Neonates Part I Flashcards

1
Q

Define the neonatal period.

A
  • First 28 days of extrauterine life.
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2
Q

Why might anesthesia be required for neonates?

A
  • Life-threatening illness.
  • Medical conditions needing surgical intervention.
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3
Q

What types of surgical interventions might neonates need anesthesia for?

A
  • Palliative
  • Staged
  • Corrective
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4
Q

Why is the neonate particularly vulnerable during the neonatal period?

A
  • Vulnerable to internal and external stressors.
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5
Q

How should the anesthetic plan for neonates be tailored?

A
  • To mitigate physiologic stress
  • Improves neonatal morbidity and mortality.
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6
Q

What does anesthetic management of neonates require?

A
  • Specialized knowledge about patients
  • Extreme vigilance
  • Refinement of technical skills.
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7
Q

Does anesthetic management differ between term and premature neonates?

A
  • Requires integration of specialized knowledge for both term and premature neonates.
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8
Q

How does fetal circulation’s organ of respiration differ from the adult’s?

A
  • Fetal: Placenta
  • Adult: Lungs
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9
Q

How is fetal circulation arranged compared to adult circulation?

A
  • Fetal: In parallel
  • Adult: In series
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10
Q

What shunting occurs in fetal circulation?

A
  • Right-to-left shunting across the foramen ovale and ductus arteriosus.
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11
Q

Compare the Systemic Vascular Resistance (SVR) between fetal and adult circulation.

A
  • Fetal: SVR is low
  • Adult: SVR is higher.
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12
Q

Compare the Pulmonary Vascular Resistance (PVR) between fetal and adult circulation.

A
  • Fetal: PVR is high
  • Adult: PVR is lower
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13
Q

Describe the pulmonary blood flow and left atrial pressure in fetal circulation.

A
  • Minimal pulmonary blood flow
  • Low left atrial pressure.
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14
Q

What is the purpose of the ductus venosus in fetal circulation?

A
  • Shunts blood from the umbilical vein to the IVC (bypasses liver).
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15
Q

What role does the foramen ovale play in fetal circulation?

A
  • Shunts blood from the RA to the LA (bypasses lungs).
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16
Q

What is the function of the ductus arteriosus in fetal circulation?

A
  • Shunts blood from the pulmonary artery to the aorta (bypasses lungs).
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17
Q

How many umbilical veins are there and what is their function?

A
  • One umbilical vein
  • Carries oxygenated blood from the mother to the fetus.
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18
Q

How many umbilical arteries are there and what is their function?

A
  • Two umbilical arteries
  • Carry deoxygenated blood from the fetus to the mother.
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19
Q

Why can fetal shunts be problematic during extrauterine life?

A
  • Beneficial in-utero
  • Problematic if remain open during extrauterine life.
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20
Q

What is the function of the one umbilical vein in fetal circulation?

A
  • Provides oxygen-rich blood to the fetus.
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21
Q

How does the ductus venosus contribute to fetal circulation?

A
  • Shunts oxygenated blood past the liver
  • Saving oxygen for the heart and brain.
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22
Q

Describe the mixing of blood in the inferior vena cava (IVC) in fetal circulation.

A
  • Oxygenated blood from the ductus venosus and deoxygenated blood from the lower body converge, creating two streams of blood at different rates.
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23
Q

What is the significance of the higher velocity of oxygenated blood in the fetal heart?

A
  • Enters the RA and
  • Is preferentially diverted across the foramen ovale to the LA
  • Perfusing the myocardium and brain.
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24
Q

How is deoxygenated blood directed in fetal circulation?

A
  • Lower velocity blood is directed to the RV and pulmonary trunk
  • then shunted via the ductus arteriosus to the descending aorta
  • perfusing the lower body and returning to the placenta through two umbilical arteries.
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25
Q

What causes shunting between the pulmonary and systemic circulations?

A
  • Abnormal communication between the pulmonary and systemic circulations.
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26
Q

What factors determine the size and direction of a shunt?

A
  • Ratio of PVR to SVR
  • Pressure gradients between cardiac chambers or arteries
  • Compliances of the cardiac chambers.
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27
Q

What happens when PVR is greater than SVR?

A
  • Right-to-left (R → L) shunt occurs.
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28
Q

What happens when SVR is greater than PVR?

A
  • Left-to-right (L → R) shunt occurs.
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29
Q

What is a cyanotic shunt and give an example?

A
  • Cyanotic shunt (R → L): Tetralogy of Fallot.
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30
Q

What is an acyanotic shunt and give an example?

A
  • Acyanotic shunt (L → R): Ventricular septal defect.
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31
Q

How does a right-to-left shunt affect anesthesia induction?

A
  • Slower inhalation induction
  • Faster IV induction.
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32
Q

How does a left-to-right shunt affect anesthesia induction?

A
  • Negligible effect on inhalation induction rate.
  • Possibly prolongs IV induction onset.
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33
Q

What is Eisenmenger syndrome?

A
  • A left-to-right shunt changes to a right-to-left shunt due to pulmonary hypertension.
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34
Q

What is a Cyanotic Shunt (R → L) also known as?

A
  • Known as “Blue Baby.”
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35
Q

What happens in a cyanotic shunt?

A
  • Blood bypasses the pulmonary circulation.
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36
Q

Why does the blood appear blue in a cyanotic shunt?

A
  • Shunted blood does not bind oxygen in the lungs
  • Diluting the final PO2 of blood ejected by the left ventricle.
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37
Q

What is an Acyanotic Shunt (L → R) also known as?

A
  • Known as “Pink Baby.”
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38
Q

What occurs in an acyanotic shunt?

A
  • Oxygenated pulmonary venous blood is recirculated through the right heart and lungs
  • Instead of being pumped to the body.
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39
Q

What are the consequences of an acyanotic shunt?

A
  • Robs the body of blood flow.
  • Overloads the right heart and pulmonary vasculature.
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40
Q

What determines cardiac output in neonates?

A
  • Heart rate.
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41
Q

How do neonates’ oxygen consumption and CO2 production compare to adults?

A
  • Twice as much per weight.
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42
Q

What’s more efficient for neonates, increasing respiratory rate or tidal volume?

A
  • Increasing respiratory rate.
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43
Q

Is stroke volume fixed or variable in neonates?

A
  • Fixed.
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44
Q

How does the neonate’s left ventricle respond to increased afterload?

A
  • By increasing heart rate.
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45
Q

Which part of the autonomic nervous system is less mature in neonates?

A
  • Sympathetic nervous system (SNS).
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46
Q

How do neonates respond to laryngoscopy?

A
  • With bradycardia.
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47
Q

What risk does pain pose in neonates?

A
  • Predisposes to intracerebral hemorrhage.
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48
Q

Up to what age do infants prefer nose breathing?

A
  • Up to 5 months.
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49
Q

How does the size of the tongue in infants compare to their mouth volume?

A
  • Larger tongue relative to mouth volume.
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50
Q

Describe the neck length in pediatric patients.

A
  • Shorter neck.
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51
Q

What is the shape and characteristics of the epiglottis in infants?

A
  • U or omega shape
  • Longer and stiffer
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52
Q

How do vocal cords in infants differ from adults?

A
  • Anterior slant.
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53
Q

Where does the laryngeal position correspond in infants?

A
  • C3 - C4.
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54
Q

What is the narrowest fixed region in the pediatric airway?

A
  • Cricoid ring.
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55
Q

What is the narrowest dynamic region in the pediatric airway?

A
  • Vocal cords.
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56
Q

Describe the shape of the subglottic airway in infants.

A
  • Resembles a funnel.
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57
Q

How does the position of the right mainstem bronchus in infants compare to adults?

A
  • Less vertical
  • Takes off 55 degrees from midline.
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58
Q

Neonates’ oxygen consumption rate?

A
  • 6 mL/kg/min.
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59
Q

Neonates’ alveolar ventilation compared to adults?

A
  • Increased.
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60
Q

Neonates’ FRC level?

A
  • Slightly decreased.
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61
Q

Result of neonates’ hypoventilation/apnea?

A
  • Rapid desaturation.
62
Q

Effect of FRC turnover on anesthetic induction in neonates?

A
  • Faster inhalation induction.
63
Q

What is the primary muscle of inspiration?

A
  • Diaphragm.
64
Q

How do intercostal muscles contribute to ventilation in neonates?

A
  • Very little due to inadequate development.
65
Q

How does the position of the ribs affect thoracic volume in neonates?

A
  • Less able to augment due to more horizontal position.
66
Q

What types of muscle fibers compose the diaphragm and intercostal muscles?

A
  • Type 1: Slow-twitch, endurance, fatigue-resistant
  • Type 2: Fast-twitch, short bursts, tires easily.
67
Q

Percentage of type 1 fibers in the neonatal diaphragm?

A
  • 25% (Adults have 55%).
68
Q

How does the composition of muscle fibers in the neonate’s diaphragm affect respiratory function?

A
  • Reduced ventilatory reserve due to fewer type 1 fibers.
69
Q

Risk associated with fewer type 1 fibers in the neonate’s diaphragm?

A
  • Increased risk for respiratory fatigue and failure.
70
Q

How does lung compliance in newborns compare to adults?

A
  • Lower lung compliance.
71
Q

What is the chest wall compliance in newborns?

A
  • Higher
  • Leading to potential chest wall collapse during inspiration.
72
Q

How do neonatal lung volumes compare to adults?

A
  • Smaller FRC, vital capacity
  • Total lung capacity
  • Greater residual volume, closing capacity
  • Similar tidal volume
73
Q

What challenges do neonates face during inspiration?

A
  • Must overcome airflow resistance and elastic properties of chest wall and lungs.
74
Q

What impact do minor reductions in airway diameter have on neonates?

A
  • Significantly increases work of breathing.
75
Q

What is unique about fetal circulation?

A
  • Umbilical vein supplies oxygen
  • Umbilical arteries return CO2-rich blood.
76
Q

What stimulates a newborn to breathe rhythmically?

A
  • Clamping the umbilical cord.
77
Q

How does PaO2 level affect neonatal breathing?

A
  • Acute rise promotes continuous breathing
  • Hypoxemia causes apnea
78
Q

What is the neonate’s pH at birth and 1 hour after delivery?

A
  • Birth: pH = 7.20
  • Stabilizes to 7.35 after 1 hour.
79
Q

When does respiratory control mature in neonates?

A
  • Between 42 - 44 weeks post-conceptional age.
80
Q

How does hypoxemia affect neonates before respiratory control matures?

A
  • Inhibits ventilation.
81
Q

What is the P50 value of fetal hemoglobin (Hgb F)?

A
  • 19 mmHg.
82
Q

How does Hgb F affect the oxygen dissociation curve?

A
  • Shifts the curve to the left (left = love).
83
Q

Why is the left shift of Hgb F beneficial for the fetus?

A
  • Facilitates O2 passage from mother to fetus
  • By creating an oxygen partial pressure gradient across the uteroplacental membrane.
84
Q

How does the CNS in newborns differ from older children?

A
  • Less myelination
  • Different muscle tone Reflexes
  • Underdeveloped cerebral cortex.
85
Q

When is myelination of the nervous system complete?

A
  • By age 3.
86
Q

How does the neuromuscular junction change in the first 2 months of life?

A
  • Undergoes developmental changes.
87
Q

Are pain pathways and receptors present at birth?

A
  • Yes, present within the CNS.
88
Q

Signs of pain in preverbal patients include?

A
  • Tachycardia
  • Elevated BP
  • Crying
  • Restlessness
  • Grimacing
89
Q

Why is increased BP dangerous in newborns, especially preemies?

A
  • Lack of cerebral vascular autoregulation can lead to intracerebral bleeding.
90
Q

How quickly does the brain grow in the first year of life?

A
  • Doubles in weight in the first 6 months
  • Triples by 1 year
91
Q

When do the major fontanelles close in neonates?

A
  • Anterior by 2 years
  • Posterior by approximately 4 months.
92
Q

What can the anterior fontanelle indicate in newborns?

A
  • Increased intracranial pressure
  • Dehydration.
93
Q

At what age does the blood-brain barrier mature?

A
  • Approximately 1 year of age.
94
Q

What migration occurs in the conus medullaris and dural sac with pediatric growth?

A

Migrate cephalad.

95
Q

Where is the conus medullaris in neonates?

A

Between L2 and L3.

96
Q

Where does the dural sac end until 6 years of age?

A

Between S2 and S3.

97
Q

At what age is the spinal cord position similar to an adult?

A

Age 8.

98
Q

How does the neonatal kidney compare to the adult kidney at birth?

A
  • Immature with decreased perfusion pressure
  • Decrease glomerular filtration rate
  • Decrease diluting and concentrating ability.
99
Q

Why are neonates intolerant of fluid restriction?

A

Poor water conservation.

100
Q

What is the neonate’s ability regarding fluid overload?

A

Unable to excrete large volumes of water.

101
Q

What is the most significant source of water loss in neonates?

A

Evaporation from high insensible losses.

102
Q

How do neonates handle sodium in the first few days of life?

A

Obligate sodium loser.

103
Q

When do neonates improve in retaining sodium?

A

After the first few days, better at retaining than excreting sodium.

104
Q

When does GFR reach adult levels in neonates?

A

8 - 24 months of age.

105
Q

When does renal tubular function achieve full concentrating ability?

A

~ 2 years of age.

106
Q

What is the total body water status in premature newborns?

A
  • Highest in premature newborns
  • Decreases with age.
107
Q

How does total body water (TBW) change with age?

A
  • Highest at birth
  • Decreases with age.
108
Q

How does extracellular fluid (ECF) change with age?

A
  • Highest at birth
  • Decreases with age
109
Q

How does intracellular fluid (ICF) change with age?

A
  • Lowest at birth
  • Increases with age
110
Q

What are signs of dehydration in infants?

A
  • Sunken anterior fontanel
  • Weight loss
  • Lethargy
  • Dry mucus membranes
  • Increased hematocrit
111
Q

When does total body water as a function of weight reach adult values?

A

By one year of age.

112
Q

What is the basis of fluid management in neonates?

A
  • The 4:2:1 rule
  • Consisting of hourly maintenance
  • NPO deficit
  • Third-space loss
  • Blood loss.
113
Q

How much fluid does a baby require after the first week?

A

150 mL/kg/day.

114
Q

When is the routine use of glucose-containing solutions recommended for neonates?

A

Only if the neonate is at risk for hypoglycemia.

115
Q

What hepatic function is enhanced just before birth?

A

Synthesis and storage capacity for glycogen greatly increased.

116
Q

What percentage of stored glycogen is released within the first 48 hours of life?

A

98%

117
Q

When are glycogen levels restored to adult levels?

A

By the third week of life.

118
Q

What percentage of adult albumin levels is present at birth?

A

75-80%

119
Q

How does the newborn’s ability to bind drug to plasma proteins affect drug levels?

A

Results in a greater level of free drug due to lower binding ability.

120
Q

When may hyperbilirubinemia develop in term infants?

A

Within the first day of life.

121
Q

What are common bilirubin levels in term infants?

A

6-8 mg/100mL

122
Q

Why do neonates have problems with thermoregulation?

A
  • Large surface area
  • Poor insulation
  • Small mass
  • Inability to shiver
123
Q

What is the neonate’s primary defense against hypothermia?

A

Non-shivering thermogenesis.

124
Q

How does hypothermia trigger heat generation in neonates?

A
  • Stimulates norepinephrine release
  • Which acts on brown fat
  • To uncouple oxidative phosphorylation
125
Q

What effect do anesthetic agents have on thermoregulation in neonates?

A

Inhibit thermoregulatory response.

126
Q

How much can core temperature decrease in neonates?

A

1℃ to 3℃.

127
Q

What characteristic of neonate’s skin contributes to heat loss?

A
  • Thinner skin
  • Less subcutaneous tissue
  • Increase evaporative heat loss.
128
Q

What is the cardiac output in newborns and its impact?

A
  • 200 mL/kg/min
  • Faster drug delivery/removal.
129
Q

Why do neonates need higher doses of water-soluble drugs?

A

Higher body water percentage.

130
Q

How does protein binding in neonates affect drug levels?

A
  • Lower albumin/alpha-1 acid glycoprotein
  • Increased free drug levels
  • Toxicity risk.
131
Q

How does neonate’s body composition affect drug duration?

A
  • More water
  • Less fat/muscle
  • Longer drug action
132
Q

What enzyme’s reduction affects neonates’ drug metabolism?

A
  • Glucuronyl transferase
  • Impacts bilirubin and acetaminophen metabolism.
133
Q

When is normal GFR achieved in neonates?

A

8 - 24 months of age.

134
Q

When is normal tubular function achieved in neonates?

A

2 years of age.

135
Q

How does the immature BBB affect drug passage in neonates?

A
  • Allows more drugs to enter the brain
  • Increasing sensitivity to sedative-hypnotics
136
Q

How does MAC vary in neonates and infants?

A
  • Neonate: Lower than infant.
  • Premature: Lower than neonate.
  • 1-6 months: Higher than adult.
  • 2-3 months: Peaks at highest level.
137
Q

How does the MAC requirement for sevoflurane vary from 0 days to 12 years?

A
  • 0-6 months: Higher (3.2%).
  • 6 months-12 years: Lower than 0-6 months but higher than adult (2.5%).
138
Q

What is the required dose of succinylcholine in neonates and why?

A
  • 2 mg/kg
  • Due to increased ECF
  • Normal sensitivity
139
Q

How does increased ECF affect dosage of nondepolarizers in neonates?

A
  • Dose remains the same as adults
  • Duration may be prolonged due to immature metabolism
140
Q

What does the FDA black box warning for succinylcholine in children under 8 highlight?

A
  • Risk of hyperkalemia from undiagnosed muscular dystrophy
  • IV calcium is priority for hyperkalemia following cardiac arrest.
141
Q

Which neuromuscular blockers can be administered intramuscularly?

A
  • Succinylcholine
  • Rocuronium
142
Q

What objective data suggests recovery from neuromuscular blockade?

A
  • TOF ratio > 90%
  • MIF less than -25 cm H2O.
143
Q

What are subjective signs of adequate recovery from neuromuscular blockade?

A
  • Grimacing
  • Elbow and hip flexion
  • Bringing knees to the chest
144
Q

Which two body systems are of primary interest in a preanesthetic system review?

A

Respiratory and cardiovascular systems.

145
Q

Besides respiratory and cardiovascular, what other issues are crucial for anesthesia planning?

A

Metabolic and structural problems.

146
Q

What should an anesthetist assess for during a physical assessment?

A

Presence of congenital anomalies.

147
Q

CV, Respiratory, metabolic and structural problems most often occur?

A
  • SGA (Small for Gestational Age)
  • LGA (Large for Gestational Age) neonates.
148
Q

What is caudal anesthesia and when is it used?

A
  • Most used regional anesthetic in pediatric anesthesia
  • For procedures involving sacral, lumbar, or lower thoracic dermatomes
149
Q

How is the patient positioned for caudal anesthesia?

A
  • Lateral position with knees flexed
  • Landmarks are the tip of the coccyx and sacral cornu.
150
Q

How does the volume of local anesthetic affect caudal anesthesia?

A
  • 1.2 to 1.5 mL/kg reaches T4-T6 dermatomes
  • 1 mL/kg is used for lower procedures.
151
Q

What guides the choice and dose of local anesthetic in caudal anesthesia?

A
  • Practitioner’s preference
  • Concentration adjusted to max 2.5 mg/kg.