Transcript Pediatric Anesthesia

Presented May 2003
Pediatric Anesthesia
Abdulaziz Hisham Al Gain
Development:
 Organogenesis - 1st 8 weeks
 Organ function - 2nd trimester
 Body mass - 3rd trimester
Changes in cardiovascular system:
 Removal of placenta from circulation
 Increasing of systemic vascular resistance
 Decreasing of pulmonary vascular resistance
 True closure of PDA ~ 2-3 weeks  critical
transitional circulation
 Myocardial cell mass less developed  prone to
biventricular failure, volume loading, poor
tolerance to afterload, heart rate-dependent CO*
* True for young infants
Changes in pulmonary system:
 Small airway diameter - increased resistance
 Little support from the ribs
 VO2 2x > adults
 Diaphragm and intercostal muscles do not achieve
type-1 adult muscle fibers until age 2
 Obligate nasal breathers
Airway difference:
 Large tongue
 Higher located larynx
 Epiglottis short and stubby, angled over the inlet
 Angled vocal cords  we must rotate ETT to correct
lodging at anterior comissure
 Narrowest portion is cricoid cartilage
Chest wall/Respiratory difference:
 Ribs are horizontal in neonates (vertical in adults)
 Ribs and cartilages are more pliable
 Chest wall collapse more with increased negative
intrathoracic pressure
 Atelectasis is more common
  FRC
  number of alveoli
 Alveolar ventilation/FRC:
Adults = 1.5:1
Infants = 5:1 ( respiratory rate)
Kidney and liver difference:
 Low renal perfusion pressure, immature GF, TF,
obligate Na loser in the 1st month of life
 Complete maturation @ 2 years of age
 Impaired liver enzymes, including conjugation
react.
 Lower levels of albumen and proteins - prone to
neonatal coagulopathy, and less drug
bound 
higher drug levels
GI system and thermoregulation:
 Full coordination of swallowing ~ 4-5 months 
increased risk for GE reflux
 Large body surface area/weight
 Limited ability to cope stress
 Minimal ability to shiver in 1st 3 months
 Heat whole body including the head
Pharmacology/dynamics:
 Increased total body water:
 Large initial dose required
 Less fat  longer clinical drugs effect
 Redistribution of the drug into muscle will
increase duration of clinical effect (fentanyl)
 Consider liver and kidney immaturity
Volatile anesthetics
Isoflurane:
 Less myocardial depression than Halothane
 Preservation of heart rate
 CMRO2 reduction rate
Desflurane:
 Increased incidence of coughing, laryngospasm,
secretions
 Concern of hypertension and tachycardia from
sympathetic activation
Volatile anesthetics (2)
Sevoflurane
 Less pungent than Isoflurane
 Concern of compound A (nephrotoxicity)
 Most suitable for induction
Remember: MAC for potent volatile anesthetics
is increased in neonates, but may be lower for
sicker neonates and premies
Induction drugs:
Methohexital:
 1-2 mg/kg i.v. or 25-30 mg/kg per rectum
 Side effects:
burning
hiccup
apnea
extrapyramidal syndrome
 Contraindication: temporal lobe epilepsy
Thiopental:
 5-6 mg/kg i.v.
 Caution in low fat children and malnourished
Induction drugs:
Propofol:
 3 mg/kg i.v. (until 6 years of age)
 Pain on injection - 0.2 mg/kg Lidocaine i.v.
Ketamine:
 10 mg/kg IM, PR, orally
 Increased salivation
Contraindications:
Increased ICP
Open globe injury
Induction drugs:
Benzodiazepines:
Diazepam:
 0.1-0.3 mg/kg orally
 T1/2 80 hours  contraindicated < 6 months
Midazolam:
 Only FDA benzodiazepine approved in neonates
 0.1-0.15 mg/kg IM
 0.5-0.75 mg/kg orally
 0.75-1.0 mg/kg rectally
 Reduce dose in drugs  cause Cytochrome P450 inhibition
Induction drugs:
Narcotics:
Morphine:
 Increased permeability of blood/brain barrier
 50 mcg/kg IV
Meperidine:
 Less respiratory depression than morphine
 Be cautious in long term administration because
of its metabolite normeperidine
Induction drugs:
Narcotics(2):
Fentanyl:
 12.5 mcg/kg IV during induction provides stable
cardiovascular response
 1-2 mcg/kg adjuvant to anesthesia
 Stable cardiovascular response
Alfentanyl and Sufentanyl:
 More rapid clearance than adults
 Can cause parasympatholysis  bradycardia,
hypotension
Induction drugs:
Muscle relaxants:
Succinylcholine:
 2.0 mg/kg IV; 4.0 mg/kg IM
 Consider Atropine 10-15 mcg/kg given prior SUX
 Potential side effects:
Rhabdomyolysis
Hyperkalemia
Masseter spasm
MH
Induction drugs:
Muscle relaxants(2):
 If tachycardia desired - Pancuronium
 Mivacurium - brief surgeries, beware of
histamine release, bronchospasm
 Rocuronium - useful for modified RSI, and can
be administered IM (1 mg/kg)
Muscle relaxants - Summary:
MAINTENANCE DOSE (ED95)
(mg/kg) DURING ANESTHESIA
WITH
Muscle relaxanta
d-Tubocurarine
Pancuronium
Metocurine
Atracurium
Cisatracurium
Vecuronium
Mivacurium
Doxacurium
Pipecuronium
Reversal agentsb
Edrophonium
Neostigmine
N2O/O2
HALOTHANE
0.60
0.08
0.34
0.30
0.10
0.08
0.10
0.030
0.080
0.30
0.06
0.15
0.20
0.080
0.06
0.10
0.030
0.080
(0.3–1.0 mg/kg) +
atropine (0.01–0.02
mg/kg)
(0.02–0.06 mg/kg)
+ atropine (0.01–
0.02 mg/kg)
SUGGESTED DOSE (mg/kg) FOR
TRACHEAL INTUBATION
(2 × ED95)
0.80
0.10–0.15
0.50–0.60
0.50–0.60
0.10
0.10–0.15
0.20–0.25
0.050–0.060
0.080–0.120
Premedication:
 Almost all sedatives are effective
 Usually not necessary < 6 months
 Most common route used is oral
 Side effects:
Oral - slow onset
IM - pain, sterile abscess
Rectal - uncomfortable, defecation, burn
Nasal -irritating
Sublingual -bad taste
Pharmacological premedication
options
1. Role when awake separation of child from
parent before induction is planned.
2. Its success may be judged by the peacefulness of
the separation.
3. Large volume of literature indicates lack of
clearly ideal technique
http://metrohealthanesthesia.com/edu/ped/pedspreop6.htm
Pharmacological premedication options
Midazolam (Versed)
•
•
•
•
•
•
PO: 0.5 to 1.0 mg/kg up to 10 mg max.
Bioavailability = 30%
Peak serum levels after about 45 minutes
Peak sedation by about 30 minutes
85% peaceful separation
Mix with grape concentrate or acetaminophen
(Tylenol) syrup or elixir or Motrin Suspension (10
mg/kg of the 2% suspension)
Pharmacological premedication options (3)
Midazolam (Versed)(2)
•
•
•
•
•
Nasal: 0.2 to 0.6 mg/kg
Peak serum level in 10 minutes
0.2 mg/kg same as 0.6 mg/kg except
0.2 mg/kg did not delay recovery
0.6 mg/kg may delay extubation
• Possible concern: animal studies reveal
neurotoxicity after topical applicaton.
Pharmacological premedication options (4)
Midazolam (Versed)(3)
• Sublingual: 0.2-0.3 mg/kg as effective as 0.2
mg/kg intranasal
• Rectal: 0.35 to 1.0 mg/kg
• Some effect by 10 minutes, peak effect 20-30
minutes.
• 1.0 mg/kg did not delay PACU discharge.
Pharmacological premedication options (5)
Methohexital (Brevital)
• Rectal 25 to 30 mg/kg as 10% solution in warm
tap water
• 85% sleeping within 10 minutes = rectal
induction of GA (very peaceful separation)
• Sleep duration: about 45 to 90 minutes
• 25 mg/kg did not delay recovery in one study, but
some delay may be expected after a short (less
than 30-minute) case.
Pharmacological premedication options (6)
Ketamine
• PO: 6 to 10 mg/kg
• May slightly prolong time to discharge after a
short case
• IM: 3 to 4 mg/kg sedation;
• 2 mg/kg did not delay recovery
• 6 to 10 mg/kg = IM induction of general
anesthesia
• 10 mg/kg: as effective as Midazolam 1 mg/kg but
some delay in recovery may be expected
Pharmacological premedication options (7)
Midazolam + Ketamine:
• PO 0.4 mg/kg + 4 mg/kg respectively
• 100% successful separation
• 85% easy mask induction
• Doubling dose leads to "oral induction of general
anesthesia" in most cases. Lasts 30 to 60
minutes.
Pharmacological premedication options (8)
Fentanyl "lollipops" (oral transmucosal Fentanyl)
• 15 to 20 mcg/kg
• Increased volume of gastric contents
• Nausea and vomiting
• Pruritus
• Hypoventilation (SpO2 <90)
Pharmacological premedication options (9)
1. Metoclopramide (Reglan) PO or IV: 0.2 mg/kg
2. Ranitidine (Zantac) PO 2.5 mg/kg
3. EMLA cream: Eutectic mixture of Lidocaine and
Prilocaine. For cutaneous application by occlusive
dressing one hour preoperative
4. Glycopyrrolate: consider for selected patients for
planned airway instrumentation; e.g.: fiberoptic
endoscopy, oral or upper airway surgery, cleft
palate)5-10 mcg/kg IV or 10 mcg/kg IM
Preoperative interview:
SAY
NOT
GOOD, YES
BAD, NO
sleepy breeze
anesthetic vapors
pinch
hug your arm
stickers
will be neat! fun!
might get the giggles
make you laugh
feels funny
take a little nap
good job, good boy/girl
proud of you
cool, refreshing
nice little back rub
gas
bad smell, stink, stench,
bee sting
take blood pressure
ekg pads
won't hurt
don't cry
make you cry
feels bad
put you to sleep
don't be bad
cold solution
press on your back
http://metrohealthanesthesia.com/edu/ped/pedspreop4.htm
Fasting:
 Clear liquids - 2-3 h before the procedure
 If infants are breast fed - 4 h before the procedure
 For older patients = the adults rule
 Be aware of dehydration
Induction of Anesthesia:
Inhalational induction:
 Younger than 12 months
 After the induction, place the intravenous catheter
 Use suggestions in older child (pilot’s mask)
 In a case of difficult airway - Fiberoptic intubation
Induction of Anesthesia:
Rectal induction:
 Methohexital
 Thiopental
 Ketamine
 Midazolam
 Technique no more intimidating than rectal
temperature measurement
 Usual time of onset ~ 10-15 min
Induction of Anesthesia:
Intramuscular induction:
 Most common used Ketamine
 Disadvantage painful needle insertion
 Advantage: reliability
Induction of Anesthesia:
Intravenous induction:
 The most reliable and rapid technique
 Disadvantage - starting intravenous line
 If patient is older ask the patient
 If you insert IV line:
I.
Do not allow the patient to see it
II.
Use EMLA cream
III. If use local - ask the patient if there is
any sensation on puncture
Patient with full stomach:
Treat the same as adult with full stomach:
 RSI with ODL using cricoid pressure
 Tell the patient that will feel “touching on the neck”
 Be aware of  VO2 (desaturation)
 0.02 mg/kg of Atropine administer before SUX to
avoid bradycardia (usually after 2nd dose)
 Use Rocuronium 1.2 mg/kg
 Use Succinylcholine 1-2 mg/kg  if really need
short duration (difficult airway)
Endotracheal tubes:
Recommended Sizes and Distance of Insertion of Endotracheal
Tubes and Laryngoscope Blades for Use in Pediatric Patients
RECOMMENDED
Age Of The
Diameter
Size of the
Patient
Distance
(internal)
Blade
Premature
2.5
0
6–7
(<1,250 g)
Full term
3.0
0–1
8–10
1y
4.0
1
11
2y
5.0
1–1.5
12
6y
5.5
1.5–2
15
10 y
6.5
2–3
17
18 y
7–8
3
19
4 + (1/4) (age) = size;
12 + (1/2) (age) = depth
Intravenous fluids:
Calculation of Maintenance Fluid Requirements for Pediatric
Patients
Weight
Fluids (mL/hour)
24-H Fluids (mL)
(kg)
<10
4 mL/kg
100 mL/kg
11–20
40 mL + 2 mL/kg > 10
1,000 mL + 50 mL/kg > 10
>20
60 mL + 1 mL/kg > 20
1,500 mL + 20 mL/kg > 20
Include if present: Fluid deficits
Third spaces losses
Hypo/hyperthermia
Unusual metabolic fluids demands
Fluid requirements in neonates:
During the 1st week reduced fluid requirements:
Day 1 - 70 ml/kg
Day 3 - 80 ml/kg
Day 5 - 90 ml/kg
Day 7 - 120 ml/kg
 Concern is immaturity of the neonatal kidney
 The volume of extracellular fluids in neonates is
large
 Consider use of radiant warmers, and heated
humidifiers - decrease insensible water loss
 Use LR for replacement, D5% with 0.45 NS by
piggyback
Packed Red Blood Cells:
The use has diminished because of disease
transmission (HIV, Hep C,B. etc)
Blood volume:
Premature infant - 100 -120 ml/kg
Full-term infant - 90 ml/kg
3-12 month old child - 80 ml/kg
1 year and older child - 70 ml/kg
EBV (starting Hct - target Hct)
MABL =
Starting Hct
Packed Red Blood Cells (2):
 Child usually tolerates Hct ~ 20 in mature children
 If:
Premature,
Cyanotic congenital disease
Hct ~ 30
 O2 carrying capacity
 No one formula permits a definitive decision
 Replace 1ml blood with 3 ml of LR
 Lactic acidosis is a late sing of decreased O2
carrying capacity
 Be aware of blood disorders (sickle cell disease)
Fresh Frozen Plasma:
 Use to replenish clotting factors during massive
transfusion, DIC, congenital clotting factor deficits
 Usually replenished if EBL = 1-1.5 TBV
 A patient should be never given FFP to replace bleeding that
is surgical in nature
 If transfused faster than 1.0 ml/kg/min severe
ionized hypocalcemia may occur
 If occurs - Rx. with 7.5-15 mg/kg Ca++ gluconate
 Ionized hypocalcemia can occur in neonates
frequently because of decreased ability to
mobilize Ca++ and metabolize citrate
Ionized Hypocalcemia:
Platelets:
 Find etiology - TTP, ITP, HIT, DIC, hemodilution
after massive blood transfusion
 Consider transfusion if Platelets < 50.000
 In certain hospitals platelet function test is available
 If Platelets < 100.000 and EBL = 1-2 TBV transfusion more likely
 If Platelets > 150.000 and EBL > 2 TBV
transfusion more likely
Monitoring the Pediatric Patients:
 Must be consistent with the severity of the
underlying medical condition
 Minimal monitoring:
I. 5 ASA monitors
II. Precordial stethoscope
III. Anesthetic agent analyzer
 Use of capnograph and O2 analyzers is associated
with high incidence of false alarms from:
movement artifact
light interference
electrocautery
Special Monitoring the Pediatric
Patients:
 Intraarterial catheter - most common radial
 Pulmonary artery catheters are rarely indicated
because equalization of the pressure right/left heart
 In a case of severe multisystem organ failure
insertion of PAC might be particularly useful
 Multilumen catheters are valuable in ICU patients
 In a case of rapid fluid replacement peripheral
venous catheter might be very useful
 Short-term cannulation of femoral/brachiocephalic
or umbilical vein may be life-saving
Anesthesia Circuits:
 Nonrebreathing circuits:
1. Minimal work of breathing
2. Speeds-up rate of inhalational induction
3. Compression and compliance volumes are
less (small circuit volume)
 Use of Mapleson D system is recommended in
children < 10 kg
More sensitive to changes in gas flow
More sensitive to humidification
Actual delivered volume is greater than
other systems
Mapleson D Circuit:
Gas disposition at end-expiration during spontaneous ventilation
Gas disposition at controlled ventilation
Neonatal Anesthesia:
 Understand differences in
Physiology
Pharmacology
Pharmacodynamic response
 Most of the complications that arise are attributable
to a lack of understanding of these special
considerations prior to induction of anesthesia
 Be aware of:
Sudden changes in hemodynamics
Unexpected responses
Unknown congenital problem
Neonatal Anesthesia (2):
 Children < 1 year old have more complications:
I. Oxygenation
II. Ventilation
III. Airway management
IV. Response to volatile agents and medications
 Stress response is poorly tolerated
 Consider:
1. Organ system immaturity
2. High metabolic rate
3. Large ratio body surface/weight
4. Ease of miscalculating a drug dose
Neonatal Anesthesia (3):
 Prevention of paradoxical air emboli
 Fluids instituted with volume-limiting devices
 Minimize thermal stress
 Use flow-through capnograph if possible
 Prevent retinopathy of prematurity by:
Lower FiO2
Keep CO2 within normal range
Neonatal Anesthesia (4):
Stress Response:
 Poorly tolerated
 Use opioid technique (blunt pain response)
 Ketamine is excellent choice –stable intraoperative
hemodynamics
 Potent volatile anesthetics are poorly tolerated
 No one should be denied anesthesia because of
the age or weight
Special Problems in Neonatal
Anesthesia:
Meningomyelocele:
 Underestimating fluid or blood loss from the defect
 High association with hydrocephalus
 Possibility of cranial nerve palsy
 Potential for brain-stem herniation
Special Problems in Neonatal Anesthesia (2):
Pyloric stenosis:
 First 3-6 weeks in life
 Anesthesiologist concern:
I. Full stomach with barium
II. Metabolic alkalosis with
Hypochloremia and Hypokalemia
III. Severe dehydration
 Surgery is never emergency
 Metabolic correction mandatory before the surgery
 Suction the stomach before induction
 Consider awake intubation or RSI
Special Problems in Neonatal Anesthesia (3):
Omphalocele and Gastroschisis:
 Omphalocele occurs because of failure of the gut to
return to the abdominal cavity at 10th week of life
 Fine membrane covers intestines and abdominal
contents
 Gastroschisis develops later in life after gut has
returned into abdominal cavity
 Abdominal contents and organs are not covered with
any membrane – risk of infection
Special Problems in Neonatal Anesthesia (3):
Omphalocele
Special Problems in Neonatal Anesthesia (3):
Gastroschisis
Special Problems in Neonatal Anesthesia (3):
Omphalocele and Gastroschisis(2):
 Anesthesiology concern:
1. Dehydration
2. Massive fluid loss (exposed
viscera and 3rd space loss)
3. Heat loss
4. Difficulty of surgical closure
5. High association with prematurity, congenital
defects, including cardiac anomalies
 Minimize infection, Replenish fluids, be liberal in
muscle relaxants, consider hypotension and
difficulty ventilation
Special Problems in Neonatal Anesthesia (3):
Omphalocele and Gastroschisis(3):
 During closure consider
* difficulty ventilation
* hypotension
*  abdominal pressure may compromise liver
function and alter drug metabolism
 During closure of big defects monitoring of the
bladder pressures is important: if the pressure is
< 20 cm H2O attempt is to close, > 20 cm H2O
closing in stages.
Special Problems in Neonatal Anesthesia(3):
Omphalocele and Gastroschisis (4):

Be aware of Beckwith-Wiedemann syndrome:
Profound hypoglycemia
Hyperviscosity syndrome
Associated visceromegaly
Special Problems in Neonatal Anesthesia(3):
Omphalocele and Gastroschisis ddx. (5):
1.
Much greater associated defects with Omphalocele
2.
More fluid loss associated with Gastroschisis
Special Problems in Neonatal Anesthesia(4):
Tracheoesophageal fistula anomaly(1):
 90 % proximal atresia of esophagus
with distal fistula
 Consider aspiration pneumonitis.
Trachea
 VATER syndrome:
I. Vertebral
II. Anal
T-type
III. Tracheoesophageal
IV. Renal
 MCC of death – cardiac anomalies
Special Problems in Neonatal Anesthesia(4):
Tracheoesophageal fistula anomaly(1):
 90 % proximal atresia of esophagus
with distal fistula
 Consider aspiration pneumonitis.
Trachea
 VATER syndrome:
I. Vertebral
II. Anal
T-type
III. Tracheoesophageal
IV. Renal
 MCC of death – cardiac anomalies
Special Problems in Neonatal Anesthesia(4):
Tracheoesophageal fistula anomaly(2):
 Major issues are:
 Aspiration pneumonia
Trachea
 Overdistention of the stomach
 Inability to ventilate
 Postoperative intensive care
T-type
Special Problems in Neonatal Anesthesia (4):
Tracheoesophageal fistula anomaly(3):
Induction:
 Awake intubation
 Deliberate right main stem intubation
 Catheter in esophagus
Trachea
 Prone position with head-up
T-type
 Avoid massive distention of the stomach
by gentle ventilation
 Careful confirmation of tube position
by moving tube mm by mm (position must be
between fistula and tracheal bifurcation)
 Tape precordial stethoscope over the left chest
Special Problems in Neonatal Anesthesia (5):
Diaphragmatic hernia:
 Usually presentation on
1st day of life
 Almost all viscera can be in the
chest cavity
 Anesthesia concerns:
I. Hypoxemia
II. Hypotension
III. Stomach herniation
IV. Pulmonary hypertension
V. Systemic hypotension
Shifted
mediastinum
Diaphragmatic hernia
Special Problems in Neonatal Anesthesia (5):
Diaphragmatic hernia (2):
1. Awake intubation
2. Intraarterial catheter
3. Use opioids (stress response)
4. Use Pancuronium
Shifted
mediastinum
5. Avoid hypothermia
Diaphragmatic hernia
6. Avoid any myocardial depressant
7. Avoid N2O (abdominal distention)
8. Aware of barotrauma-induced pneumothorax
9. Adequate intravenous access
10. Plan postoperative care
Special Problems in Neonatal Anesthesia (6):
Former preterm infant (<37 weeks):
 High incidence of apnea risk factors:
Respiratory distress syndrome
Bronchopulmonary dysplasia
Neonatal dyspnea
Necrotizing enterocolitis
Ongoing apnea at the time of surgery
Use of narcotics
Long acting muscle relaxants
Anemia (Hct < 30)
Regional Anesthesia and Anesthesia:
(brief overview)
 Most regional anesthetics are safe to use
 Strict attention to:
Dose
Route of administration
Proper equipment used
 Common:
Caudal blocks