pediatricanesthesia mlg

8/6/2019 pediatricAnesthesia mlg

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Pediatric Anesthesia

Darko J Vodopich MD

Resident @ CWRUMHMC

Revised by: Greg Gordon MD, and Susan Sweda MD

Presented May 2003


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Development:

Organogenesis - 1st 8 weeks

Organ function - 2nd trimester

Body mass - 3rd trimester


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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 criticaltransitional circulation

Myocardial cell mass less developed prone tobiventricular failure, volume loading, poortolerance to afterload, heart rate-dependent CO*

* True for young infants


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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


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Airway difference:

Large tongue

Higher located larynx

Epiglottis short and stubby, angled over the inlet

Angled vocal cordswe must rotate ETT to correct

lodging at anterior comissure

Narrowest portion is cricoid cartilage


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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 pressureAtelectasis is more common

FRC

number of alveoli

Alveolar ventilation/FRC:Adults = 1.5:1Infants = 5:1 ( respiratory rate)


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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 conjugationreact.

Lower levels of albumen and proteins - prone toneonatal coagulopathy, and less drug

bound higher drug levels


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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 bodyincluding the head


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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


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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


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Volatile anesthetics (2)

Sevoflurane Less pungent than Isoflurane

Concern of compound A (nephrotoxicity)

Most suitable for induction

Remember: MAC for potent volatile anesthetics is increasedin neonates, but may be lower for sicker neonates and premies


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Induction drugs:

Methohexital: 1-2 mg/kg i.v. or 25-30 mg/kg per rectum Side effects:

burning

hiccupapneaextrapyramidal syndrome

Contraindication:temporal lobe epilepsy

Thiopental: 5-6 mg/kg i.v.

Caution in low fat children and malnourished


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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 salivationContraindications: Increased ICP

Open globe injury


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Induction drugs:

Benzodiazepines:Diazepam:

0.1-0.3 mg/kg orallyT1/2 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 drugsB cause Cytochrome P-

450 inhibition


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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 becauseof its metabolite normeperidine


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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


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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

HyperkalemiaMasseter spasmMH


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Induction drugs:

Muscle relaxants(2):

If tachycardia desired - Pancuronium

Mivacurium- brief surgeries, beware ofhistamine release, bronchospasm

Rocuronium- useful for modified RSI, and canbe administered IM (1 mg/kg)


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Muscle relaxants - Summary:


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Premedication:

Almost all sedatives are effective Usually not necessary < 6 months Most common route used is oral Side effects:

Oral - slow onsetIM - pain, sterile abscessRectal - uncomfortable, defecation, burnNasal -irritatingSublingual -bad taste


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Pharmacological premedication options

1. Role when awa e separation of child from

parent before induction is planned.

2. Its success may be judged by the peacefulness ofthe separation.

3. Large volume of literature indicates lack ofclearly ideal technique

http://metrohealthanesthesia.com/edu/ped/pedspreop6.htm


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Pharmacological premedication options

Midazolam (Versed)

PO: 0.5 to 1.0 mg/kg up to 10 mg max.

Bioavailability = 30% Pea serum levels after about 45 minutes Pea sedation by about 30 minutes 85% peaceful separation

Mix with grape concentrate or acetaminophen(Tylenol) syrup or elixir or Motrin Suspension (10mg/kg of the 2% suspension)


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Pharmacological premedication options(3)

Midazolam (Versed)(2)

Nasal: 0.2 to 0.6 mg/kg

Pea 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 revealneurotoxicity after topical applicaton.


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Midazolam (Versed)(3)

Sublingual: 0.2-0.3 mg/kg as effective as 0.2mg/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.


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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, butsome delay may be expected after a short (lessthan 30-minute) case.


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Ketamine

PO: 6 to 10 mg/kg

May slightly prolong time to discharge after ashort case IM: 3 to 4 mg/kg sedation; 2 mg/kg did not delay recovery

6 to 10 mg/kg = IM induction of generalanesthesia

10 mg/kg: as effective as Midazolam 1 mg/kg butsome delay in recovery may be expected


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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 generalanesthesia" in most cases. Lasts 30 to 60minutes.


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Fentanyl "lollipops"(oral transmucosal Fentanyl)

15 to 20 mcg/kg

Increased volume of gastric contents

Nausea and vomiting

Pruritus

Hypoventilation (SpO2


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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 andPrilocaine. For cutaneous application by occlusivedressingone hourpreoperative

4. Glycopyrrolate: consider for selected patients forplanned airway instrumentation; e.g.: fiberopticendoscopy, oral or upper airway surgery, cleftpalate)5-10 mcg/kg IV or 10 mcg/kg IM


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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


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Induction of Anesthesia:

Inhalational induction:

Younger than 12 months

After the induction, place the intravenous catheter

Use suggestions in older child (pilots mask)

In a case of difficult airway - Fiberoptic intubation


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Rectal induction:

MethohexitalThiopental Ketamine MidazolamTechnique no more intimidating than rectal

temperature measurement Usual time of onset ~ 10-15 min


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Intramuscular induction:

Most common used Ketamine

Disadvantage painful needle insertion

Advantage: reliability


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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 itII. Use EMLA creamIII. If use local - ask the patient if there is

any sensation on puncture


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Patient with full stomach:

Treat the same as adult with full stomach:

RSI with

O

DL using cricoid pressureTell 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)


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Endotracheal tubes:Recommended Sizes andDistance ofInsertion ofEndotracheal

Tubes and Laryngoscope lades for se in Pediatric PatientsRECO ENDED

AgeOf ThePatient Diameter

(internal)Size of the

ladeDistance

Premature(


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Intravenous fluids:

Calculation ofMaintenance Fluid Require ents for ediatricatients

Wei t(k )

Fluids ( L/h o u r ) 24-H Fluids ( L)


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Fluid re uirements in neonates:

During the 1st week reduced fluid requirements:Day 1 - 70 ml/kgDay 3 - 80 ml/kgDay 5 - 90 ml/kg

Day 7 - 120 ml/kg Concern is immaturity of the neonatal kidneyThe volume of extracellular fluids in neonates is

large

Consider use of radiant warmers, and heatedhumidifiers - decrease insensible water loss

Use LR for replacement, D5% with 0.45 NS bypiggyback


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Pac ed Red lood Cells:

The use has diminished because of diseasetransmission (HIV, Hep C,B. etc)

Blood volume:Premature infant - 100 -120 ml/kg

Full-term infant - 90 ml/kg3-12 month old child - 80 ml/kg1 year and older child - 70 ml/kg

EBV (starting Hct - target Hct)MABL =

Starting Hct


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Pac ed Red lood 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 decreasedO2carrying capacity

Be aware of blood disorders (sickle cell disease)


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Fresh Frozen Plasma:

Use to replenish clotting factors during massivetransfusion, DIC, congenital clotting factor deficits

Usually replenished if EBL = 1-1.5 TBVA 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 hypocalcemiamay occur If occurs - Rx. with 7.5-15 mg/kg Ca gluconate Ionized hypocalcemia can occur in neonates

frequently because of decreased ability tomobilize Ca++ and metabolize citrate


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Ionized Hypocalcemia:


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Platelets:

Find etiology - TTP, ITP, HIT, DIC, hemodilutionafter 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 TBVtransfusion more likely


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Monitoring the Pediatric Patients:

Must be consistent with the severity of theunderlying medical condition

Minimal monitoring:

I. 5 ASA monitorsII. Precordial stethoscopeIII. Anesthetic agent analyzer

Use of capnograph and O2 analyzers is associated

with high incidence of false alarms from:movement artifact

light interferenceelectrocautery


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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 failureinsertion of PAC might be particularly useful Multilumen catheters are valuable in ICU patients

In a case of rapid fluid replacement peripheralvenous catheter might be very useful Short-term cannulation of femoral/brachiocephalicor umbilical vein may be life-saving

SpecialMonitoring the Pediatric

Patients:


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Anesthesia Circuits:

Nonrebreathing circuits:1. Minimal work of breathing2. Speeds-up rate of inhalational induction

3. Compression and compliance volumes areless (small circuit volume) Use of Mapleson D system is recommended in

children < 10 kg

More sensitive to changes in gas flowMore sensitive to humidificationActual delivered volume is greater than

other systems


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MaplesonDCircuit:

Gas disposition at end-expiration during spontaneous ventilation

Gas disposition at controlled ventilation


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Neonatal Anesthesia:

Understand differences inPhysiologyPharmacologyP

harmacodynamic response Most of the complications that arise are attributableto a lack of understanding of these special considerations priorto induction of anesthesia

Be aware of:Sudden changes in hemodynamicsUnexpected responsesUnknown congenital problem


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Neonatal Anesthesia (2):

Children < 1 year old have more complications:I. OxygenationII. Ventilation

III. Airway managementIV. Response to volatile agents and medications Stress response is poorly tolerated Consider:

1.O

rgan system immaturity2. High metabolic rate3. Large ratio body surface/weight4. Ease of miscalculating a drug dose


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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 FiO2Keep CO2within normal range


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StressR

esponse: Poorly tolerated

Use opioid technique (blunt pain response)

Ketamine is excellent choice stable intraoperativehemodynamics

Potent volatile anesthetics are poorly tolerated

No one should be denied anesthesia because ofthe age or weight


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Special Problems in Neonatal Anesthesia (2):

Pyloric stenosis: First 3-6 weeks in lifeAnesthesiologist concern:

I. Full stomach with bariumII. Metabolic alkalosis withHypochloremia and HypokalemiaIII. Severe dehydration

Surgery is never emergency Metabolic correction mandatory before the surgery Suction the stomach before induction Consider awake intubation or RSI


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Omphalocele and Gastroschisis:

Omphalocele occurs because of failure of the gut toreturn to the abdominal cavity at 10thweek of life

Fine membrane covers intestines and abdominalcontents

Gastroschisis develops later in life after gut has

returned into abdominal cavityAbdominal contents and organs are not covered with

any membrane risk of infection


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Omphalocele


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Gastroschisis


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Omphalocele and Gastroschisis(2):Anesthesiology concern:

1. Dehydration2. Massive fluid loss (exposed

viscera and 3rd space loss)3. Heat loss4. Difficulty of surgical closure5. High association with prematurity, congenital

defects, including cardiac anomalies Minimize infection, Replenish fluids, be liberal in

muscle relaxants, consider hypotension anddifficulty ventilation


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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 thebladder pressures is important: if the pressure is< 20 cm H2O attempt is to close, > 20 cm H2Oclosing in stages.


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Special Problems in Neonatal Anesthesia(3):

Omphalocele and Gastroschisis(4):

Be aware of Beckwith-Wiedemann syndrome:

Profound hypoglycemia

Hyperviscosity syndrome

Associated visceromegaly


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Omphalocele and Gastroschisisddx. (5):

1. Much greater associated defectswith Omphalocele

2. More fluid loss associated with Gastroschisis


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Tracheoesophageal fistula anomaly(1):

90 % proximal atresia of esophaguswith distal fistula

Consider aspiration pneumonitis.VATER syndrome:

I. VertebralII. Anal

III. TracheoesophagealIV. Renal

MCC of death cardiac anomalies

T-type

Trachea


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90 % proximal atresia of esophaguswith distal fistula

Consider aspiration pneumonitis.VATER syndrome:

I. VertebralII. Anal

III. TracheoesophagealIV. Renal

MCC of death cardiac anomalies

T-type

Trachea


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Major issues are:

Aspiration pneumonia

Overdistention of the stomach

Inability to ventilate

Postoperative intensive care

T-type

Trachea


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Tracheoesophageal fistula anomaly(3):Induction:Awake intubation Deliberate right main stem intubation

Catheter in esophagus Prone position with head-upAvoid massive distention of the stomach

by gentle ventilation

Careful confirmation of tube positionby moving tube mm by mm(position must bebetween fistula and tracheal bifurcation)

Tape precordial stethoscope over the left chest

T-type

Trachea


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Diaphragmatic hernia: Usually presentation on

1st day of life

Almost all viscera can be in thechest cavity

Anesthesia concerns:I. Hypoxemia

II. HypotensionIII. Stomach herniationIV. Pulmonary hypertensionV. Systemic hypotension

Shifted

mediastinum

Diaphragmatic hernia


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Diaphragmatic hernia(2):1. Awake intubation2. Intraarterial catheter

3. Use opioids (stress response)4. Use Pancuronium5. Avoid hypothermia6. Avoid any myocardial depressant

7. Avoid N2O (abdominal distention)8. Aware of barotrauma-induced pneumothorax9. Adequate intravenous access10. Plan postoperative care

Shifted

mediastinum

Diaphragmatic hernia


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Former preterm infant(


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Regional Anesthesia and Anesthesia:(brief overview)

Most regional anesthetics are safe to use

Strict attention to:DoseRoute of administrationProper equipment used

Common:Caudal blocks

pediatricanesthesia mlg

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