal sera
E. viral
culture of swabs of infant’s throat and conjunctivae
Answer :
C
Answer :
C
The
congenital infections most likely to present with the constellation of findings
described for the infant in the vignette include toxoplasmosis and
cytomegalovirus (CMV) infection. Human immunodeficiency virus (HIV) and herpes
simplex virus usually are acquired at the time of delivery, and the infant
generally is asymptomatic at birth. Therefore, maternal HIV serology and viral
culture of swabs from the infant’s throat and conjunctivae for HSV are unlikely
to yield a diagnosis. Congenital syphilis also rarely is symptomatic at birth,
although the most common symptoms include rash , snuffles, and bony
changes.
Diagnostic
testing is the best means to distinguish CMV infection from toxoplasmosis
because many of their clinical features overlap. Toxoplasmosis is more apt to
present with chorioretinitis and scattered cerebral
calcifications; CMV infection more frequently is associated with periventricular
calcifications . CMV is diagnosed best by culture of the infant’s
urine in the first 3 to 4 weeks of life. Serologic testing of maternal and
infant sera is the best method for diagnosing congenital toxoplasmosis, but it
is less useful in identifying CMV infection.
-----
Q16:
-----------
Q 17 :
-----
Q16:
A
newborn whose estimated gestational age is 34 weeks has had worsening
respiratory distress since birth. Maternal history is significant for prolonged
premature rupture of membranes, abdominal tenderness, foul-smelling amniotic
fluid, and fever. Chest radiography reveals bilateral patchy infiltrates and
fluid in the costophrenic angles. Blood samples are obtained for white blood cell
count with differential and culture, and antibiotic treatment is started.
Of
the following, the MOST appropriate initial combination of antibiotics is:
A. ampicillin
and gentamicin
B. ceftazidime
and tobramycin
C. imipenem
and cilastin
D. trimethoprim-sulfamethoxazole
E. vancomycin
and amikacin
Answer :
A
Answer :
A
The
choice of antimicrobial agents for treatment of suspected or proven neonatal
bacterial sepsis during the first days of life (early-onset sepsis) is based on
the prevalent organisms responsible for the infection and the pattern of their
antimicrobial susceptibility. The organisms most likely to be encountered in
early-onset neonatal sepsis include group B streptococci, Escherichia coli,
Listeria monocytogenes, Haemophilus influenzae, and enterococci. Ampicillin is
effective against most gram-positive organisms and gentamicin against most
gram-negative organisms associated with early-onset neonatal sepsis, making
this combination one of the most commonly used for this indication.
-----------
Q 17 :
You
are examining a newborn in the nursery and palpate a large mass in the abdomen.
Of
the following, the MOST likely diagnosis is:
A. autosomal
dominant polycystic kidney disease
B. horseshoe
kidney
C. multicystic
kidney dysplasia
D. renal
vein thrombosis
E. Wilms
tumor
Answer
C
A
palpable abdominal mass in a newborn constitutes a medical emergency. The most
common cause of an abdominal mass in the neonatal period is hydronephrosis. One
common cause of hydronephrosis is multicystic kidney dysplasia (MKD) .
This congenital malformation is caused by obstruction to urine flow
during in utero development, which results in abnormal parenchymal development.
Renal ultrasonography reveals multiple cysts scattered throughout the renal
parenchyma, with marked echogenicity of the parenchyma, indicating nonspecific
renal dysplasia. The cysts are of varying size, often replacing normal renal
tissue. Because the anomaly usually is unilateral, most children who have MKD
have normal renal function. However, because at least 50% of patients have an
abnormality of the contralateral kidney, voiding cystourethrography (VCUG) to
evaluate for vesicoureteral reflux is essential. Other anomalies of the
contralateral kidney include ureteropelvic junction obstruction (with
hydronephrosis), duplicated ureters, renal dysplasia, and hydronephrosis. If
MKD is bilateral, renal failure is assured.
Autosomal
dominant polycystic kidney disease (ADPKD) is a very common cause of renal
failure in adults. However, because it is a very slowly progressive disease, it
rarely is seen in newborns. ADPKD typically presents with hematuria, urinary
tract infection, and hypertension. Although horseshoe kidneys are infrequently
observed in newborns, they may present with urinary tract infections,
hematuria, or abdominal mass.
Nephroblastoma
is a general term used to describe a tumor of the kidney. The most common cause
in early childhood is Wilms tumor, which presents as an abdominal or flank mass
and may be heralded by hematuria and rarely, hypertension. It can be associated
with other congenital anomalies, including genitourinary anomalies,
hemihypertrophy, aniridia, gastrointestinal anomalies, polydactyly, and
hydrocephalus. Although this is the most common solid tumor in childhood, it
rarely presents during the newborn period.
The
typical presentation of renal vein thrombosis in a child is gross hematuria and
an abdominal mass. Although rare, it often results in complete loss of function
of the affected kidney.
-----------------------------
Q 18
Q 18
A
term newborn whose growth is appropriate for gestational age develops
irritability, jitteriness, and tremulousness at 7 days of life. Physical
examination reveals flushed cheeks, sweating, prominent eyes, and
hepatosplenomegaly. Axillary temperature is 100.4°F (38°C), heart rate is 210
beats/min, respiratory rate is 48 breaths/ min, and blood pressure is 88/56 mm
Hg. Muscle tone and deep tendon reflexes are normal.
Of
the following, the MOST likely diagnosis is:
A. congenital
heart disease
B. familial
dysautonomia
C. intrauterine
infection
D. narcotic
withdrawal
E. neonatal
thyrotoxicosis
Answer
E
Answer
E
Most
cases of neonatal thyrotoxicosis are caused by transplacental
transfer of thyroid-stimulating hormone (TSH) receptor-stimulating antibodies
from the mother. Maternal history often includes Graves disease, and maternal
antibody titer may influence symptoms in the neonate. The symptoms and signs of
neonatal thyrotoxicosis result from an increased metabolic rate, a generalized
enlargement of the reticuloendothelial system, high-output cardiac failure, and
exophthalmos of a variable degree. A goiter may be barely visible or large
enough to cause tracheal compression. The diagnosis of neonatal thyrotoxicosis
can be confirmed by measurements of serum free thyroxine and TSH
receptor-stimulating antibody titer.
-----
Q 19
-----
Q 19
You
are reviewing results of head ultrasonography performed on a 4-week-old
extremely low-birthweight infant. The scan shows a large, encapsulated,
fluid-filled cavity in the right cerebrum. The infant has required prolonged
ventilator assistance and parenteral nutrition through a central venous
catheter. She also has received broad-spectrum antibiotic therapy for multiple
episodes of suspected sepsis.
Of
the following, the MOST likely organism to cause this brain lesion is:
A. Citrobacter
diversus
B. Clostridium
perfringens
C. Gardnerella
vaginalis
D. Leptospira
canicola
E. Yersinia
enterocolitica
Answer
A
Citrobacter
diversus causes sporadic and epidemic neonatal sepsis and meningitis. It is
uniquely associated with brain abscesses, which usually are multiloculated and
located in the cerebrum. The pathogenesis of brain abscess caused
by C diversus involves cerebral vasculitis, with infarction and bacterial
invasion of the necrotic tissue. Early manifestations of brain abscess include
increased intracranial pressure, focal cerebral signs, and meningitis. The
disease is associated with a high fatality rate, and mental retardation is
common among survivors.
Clostridium
perfringens rarely is isolated in the neonate. Infection with this pathogen
usually presents as omphalitis, localized cellulitis, necrotizing fasciitis, or
generalized septicemia. Clostridial sepsis may include active hemolysis,
hyperbilirubinemia, and hemoglobinuria.
Gardnerella
vaginalis is a gram-negative coccobacillus that is present in the genital
tracts of up to one third of pregnant women. Infection in the neonate usually
occurs in early postnatal life. Most infants are asymptomatic, but some may
have signs and symptoms of congenital pneumonia.
Leptospira
canicola infection also is rare in the neonate. The organism usually is
acquired by the transplacental route and largely affects the liver in the
neonate.
Yersinia
enterocolitica is a rare pathogen in the neonate. Infection with this pathogen
causes watery diarrhea, fecal blood, and other symptoms and signs of
gastroenteritis. Rarely, autoimmune manifestations, such as arthritis and
erythema nodosum, may occur.
--
Q 20
Answer
E
Increased pancreatic insulin secretion is the cause of hypoglycemia in an infant of a diabetic mother. In the absence of adequate glycemic control during pregnancy, diabetes causes maternal hyperglycemia, which is paralleled by fetal hyperglycemia. Persistent or recurrent fetal hyperglycemia stimulates the fetal pancreas and causes beta-cell hypertrophy and hyperplasia, with a resultant increase in insulin content and secretion. Upon separation of the fetus from the mother at birth, the transplacental transfer of glucose is interrupted. In the absence of an adequate exogenous intake of glucose, the hyperinsulinemic neonate becomes hypoglycemic. This hypothesis, proposed by Pedersen, is supported by the observation of high blood levels of insulin in the neonate.
-------
Q 21
Answer :
A
--
Q 20
A
newborn who weighs 4,700 g and whose estimated gestational age is 37 weeks has
a blood glucose concentration of 18 mg/dL (1.00 mmol/L) at 30 minutes after
birth. Maternal history is significant for type 1 diabetes mellitus. Blood
count reveals polycythemia. Echocardiographic examination reveals septal
hypertrophy of the heart.
Of
the following, the MOST important cause of hypoglycemia in this infant is:
A. abnormal
gluconeogenesis
B. abnormal
glycogenolysis
C. depleted
liver glycogen stores
D. excess
catecholamine secretion
E. increased
pancreatic insulin secretion
Answer
E
Increased pancreatic insulin secretion is the cause of hypoglycemia in an infant of a diabetic mother. In the absence of adequate glycemic control during pregnancy, diabetes causes maternal hyperglycemia, which is paralleled by fetal hyperglycemia. Persistent or recurrent fetal hyperglycemia stimulates the fetal pancreas and causes beta-cell hypertrophy and hyperplasia, with a resultant increase in insulin content and secretion. Upon separation of the fetus from the mother at birth, the transplacental transfer of glucose is interrupted. In the absence of an adequate exogenous intake of glucose, the hyperinsulinemic neonate becomes hypoglycemic. This hypothesis, proposed by Pedersen, is supported by the observation of high blood levels of insulin in the neonate.
-------
Q 21
You
are attending the birth of an infant whose mother smoked two packs of
cigarettes per day during the pregnancy.
Of
the following, the finding that would be MOST likely to be present in the
newborn is:
A. growth
restriction
B. hydronephrosis
C. microcephaly
D. respiratory
distress syndrome
E. talipes equinovarusAnswer :
A
Tobacco
smoking during pregnancy causes fetal hypoxia and morphologic changes in the
placenta (eg, placenta previa, placental abruption) and premature rupture of
the membranes. These adverse effects result in an increased risk for
intrauterine growth restriction, preterm birth, and in some cases, late fetal
demise. Maternal smoking also is associated with increased risks for
postneonatal morbidity and mortality, including poor lung development, asthma,
respiratory infections, and sudden infant death syndrome.
Q 22
-----------------
Q 23
Q 22
A
3-week-old infant is brought to you for evaluation of poor feeding and
lethargy. On physical examination, you note decreased movement of the right
leg. Hip aspiration confirms the diagnosis of septic arthritis.
Of
the following, the MOST likely causative organism in this patient is:
A. Escherichia
coli
B. Group
A Streptococcus
C. Group
B Streptococcus
D. Haemophilus
influenzae type B
E. Listeria
monocytogenes
The Answer
C
The
most common organisms associated with neonatal septic arthritis are group B
Streptococcus, Staphylococcus aureus, and coliform bacteria. Haemophilus
influenzae type b (Hib) is much less prevalent now in the older child because
of the use of the Hib vaccine. Group A Streptococcus, Escherichia coli, and
Listeria monocytogenes are uncommon organisms causing septic arthritis in the
neonateThe Answer
C
-----------------
Q 23
A
male infant is born at an estimated gestational age of 34 weeks. His body
measurements are: weight, 1,200 g (<3rd percentile); crown-heel length, 41
cm (3rd percentile); and head circumference, 32 cm (50th percentile). Maternal
history is significant for pregnancy-induced hypertension.
Of
the following, the complication MOST likely to occur in this infant is:
A. anemia
B. hyperglycemia
C. hyperthermia
D. hypoxic-ischemic
encephalopathy
E. respiratory
distress syndrome
Answer
D
-------------------------
Q 23
Answer
D
The
failure of growth in the small-for-gestational age (SGA) infant described in
the vignette can be attributed to chronic placental insufficiency from maternal
hypertension. Uterine contractions can exacerbate the chronic hypoxia in the
presence of a marginally functioning placenta. With repeated episodes of
hypoxia, myocardial glycogen reserves are depleted, further limiting the
cardiopulmonary adaptation to hypoxia in fetal life as well as at birth. If
resuscitation is inadequate at birth, the combination of antepartum,
intrapartum, and neonatal asphyxia places the infant at high risk for
hypoxic-ischemic encephalopathy.
The
SGA infant is more likely to have polycythemia than anemia. Chronic fetal
hypoxia from placental insufficiency induces erythropoietin synthesis, which
increases red blood cell production in the fetus. Additionally, increased
placental vascular resistance from maternal hypertension may promote a shift of
placental blood to the fetus. Both of these factors place the SGA infant at high
risk for polycythemia and associated hyperviscosity.
The
SGA infant is more likely to have hypoglycemia than hyperglycemia. The
propensity for hypoglycemia may be attributed to depleted glycogen stores in
the liver following chronic placental insufficiency and resultant disturbance
in the transplacental transfer of nutrients. Additionally, the SGA infant is
unable to stimulate gluconeogenesis in response to hypoglycemia. This
limitation is believed to result not from a lack of nonglucose precursors, such
as lactate, alanine, and glycerol, but from a lack of enzymes necessary for
gluconeogenesis.
The
SGA infant may suffer hypothermia due to excessive heat loss rather than
inadequate heat production. The excessive heat loss is related primarily to the
deficient insulating layer of subcutaneous adipose tissue that results from
chronic placental insufficiency and associated nutritional deprivation. A large
surface area in relation to body weight, which is characteristic of the SGA
infant, adds to the heat loss.
Respiratory
distress syndrome occurs less frequently and is less severe in the SGA infant
than in the infant whose growth is appropriate for gestational age. Chronic
fetal hypoxia in the SGA infant induces endogenous glucocorticosteroid
secretion in response to stress that, in turn, accelerates fetal pulmonary
maturation, including the machinery for surfactant synthesis and secretion.
-------------------------
Q 23
You
are seeing a 2-week-old infant for the first time in your office. On physical
examination, you note ptosis of the right upper eyelid. Findings on the
remainder of the physical examination are normal.
Of
the following, the MOST likely cause for the ptosis in this patient is:
A. botulism
B. brainstem
glioma
C. Horner
syndrome
D. malformed
levator muscle
E. neonatal
myasthenia gravis
Answer
D
Answer
D
Congenital
ptosis is usually due to malformation of the levator muscle,
which is the muscle that primarily elevates the eyelid. The levator muscle is
innervated by the third cranial nerve. If the ptosis is severe, the infant’s
vision will be greatly diminished. The infant often keeps the chin up in order
to see. Absence of the faint lid crease will be present on the affected side.
One or both eyebrows are often markedly elevated.
The
treatment for this condition is surgical correction. If untreated, amblyopia
and loss of vision occur in many cases. Ophthamologic referral as soon as
possible after birth is indicated.
Myasthenia
gravis is due to gradual destruction of the motor endplates at the
neuromuscular junction. Circulating antibodies to the acetylcholine receptor
bind to the receptor on the motor endplate, blocking its function. Ptosis is
usually bilateral, and older patients also may complain of diplopia. Infants
born to mothers who have myasthenia gravis may manifest neonatal myasthenia
gravis, characterized by respiratory insufficiency, inability to suck or
swallow, and generalized weakness and hypotonia. After the transplacentally
acquired antibodies disappear, the infants have normal strength and are not at
increased risk for myasthenia gravis. Congenital myasthenia gravis is a rare, often
hereditary disorder that differs from transient neonatal myasthenia gravis.
Congenital myasthenia gravis is not due to maternal antibodies and is almost
always a permanent disorder without spontaneous remission.
Botulism
caused by preformed botulinum toxin is a type of food poisoning. It presents as
a rapid onset of cranial nerve weakness; a descending paralysis of limb and
respiratory muscles develops later. Botulism evolves rapidly over hours to days
and has a progressive course. Infants who have botulism usually present with
constipation, poor feeding, lethargy, and weak cry.
Brainstem
gliomas are uncommon in infants. They should be considered in any child who has
cranial nerve abnormalities. Characteristic long tract findings include
spasticity of limbs, exaggerated reflexes, positive Babinski sign, and ataxia.
Mild
ptosis with a lid crease, a small pupil (miosis), a difference in iris color
(heterochromia) , and an inability to sweat (anhidrosis) on one
side of the face are signs of Horner syndrome caused by sympathetic nerve
interruption. In congenital cases, a history of brachial plexus injury
resulting from a difficult delivery may help determine the etiology.
-----
Q 24
Answer
A
-----
Q 24
Ultrasonography
of a 20-week fetus reveals urinary bladder distension and bilateral hydronephrosis.
The volume of amniotic fluid is scant. The mother asks your advice regarding
vesicoamniotic shunting as an intrauterine intervention.
Of
the following, the MOST useful indicator of a favorable outcome following this
procedure is:
A. amniotic
fluid volume
B. bladder
volume
C. female
gender
D. fetal
urine electrolyte levels
E. renal pelvis diameterAnswer
A
Amniotic
fluid volume is a good indicator of fetal renal function and of the potential
success of vesicoamniotic shunting. Failure of urine to fill the amniotic space
leads to progressive oligohydramnios, which results in poor pulmonary growth.
The primary cause of death in prenatally diagnosed obstructive uropathy is
pulmonary hypoplasia. The degree of renal dysplasia and pulmonary hypoplasia
depends on the gestational age at onset and the duration of obstruction.
Intrauterine relief of obstruction and restoration of amniotic fluid volume
leads to normal lung growth and development, which is the basis for
vesicoamniotic shunting as a means of preventing pulmonary hypoplasia.
-------------------------
Q 25
-------------------------
Q 25
A
newborn who weighs 1,800 g and whose estimated gestational age is 36 weeks has
a central venous hematocrit of 75% (0.75). Maternal history is significant for
smoking during pregnancy. The infant is lethargic, jittery, tremulous, and
feeding poorly. Cardiopulmonary findings include tachypnea, tachycardia, and
cyanosis. A partial exchange transfusion is ordered.
Of
the following, the MOST appropriate diluent for partial exchange transfusion is:
A. albumin
B. fresh
frozen plasma
C. glucose
D. normal
saline
E. plasma
substitute
Answer :
Answer :
The
infant described in the vignette has polycythemia-hyperviscosity syndrome.
Polycythemia is defined as a central venous hematocrit in excess of 65% (0.65).
Hyperviscosity of blood at this high hematocrit compromises microcirculation in
various organs and makes the infant symptomatic. Hemodilution with a partial
exchange transfusion is the treatment of choice. A randomized trial has shown
that normal saline (crystalloid) is as effective as albumin (colloid) when used
as replacement fluid in partial exchange transfusion for the treatment of
polycythemia. Normal saline is easily available, relatively inexpensive, and
free of infection hazard.
Albumin
(5%) also can be used as a diluent for partial exchange transfusion. It is
believed to be retained in the intravascular space longer than a crystalloid
solution because of its high oncotic pressure, thereby offering the theoretical
advantage of a greater and more sustained hemodilution. However, this advantage
is offset by the potential risk of protein leakage into the extravascular
compartment, resulting in interstitial and pulmonary edema.
Fresh
frozen plasma has a similar theoretical advantage to albumin with regard to
efficient hemodilution, but it contains fibrinogen, which increases the
viscosity of blood. Accordingly, fresh frozen plasma is relatively less
effective in reducing high viscosity. Moreover, as a biologic product, it has
the potential risk of infection.
The
use of glucose as a diluent for partial exchange transfusion is discouraged.
The large bolus of glucose infusion that accompanies a partial exchange
transfusion may cause hyperglycemia. The high osmolality (approximately 500
mOsm/L) of a 10% glucose solution also carries the risk of fluid shifts induced
by a high osmotic load.
Plasma
substitute, which can be used as a diluent for partial exchange transfusion,
has similar theoretical advantages and potential risks as albumin and fresh
frozen plasma, but it offers no advantage over normal saline and is more
expensive.
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