Introduction
Anesthesia-related morbidity and mortality is higher in infants than adults, as well as in
younger compared to older children. In particular, airway complications are more likely
in very young infants. Critical events are highest in infants < 2 kg [Tay et. al. Paediatr
Anaesth 11: 711, 2001]
Podcast on Neurotoxicity, Pediatric Anesthesiology: Discussion with Sulpicio G.
Soriano from March 2010
Podcast on Pediatric anesthesia, neurotoxicity, postoperative delirium: Discussion
with Peter Davis from April 2011
Preoperative Checklist
Warm the room, peds Bear hugger, overhead warming lights, age appropriate headrest
and monitors. IV setup in room. See patient early to determine need for premedication
needs. For latex precautions, use latex free gloves, black bag on circuit, latex-free IV
setup (clear masks are OK, as are ETT, LMA, and pink tape)
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Warm the room
Peds Bair hugger
Overhead
Warming lights
Age appropriate headrest and monitors
IV setup in room
See patient early to determine need for premedication needs
For latex precautions, use latex free gloves, black bag on circuit, latex-free IV
setup (clear masks are OK, as are ETT, LMA, and tape)
Pediatric Airway
The tongue is relatively larger, thus making a disproportionate contribution to airway
obstruction and moving the glottis anteriorly (especially in children with craniofacial
abnormalities, NMJ or CNS disease, tumors, hemangiomas, or URIs). Flexion of an
infant's head may collapse the airway
Pediatric patients often have less pulmonary reserve than adults, and require significantly
more oxygen intake, thus they are prone to apnea during direct laryngoscopy
The larynx in infants is located at C3-4 (as opposed to C4-5 in adults). The infant
epiglottis is large but short and narrow, possibly making a direct view of the larynx easier
than in an adult. Note that the posterior commissure is relatively cephalad, predisposing
the anterior sublaryngeal airway to trauma from the ETT. The narrowest portion of the
infant airway is the cricoid cartilage, which can lead to resistance after passing an ETT
through the cords
Cuffed vs. Uncuffed ETT
In 2009 a multicenter study comparing Microcuff tubes to uncuffed tubes in 2246
children showed that rates of tube exchange were 2.1% with cuffed compared with
30.8% for conventional tubes (p < 0.0001), and that rates of post-extubation stridor
were equal in both groups. Furthermore, the cuff significantly improved the accuracy
of the ET monitor. Anesthesia providers could ventilate with an average cuff pressure of
10 cm H20 [Weiss M et al. Br J Anaesth 103: 867, 2009; Full-text at BJA]
Pediatric Endotracheal Tube Size
Internal
Depth (cm)
Diameter (mm)
Preterm 2.5
6-8
Term
3.0
9 - 10
6 months 3-3.5
10
1 - 2 years 4.0
10 - 11
3 - 4 years 4.5
12 - 13
5 - 6 years 5.0
14 - 15
10 years 6.0
16 - 17
Age
Pediatric Endotracheal Tube Depth
For preemies and neonates (cm) = weight (in kg) + 6 For 1 year or older (cm) = age + 10
cm
Pediatric Airway Equipment
Age
Miller Blade
< 32 weeks 00
Term
0 (< 3 kg)
3-18 mo. 1 (3-10 kg)
> 18 mo 2 (> 12 kg)
Pediatric LMA Size
LMA sizes ~ weight (kg) / 20 + 1 (round to nearest 0.5)
Organ Systems
Cardiovascular
Fetal circulation displays 1) increased PVR 2) decreased Qpulm 3) decreased SVR 4)
RtoL shunting through foramen ovale. Hypoxemia or acidosis in the newborn can cause a
return to fetal circulation
Neonatal hearts are relatively non-compliant and thus stroke volume is relatively fixed they rely entirely on heart rate to manage cardiac output
Murmurs, abnormal heart sounds, dysrhythmias, and cardiomegaly are all important
when noted in a newborn. EKG, CXR, and echo are therefore often required
Normal Physiologic Variables
Age
BP (mmHg) HR (/min) RR (/min) Hct (%)
1 kg
45/30
120 - 180
40 - 50
2 kg
55/35
110 - 180
40 - 50
3 kg
65/40
100 - 180 40 - 60
45 - 65
Neonate 75/45
100 - 180 35 - 55
45 - 65
6 mo. 85/50
80 - 180 30 - 50
30 - 40 (nadir)
1 year 95/55
80 - 130 20 - 30
34 - 42
10 year 110/60
60 - 100 20
35 - 43
Adult 110/60
60 - 100 15
40 - 50
Hypovolemia
Hypotension is a late finding in pediatric patients (children may maintain a normal
blood pressure until 35% of blood volume is lost). Tachycardia is sensitive but not
specific indicator. Prolonged capillary refill (> 2 seconds), especially when combined
with tachycardia, is more specific, although it may be difficult to measure. Cold skin and
decreased urine output may be present. Weak pulses, mottling, cyanosis, and
impaired consciousness may all precede hypotension. In fact, hypotension is an ominous
sign in pediatric patients
Hypovolemia in Pediatrics: Signs
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Tachycardia: sensitive but not specific. Resolution may help guide therapy
Delayed Capillary Refill: specific if > 2 seconds
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Others: weak pulses, mottling, cyanosis, and impaired consciousness (may all
precede hypotension), cold skin, decreased urine output
Hypotension: late finding. OMINOUS
(for more information, see Rasmussen GE, Grandes CM: Blood, fluids, and electrolytes
in the pediatric trauma patient, Int Anesthesiol Clin 32:79-101, 1994 or TABLE 30-5 in
Smith's Anesthesia...)
Source: Smith's Anesthesia for Infants and Children, 8th Edition. Chapters 5, 30, 39
(ISBN 0323066127)
Pulmonary
The lung is not fully formed at birth, and increases from 20 MM alveoli to 300 MM by
18 months of age. Newborn ribcages are particularly compliant and have a circular (nonellipsoid) configuration as well as a horizontal (non-oblique) insertion of the diaphragm,
all of which lead to inefficient diaphragmatic contraction. Worse, full-term infant
diaphragms only have 25% type I (slow twitch) fibers, as opposed to 55% in adults
FEN/Renal System
Newborns
Newborns have decreased GFR, decreased ability to excrete solid material, and decreased
ability to concentrate urine (ie conserve water). Adult values of GFR are reached between
12 and 24 months of life
Age (weeks) Urine Output (ml/h)
20
5 cc/hr
30
18 cc/hr
40
50 cc/hr
This limited renal resorptive function explains the "physiologic" decrease in bicarbonate
(and corresponding acidosis) in newborns (pH 7.26-7.29 at birth, 7.37 at 24h, 7.40 at 1
week)
Estimated blood volume changes with age - at term, the body is 78% water, and adult
proportions are not reached until between 9 and 24 months.
Infants have higher plasma chloride and lower bicarbonate (and pH). In the first ten days
of life, normal K values may be as high as 6.5 mEq/L. This drops to 3.5-5.5 mEq/L after
2-3 weeks of life. Water exchange is also negative during the first week of life due to
limited intake. Infants are at high risk for both over and under hydration
Children
Maintenance Requirements in Children
Weight (kg)
0-10
11-20
> 20 kg
Maintenance Requirements in Children
(mL/hour)
4 (mL/kg)
40 + 2 (mL/kg)
60 + 1 (mL/kg)
Replacement of Losses
Procedure
Insesnsible losses
Non-invasive (inguinal hernia, clubfoot)
0-2 cc/kg/hr
Mildly invasive (uteteral reimplantation) 2-4 cc/kg/hr
Moderately invasive (bowel reanastamosis) 4-8 cc/kg/hr
Significantly invasive (NEC)
> 10 cc/kg/hr
Endocrine
Intraoperative Glucose Infants: 4 mg/kg/min = 240 mg/kg/hr maintenance requirements
D5 = 50 mg/mL Delivery of D5 @ > 4 mL/kg/hr may lead to hyperglycemia
Hematology
At birth, full term infants have 18-20 g/dL of hemoglobin, 75% of which is HgF (which
normalizes by 3-6 months). Hgb will naturally decrease as the infant progresses, reaching
a nadir as low as 9-10 g/dL (avg 11.2 g/dL) around 2 months of age [Harriet Lane, 16th
ed. CV Mosby, 2002]. In premature infants, however, the nadir may be as low as 6-7
g/dL at 3 or 4 months of age
Cross matched blood should be available for newborn surgery. Assessment of clotting
function should be considered because prothrombin as well as factors II, VII, and X are
limited in young livers
Blocks
Caudal Block
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Equipment: 22g B-bevel needle (or angiocath)
Drugs: 0.25% bupivacaine or 0.2% ropivacaine +/- morphine 25 ucg/kg or
hydromorphone 6 ucg/kg
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Desired level and volume:
o Sacral Block: 0.5 ml/kg
o Midthoracic Block: 1.25 ml/kg
Complicating Issues in Peds
Upper Respiratory Tract Infection
Children recovering from URI are at increased risk for respiratory complications. For
short procedures via mask, the increased risk is minimal. If reactive airways accompany
the infection, the effects of URI may last 2-7 weeks. In particular, those who already have
asthma, bronchopulmonary dysplasia, < 1 yoa, sickle cell, or live in a household of
smokers are at high risk, suggesting a "two hit" phenomena [Tait et. al. Anesthesiology
95: 299, 2001]. Bronchial hyperreactivity may last as long as 7 weeks after URI [Collier
et. al. Am Rev Resp Dis 117: 47, 1978]. Note that in these patients MASK anesthetics
have significantly lower complications than LMA or ETT
If an ETT tube is required, the risk of anesthesia in an infant can be increased as much as
10-fold when compared to an infant with no URI and which does not require ETT. Risk
of an LMA are about halfway between those of a facemask and an ETT
Postoperative Croup (< 3 hrs after extubation)
IV decadron 0.25 - 0.5 mg/kg Racemic epinephrine 0.25-0.5 mL of 2.25% solution in 2.5
ml NS
Outpatient Surgery
Inguinal herniorrhaphy, hypospadias repair, and various orthopedic procedures are
performed on an outpatient basis in the pediatric population. LMA + caudal block (1
mg/kg 0.125-0.25% bupivacaine) can provide excellent postoperative pain control and
lower the anesthetic requirements. A more dilute anesthetic may be used to maintain
ambulation
Ex-Premature Infant
Post-operative apnea is always a concern, however it is impossible to fully develop a
monitoring protocol [Cote et. al. Anesthesiology 82: 809, 1995]. Apnea is rare after 48
weeks of conceptual age, but the incidence is not zero. The decision of whether or not to
admit an ex-premature infant s/p surgery must be individualized. The most conservative
approach would be to admit all infants younger than 60 weeks post-conception but this is
often impractical. Note that many of these children have chronic lung conditions that last
as many as ten years (mostly secondary to reactive airway disease). Hepatic and renal
function, as well as developmental delay may also occur.
Cote combined data from eight prospective studies (255 patients) to develop an algorithm
based on gestational age, post-conceptual age, apnea at home, size at gestational age, and
anemia [Cote CJ et. al. Anesthesiology 82: 809, 1995]. Cotes data showed that the
incidence of apnea following inguinal hernia repair did not fall below 5% until
gestational age reached 35 weeks and post-conceptual age reached 48 weeks, and that the
incidence of apnea following inguinal hernia repair did not fall below 1% until
gestational age reached 32 weeks and post-conceptual age reached 56 weeks (or postgestational 35 weeks with post-conceptual 54 weeks). Any infant that exhibits apnea, has
a history of apnea, or is anemic, should not undergo outpatient surgery
Formulas
Maintenance Requirements in Children
Weight (kg)
0-10
11-20
> 20 kg
Maintenance Requirements in Children
(mL/hour)
4 (mL/kg)
40 + 2 (mL/kg)
60 + 1 (mL/kg)
Replacement of Losses
Procedure
Insesnsible losses
Non-invasive (inguinal hernia, clubfoot)
0-2 cc/kg/hr
Mildly invasive (uteteral reimplantation) 2-4 cc/kg/hr
Moderately invasive (bowel reanastamosis) 4-8 cc/kg/hr
Significantly invasive (NEC)
> 10 cc/kg/hr
Intraoperative Glucose
Infants: 4 mg/kg/min = 240 mg/kg/hr maintenance requirements D5 = 50 mg/mL
Delivery of D5 @ > 4 mL/kg/hr may lead to hyperglycemia
Medications for Children
Preoperative Medication in Children
PO
Nasal
IV
IM
Midazolam 0.5 - 1.0 mg/kg
0.05 - 0.10 mg/kg
Fentanyl
1 - 3 ucg/kg
Morphine
0.05 - 0.10 mg/kg
Sufentanil
0.25 - 0.5 ucg/kg
Ketamine 2-4 mg/kg
4-6 mg/kg
Resuscitation Medication in Children
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Epinephrine = 10-100 ucg/kg for arrest (100 ucg/kg in ETT), 1-4 ucg/kg for
hypotension
Atropine = 0.01 - 0.02 mg/kg (0.3 mg/kg in ETT) - actual dose 0.1 - 1 mg
Adenosine = 0.1 mg/kg (max dose 6 mg)
Lidocaine = 1-1.5 mg/kg
SCh = 2-3 mg/kg
Rocuronium 1 mg/kg
Calcium chloride = 10-20 mg/kg (dilute to 10 mg/cc or else veins will sclerose,
try to give centrally if possible)
Bicarbonate = 1 mEq/kg (dilute to 1 mEq/cc or else veins will sclerose)
Naloxone = 0.1 mg/kg
DEFIBRILLATION = 2 J/kg (can increase up to 4 J/kg)
Preoperative Medication in Children
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Midazolam 0.05-0.1 mg/kg IV (0.5-1 mg/kg PO, 15 mg max)
Methohexital 1-2 mg/kg IV (25-30 mg/kg PR, 500 mg max)
Ketamine 1-2 mg/kg IV, 10 mg/kg IM, 5-8 mg/kg PO
Sodium Pentothal 1-2 mg/kg IV (separation), 4-6 mg/kg IV (induction)
Propofol 0.1-1 mg/kg IV (separation), 2-4 mg/kg IV (induction)
Etomidate 0.2-0.3 mg/kg IV
Antibiotic Doses in Children
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Cefazolin 25 mg/kg q6-8h up to 1-2 grams
Cefotaxime 20-30 mg/kg q6h
Ampicillin 50-100 mg/kg q6h up to 3 grams
Gentamicin 2-2.5 mg/kg q8h (must monitor serum levels, longer interval in renal
impairment)
Clindamycin 5-10 mg/kg q6-8h up to 900mg
Mezlocillinn 50-100 mg/kg q6h up to 2g
Vancomycin 10 mg/kg q6h up to 1g
Other Useful Medication in Children
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Glycopyrrolate 0.01 mg/kg IV, IM, ETT (max 0.4 mg)
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Morphine 0.05 - 0.1 mg/kg IV (max 0.4 mg/kg)
Fentanyl 1-5 ucg/kg IV
Ketorolac 0.5 mg/kg IV
Tylenol 20 mg/kg PO, 40 mg/kg PR
Zofran 0.05-0.15 mg/kg
Droperidol 20-25 ucg/kg
Dexamethasone 0.1-0.5 mg/kg for pain, N/V prophylaxis
Neostigmine 0.07 mg/kg
Dexamethasone 0.5-1 mg/kg for tracheal edema
Solumedrol 1 mg/kg IV
Source:
http://www.openanesthesia.org/