PEDS

Question 1

The oxyhemoglobin dissociation curve of the newborn is shifted to the left or the right? Why?

Answer 1

Left. Fetal Hgb does not bind with 2,3 DPG. Thus, the newborn’s oxyhe- moglobin dissociation curve will be shifted to the left. This gives the fetus the advantage ofloading more oxygen at low fetal oxygen partial pres- sures (fetal arterial PCh of20-30 mmHg). [Ped. Anesthesia, George Greg- ory, M.D., Vol!, p52j

Question 2

What happens to the oxyhemoglobin disso- ciation curve during the first few months of life1 Why?

Answer 2

The oxyhemoglobin dissociation curve shifts right. As fetal Hgb is re- placed by adult Hgb (at 3-4 months of age, infants have increased levels of2,3 DPG as compared to adults), the infants l\0 increases (the curve shifts right) to approximate that of the adult, enhancing 0 2 delivery. [Gregory, Ped. Anesthesia, Vol!, p52]

Question 3

An infant is considered premature if born before what gestational age and has what weight? In what five ways is the premature infant different from the full-term neonate?

Answer 3

Prematurity is defined as less than 38 weeks gestation and less than 2500 gm at birth. As compared to the term infant, the premature infant is less able to: (1) suck, (2) maintain body temperature, (3) swallow, (4) eat, and (5) sustain ventilation. [Gregory, Ped. Anes., pp30-31]

Question 4

At what conceptual age is surfactant devel- oped?

Answer 4

Surfactant appears initially between 23 and 24 weeks gestational age and increases in concentration during the last 10 weeks of gestational life. [Miller, Anesthesia, 1994, p2451]

Question 5

What pressure is needed to open airways at birth?

Answer 5

Inspiratory pressures more negative than 25-40 mm Hg are required to overcome the surface tension when opening the alveoli for the first time. [Guyton, TMP, 1996, pp1049-1050; Barash, Clinical Anesthesia, 1997, pl082]

Question 6

Identify the two limitations of kidney func- tion in the newborn. What is the significance of these limitations?

Answer 6

GFR at birth is 15-30% of the normal adult on a weight basis, and the ability to concentrate the urine is diminished. Hence, infants do not toler- ate large volumes of water and salts because oflow GD\ and decreased tubular concentrating ability. [Davison, Eckhardt, and Perese, Mass Gen- eral, 1993, p387]

Question 7

When do liver enzymes become completely functional in the neonate?

Answer 7

During the first week oflife the liver functions poorly and is incapable of conjugating significant quantities of bilirubin with glucuronic acid. Re- duced quantities of blood clotting factors are also synthesized. The cyto- chrome P450 enzyme system isfully functional at one month ofage. Sum- mary: Liver metabolism is decreased in the neonate until one month of age.[Guyton, TMP, 1996, ppl052-1053; Morgan and Mikhail, Clinical Anesthesiology, 1996, p730]

Question 8

Where does the spinal cord end in the neo- nate?

Answer 8

The spinal cord of the newborn ends at the lower border of L3. [Ellis & feldman, Anatomyfor Anaesthetists. 8e. 2004 pp126]

Question 9

What are the angles of the left and right bronchi in a child less than three years of age?

Answer 9

Left, 55 degrees. Right, 25 to 70 degrees. [Smith, Anes. for Infants and Children, p12, Adriani and Griggs]

Question 10

Why is subglottic stenosis potentially more severe in the pediatric patient than in the adult?

Answer 10

The pediatric airway has a relatively small cross-sectional area in a nor- mal pediatric patient. With the presence of a subglottic stenosis, which may be congenital or acquired, even a small amount of swelling can rapid- ly occlude the opening. [Rasch and Webster, Clinical Manual of Ped. Anes., 1994, p19; Steward, Manual ofPed. Anes., 1995, p246; Authors]

Question 11

What factors contribute to the decreased functional residual capacity (FRC) in the neonate and infant during general anesthe- sia?

Answer 11

The chest wall in infants is less rigid (more compliant) because ribs are cartilaginous and not bony. In addition, the boxlike configuration of an infant’s thorax permits less elastic recoil than the dorsoventrally flattened thoracic cage of the adult does. Additionally, an infant is more vulnerable to muscle fatigue, which may further decrease the stability of the chest wall. As a result of all these factors, an infant’s chest wall is extremely compliant. The net effect of the compliant chest wall and the poorly com- pliant lungs is a reduced functional residual capacity (FRC). [Miller, Anesthesia. 6e. 2005 pp2842; Davis & Motoyama, Smith’s Anes. for In- fants and Children. 7e. 2006 pp34; Cote, PA1C. 3e. 2001 pp13]

Question 12

In newborns, the closing capacity is higher than FRC. What does this mean?

Answer 12

Some airways close during the expiratory phase of normal tidal breathing. [Barash, Clinical Anesthesia, 1997, pp1095-1097]

Question 13

How is the in children calculat- ed? What is the dead-space of a 30 kg child?

Answer 13

Dead-space is 2.0-2.5 mL/kg. Multiply patient weight by 2.0 or 2.5 to get dead-space. The dead-space of a 30 kg child is 30 kg x 2 mL!kg = 60 mL. [Davison, Eckhardt, and Perese, Mass General, 1993, p568; Barash Hand- book, Clinical Anesthesia, 1997, p407; Barash, Clinical Anesthesia, 1997, p1097]

Question 14

What is the tidal volume of a neonate in mL/kg?

Answer 14

A neonate should have a ventilator setting for tidal volume of7 mL!kg (6-8 mL/kg is the normal range). This is the same as the adult range. [Barash, Clinical Anesthesia, 1997, p1097]

Question 15

What is the minute volume per kg for the neonate?

Answer 15

Tidal volume in the neonate is 7 mL/kg and respiratory rate is 30-50 per minute. Ventilation “” tidal volume x respiratory rate. An estimate of minute ventilation in the neonate is: minute ventilation::::: 7 mL!kg x 30- 50 per minute= 210-300 mL!kg/min. 250 mL!kg!min is a reasonable nwnber to remember. Minute ventilation is 250 mL!kg. [Barash, Clinical Anesthesia, 1997, p1097; Authors]

Question 16

Calculate the minute volume of a newborn who weighs 3 kg and has a respiratmy rate of 40 breaths per minute?

Answer 16

Minute volume::::: respiratory rate (breaths per minute) x tidal volume. Tidal volume is 7 rnL!kg (tidal volume is the same in the adult and the infant). If respiratory rate is 40 and the newborn weighs 3 kg, minute ventilation is 40 x (3 kg) x (7 mL!kg) = 840 mL/min. [Clinical Anesthesia, 2e, 1992, Barash, p1314]

Question 17

How does chest wall compliance and pul- monary (lung) compliance differ in the in the neonate compared with the young, healthy adult’

Answer 17

In the neonate, chest wall compliance is increased and pulmonary coiTt- pliance is decreased. This means the chest wall is easier to distend (it is less rigid) but the lung is more difficult to distend (it is more rigid). [Bell and Kain, Peel. Anes. Handbook, 1997, p113]

Question 18

What is the length of the infant trachea from the cords to carina?

Answer 18

The length of the trachea (vocal cords to carina) in infants and neonates and children up to one year of age varies from 5-9 em. [Cote, PAIC. 3e. 2001 pp92]

Question 19

What is the distance from the teeth (alveolar ridge) to midtrachea in the newborn? In the infant who is six month to one-year-old? In the two-year-old, three-year-old, and four- year-old?

Answer 19

Newborn::::: 10 cm;6 mo to 1yr = ll cm; 2yr= 12 cm; 3yr::: 13-14 cm; 4 yr = 15 cm; 5 yr = 15-16 cm. [Cote, PAlC. 3e. 2001 pp93t]

Question 20

lis the infant larynx located higher, at the same, or at a lower level in the neck com- pared to the adult larynx? Identify the level of the infant larynx.

Answer 20

The infant larynx is located higher in the neck, at the level of C3-4 than in the adults, where the larynx is located at the level of C4–5. Author’s com- ment: I find these text statements somewhat misleading-as you know, the cricoid cartilage-certainly part of the larynx-lies at C6, and many texts (Miller, for example) state that the adult larynx ranges from C3-C6. Perhaps the more accurate statement is: the thyroid cartilage is located at C3–4 in infants compared to C4-5 in adults. [Miller & Stoelting, Basics. 5e. 2007 pp233; Cote, PAIC. 3e. 2001 pp81; Authors]

Question 21

How does the longue differ in the child compared with the adult?

Answer 21

A child’s tongue is relatively larger in proportion to the rest of the oral
cavity, compared to the adult tongue. [Cote, PAlC. 3e. 2001 pp81 I

Question 22

Why are infants more prone to airway ob- struction?

Answer 22

Infants have a proportionately larger tongue than adults. [Gregory, Ped.
Anes., 2002, p223]

Question 23

What part of a child’s airway has the small- est diameter?

Answer 23

The cricoid cartilage is the narrowest part. [Davison, Eckhardt, and Perese, Mass General, 1993, p434; Morgan and Mikhail, Clinical Anesthe- siology,1996,p730;Miller,AHesthesio, 1994,p2l01]

Question 24

What is the blood volume (mL!kg) of the preterm neonate, term neonate, infant, child, and adult? What is the estimated blood volume of a 3.5 kg neonate?

Answer 24

Pre term neonate) 95-100 mL!kg; term neonate, 85-90 mL/kg; infant, 80 mL!kg; child, 75 mL!kg; adult, 65-75 mL!kg. The estimated blood volume of a 3.5 kg term neonate is: 85-90 mL!kgx 3.5 kg= 297.5-315 mL. [Da- vison, Eckhardt, and Perese, Mass General, 1993, p387; Morgan and Mikhail, Clinical Anesthesia, 1996, p7281

Question 25

What is the hemoglobin (Hgb) concentra- tion at 2 weeks of 2-3 months of age? 2 years of age?

Answer 25

At 2 weeks, Hgb is !3-19 gllOO mL blood; at 2-3months, Hgb is less than !O-Il g/100 mL blood; at 2 years, Hgb is less than 12.5 gllOO mL blood. [Bell and Kain, Ped. Anes. Handbook, 1997, pp16, 2811

Question 26

Describe the physiological anemia of the neonate and pediatric patient.

Answer 26

Normal hemoglobin levels in the full-term newborn infant range between 14-20 g/dL. The hemoglobin concentration progressively “bottoms out” during the 9th to 12th week reaching a minimum of 10-ll g/dL, with a hematocrit of 33%. Afler the third month ( 12 weeks) the hemoglobin levels stabilize at 11.5-12.0 gldL until about 2 years of age. After 2 years of age, the hemoglobin levels gradual increase to reach adult levels of 14.0- 15.5 gldL by puberty. [Cote, PA/C, 2001, ppl9-20; Gregory, Ped. Anes., 2002, p124]

Question 27

Compare the physiological anemia in the preterm neonate to the full-term neonate.

Answer 27

In preterm infants, the decrease in hemoglobin levels is greater and earli- er, reaching the minimum hemoglobin concentration of8 g/dL by 4-8 weeks (hemoglobin “bottoms out” earlier and lower). At about l year old, the preterm and full-term infants hemoglobin levels are comparable and pre term infants following the same progression, reaching normal adult levels at puberty. [Cote, PAIC, 200l, pp19-20; Gregory, Ped. Anes., 2002, p124]

Question 28

Below what hemoglobin concentration is anemia sufficient to jeopardize oxygen carrying capacity (and hence cause you to cancel elective surgery) in the neonate? Infant older than three months?

Answer 28

Less than I3 g/dL in the newborn and less than 10 g/dL in the pediatric patient older than three months.(Steward, Manual ofPed. Anes., 1995, p3IS; Stoelting and Miller, Basics, 1994, p381 I

Question 29

A three-month-old infant, who is scheduled for surgery, has a hemoglobin of 10.5 mg/dL. What action should be taken?

Answer 29

None; this hemoglobin level is normal for this age. At three months of age, hemoglobin concentration normally decreases to this level. “It is rare for infants to develop any clinically significant symptoms from physiolog- ic anemia of the newborn.” [Bell and Kain, Ped. Anes. Handbook, 1997, p282l

Question 30

During the preoperative evaluation of a 6- month-old surgical candidate, you note physiologic anemia. What is a likely cause for the physiologic anemia?

Answer 30

he infant with physiologic anemia at 6 months of age is most likely a formerly premature infant (expremie). “Even at several months of age,
expremies remain anemic because of poor nutrition and delayed hemato- poiesis that is induced by earlier transfusions.” Reminder: the nadir (low point) of physiologic anemia typically occurs at 2-3 months for full-term infants. [Gregory, Ped. Anes., 4e, 2002, p373; Cote, PAIC, 3”1 ed., 2001, p20; Yemen, Ped. Anes. Handbook, 2002, p139]

Question 31

How are maintenance fluid requirements calculated for the pediatric patient?

Answer 31

4 mL!kg/hr. for first 10 kg; 2 mL!kg/hr. for second 10 kg; 1 mL!kg/hr. for each additional kg. [Morgan and Mikhail, Clinical Anesthesiology, 1996, p728]

Question 32

For a 3-week-old, 4 kg newborn undergoing prolonged surgery, maintenance fluids should be delivered at how many mL!hr.?

Answer 32

Maintenance fluid delivery rate for a 4 kg newborn is: 4 mL/kg/hr. x 4 kg = 16 mL!hr. [Morgan and Mikhail, Clinical Anesthesiology, 1996, p728]

Question 33

What is the fluid deficit of a normal66lb child NPO for 5 hours? Hint: first calculate the weight of the child in kg.

Answer 33

The fluid deficit is 350 mL. There are 2.2lb per kg. 66lb divided by 2.2 Jb/kg = 30 kg. Maintenance fluid for 30 kg child = (4 mL!kg/hr. x 10 kg) + (2mL/kg/hr. x 10 kg)+ (1 mL!kg/hour x IO kg)= 40 mi./hr.+ 20 mL!hr. + 10 mL!hr. = 70 mL!hr. 70 mi./hr. x 5 hrs. = 350 mL deficit. [Rasch and Webster, Clin. Manual ofPed. Anes., 1994, pl49]

Question 34

Pediatric fluid replacement for blood loss is best determined by which method of moni- toring?

Answer 34

Hematocrit. Blood loss is typically replaced with crystalloid (3 mL of lactated Ringer’s per mL of blood loss) or colloid (1 mL of 5% albumin per mL of blood loss) until hematocrit falls to a pre-determined level. [Mor- gan and Mikhail, Clinical Anesthesiology, 1996, p728; Pediatric Anes., pp475-476]

Question 35

Why is the cardiac output in infants de- pendent on heart rate and not stroke vol- ume?

Answer 35

Infants cannot alter stroke volume, so the only way to alter cardiac output is to change heart rate. Stroke volume cannot be altered because of the low contractile mass per gram of cardiac tissue, which results in limited ability to increase myocardial contractility, and also because left ventricu- lar compliance is reduced which makes ventricular fil!ing difficult. [Ba- rash, Clinicnl Anesthesia, 1997, p1097]

Question 36

What is the normal heart rate of the term infant?

Answer 36

Heart rate of the term infant is reported to be 100-180 beats per minute {Mass General). Bell and Kain indicate that the normal heart rate of the neonate is greater than 120 beats per minute. 120-180 beats per minute might be considered an appropriate range for the term infant. [Davison, Eckhardt, and Perese, Clinical Procedures of the Massachusetts General Hospital, 1993, p.438; Bell and Kain, Ped. Anes. Handbook, !997, p420; Authors]

Question 37

List two ways the physiology ofthe cardio- vascular system of the neonate differs from that of the adult.

Answer 37

In the neonate: (1) cardiac output is heart-rate-dependent, and (2) left ventricular compliance is decreased. [Morgan and Mikhail, Clinical Anes- thesiology, 1996, p726]

Question 38

At what age is basal metabolic rate normally the highest?

Answer 38

Basal metabolic rate (BMR) peaks somewhere between 6-12 months old. In a full-term infant, BMR rises progressively during the first 10 days of life. After the first few weeks of life, BMR decreases nearly linearly throughout life (Nagelhout & Zag!aniczny). However, if you look at calor-ic requirements, infants under 1year old require about 100 cal!kg/day, whereas older infants require 75 cal/kg/day, and adults require 35 cal!kg/day. [Nagelhout and Zaglaniczny, NA, 2001, p397; Gregory, Ped. Anes., 2002, p87]

Question 39

Give four reasons why it is so difficult to keep newborns warm?

Answer 39

(l) Newborns readily lose heat because of their greater surface area to body weight ratio. (2) They cannot compensate by shivering. (3) They have limited subQ fat for insulation. (4) They have limited stores of brown fat and unstable thermoregulatory systems. [Davison, Eckhardt, and Perese, Mass General, 1993, pp387,512]

Question 40

By what route do infants lose most of their body heat?

Answer 40

Most heat loss is lost by radiation. [Davison, Eckhardt, and Perese, Mass General, 1993, p389; Barash Handbook, Clinical Anesthesia, 1997, p330; Stoelting, PPAP, 1987, p638]

Question 41

Newborns produce heal primarily by what mechanism?

Answer 41

Newborns produce heat by non-shivering thermogenesis by metabolism of brown fat. [Morgan and Mikhail, Clinical Anesthesiology, 1996, p727; Steward, Manual ofPed. Alles., 1995, p37]

Question 42

What is the significance of brown fat? Where is brown fat located?

Answer 42

Infants respond to cold stress by increasing norepinephrine production, which enhances metabolism of brown fat and increases body heat, i.e., chemical thermogenesis. Brown fat is located in the interscapular space and around large blood vessels, around the neck, behind the sternum, and around the kidneys and adrenals. [Steward, Manual ofPed. Anes. 4e. 1995 pp37]

Question 43

What controls non-shivering thermogenesis in infants?

Answer 43

The autonomic nervous system activates non-shivering thermogenesis in infants. [Steward, Manual ofPed. Anes., 1995, p37]

Question 44

INon-shivering (cellular) thermogenesis is a crucial heat -generating mechanism in the neonate and infant, as you know. At approx- imately what age does non-shivering ther- mogenesis cease to be clinically significant?

Answer 44

Clinically and physiologically significant non-shivering thermogenesis persists up to the age of 2 years. Non-shivering thermogenesis may con- tinue into adulthood, but generally is not a relevant and significant source of heat generation in the adult. [Davis & Motoyama, Smith’s Anes.Jor Infants and Children. ?e. 2006 pp162; Gregory, Pediatric Anes. 4e. 2002 pp67]

Question 45

What is the best way to maintain an infant’s body heat? What is the best way to warm an infant in the operating room?

Answer 45

The best way to maintain an infant’s body heat is to maintain high ambi- ent temperature. Increasing operating room temperature is the best way to warm an infant. [Cote, PAIC. 3e. 2001 pp628]

Question 46

Premature infants may require what ambi- ent temperature to maintain a normother- mic state?

Answer 46

26’C. [Cote, PAlC. 3e. 2001 pp628]

Question 47

At what rate do infants consume oxygen? How does this compare with the adult?

Answer 47

Resting 0 2 consumption in healt-hy infants is 7 mL!kg/min (twice that of the adult). [Davison, Eckhardt, and Pcrese, Mass General, 1993, p387]

Question 48

To what do preductal or postductal coarcta- tion of the aorta refer?

Answer 48

Coarctation of the aorta refers to a discrete narrowing of the aorta imme- diately distal to the origin of the left subclavian artery. A preductal coarc- tation refers to a coarctation in a neonate or infant in which the narrow- ing occurs proximal to the opening of the ductus arteriosus. Postductal coarctations supposedly present in adulthood long after closure of the ductus arteriosus. [Rasch and Webster, Clin. Manual ofPed. Anes., p435; Morgan and Mikhail, Clinical Anesthesiology, 1996, p402]

Question 49

Should upper extremity blood pressure be monitored in the neonate with preductal coarctation of the aorta on the right or the left side?

Answer 49

Monitoring of blood pressure is best achieved in a patient with a preduc- tal coarctation by placing a catheter in the right radial artety. [Stoelting, Co-Existing, 1993, p52; Bell, Kain, and Hughes, Ped. Anes. Handbook, 1997, pp158-159]

Question 50

Blood shunts through what two structures in the neonate with persistent fetal circulation?

Answer 50

Blood shunts through the ductus arteriosus and the foramen ovale. [Mor- gan and Mikhail, Clinical Anesthesiology, 1996, p702]

Question 51

What causes the foramen ovale to close in the newborn?

Answer 51

The closure of the foramen ovale is due to the decrease in pulmonary vascular resistance and increased pulmonary flow that occurs as the infant takes his/her first breaths and the alveoli expand. The decrease in pulmo- nary vascular resistance is accompanied by constriction of the ductus arteriosus secondary to oxygenation. This results in an increase in pul- monary blood flow and an increase in left atrial pressure. The increased ptessureintheleftatriumshutstheflap, locatedontheleftsideofthefo- ramen ova/e. [Barash, Clinical Anesthesia, 1997, pl09I; Guyton, TMP, 1996, pl05l]

Question 52

Name the physiologic factor most responsi- ble for closure of the ductus arteriosus after birth.

Answer 52

Nonnal closure of the ductus arteriosus occurs in response to increased arterial oxygen tension (PnOJJ, as well as to reduction in circulating pros- taglandins that follow separation of the placenta. (Realize that a number ofother substances such as eicosanoids and factors such as PaC02 and pH have been implicated, but that increased oxygen tension seems to be the major factor precipitating ductus arteriosus closure.) [Cot, PAIC, yd ed. 2001, p356; Gregory, Ped. Anes., 4th eel. 2002, p424]

Question 53

What is a patent ductus arteriosus? When does the ductus arteriosus normally close?

Answer 53

Patent ductus arteriosus is the abnormal persistence in the newborn of blood flow through the ductus arteriosus, an opening between the pulmo- nary artery and aorta. Normally, the ductus closes within a few hours to a few days after birth due to changes in the pressures of the pulmonary vasculature. [Guyton, TMP, 1996, p1051]

Question 54

Is the shunt of a patent ductus arteriosus right-to-left or left-to-right?

Answer 54

The shunt is left-to-right. [Stoelting, Co-Existing, 1993, p40]

Question 55

With a patent ductus arteriosus, what cardi- ovascular changes occur?

Answer 55

A patent ductus arteriosus allows blood to flow from the aorta into the pulmonary artery. The additional blood is reoxygenated in the lungs and returned to the left atrium and left ventricle and this causes increased workload on the left side of the heart and left ventricular hypertrophy, and increased pulmonary vascular congestion and resistance. Most pa- tients are asymptomatic. [Stoelting, Co-Existing, 1993, p41]

Question 56

hat hemodynamic alteration may wors- en (increase flow through) a left-to-right intracardiac shunt?

Answer 56

An increase in systemic vascular resistance (SVR) may increase left-to- right intracardiac shunt flow, such as occurs in atrial septal defect. Avoid interventions that may increase SVR in the patient with an ASD. [Mor- gan, Mikhail, and Murray, Clinical Anesthesiology, 4e, 2006, p481]

Question 57

What is the probable problem if the pediat- ric patient has a systolic and diastolic murmur?

Answer 57

Patent ductus arteriosus. A continuous systolic and diastolic murmur is often the only manifestation of patent ductus arteriosus. [Stoelting and Miller, 1994, p260; Guyton, TMP, 1996, pp276-277]

Question 58

Where are pulse oximeters placed on the neonate to monitor preductal and postductal oxygenation?

Answer 58

Preductal oxygenation should be measured with a pulse oximeter on the right hand orfinger. Postductal oxygenation should be measured with a pulse oximeter on the left foot or a left toe. [Cote, PAIC, 2001, p395; Duke, Secrets, 2000, p302]

Question 59

What is the purpose of a preductal pulse oximeter in the neonatal patient undergoing cardiac surgery?

Answer 59

Measurements of arterial oxygen saturation taken at a preductallocation (right hand/finger) are a better index of neonatal cerebral oxygenation than are those taken at a postductallocation (left foot/toes). The right-to- left shunt at the ductus arteriosus persists for some time after birth and this shunt may affect oxygen saturation readings, thus preductal place- ment of the pulse oximeter is preferred. A postductal pulse oximeter may be used in addition to the preductal pulse oximeter to quantitate the severity of the right-to-left shunt. [Birnbach, Textbook Ob. Anes., 2000, p7l4; Norris, Ob. Anes., 1999, pp680-68l; Duke, Secrets, 2000, pp301- 302]

Question 60

Where should arterial blood pressure be measured in a patient undergoing repair of a patent ductus arteriosus (PDA)?

Answer 60

The catheter for measuring blood pressure should be placed in a periph- eral artery such as the femoral. [Stoelting, Co-Existing, 1993, p 42; Au- thors]

Question 61

Identify the best site to obtain arterial blood gases from in the neonate.

Answer 61

Arterial blood gases in the neonate are best obtained from the radial arte1y.ln additional to ease of access, this site will reflect preductal oxy- gen saturation, which better reflects cerebral oxygenation. [Gregory, Peel. Anes., 2002, p257]

Question 62

Which two sites are to be avoided when obtaining arterial blood gases in the neo- nate? Why?

Answer 62

Arterial blood gases samples are usually not obtained from the brachial or femoral arteries. Obtaining blood samples from a brachial artery has been associated with nerve damage. Obtaining blood samples from a femoral artery has been associated with femoral head necrosis and limb shorten- ing. The artery of first choice for obtaining arterial blood gas samples is the radial artery. [Gregory, Ped. Anes., 2002, p257]

Question 63

Identify 4 factors that may cause a neonate/infant to return to fetal circulation.

Answer 63

Persistent fetal circulation (or a return to fetal circulation) is common in pre term infants and infants with metabolic derangements (asphyxia, sepsis, meconium aspiration, congenital diaphragmatic hernia). Hypox- emia, acidosis, pneumonia, and hypothermia are 4 primary precipitating factors in persistent fetal circulation. The pathologic mechanism common to all4 factors is increased pulmonary vascular resistance (PVR) and to-left shunting. [Nagelhout and Zaglaniczny, NA, 2”’ eel. 2001, pll35; Gregory, Ped. Anes., 4th ed. 2002, pp424-425]

Question 64

What is the usual cause of persistent pulmo- nary hypertension (persistent fetal circula- tion)? Is the shunt associated with persistent pulmonary hypertension left-to-right or right-to-left?

Answer 64

Hypoxia, acidosis, and other factors cause a high pulmonary vascular resistance; the resulting pulmonary hypertension causes blood to shunt from right-to-left. [Morgan and Mikhail, Clinical Anesthesiology, 1996, p702; Barash, Clinical Anesthesia, 1997, p1092)

Question 65

List three congenital defects in which there isaright-to-leftshunt.

Answer 65

(1) Tetralogy ofFallot; (2) pulmonary atresia with ventricular septal defect;and(3)patentforamenovale.[Miller,Anesthesia, 1994,pp1815- 1816)

Question 66

What is the anesthetic concern for the pedi- atric patient undergoing repair of a ventricu- lar septal defect (VSD) without significant pulmonatyhypertension?

Answer 66

Ventricular septal defect (VSD) without significant pulmonary hyperten- sion should be managed to avoid arrhythmias, RV dysfunction, pulmo- nary vascular obstructive disease, and paradoxical embolus. [Kaplan, CardiacAnesthesia, 1999,pp809-810)

Question 67

What is the anesthetic concern for the pedi- atric patient undergoing repair of a ventricu- lar septal defect (VSD) with significant pulmonary hypertension?

Answer 67

The patient with an unrepaired VSD and irreversible pulmonary hyper- tension often displays right-to-left shunting through the VSD (Eisen- menger’s physiology). Manipulations that may increase PVR can cause rapid deterioration and include hypoxia, hypercarbia, acidosis, hypo- thermia, atelectasis, sympathetic stimulation and polycythemia. Early closure ofVSD before I year old results in normal ventricular function and ejection fraction. [Kaplan, Cardiac Anesthesia, 1999, pp809-810)

Question 68

A right-to-left intracardiac shunt is pre- sent in the patient with a ventricular septal defect (VSD with Eisenmenger’s syndrome). What hemodynamic alterations may worsen (increase shunt Oow) the right-to-left shunt ofVSD with Eisenmenger’s syndrome?

Answer 68

An abrupt increase in pulmonary vascular resistance (PVR) or a decrease in systemic vascular resistance (SVR) is poorly tolerated in the patient with ventricular septal defect {VSD). Avoid interventions that may increase PVR or decrease SVR in the patient with a right-to-left intracardiac shunt. [Nagelhout & Zaglaniczny, NA, 3’’ ed., 2004, p432)

Question 69

List three conditions that increase right-to- left shunt (tetralogy ofFallot).

Answer 69

Acidosis, hypercarbia, and hypotension {decreased SVR) increase right-to- left shunt. In general, increases in pulmonary vascular resistance or de- creases in systemic vascular resistance (caused by acidosis or hypercarbia) increase right-to-left shunt. Volatile anesthetics and histamine release decrease SVR. [Stoelting and Mil!er, Basics, 2000, p258; Hurford, Bailin, Davison, Haspel, Rosow, Mass Gen Handbook, 1998, p411; Morgan and Mikhail, Clinical Anesthesia, 1996, p370)

Question 70

List four congenital heart defects involved with tetralogy of Fallot (cyanotic heart dis- ease).

Answer 70

(1) Ventricular septal defect, {2) right ventricular outflow tract obstruc- tion (pulmonary stenosis), (3) right ventricular hypertrophy, and
(4) dextroposition (to the right) of the aorta with overriding of the ven- tricular septal defect. [Morgan, Clinical Anesthesiology, 1996, p370)

Question 71

Does blood shunt right-to-left or left-to- right through the ventricular septal defect in tetralogy of Fallot (cyanotic heart disease)?

Answer 71

Blood shunts right-to-left, permitting unoxygenated blood to mix with oxygenated blood, resulting in cyanosis. [Morgan and Mikhail, Clinical Anesthesiology, !996, p370)

Question 72

An infant has Tetralogy of Fallot (cyanotic heart disease). Which of the following arte- rial blood gas parameters will not typically be changed: 1’,02, pH, P,CO,?

Answer 72

pH and P.C02 are likely to be in the normal range. P,02 is usually marked- lydecreased (

Question 73

What are the goals of anesthetic

management for the patient who has tetralogy of Fallot (cyanotic heart disease)?

Answer 73

The goals of anesthetic management should be to maintain intravascular volume and systemic vascular resistance (SVR). Increases in pulmonary vascular resistance also should be avoided. [Morgan and Mildlail, Clinical Anesthesiology, 1996, pp370-371]

Question 74

What change in systemic vascular resistance and in pulmonary vascular resistance in- crease shunt in the patient with tetralogy of Fallot? What drugs increase shunt in the patient with tetralogy of Fallot by altering systemic vascular resistance or pulmonary vascular resistance?

Answer 74

Shunt increases when systemic vascular resistance decreases or pulmo- nary vascular resistance increases. Volatile anesthetics, drugs that cause histamine release, ganglionic blockers, alpha blockers, or other vasodila- tors (nitroprusside) decrease systemic vascular resistance, increase right- to-left shunt, and worsen arterial hypoxemia. Increased pulmonary vascu- lar resistance increases shunt in a child with cyanotic heart disyase. N20 increases pulmonary vascular resistance, which is detrimental to children with right-to-left shunts. [Greg01y, Pediatric Anes., 2e, p857; Stoelting, Co-Existing, 1993, p44]

Question 75

What pharmacologic agent decreases a right to left shunt?

Answer 75

A decrease in the magnitude of a righHo-left shunt (tetralogy of Fallot is a right-to-left shunt) occurs if systemic vascular resistance (SVR) increas- es. Phenylephrine increases SVR and decreases a right-to-left shunt. [Stoelting and Miller, Basics, 2000, p258; Hurford, Bailin, Davison, Haspel, Rosow, Mass Gen Handbook, 1998, p411]

Question 76

During the case, oxygen saturation decreas- es, apparently because of increased shunt* ing. The patient has tetralogy ofFallot. What agents might be selected to decrease shunt and increase oxygen saturation?

Answer 76

Intravascular fluid volume must be maintained with IV fluid
administration since acute hypovolemia will tend to increase the magnitude of the righHo-left intracardiac shunt. A n alpha- agonist drug such as phe- nylephrine must be promptly available to treat an undesirable decrease in systemic blood pressure caused by a decrease in SVR. [Stoelting, Co- Existing, 1993, pp44-45]

Question 77

Will a intracardiac shunt theo- retically slow or accelerate inhalation induc- tion? Is the effect be clinically significant?

Answer 77

A right-to-left intracardiac shunt will theoretica!ly slow inhalation induc- tion, because less anesthetic is absorbed from the lung, and mixing will further dilute blood passing to the left, decreasing the arterial concentra- tion of the blood going to the brain, especially the less soluble agents. This effect is rarely problematic. [Fleisher, Anesthesia and Uncommon Disease, 5e, 2006 p91]

Question 78

Will a intracardiac shunt theo- retically slow or accelerate intravenous induction?

Answer 78

An intravenous induction will be theoretically accelerated with a
right to left intracardiac shunt. [Fleisher, Anesthesia and Uncommon Disease, 5e, 2006 p91]

Question 79

Will a intracardiac shunt theo- retically slow or accelerate inhalation indue· Lion? Why is this phenomenon rarely evi- dent clinically?

Answer 79

A inlracardiac shunt shou!d accelerate the speed of inhalation induction because the rate of transfer of anesthetic agent from the lungs to the blood is increased. However, this effect is rarely clinically evident because decreased delivery of anesthetic to the target tissues negates the increased uptake of agent with a left -to-right inlracardiac shunt. [Fleisher, Arwsthesia and Uncommon Disease, 5e, 2006 p9l; Barash, Clinical Anes- thesia, Se, 2006, pp1209-1210]

Question 80

Will a intracardiac shunt theo· retically slow or accelerate intravenous induction? Why is this phenomenon rarely evidentclinically?

Answer 80

Intravenous induction should be slowed by a lefHo-right shunt; however, unless cardiac output is very poor, the effect is clinically irrelevant. [Fleisher, Anesthesia and Uncommon Disease, Se, 2006 p91; Barash, ClinicalAnesthesia,Se, 2006,pp1209-1210]

Question 81

Where is the fistula usually located in a patient with a tracheal-esophageal fistula?

Answer 81

In 90% of tracheal-esophageal fistulas, the lower segment of the esopha- gus inserts just above the carina onto the posterior wall of the trachea. [Barash, Clinical Anesthesia, 1997, p1107; The Physiologic Basis ofSur- gery, 1993, p63; Yao and Artusio, Problem Oriented Patient Management, 1993]

Question 82

Where is the proper placement of the endo- tracheal tube in a patient with a tracheal- esophageal fistula? Describe the procedure for intubating the patient with a tracheal- esophageal fistula.

Answer 82

The tip of the endotracheal tube can be placed just distal to the tracheal- esophageal fistula (between the fistula and the carina). The endotracheal tube can be inserted until it enters one or the other mainstem bronchi. Look for unilateral expansion of the chest and unilateral breath sounds. The endotracheal tube is then slowly withdrawn until bilateral breath sounds are present. [Barash, Clinical Anesthesia, 1997, pll07; Morgan and Mikhail, Clinical Anesthesiology, 1996, p735]

Question 83

What is trachea malacia (also known as tracheobronchomalacia)? What patients are at risk for developing tracheomalacia?

Answer 83

Malacia” means abnormal softening of tissue, therefore tracheomalacia would be softening of the tracheal tissue, especially the cartilaginous rings. Tracheoma!acia is sometimes seen in neonates/infants, often in association with esophageal atresia (e.g., tracheoesophageal fistula, TEF) or with extrinsic compression by vascular anomalies or mediastinal mass- es. Tracheomalacia may also be associated with hyperthyroidism. [Bissonnette, Ped. Anes., 2002, p1203; Barash, Clinical Anesthesia, 4th ed. 2001, p1188; Barash, Handbook, 4th ed. 2001, p596; Authors]

Question 84

What is the anesthetic concern for the pa- tient with tracheomalacia?

Answer 84

Airway obstruction, possibly requiring urgent intubation, is of great con- cern for the patient with tracheomalacia. Airway obstruction due to tra- cheomalacia may be intrathoracic or extrathoracic; flow-volume loops will differentiate between intra-and extrathoracic obstruction. [Bis- sonnette, Ped. Anes., 2002, p1203; Barash, Handbook, 4th eeL 2001, p596; Yao, POPM, Sthed. 2003, pp700-701]

Question 85

The key to successful anesthetic manage- ment of the neonate with a tracheal- esophageal fistula is correct positioning of the endotracheal tube. What is the im- portant consideration for intubating the infant with a tracheal-esophageal fistula? What intubation techniques are appropri- ate?

Answer 85

An important issue is to avoid positive pressure ventilation, which will distend the stomach, thereby increasing the risk for reflux and ventilatory compromise. There are two approaches to tracheal intubation after indue- lion of anesthesia. One is to use an inhalation induction, followed by topical application of lidocaine and intubation while the infant is breath- ing spontaneously. The other technique is to use an IV or inhalation induction and intubate the trachea after muscle paralysis. This latter technique may lead to distention of the fistula and stomach after onset of positive pressure ventilation. [Barash, Clinical Anesthesia, 1997, 1107]

Question 86

Compare gastroschisis and omphalocele with regard to location, hernial sac, and associated congenital anomalies?

Answer 86

Gastroschisis: location is lateral to umbilicus; hernial sac is absent; associ- ated congenital anomalies are absent. Omphalocele: location is at the base of umbilicus; hernial sac is present; associated congenital anomalies are present and include trisomy 21 (Down’s syndrome), cardiac anomalies, diaphragmatic hernia, and bladder anornalies. [Morgan and Mikhail, Clinical Anesthesiology, 1996, pp736-737J

Question 87

Perioperative management of gastroschisis and omphalocele centers around what three preventative measures?

Answer 87

Perioperative management of gastroschisis and omphatocele is aimed at prevention of: (1) hypothermia, (2) dehydration, and (3) infection. [Barash, Clinical Anesthesia, 1997, p11051

Question 88

In which disorder, gastroschisis or

omphalocele, are hypothermia, dehydration, and infection most serious? Why?

Answer 88

These problems are more serious in gastroschisis because the hernial sac
is absent. [Morgan and Mikhail, Clinical Anesthesiology, 1996, p736]

Question 89

List three congenital anomalies associated with prune-belly syndrome.

Answer 89

Prune-belly syndrome is associated with (1) cryptorchidism (undescend- ed testicles), (2) club feet, and (3) genitourinary tract abnormalities. Tip: even though the syndrome is called prune-belly, there are no associated gastrointestinal anomalies, notwithstanding the underdevelopment of the abdominal musculature. [Morgan, Milduil, and Murray, Clinical Anesthe- siology, 3’’ ed., 2002, p866; Authors]

Question 90

Name four conditions in which the patient presents with a large tongue. What is the concernifthepatienthasalargetongue?

Answer 90

Down’s syndrome, Pierre Robin syndrome, acromegaly, and hypothyroidism. Patients with large tongues are prone to respiratory obstruction. [Miller,Anesthesia, 1994,pp1406-1407]

Question 91

Mandibular hypoplasia is associated with what three congenital diseases? Should these patients generally be intubated awake or asleep?

Answer 91

Patients with Pierre Robin syndrome, Treacher Collins syndrome, and Goldenhar syndrome have mandibular hypoplasia and may be difficult to intubate. These patients are more often intubated after induction of anes- thesia with a volatile anesthetic. While awake intubation can sometimes be accomplished, awake intubation of these patients may produce severe trauma to the upper airway and does not eliminate the risk of pulmonary aspiration. [Stoelting, Co-Existing, 1993, p605]

Question 92

What is Pierre Robin syndrome? What are the concerns and how should this patient be managed? What intubation technique should be used?

Answer 92

Pierre Robin syndrome is a combination of a cleft palate, micrognathia (small lower jaw with receding chin), glossoptosis (downward retraction or displacement of the tongue). Respiratory obstruction may occur (the tongue may cause total airway occlusion) and can lead to cor pulmonale; maintain airway by placing prone on a frame; may require tongue suture, intubation, or tracheotomy. [Steward, Manual ofPeel. Anes., 1995, p379]

Question 93

Describe the suggested tracheal intubation technique for a patient with Treacher- Collins syndrome.

Answer 93

Treacher-Collins syndrorne is the most common of the mandibulofacial dystoses, a group of syndromes that feature mandibular hypoplasia. In addition, up to 30% ofTreacher-Collins patients have an associated deft palate. An awake tracheal intubation (oral or nasal) with aid of a fiberop- tic laryngoscope after adequate topical anesthesia is recommended. Miller advocates: (1) topicalization with 1% lidocaine, {2) LMA insertion, fol- lowed by (3) fiberoptic intubation through theLMA. Also consider fiber- optic tracheal intubation after induction with a volatile agent. [Stoelting & Dierdorf, Handbook ofAnesthesia and Co-Existing Disease, 4e, 2002, p709; Miller, Anesthesia, 6e, 2005, pp2384-2388]

Question 94

Treacher-Collins syndrome is associated with cleft palate, as you know, indicating a difficult airway. What congenital heart disease is associated with Treacher-Collins syndrome?

Answer 94

Treacher-Collins syndrome is frequently accompanied by congenital heart disease, most prominently ventricular septal defect. Concept: ventricular septal defect is the most commonly occurring congenital heart disease, therefore VSD is frequently associated with many other congenital anom- alies. [Hines, Stoelting’s Co-existing. Se. 2008 pp6l3; Yao, Yao & Artusio’s POPM. 6e. 2008 ppl053]

Question 95

At what age is cleft palate usually repaired?

Answer 95

Cleft palate repair is usually undertaken when the infant is 12-18 months old, but sometimes younger. [Steward, Manual ofPed. Anes., 1995, p255]

Question 96

What is the concern with an infant who has a cleft palate?

Answer 96

In infants with a large cavernous defect of the palate, intubation of the trachea becomes difficult if the blade slips into the cleft and cannot be adequately manipulated. [Stoelting, Co-Existing, 1993, pp604-605]

Question 97

What intubating techniques would you use on a child with a cleft palate?

Answer 97

Insert a small piece of sponge or dental roll to fill the gap of the cleft and thus reduce the likelihood of the blade lodging in the gap. Tape the endo- tracheal tube to the lower lip in the midline. Use a preformed RAE tube to reduce the chance of tracheal tube occlusion by the palate retractor during palatoplasty. [Stoelting, Co-Existing, 1993, pp604-605; Steward, Manual ofPed. Anes., 1995, p255]

Question 98

What causes myelomeningocele? What is the difference between a meningocele and a meningomyelocele?

Answer 98

Myelomeningocele is caused from failure of the neural tube to close in the fetus during development. Failure of the caudal end to close results in spina bifida. A sac is present which contains meninges and neural ele- ments. A meningocele is a sac containing only the meninges. [Rasch and Webster, Clin. Manual ofPed. Anes., 1994, p498; Steward, Manual ofPed. Anes., 1995, pp201-202]

Question 99

List 7 anomalies often co-existent with myelomeningocele.

Answer 99

Myelomeningocele is often associated with: (I) club foot, (2) hydrocepha- lus (along with stenosis of the aqueduct ofSylvius and Arnold-Chiari malformation), (3) dislocation of hips, (4) exstrophy of bladder (possible incontinence), (5) prolapsed uterus, (6) Klippel-Peil syndrome, and (7) congenital cardiac defects. [Stoelting, Co-Existing, 3’” ed. 2002, p705]

Question 100

What are the concerns for anesthetizing the newborn with meningomyeloce!e?

Answer 100

The patient may not be able to lay supine for intubation due to possible sac disruption. The awake lateral decubitus position may be necessary. [Rasch, p498; Steward, Manual ofPed. A11es., 1995, pp20!-202; Stoelting, Co-Existing, 1993, p600]

Question 101

What is Arnold-Chiari malformation? What are four symptoms of Arnold-Chiari mal- formation?

Answer 101

Arnold-Chiari malformation is a malformation consisting of an elongated cerebellar vermis that herniates through the foramen magnum and also compresses the brain stem. Symptoms of Arnold-Chiari malformation are: (1) difficulty swallowing, (2) recurrent aspiration, (3) stridor, and possibly (4) apneic episodes. [Steward, Manual ofPed. Anes., 1995, p203]

Question 102

A seven-year-old patient with spina bifida comes to the operating room for a ventricu- lar-peritoneal shunt. What is the primary concern?

Answer 102

The major concern for this patient is the high probability of a latex aller- gy, which may trigger an anaphylactic episode in the operating room. While the incidence oflatex allergy among medical personnel is 6-7%, 18-34% of patients with spina bifida have a latex allergy. Most children who have had intraoperative anaphylaxis had spina bifida. [Motoyama and Davis, Smith’s AIC, !996, p; Stoelting, Co-Existing, 1993, p601]

Question 103

In addition to cleft palate and ventricu- loseptal defects, what other conditions are associated with Treacher-Collins syndrome? Is a macroglossia (large tongue) associated with Treacher-Collins syndrome?

Answer 103

Treacher-Collins syndrome is associated with cleft palate (30%), ventricu- loseptal defect (VSD), malar hypoplasia, colobomas (notching of the lower eyelids), macrostomia (large mouth), malocclusion, and a small oral cavity. Treacher-Co!lins syndrome is not associated with macro- glossia (large tongue) or mental retardation. [Hines, Stoeltiug’s Co- existing. Se. 2008 pp613; Yao, Yao & Artusio’s POP/vi. 6e. 2008 ppl053]

Question 104

What is the most frequent pediatric surgical emergency?

Answer 104

Foreign body aspiration into the airway or esophagus is the most frequent pediatric surgical emergency. [Roizen & Fleisher, Essence ofAnesthesia Practice, 2”’ ed. 2002, p144]

Question 105

Children with long-standing obstructive sleep apnea (caused by hypertrophied ton- sils, for example) show what anatomic changes in the heart?

Answer 105

In children with long-standing hypoxemia and hypercarbia, pulmonary artery hypertension and right ventricular hypertrophy develop. [Barash, Clinical Anesthesia, 1997, p929]

Question 106

Children of what ages get croup (laryngotra- cheobronchitis)?

Answer 106

Croup usually occurs in children aged 2 or less. [Cote, PAIC, 2e, pp251- 254, 1992]

Question 107

What are four signs and symptoms of croup?

Answer 107

The affected child demonstrates: (1) a low-grade fever, (2) a “croupy” cough with inspiratory stridor and chest retractions, (3) fever rarely above 39’ Celsius, and (4) cyanosis. [Cole et al., PAIC, 2”’ ed. 1992, pp251-254]

Question 108

List three (3) treatments for postintuba- tion laryngeal edema (postintubation “croup”).

Answer 108

Treatment ofpostintubation laryngeal edema (“croup”) is aimed at reduc- ing airway edema. Mild cases often improve with cool, humidified mist and oxygen therapy, ideally administered by a face tent. More severe cases require hourly administration of aerosolized racemic epinephrine, 0.05 mL!kg of2.25% epinephrine in 3.0 mL of saline. Intravenous dexame- thasone mg/kg) may prevent the edema, but the effect takes up to 4-6 hours to manifest. [Hines, Stoelting’s Co-existing. Se. 2008 pp616; Barash, Clin. Anes. 6th. 2009 pp1313; Hagberg, Benumofs Airway Man- agement. 2e. 2007 pp796; Morgan, et al., Clin. Anesth. 4e. 2006 pp939]

Question 109

What is the usual cause of croup (laryn- gotracheobronchitis )?

Answer 109

The cause is usually viral. [Cote et al., PAIC, 211d ed. 1992,

Question 110

What is the pathogenesis of post-intubation croup? Identify 6 risk factors for post- intubation croup.

Answer 110

Post-intubation croup is due to glottic or tracheal edema. Post-intubation croup is associated with: (l) early childhood (age 14 years), (2) repeated intubation attempts, (3) large endotracheal tube, (4) prolonged surgery, (5) head and neck procedures, and (6) excessive movement of the endo- tracheal tube. [Morgan el al., Clinical Anesthesiology, 3’’ ed. 2002, p863]

Question 111

What is the appropriate treatment for post- intubation croup.

Answer 111

Post-intubation croup is treated with inhalation of nebulized racemic epinephrine (0.25-0.50 mL of2.25% solution in 2.5 mL ofNS). Intrave- nous dexamethasone (0.25-0.50 mg/kg) may prevent edema. [Morgan et al., Clinical Anesthesiology, 3’” ed. 2002, p863j

Question 112

What is the etiology of epiglottitis?

Answer 112

Epiglottitis is due to life-threatening infection by Haemophilus irifluenza type ll bacteria. [Cote et al., PA/C, 2”’ ed. 1992, pp251-254j

Question 113

List nine signs and symptoms of epiglottitis

Answer 113

Signs and symptoms of epiglottitis include: (1) upper airway obstruction, (2) inspiratory stridor, (3) chest retractions (4) tachypnea, (5) cyanosis, (6) drooling, and (7) difficulty swallowing. The child also (8) insists on sitting and (9) is restless. [Cote et al., PAIC, 2”” ed. 1992, pp25l-254]

Question 114

Children of what ages get epiglottitis?

Answer 114

Affected children are usually I to 7 years old. Epiglottitis occurs with greater frequency in children less than 3 years of age. [Cote eta!., PAIC. 2”“ed.1992, pp25l-254)

Question 115

Where is the optimal hospital location for intubation of a patient with epiglottitis? Why?

Answer 115

Intubation should occur in the operating room. Total obstruction of the airway could occur at any moment. An attempt to visualize the epiglottis should not be undertaken until the child is in the operating room where intubation of the trachea and possible emergency tracheostomy should be performed. [Morgan and Mikhail, Clinical Anesthesiology, 1996, p736; Stoelting and Miller, Basics, 1994, p390)

Question 116

What induction agent and what endotrache- al tube size should be used in the patient with epiglottitis?

Answer 116

An inhalation induction is followed by intubation with an endotracheal tube 1/2 to 1size smaller than usual. [Morgan and Mikhail, Clinical Anes- thesiology, 1996, p736)

Question 117

How long might one expect the endotracheal tube to be left in place in the patient with epiglottitis? What is one signal suggesting it is time for extubation?

Answer 117

The endotracheal tube is left in place for 24-96 hours. At this time an air leak usually appears around the endotracheal tube (because swelling has gone down) signaling the possibility of extubation. [Cote, PAJC, 211(1 ed. 1992, p253)

Question 118

Where and when should the patient with epiglottitis be extubated?

Answer 118

Extubation of the trachea is performed in the operating room only after direct laryngoscopy has confirmed resolution of the swelling of the epi- glottis. [Stoelting and Miller, Basics, 1994, p390; Cote eta!., PAIC, 2”” eel. 1992, p253)

Question 119

How is general anesthesia induced in the child with acute epiglottitis?

Answer 119

Parents should be present until the airway is secure. The operating room should be quiet. Monitors should be applied as tolerated, especially the pulse oximeter. Initiate induclion with 100% Ot/halothane or 02/sevoOurane with the patient in a sitting position. Start an IV, give fluids and atropine and ora!!y intubate. Do not use muscle relaxants. Avoid touching the epiglottis with the laryngoscope blade. Go into the vallecula. If oral intubation fails, try with a bronchoscope. If that fails then a tracheostomy is performed. [Rasch, p246; Cote, Ryan, Todres and Goudsouzian, pp252-253]

Question 120

In what position would you induce the patient with epiglottitis?

Answer 120

A parent should hold the child on his/her lap, and after mask induction the d1ild is placed supine with head slightly up. [Cote, Ryan, Todres and Goudsouzian, p252]

Question 121

List four anesthesia considerations for the patient with congenital diaphragmatic her- nia?

Answer 121

(l) Use ketamine 0.5-1.0 mg/kg or fentanyll-3 meg/kg. (2) Avoid nitrous oxide. (3) Gently atlempt tore-expand the lungs under direct vision using pressures no greater than 30 em I-hO after repair. (4) Antici- pate the need for postoperative support of ventilation. [Barash Handbook, Clinical Anesthesia, !997, pp1!04-1!05)

Question 122

In the patient with diaphragmatic hernia, what lung is usually involved?

Answer 122

Herniation on the left side through the foramen ofBochdalek occurs in 80% of congenital diaphragmatic hernias. Hence, the left lung is involved. [Morgan eta!., Clinical Anesthesiology, 2002, pp734-735)

Question 123

What peak inspiratory pressure should be used with a patient who has a diaphragmatic hernia? Why?

Answer 123

Peak inspiratory pressure should be less than 30 em I·hO. Pneumothorax of the contralateral (usually right) lung can occur if peak inspiratory pressure is too high. [Morgan and Mikhail, Clinical Anesthesiology, 1996, pp734-735]

Question 124

Is the infant with a diaphragmatic hernia with bowels extending into the chest an emergency? List seven anesthetic considera- tions for managing an infant with a dia- phragmatic hernia with bowels extending into the chest.

Answer 124

This is an emergency. Anesthetic considerations for managing this patient include: (1) Place a nasogastric tube, (2) do not apply positive ventilation via mask, (3) intubate with controlled ventilation, (4) do not use N20,
(5) monitor PaC02 and Sa02, (6) use 100%02, (7) give muscle relaxants and opioid after the chest is opened. [Davison, Eckhardt, and Perese, Mass General, 1993, pp404-405]

Question 125

During the intraoperative period of a con- genital diaphragmatic hernia repair, the Sa02 suddenly falls to 65% and heart rate decreas- es to 50 beats/min. What is the likely cause and what should be done?

Answer 125

Any sudden deterioration in lung compliance, heart rate, oxygen satura- tion, or blood pressure suggests a tension pneumothorax on the contrala- teral side. Absent or diminished breath sounds confirm the diagnosis of pneumothorax, and a chest tube should be inserted immediately. [Yao, Yao & Artusio’s POPM, 5e, 2003, p112; Gregory, Ped. Anes., 4e, 2002, p437]

Question 126

What might be signaled by a sudden fall in lung compliance (reflected by an increased peak inspiratory pressure), blood pressure, or oxygenation during repair of a congenital diaphragmatic hernia?

Answer 126

A contralateral (usually right-sided) pneumothorax should be suspected. [Morgan and Mikhail, Clinical Anesthesiology, 1996, p735]

Question 127

What nerves are blocked for repair of an inguinal hernia?

Answer 127

The ilioirzguinal and iliohypogastric nerves are blocked for inguinal hernia repair. [Morgan and Mikhail, Clinical Anesthesiology, 1996, p271j

Question 128

What two electrolyte abnormalities will be seen with projectile vomiting?

Answer 128

(l) Hypokalemia and (2) hypochloremia. [Stoelting and Miller, Basics, 1993, pp 226, 392]

Question 129

What acid -base disturbance will be seen with significant loss of bile vomitus?

Answer 129

Significant loss ‘of bile vomitus will result in metabolic acidosis. [Katz, Anesthesia and Uncommon Diseases, pp430-43l]

Question 130

What acid-base and electrolyte abnormali-
ties develop in the patient with pyloric ste-
.1 !lOSIS.

Answer 130

As a result of persistent vomiting, the infant becomes alkalotic (metabolic alkalosis), hypochloremic, hypokalemic, and possibly hyponatremic. 71ze infant is dehydrated with a hypokalemic, hypochloremic metabolic alkalo- sis. [Stoelting, Co-Existing, 1993, p597; Miller, Anesthesia, 1994, p2118; Barash Handbook, Clinica Anesthesia, 1997, pp607-608j

Question 131

What serum sodium, potassium, and chlo- ride concentrations and what urine output are needed before surgery in the patient with pyloric stenosis?

Answer 131

Electrolytes need to be: sodium > 130 mEq/L, potassium> 3 mEq/L, chloride> 85 mEq/L and a urinary output ofat least 1-2mL/kglhr. [Mil- ler, Anesthesia, 1994, p21!8; Stoelting and Miller, Basics, 1994, p392; Davison, Eckhardt, and Perese, Mass General, 1993, p400J

Question 132

A neonate diagnosed with pyloric stenosis presents with aNa’ of 120, C! of 84, and a respiratory rate of 16. What is the appropri- ate course of action for this patient?

Answer 132

Pyloric stenosis is characterized by persistent vomiting which depletes sodium, potassium, chloride, and hydrogen ions, causing hypochloremic metabolic alkalo- sis. In this particular presentation the disturbances are moderately severe and the patient should be given IV 5 percent dextrose in 0.45 percent normal saline with 20-40 mEq/L potassium chloride administered at a rate of 10 mL!kg/hr. Avoid lactated Ringer solution, because lactate is metabolized to bicarbonate. [Gregory, Pe(i. Anes., 2002, pp579-580; Morgan et aL, Clinical Anesthesiology, 2002, pp866- 867j

Question 133

What happens to the oxyhemoglobin disso- ciation curve in pyloric stenosis? Why?

Answer 133

The oxyhemoglobin dissociation curve shifts to the left because of meta- bolic alkalosis secondmy to vomiting. [Stoelting, Co-Existing, 1993, p597; Stoelting and Miller, Basics, 1994, pp392, 230]

Question 134

Is pyloric stenosis a medical emergency or a surgical emergency?

Answer 134

Pyloric stenosis is a medical, but not a surgical, emergency. Surgery should be postponed for 24-48 hours until fluid and electrolyte abnor- malities are corrected. [Stoelting, Co-Existing, 1993, p597; Yao and Artu- sio, POPM, 1993, pp318-19; Barash, Clinical Anesthesia, 1997, pp 1117- 1118; Authors]

Question 135

How is the infant with pyloric stenosis pre- pared for surgery?

Answer 135

The emergent therapy for pyloric stenosis is to stop oral intake (stop formula feeding or breast feeding) and metabolically reconstitute the child with intravenous sodium chloride, potassium, and glucose (dextrose). The metabolic abnormalities can be corrected in 12 to 24 hours by IV therapy.
Surgery should be postponed for 24-48 hours. [Stoelting, Co-Existing, 1993, p597; Longnecker et al., PPA, 1998, p21 OS]

Question 136

What concentrations of sodium chloride (saline), potassium, and glucose are used to prepare the infant with pyloric stenosis for surgery?

Answer 136

The dehydration and hyponatremia can be corrected with IV saline (0.45% to 0.9%). When urine output is restored, potassium (usually 40 mEq/L) must be added to this to correct the hypokalemia. Maintenance fluid should be added to this regimen, and for this purpose 5% dextrose in 0.225% saline is usually adequate. [Yao and Artusio, POPM, 1998, p427]

Question 137

What is the major concern for inducing an infant who is scheduled for a pyloromyoto- my? What do you need to do before induc- ing a patient with pyloric stenosis?

Answer 137

Pulmonary aspiration is the rnajor concern darir1g induction. The stomach is emptied as much as possible with a large-bore catheter prior to induc- tion. [Barash Handbook, Clinical Anesthesia, 1997, p608; Stoelting, Co- Existing, 1993, p597; Yao and Artusio, POPM, 1993, pp318-l9; Barash, Clinical Anesthesia, 1997, pp 1117-1118; Authors]

Question 138

In addition to emptying the stomach, list three actions that should be taken to manage a patient with pyloric stenosis.

Answer 138

In addition to emptying the stomach, (1) use rapid sequence induction, (2) perform awake intubation, and (3) extubate awake. [Miller, Anesthe- sia, 1994, p2118; Stoelting and Miller, Basics, 1994, p392; Davison, Eck- hardt, and Perese, Mass General, 1993, p400]

Question 139

How might you intubate a lethargic infant scheduled for pyloromyotomy? An alert infant with an IV line in place? An alert infant without an IV line in place?

Answer 139

An awake intubation may be performed for a lethargic infant. If the infant has an IV in place, intubation can be done after rapid-sequence induction with cricoid pressure. If there is no IV line, the patient may be induced wilh 50%02, 50% N20, and 1.5-3% halothane or 3-6% sevoflurane. [Stoelting, Co-Existing, 3”1 ed, 1993, p597; Yao and Artusio, POPM, 1993, pp318-l9; Barash, Clinical Anesthesia, 1997, pp 11!7-1118; Authors]

Question 140

The newborn has undergone a pyloromyo- tomy. What might you be concerned about in the postoperative period?

Answer 140

Neonates who have undergone pyloromyotomy maybe at increased risk for respiratory depression and hypoventilation in the recovery room because of persistent metabolic or cerebrospinal fluid alkalosis. [Morgan and Mikhail, Clinical Anesthesiology, 1996, p736]

Question 141

What are six primary anesthetic considera- tions for the pediatric patient with hyper- trophic pyloric stenosis?

Answer 141

(1) Postpone surgery until volume and electrolyte deficiencies have been corrected; (2) correction of the volume deficit and metabolic alkalosis requires hydration with sodium chloride solution supplemented with potassium; (3) do not use lactated Ringer’s because lactate is metabolized to bicarbonate, which would aggravate the metabolic alkalosis; (4) thestomach should be emptied prior to surgery; (5) there is a high risk of aspiration during induction; (6) postoperative respiratory depression secondary to cerebrospinal fluid alkalosis should be anticipated. [Morgan and Mild1ail, Clinical Anesthesiology, 1996, p736]

Question 142

What is the average amount of blood lost (in mL/kg) during tonsillectomy?

Answer 142

During tonsillectomy, blood loss averages 4 mL!kg and must be carefully monitored. In terms of percentage, Gregory states lhat 5-10% of blood volume may be lost during tonsillectomy. [Longnecker, Tinker, and Mor- gan, PPA, 2e, 1998, p2209; Waugaman, PPNA, 3’’ ed., 1999, p740; Grego- ry, Ped. Anes., 4e, 2002, p674]

Question 143

What are three complications of tonsil and adenoid surgery?

Answer 143

Bleeding; laryngospasm; emesis. [Barash, Clinical Anesthesia, 1997, pp930-932]

Question 144

Should extubation be performed while the patient is awake or asleep after a tonsillec- tomy? Why?

Answer 144

An awake exlubation is preferred by most anesthetists because risk of aspiration is reduced. [Morgan and Mikhail, Clinical Anesthesiology, 1996, p737]

Question 145

What actions are taken if the tonsillectomy patient begins bleeding? What are the major considerations if the patient needs to be taken back to the operating room?

Answer 145

Initial attempts to control bleeding may be made using pharyngeal packs and cautery. If the patient needs to be taken back to the operating room, (1) intravascular volume must first be restored, and (2) the patient must be considered to have a full stomach because large quantities of blood can be swallowed. [Barash, Clinical Anesthesia, 2001, p991; Atlee, Complica- tions in Anesthesia, 1999, p633; Morgan and Mikhail, Clinical Anesthesi- ology, 1996, p737]

Question 146

Postoperative bleeding after tonsillectomy is suggested by restlessness, pallor, tachycar- dia, or hypotension. If reoperation is neces- sary, what should be done first? Second? How should the patient be induced?

Answer 146

First, restore intravascular volume. Second, empty the stomach with a nasogastric tube. Morgan and Mikhail recommend a rapid sequence induction with cricoid pressure. Barash recommends an awake intubation or ketamine or an inhalation induction. [Morgan and Mikhail, Clinical Anesthesiology, 1992, p639; Barash Handbook, Clinical Anesthesia, 1996, p737]

Question 147

What causes kernicterus?

Answer 147

Kernicterus, also known as bilirubin encephalopathy, affects neonates and is caused by the toxic effects of unconjugated bilirubin on the central nervous system. The signs and symptoms of kernicterus include hyperto- nicity, opisthotonus, and spasticity. Unconjugated bilirubin doesn’t readi- ly cross the normal blood-brain barrier, but neonates have an immature blood-brain barrier. [Stoelting & Dierdorf, Co-Existing, 4th eeL 2002, pp694-695]

Question 148

What drugs may cause kernicterus in the neonate?

Answer 148

Bilirubin is normally conjugated to albumin, therefore any drug that competes for albumin binding sites may increase unconjugated bilirubin and increase the risk of kernicterus. Commonly used drugs that may displace bilirubin from albumin include furosemide, suifonamides, and diazepam (the preservative, benzyl alcohol, in diazepam is actually the culprit). [Duke, Secrets, 2”’ ed. 2000, p295; Barash, Clinical Anesthesia, 4th ecl.200Lp1158]

Question 149

Which type of shock is most frequent in the pediatric patient?

Answer 149

Hypovolemic shock, often due to blood loss from trauma, is the most common cause of shock in children. Appreciate that the compensatory mechanisms (vasoconstriction and tachycardia) in children are very efficient at maintaining perfusion; children may lose as much as one- fourth of their blood volume without significant cardiovascular changes in the supine position. Hypovolemic shock due to plasma loss can be seen with burns and peritonitis, and may be a component of septic shock. [Cote, PAIC, 2001, p325; Gregory, Peel. Anes., 2002, pp102-103]

Question 150

What is the best fluid replacement for the pediatric patient in hypovolemic shock?

Answer 150

Crystalloid solutions (e.g., lactated Ringer solution) are effective in the initial treatment of hypovolemic shock in pediatric patients. Crystalloids administered early in the management of hypovolemic shock wi!l prevent renal failure and also prevent renal collapse. If indicated, blood should be transfused as soon as crossmatching has been done. [Cote, PAIC, 2001, p325; Gregory, Peel. Anes., 2002, pp102-I03]

Question 151

dentify ten (10) factors associated with postintubation laryngeal edema (“croup”),

Answer 151

The following ten factors are associated with postintubation laryngeal edema (“croup”): (I) age younger than 4 years, (2) tight-filling endotra- cheal tube, no audible leak at 15-25 ern 1-hO, (3) traumatic or repeated intubation, (4) prolonged intubation, (5) high-pressure, low-volume cuff, (5) patient “bucking” or coughing during intubation, (6) head reposition- ing while intubated, (7) history of infectious or postintubation croup, (8) neck/airway surgery, (9) upper respiratory infection, and (10) Trisomy 21. [Hines, Stoelting’s Co-existing. 5e. 2008 pp617; Hagberg, Benumofs Airway Managernent. 2e. 2007 pp796; Morgan, eta!., Clin. Anesth. 4e. 2006 pp939]

Question 152

What is the most common cause for liver transplantation in children?

Answer 152

In children, the most common cause for liver transplantation is cholestatic liver disease secondary to biliary atresia, particularly in infants (SO%). [Cole, PAIC. 4th. 2009 pp606]

Question 153

What may be the most important considera- tion for anesthetizing the Down’s patient?

Answer 153

Intubation of the trachea is generally not too difficult to accomplish. Hence, the most important consideration may be the atlanta-occipital (cervical spine) instability. [Authors]

Question 154

What are three major concerns related to anesthetizing the Down’s (trisomy 21) pa- tient?

Answer 154

(1) Intubation may be difficult owing to the large tongue, short neck, small mouth, and subglottic stenosis (select endotracheal tube one size smaller than anticipated); (2) neck flexion during lmyngoscopy and intu- bation may result in atlanta-occipital (cervical spine) dislocation because ofcongenitally weak ligaments (considergettingcervical-spinefilms);
(3) congenital heart disease is present in 40% of patients (anesthesia compatible with the patient’s congenital heart defects should be deliv- ered). [Bell and Kain, Ped. Anes. Handbook, 1997. p537; Longnecker e l al., PPA, 1998, p428; Hurford, Bailin, Davision, Hospd, Rosow, Mass General, 1998, p206; Morgan and Mikhail, Clinical Anesthesiology, 1996, p738]

Question 155

What are four pathophysiological features associated with Down’s syndrome, in addi- tion to difficult airway, atlanto-occipital instability and congenital heart defects?

Answer 155

Pathophysiological features of Down’s syndrome also include; (I) irregu- lar dentition; (2) mental retardation; (3) hypotonia; (4) tracheoesophageal fistula; (5) chronic pulmonary infections; and (6) seizures. [MorgcHl and Mikhail, Clinical Anesthesiology, t996, p738]

Question 156

Describe the preoperative fasting (NPO) guidelines for children: (1) 36 months.

Answer 156

Fasting guidelines are: (l) Children 36 months old: restrict solids for 8 hours and clear liquids for 3 hours. The American Academy of Pediatrics/American Society of Anesthesiologists task force has set recommendations that “advise restriction of clear fluids for 2 hours, breast milk for 4 hours, formula or light meals for 6 hours, and fatty solid meals for 8 hours.” The pattern is to start NPO at 2 hours for clear liquids add 2 hours for each increasingly “fatly” meal. [Cote, PA/C, 2001, p225; Barash, Clinical Anesthesia, 2001, p1196; Authors]

Question 157

ositive pressure ventilation by bag and mask has been instituted on the neonate during resuscitation. When is endotracheal intubation indicated?

Answer 157

During neonatal resuscitation, prompt endotracheal intubation is indicat- ed if there is no immediate (

Question 158

When should imrnediate endotracheal intubation be considered during neonatal resuscitation?

Answer 158

Immediate endotracheal intubation of the neonate should be considered for situations in which bag and mask ventilation is likely to be ineffective, for example, extreme prematurity with low pulmonary compliance sec- ondary to surfactant deficiency. Other situations in which bag and mask ventilation may be ineffective are large bilateral pleural effusions and congenital diaphragmatic hernia. [Hughes, el a!., Anes.Jor OB. 4e. 2002 pp662j

Question 159

What is the appropriate internal diameter of the endotracheal tube for the premature newborn? For the full-term newborn?

Answer 159

The appropriate internal diameter of the endotrachdic tube is 2.5-3.0 mm for the premature newborn and 3.0-3.5 mm for the full-term new- born. [Davison, Eckhardt, and Perese, Mass General, 1993, p441; Barash Handbook, Clinical Anesthesia, 1997, pp1119-1120J

Question 160

What endotracheal tube size and length are required for the neonate, 2-year-old, 6-year- old and 10-year-old?

Answer 160

Neonate== 3.0-3.5 and 10 em length; 2-year-old = 4.5 and 13 em length; 6-year-old = 5.5 and 15 em length; 10-year-old = 6.5 and 17 em length. [Barash Handbook, Clinical Anesthesia, 1988, p49]

Question 161

Write the formula for calculating the inter- nal diameter of the endotracheal tube for the child who is greater than 20 months of age. Calculate the appropriate internal diameter of the endotracheal tube for a 5-year-old child.

Answer 161

Par children over 20 months, 4.0 +age (years)/4 = Lhe internal diameter (ID) needed. 4.0 + 5/4::::: 5.0 mm internal diameter endotracheal tube, for the 5-year-old. [Davison, Eckhardt, and Perese, Mass General, 1993, p441]

Question 162

How is the length of the endotracheal tube from the mouth determined, in em?

Answer 162

[10 +age (years)]/2. [Davison, Eckhardt, and Perese, Mass General, 1993, p441]

Question 163

How is the French size of the endotracheal tube determined for a child? What endotra- cheal tube size is required by a six-year-old?

Answer 163

The French size for a child is age (years)+ 18. Example: A six-year-old will require a 24 French ET tube (6 + 18 24). [Davison, Eckhardt, and Perese, Mass General, 1993, p441]

Question 164

W h a t size (French) suction catheter should be used to clear the endotracheal tube of the intubated neonate? The intubat- ed 2-year-old? The intubated 6-year-old?

Answer 164

The appropriate size (French) of suction catheter for clearing the endotra- cheal tube of the intubated child is: neonate-S Fr, 6 months to 2 years old-10 Fr, and 2 to 12 years old-14 Fr. [Nagelhout & Zaglaniczny, NA, 3’d ed., 2004, p1109]

Question 165

How many days post gestation is it safe for surgery in the full-term infant? For the preterm infant, surgery should be delayed how long post-conception?

Answer 165

Surgery is safe from the 15th through 56th day post-gestation in the full- term infant. Elective or outpatient procedures should be deferred until the preterm infant reaches the age of at least 60 weeks post-conception. [Ba- rash, Clinical Anesthesia, 1997, pp1084-l087; Morgan and Mikhail, Clini- cal Anesthesiology, 1996, p734]

Question 166

Surgery in neonates poses a major con- cern-development of apnea in the postop- erative period. Which neonates are at the highest risk for postoperative apnea?

Answer 166

Neonates at highest risk for postoperative apnea are those born prema- turely, those who have multiple congenital anomalies, those with a history of apnea and bradycardia, and those with chronic lung disease. [Barash, Clinical Anesthesia, Se, 2006, p1193]

Question 167

Woutd a formerly premature infant be a candidate for outpatient surgery? What are the anesthetic concerns for the formerly premature infant?

Answer 167

No, the formerly premature infant is not an appropriate candidate for outpatient surgery. Formerly premature infants (less than 46 weeks post- conceptual age), even if healthy, have an increased rate of post-anesthetic apnea and bradycardia. These formerly premature infants should have cardiorespiratory monitoring for a minimum of24 hours postoperatively and thus are not good candidates for ambulatory day surgery. [Morgan, Mild1ail, and Murray, Clinical Anesthesiology, 4e, 2006, pp1006-!007; Dunn, eta!., Mass Gen Handbook, 7e, 2007, p516]

Question 168

The infant patient is high-risk for postop- erative apnea what agent may be given prophylactically to decrease the risk of ap- nea?

Answer 168

The infant at risk for postoperative apnea may be given caffeine prophy- lactically to ensure adequate serum levels exist prior to surgery and dur- ing the postoperative period. Caffeine is a respiratory and CNS stimulant and is generally preferred to theophylline because caffeine has a wider therapeutic margin and a decreased propensity for toxicity. The recom- mended loading dose is 10 mg/kg of caffeine base, which is often obtained from 20 mg of caffeine citrate. The clinical effects of caffeine may last several days after a single dose, but do not administer caffeine and then discharge the patient, assuming that the caffeine will prevent apnea (Cote). [Barash, Clinical Anesthesia, Sc, 2006, p1193; Gregory, Ped. Anes., 4e, 2002, pp376-377; Cote, PAIC, 3’d ed., 2001, p47]

Question 169

W h a t is retinopathy of prematurity?

Answer 169

Retinopathy of prematurity (ROP), formerly known as retrolental fibro- plasia, is a fibrovascular proliferation overlying the retina that leads to progressive visual loss. ROP occurs almost exclusively in preterm infants. The risk of ROP is inversely proportional to birth weight, and is associat- ed with neonatal oxygen exposure, apnea, blood transfusion, sepsis, and fluctuating levels of carbon dioxide. [Cote, PAlC. 4th. 2009 pp64; Hines, Stoelting’s Co-existing. Se. 2008 pp588 J

Question 170

Neonatal retrolental fibroplasia is a result of oxygen toxicity above what% inspired oxy- gen?

Answer 170

Above 40% oxygen. Physiological studies indicate that the premature infant is probably safe with up to 40% oxygen but some believe that com· plete safety can be achieved only at the normal inspired oxygen concen- tration. [Guyton, TMP, 1996, p10SS]

Question 171

At what gestational age does the risk of retinopathy of prematurity become negligi- ble? Why?

Answer 171

The risk of retinopathy of prematurity becomes negligible after 44 weeks postconception because retinal vasculogenesis is complete between 42-44 weeks postconception. [Cote, PAlC. 4th. 2009 pp64; Hines, Stoelting’s Co- existing. 5e. 2008 pp588]

Question 172

What Pa02 and Sa02 are appropriate during anesthesia for the premature infant?

Answer 172

There appear to he no clearly established guidelines in the anesthesia literature. S,O, in the 90-95% range (P,O, = 60-80 mm Hg) is believed to be reasonable for the premature infant. The goal specified by guidelines of the American Academy of Pediatrics and the American College of Obste- tricians and Gynecologists is a PaOz between 50 and 80 mm Hg in
premature infants. [Barash, Clinical Anesthesia, 1997, pl112]

Question 173

A neonate is undergoing a surgical proce- dure with the use of a spinal blockade. What sign would indicate a “high” or “total” spi- nal?

Answer 173

Decreasing oxygen saturation is the earliest sign of a high or total spinal
i n the neonate. A high or total spinal, produced either with a primary spinal technique or secondary to an attempted epidural, presents as res- piratory insufficiency rather than hypotension owing to the relatively immature sympathetic nervous system in the neonate. With an immature sympathetic nervous system, the cardiovascular parameters are remarka- bly stable in the neonate with a high or total spinal. [Gregory, Ped. Anes., 2002, pp276-277]

Question 174

How do infants react to hypoxia?

Answer 174

Infants react to hypoxia with bradycardia progressing to cardiac arrest. [Davison, Eckhardt, and Perese, Mass General, !993, pp249, 400, 508]

Question 175

Whatl\Oz is desirable when ventilating a premature infant for surgery?

Answer 175

60-80 mmHg. [Morgan and Mikhail, Clinical Anesthesia, !996, p732]

Question 176

Where should PaO2 be maintained during intracranial surgery in children?

Answer 176

For children, PaC02 may be reduced to 20-25 mmi-Ig. [Steward, Manual ofPed. Anes., 1995, p193]

Question 177

What drugs will have a larger volume of distribution in the infant compared with the adult? What drugs will have a smaller vol- ume of distribution in the infant compared with the adult?

Answer 177

The infant’s extracellular body fluid compartment is large compared to the adult, so water soluble drugs will have a larger volurne of distribution in the infant compared with the adult. Conversely, lipid soluble drugs will have a smaller volume of distribution in the infant compared with the adult. [Steward, Manual ofPed. Anes., 1995, p43j

Question 178

What is the most prominent muscarinic action of a bolus of succinylcholine in the pediatric patient? How can this action be prevented?

Answer 178

Bradycardia develops in response to succinylcholine; for this reason, atropine should be administered prior to succinylcholine. [Stoelting and Miller, Basics, 1989, p399; Morgan and Mikhail, Clinical Anesthesiology, 1996, p732]

Question 179

How much nondepolarizing muscle relaxant does a pediatric patient require compared with adults on a weight basis?
succinylcholine?

Answer 179

Neonates, infants and children require the same dose of nondepolarizing neuromuscular relaxant as adults. Neonates require twice as much suc- cinylcholine on a body weight basis than older children or adults. [Stoelt- ing and Miller, Basics, !994, p384j

Question 180

Given that the infant has greater sensitivity to non depolarizing neuromuscular relaxants than the adult (because the neuromuscular junction of the neonate is immature), why is the dose admin- istered on a weight basis the same for infants and adults?

Answer 180

Infants have a greater volume o f distribution for muscle relaxants. The increased volume of distribution, normally requiring a greater amount of drug, is by the increased sensitivity of nondepolarizing muscle relaxants at the neuromuscu- lar junction. Thus, the infant dose of nondepolarizer is the same as the adult dose on a weight basis. [Barash llundbook, Clinical Anesthesia, 1997, pp609-610]

Question 181

State two reasons why neonates require more succinylcholine on a mg/kg basis than adults.

Answer 181

(1) Neonates have a larger volume of distribution for succinylcholine than adults. 40-50% of body weight of neonate is extracellular fluid (ECF) whereas in the adult ECF is only 20-25% of body weight. Succinylcholine distributes in the extracellular volume so more drug is needed on a per kg basis. (2) Also, the neuromuscular junction is immature (less sensitive) in the neonate, so more drug is needed on this basis. [Stoelting and Miller, Basics, 1994, p384]

Question 182

Define ED90. Stale if the ED90 for succinyl- choline is increased, decreased, or un- changed in the neonate compared with the adult, and indicate what this means.

Answer 182

ED90 is the dose of drug that is effective in 90% of the population (ED9o = effective dose in 90% of population), The ED90 for succinylcholine is in- creased in the neonate compared with the adult. An increased ED90 means that a larger dose ofsuccinylcholine must be given to the neonate to achieve adequate paralysis. [Goodman and Gilman, PET, 1996, pp48-49; Au- thors]

Question 183

As you know, neonates require a higher dose of succinylcholine compared to adults. This is due to both an immature neuromuscular junction and greater body water content per unit weight. How would the ED95 for suc- cinylcholine compare between a neonate and an adult-the same, higher, or lower?

Answer 183

The ED95 of succinylcholine for the neonate would be greater than that for the adult. Specifically, for succinylcholine the ED,5 = 620 meg/kg for the neonate and the ED95 = 290 meg/kg for the adult. This simply states the need for greater dosing of succinylcholine in the neonate, compared to the adult. [Nagelhout and Zaglaniczny, NA, 2”” ed. 2001, p1!42l]

Question 184

Compare the actions ofvecuronium (Norco- ron) in the infant and the adult with respect to potency, onset, duration of action, and recovery.

Answer 184

Vecuronium (Norcuron) has similar potency in infants and adults. Onset is more rapid in infants, duration of action is longer in infants, and recov- ery is slower in infants, compared to adults. [Stoelting, PPAP, yd ed. 1999, p211]

Question 185

How does an infant’s quantity of plasma proteins, body fat, and muscle differ from the adult?

Answer 185

Plasma proteins, body fat, and muscle are reduced in the infant compared with the adult. Decreased plasma proteins mean more free drug is available to produce clinical effects. A lower dose ofdrug may be indicated. [Steward, Manual ofPed. Anes., 1995, p43]

Question 186

A two-year-old develops laryngospasm postoperatively and becomes bradycardic. Should atropine be given prior, concurrent- ly, or after succinylcholine? Explain your answer.

Answer 186

If continuous positive pressure of 10-15 em I-hO does not break the laryngospasm, then atropine 0.02 mg/kg followed by succinylcholine ( l mg/kg IV; 4 mg/kg IM) is needed. Succinylcholine mimics the effect of acetylcholine at cardiac muscarinic receptors, which can precipitate more severe bradycardia, junctional rhythms, or sinus arrest. [Stoelting, PPAP, 1989, piSO; Rasch, p!23]

Question 187

What is the appropriate volume for a pediatric epidural blood patch?

Answer 187

In the child who is awake, the practitioner should stop the blood infusion once the child feels discomfort of pressure in the back In the anesthetized patient, no more than 0.3 mL/kg of blood should be injected into the epidural space. [Motoyama and Davis, Smiths Anesthesia for Infants and Children, 7e, 2006, p468)

Question 188

For the pediatric patient weighing between 2 and 20 kg, what volume (m!Jkg) of0.25% bupivacaine (mL/kg) should be adminis- tered caudally for a block to I.-I or T-12? To T-10? To T-4 or T-5?

Answer 188

0.35 mL/kg for L-1 to T-12level block; 0.5-0.75 mL/kg for aT- 10 level block; 0.75-1.25 mL/kg for a T-4 orT -Sieve! block. [Ped. Anes. Hand- book, 1991, p520]

Question 189

What is the maximum dose of0.25% bupivacaine that should be used for pediatric caudal anesthesia?

Answer 189

upivacaine (0.25%) at a volume of 1 mL/kg up to a maximum of25 mL can provide 3 to 6 hours of anesthesia for surgical procedures below the level of the diaphragm. [Steward, Manual ofPed. Anes., 1995, p123]

Question 190

Is elimination of amide local anesthetics shortened or prolonged in the neonate compared with the adult?

Answer 190

The half-time of elimination of amide local anesthetics is prolonged 2-3 times in the neonate but approaches adult values after six months of age. [Barash Handbook, Clinical Anesthesia, 1997, p220 J

Question 191

Which local anesthetic is not metabolized in neonates?

Answer 191

Mepivacaine is not metabolized in neonates; this is controversial, but generally accepted. “The neonatal enzyme systems are adequately devel- oped to metabolize most drugs, with the possible exception of
mepivacaine.” [Stoelting & Miller, Basics, 4e, 2000, p347]

Question 192

Of the following drugs administered to the pediatric patient for sedation, which will have the shortest duration of action: keta- mine (rectal or lM), chloral hydrate (PO), methohexital (rectal), or propofol (IV)?

Answer 192

Propofol has the shortest duration of action because it is administered IV. The duration of action of a bolus ofpropofol is 5-10 minutes. Ketamine has a duration of 12-25 minutes when administered rectally or IM. azolam has a duration of2-6 hours when administered IM. Methohexital has a duration of 30-90 minutes when administered rectally. Chloral hydrate, the most commonly used hypnotic for monitored conscious sedation by nonanesthetists, has a duration of 30-60 minutes (PO). Note: IV thiopental has a duration of 5-15 min, which is similar to the duration of propofol. [Omoigui, Anesthesia Drugs Handbook, 1995, ppl72,210,231,298,345; Bell and Kain, Peel. Anes. Handbook, 1997, p447]

Question 193

Compare the onset and duration of intrave- nous morphine in the neonate with the onset and duration of intravenous morphine in the adult?

Answer 193

The onset of action of morphine is faster in the neonate compared with the adult, possibly because of greater penetration of morphine through the blood:brain barrier and greater sensitivity of the respiratory centers to morphine. The duration of action of morphine will be longer in the neo- nate because, during the first month, metabolism of morphine by the immature cytochrome P450 system is reduced. [Morgan and Mikhail, Clinical Anesthesiology, 1996, p730]

Question 194

Compare the duration of intravenous mor- phine in the infant and child with the onset and duration of intravenous morphine in the adult?

Answer 194

The duration of action of morphine is shorter in the infant and child because, after the first month, metabolisrn of morphine by the mature cytochrome P450 system is increased as a result of greater hepatic blood Oow. [Morgan and Mikhail, Clinical Anesthesiology, 1996, p730]

Question 195

IIState 3 reasons why the uptake of anes- thetic drugs is typically faster in children than in adults.

Answer 195

Uptake of anesthetic drugs is faster in children than adults for the following 3 reasons. (I) The child’s higher alveolar ventilation per weight accounts largely for this effect. (2) Increased cardiac output with greater distribution to the vessel-rich groups combined with lower muscle mass aUows more of the agent to concentrate in vital organs, especially the brain. (3) Anesthetic agents appear to be less blood soluble in children than in adults, that is, the agents work (aster in children than adults.[Nagelhout & Zaglaniczny, NA, 3’d eel., 2004, p78]

Question 196

Nitrous oxide (N20) should be avoided in what pediatric procedures?

Answer 196

Nitrous oxide should be avoided in numerous procedures including: diaphragmatic hernia, bowel obstruction, pneumoencephalography, tympanoplasty, congenital emphysema, lung cysts, pneumothorax, ne- crotizing enterocolitis, patent ductus arteriosus (PDA), and omphalocele repair. [Motoyama and Davis, Smith’s A1C, 1996, ppl80,457,458,469; Cote et al., PAIC, 2001, p142; Bell and Kain, Ped. Anes. Handbook, Mosby, 1997, p370; Steward and Lerman, Manual ofPed. Anes., 2001, p44]

Question 197

Give the two most important reasons why children are induced faster than adults with inhalational agents.

Answer 197

Children have (1) a smaller functional residual capacity per unit of body weight and (2) a greater blood flow to the brain. [Stoelting and Miller, Basics, 1994, pp382, 383I

Question 198

What is the most common type of delirium in children?

Answer 198

In children, emergence delirium is more common. Emergence delirium occurs within minutes of regaining consciousness. [Stoelting & Miller, Basics, 4e, 2000, p384l

Question 199

Which fluid is most appropriate for a nor- mal six-month-old patient requiring sur- gery?

Answer 199

For short procedures, DSlactated Ringer’s is appropriate. For long proce- dures, lactated Ringer’s is appropriate with separate DSW or DlOW at a rate of4-6 mL!kg/min after blood glucose levels are checked. [Steward, Manual ofPed. Anes., 1995, p106l

Question 200

How many breaths per minute should be produced by the ventilator for the neonate? For the adult?

Answer 200

30-50 breaths per minute for the neonate and 12-16 breaths per minute for the adult. [Barash Handbook, Clinical Anesthesia, 1997, p1097l

Question 201

What are two advantages of using Randal- Baker masks in pediatrics?

Answer 201

The Randal-Baker mask is designed to fit the facial contours more closely and to reduce dead space (firm rubber). [Smith, p97l

Question 202

The child becomes unruly and combative in the pre-operative period. What agents are appropriate in this situation? Specify the dose and routes of administration of each agent on the list.

Answer 202

(1) Methohexital (10% solution): 25-30 mg/kg rectally, produces sleep in 8 - 1 0 minutes if the child weighs less than 20 kg. (2) Ketamine: up to lO mg/kg IM: 10 mg/kg rectally: 6-10 mg/kg orally; 3-6 mglkg intranasally. (3) Midazolam: IM (.025-.05 mglkg): oral (0.5-0.75 mglkg), rectal (.75- !.0 mglkg), nasal (0.2 mg/kg), sublingual (.2 mglkg). (4) Scopolamine: 0.1 mg IM for 6-12 mo.; 0.15 mg for 1-5 yrs. [Miller, Anesthesia, 1994, pp2104-05; Barash, Clinical Anesthesia, 1997, plll7; Morgan and Mi- khail, 1996, p732l

Question 203

What is the best criteria for determining premedication dosages in kids?

Answer 203

Body weight of child. [Barash, Clinical Anesthesia, 1997, pp1116-1117l

Question 204

What 9 cardiovascular signs indicate fetal cocaine toxicity in the newborn ofa cocaine- addicted mother?

Answer 204

Nine cardiovascular signs of fetal cocaine toxicity are: (I) arterial hypox- emia, (2) increased blood pressure, (3) increased heart rate, (4) increased cerebral blood flow, (5) reduced cardiac output, (6) reduced stroke
ume, {7) right ventricular conduction delay, (8) right ventricular hyper .. trophy, and (9) ST segment and T-wave changes. [Norris, Ob. Anes., 1999, p652; Barash, Clinical Anesthesia, 2001, p1t83I

Question 205

What is the most commonly used analge- sic for pediatric outpatients?

Answer 205

Acetaminophen is the most commonly used mild analgesic for pediatric outpatients. The initial dose is often administered rectally (up to 45 mg/kg) prior to awakening from anesthesia. Supplemental doses nre then given orally (10 mg/kg every 4 hours or 20 mg/kg every 6 hours) to main- tain adequate blood levels and effective analgesia. [Cot, PAIC, 3rt! ed., 200!, p61l

Question 206

What is the drug ofchoice and dosing for prophylaxis for pediatric endocarditis?

Answer 206

Standard general prophylaxis for pediatric endocarditis is amoxicillin, 50 mg/kg orally I hour prior to procedure. [Nagelhout & Zaglaniczny, NA, 3’” ed., 2004, 229tl

Question 207

The pediatric patient is scheduled for a radiofrequency ablation of an aberrant conduction pathway (e.g., Wolff-Parkinson- White syndrome). Why is a general anes- thetic typically required for this scenario?

Answer 207

Radiofrequency ablation is a nonsurgical approach designed to eliminate atrial or ventricular re-entrant tachyarrhythmias. The technique requires mapping and precision ablation of the aberrant pathway, using a radiof- requency ablation catheter. During the ablation, unexpected movement may result in catheter dislodgment and damage to normal conducting tissue; therefore, general anesthesia is usually required in younger chil- dren. Anesthetic agents and techniques should be chosen to maintain circulating catecholamines and avoid suppression of arrhythmogenesis, for identification of the aberrant pathway. [Miller, Anesthesia. 6e. 2005 pp2043]

Question 208

Describe the 4 steps to treating hyper- kalemia in the neonate.

Answer 208

Emergent treatment of hyperkalemia in the neonate centers around an- tagonizing the cardiac effects of excess potassium-administer calcium as calcium chloride (O.l mL!kg of 10% solution) or calcium gluconate
0.3-1.0 mL!kg 10% solution) over minutes. Return potassium to the intracellular space by correcting acidosis through administration of sodi- um bicarbonate, mild hyperventilation, and a Maintain potas- sium in the intracellular space by glucose + insulin infusion, 0.5-1.0 g/kg glucose with 0.1 U/kg insulin over minutes). Remove whole-body potassium burden by Kayexalate or dialysis and correct the underlying etiology. [Cote, PA/C. 4th. 2009 pp172-173]

Question 209

An infant has a life-threatening succinyl- choline-induced hyperkalemia: what is the definitive treatment?

Answer 209

The definitive treatment of succinylcholine-induced hyperkalemia is IV calcium (10 mg/kg calcium chloride or 30 mg/kg calcium gluconate or more). This restores the gap between the resting membrane potential of the cardiac cells and the threshold potential for depolarization. Repeated doses of calcium must be administered together with cardiopulmonary resuscitation, epinephrine, sodium bicarbonate, glucose and insulin, and hyperventilation until the arrhythmias abate. [Cote, PAIC. 4th. 2009 pp128]