Pediatric Anesthesia

PEDIATRIC ANESTHESIA

Adel J. TaradjiPost Graduate Intern

Patient Data

Patient K. J.

2 years old male

11 KG

12/5/2012

Child

Roman Catholic

CC: Scrotal Mass

History of Present Illness

• 1 year PTC onsent of bulging mass on left inguinal area

• Reducible• No consult done• Until, few months PTC, still with bulging

mass, prompted consult at ZCMC. Evaluated and advised for admission.

• Scheduled for surgery

Past Medical History

• Delivered NSVD at a local institution• Complete Immunization• Mother with complete prenatal checkup

and TT immunization• No previous surgeries• No food and drug allergies

Personal and Social

• 1st child• Mother is a housewife• Father is a part time contractual worker

Physical Examination

• Awake, Alert• Anicteric Sclera, Pink palpebral

conjunctiva• No cervical lymphadenopathies• No tonsilopharyngeal congestion• Equal chest expansion, clear breath

sounds• Adynamic precordium, Normal rate and

regular rhythm• Globular, soft, NBS, no tenderness• (+) inguinal scrotal mass L• Full pulses

Impression

• Indirect Inguinal Hernia Left

Pre Anesthetic Evaluation

• All systems within normal Limits• Mallampati Classification 1• NPO approx 8 hours• Risks discussed to parents• Patient examined and chart reviewed• Patient approved for anesthesia

Intraoperative Anesthetic Record

• ASA: 1• Weight: 11kg• No allergies• GCS: 15• Awake, alert• Baseline VS:

• BP – 95/40• HR – 150• SPO2 – 100


• Diagnosis: Indirect inguinal hernia L• Anesthiologist: Dr. Mendizabel• Anesthetic Technique: GA-mask + Caudal

Block• Surgeon: Dr. Mlee / Hassan• Induction time: 4:30 PM / 4:38 PM• Cutting time: 4:52 PM• Closing time: 5:45 PM


• P – LLDP, skin asepsis antisepsis, sacral hiatus identified, hypodermic needle g24 inserted, epidural space identified, negative CSF, negative blood

• X1 – midazolam 1mg IV, fentanyl 11mcg IV, AtSO4 0.2mg IV, Propofol 10mg IV, Sevoflurane 3 volume %

• X2 – Bupivacaine isobaric 0.2 % given with negative testdose at 3cc

Anatomic and Physiologic Distinctions Between Adults and Pediatric Patients

Variable Child vs Adult Anesthetic Implication

Head size Much larger head size relative to body

Consider roll under shoulders or neck for optimal intubation positioning

Tongue size Larger size relative to mouth

Makes airway appear slightly anterior; oral airways particularly helpful during mask ventilation

Airway shape Narrowest diameter is below the glottis at cricoid level in children

Uncuffed tubes can make seal when appropriately sized in children younger than 8 years of age



Respiratory Physiology

Oxygen consumption is 2 to 3 times greater in infants than adults. FRC ranges from 8–13 mL/kg < 1/3 as large as adults

Oxygen desaturation is extremely rapid following apnea

Cardiac Physiology

Relatively fixed stroke volume in neonates and infants

Bradycardia must be treated aggressively in young age groups; consider atropine prior to airway management; heart rates less than 60 require circulatory support

Renal Function

Limited GFR at birth; does not reach adult levels until infancy; total body water and % extracellular fluid are increased in the infant

Prolonged duration of action for hydrophilic drugs, particularly those that are renally excreted



Hepatic Function

P450 system not fully developed in neonates and infants; liver blood flow decreased in newborns

Prolonged excretion for drugs, depending on hepatic metabolism

Body Surface Area

Larger surface-to-body ratio in newborn / infant / toddler

Heat loss more prominent problem for these age groups

Psychological Development

0–6 mo—stress on family8 mo–4 yr—separation anxiety4–6 yr—misconceptions of surgical mutilation6–13 yr—fear of not “waking up”≥13 yr—fear of loss of control, body image issues

Changes the manner in which each patient and family should be approached; must address issues with personal and systemic strategies

The Preoperative Evaluation

• Pertinent maternal history• Birth and neonatal history• Review of systems• Physical examination• Height• Weight• Vital signs• Preoperative use of medications• Use of herbal medications• Malformations in the child and family

The Challenge

• Anxiety in children in many forms:• Verbalization of fear• Scared• Agitated• Deep breathing• Trembling• Crying

• These behaviors prolong the induction of anesthesia

The Challenge

• Management:• Behavioral• Pharmacologic

• Behavioral interventions include tours of the operating room, written and audiovisual materials, coloring books, music, acupuncture, hypnosis

• Pharmacologic interventions such as midazolam are very effective treatment for preoperative anxiety.

Coexisting Health Conditions

• Upper respiratory infection

• Obstructive sleep apnea

• Asthma

• Former preterm infant


• Upper respiratory infection• Increased risk of laryngospasm,

bronchospasm, oxygen desaturation, postextubation croup, and postoperative atelectasis.

• Mask anesthesia has significantly lower rate of perioperative complications as compared with endotracheal tube.

• LMA has same number of airway complications as the endotracheal tube


• Obstructive sleep apnea• At risk for airway obstruction with the

use of preoperative sedative predication and during the induction process

• Postoperatively, patients with severe OSA may exhibit worsening of their obstructive symptoms secondary to tissue edema, altered response to carbon dioxide, and residual effects of anesthetic agents


• OSA often accompanies obesity.

• Obese children also have an increased incidence of difficult airway, upper airway obstruction in the PACU, extended PACU stays, and postoperative nausea and vomiting.


• Asthma• Should be under optimal medical

care prior to undergoing general anesthesia and surgery

• There is high probability of perioperative complications

• All oral and inhaled medications, such corticosteroids and β-agonists, should be continued up to and including the day of surgery.


• Recent data indicate that administration of inhaled short-acting β-agonists prior to induction of anesthesia eliminates the increase in airway pressure that is typically associated with intubation in asthmatic patients.


• The Former Preterm Infant• (1) the impact that

bronchopulmonary dysplasia might have on the patient's perioperative course

• (2) the presence of anemia and the possibility of postoperative apnea.

• Perioperative complications from bronchopulmonary dysplasia involve reactivity of airways and the risk of severe hypoxia that can accompany bronchospastic episodes.

Laboratory Evaluation

• Healthy children undergoing elective minor surgery require no laboratory evaluation

• Potassium evaluation in children on digoxin or diuretics

• For surgeries in which significant blood loss may be expected, an arbitrary value of 10 g/dL has been cited as acceptable for infants older than 3 months or age and higher values for younger infants and neonates.

Laboratory Evaluation

• Coagulation test should only be done: • (1) history or medical condition

suggests a possible hemostatic defect

• (2) surgical procedures that might induce hemostatic disturbances (e.g., cardiopulmonary bypass)

• (3) cases in which an intact coagulation system is critical for adequate hemostasis

• (4) patients for whom even minimal postoperative bleeding could be life-threatening.

Preoperative Fasting Period

• Fasting period of pediatric patients before surgery:

• Solids - 8 hours • Formula milk - 6 hours• Breast milk - 4 hours • Clear liquids – 2 hours of surgery

• Rationale: Younger children have smaller glycogen stores and are more likely to develop hypoglycemia with prolonged intervals of fasting.

Preoperative Sedatives

• Sedation is widely used for children in decreasing anxiety

• Primary goal: • Facilitate smooth and anxiety-free

separation from parents and induction of anesthesia


• Oral• Midazolam is the most commonly used

sedative premedicant• It has rapid onset and predictable effect

without causing cardiorespiratory depression

• Dose:• 0.5 – 0.75 mg/kg – peak effect is 30

mins after administration• 0.75 mg/kg – given to non responder

group of children age (4.2 ± 2.3)


• Midazolam can be reversed with flumazenil, which antagonizes benzodiazepines competitively. The initial recommended dose in children is 0.05 mg/kg given intravenously titrated up to 1.0 mg total.

• Oral ketamine - 5 to 6 mg/kg for children 1 to 6 years of age. Maximal sedation occurred within 20 minutes.


• Clonidine in combination with atropine, produces satisfactory preoperative sedation, easy separation from parents, and mask acceptance within 45 minutes.

• Clonidine dose: 4 µg/ kg causes sedation, decrease anesthetic requirements, and decrease requirement for postoperative analgesics.

• The major disadvantage of this Clonidine is slow onset as compared with midazolam.


• Dexmedetomidine, a more selective α2-agonist, creates a similar sedative and anxiolytic effect to clonidine or midazolam. Similar to clonidine, dexmedetomidine has the effect of lowering pain scores in the postanesthesia time frame.

• Dexmedetomidine dose: 1 µg/kg transmucosally or 3 to 4 µg/kg orally.


• Nasal• Advantage: Rapid absorption as well as

avoidance of first-pass hepatic metabolism of medications

• Major disadvantage: most children cry because it transiently irritates the nasal passages.

• When required, midazolam can be administered intranasally in a dose of 0.2 mg/kg.


• Rectal• 0.5 to 1.0 mg/kg of midazolam

effectively reduces the anxiety of children prior to induction.

• Both methohexital and thiopental have also been used in rectal formulations in a dose of 25 mg/kg.

• Onset of sedation requires approximately 10 minutes. Respiratory depression and oxygen desaturation may occur because of variable absorption of the medication in the rectum.

Preoperative SedativesMEDICATION ROUTE DOSE

(mg/kg)TIME TO ONSET (min)

ELIMINATION HALF-LIFE

T½(hr)

Midazolam Oral 0.25–1.010 2

Intranasal

0.2–0.3 <10 2–3

Rectal 0.3–1.0 10 2–3

Ketamine Oral 3.0–6.0 10 2–3

Intranasal

3.0–5.0 <10 3

Rectal 5.0–6.0 20–30 3

Clonidine Oral 0.002–0.004

45 8–12


• Intramuscular• Midazolam 0.3 mg/kg provides

anxiolysis in 5 to 10 minute. • Ketamine 3 to 4 mg/kg provides a

quiet, breathing, yet minimally responsive patient in approximately 5 minutes.

• Still, oral route is the most used and preferred route of sedative administration for children. Nasal, rectal, and intramuscular routes should be used only under special circumstances such as cognitively challenged children.

Anesthetic Agents

• Mask Induction Pharmacology• Most common induction technique

for pediatric anesthesia• Safe but watch out for

bradycardia, hypotension and cardiac arrest, especially in infants younger than age 1 year old.

• Thus, mask induction of anesthesia in this age group should be accompanied by monitoring of blood pressure, electrocardiogram, oxygenation, and ventilation.

Anesthetic Agents

• Minimal Alveolar Concentration• MAC of anesthetic required in

pediatric patients differs with age. There is actually a small increase in MAC between birth and 2 to 3 months of age, Then slowly decreases with age.

• For sevoflurane the change in MAC is marked, with a value of approximately 2.5% for young infants compared with 2% for adolescents and adults.30

Anesthetic Agents

• Intracardiac Shunts• Children with unrepaired or

partially repaired congenital heart malformations may safely undergo inhaled induction of anesthesia.

• R -> L shunt slows the inhaled induction of anesthesia because anesthetic concentration in the arterial blood increases more slowly.

• L -> R shunt - volatile agent induction is more rapid because the rate of anesthetic transfer from the lungs to the arterial blood is increased.

Anesthetic Agents

• Inhaled Agents for Induction of Anesthesia• Sevoflurane, halothane,• Sevoflurane - rapid onset and low

frequency of dysrhythmias or hypotension

• Halothane –

Anesthetic Agents

• Isoflurane• safe and efficacious agent for

maintenance of anesthesia in infants and children.

• Disadvantage: pungent odor and high incidence of laryngospasm

• Desflurane • Also safe maintenance of

anesthesia in infants and children• unacceptable incidence of

coughing, increased secretions, and laryngospasm preclude its use as a mask induction agent

Intravenous Agents

• Sedative Hypnotics• may be employed after inhaled

induction of anesthesia • may be used as primary induction and

maintenance agents in children who have an intravenous line in place

• Propofol, thiopental, methohexital, etomidate, midazolam, and ketamine have all been used to produce effective intravenous induction of anesthesia or sedation in infants and children.

Intravenous Agents

• Propofol• most widely used agent for

induction and maintenance of anesthesia or sedation in children

• 3 to 4 mg/kg - < 2 years• 2.5 to 3 mg/kg - older children• Pain on injection of propofol is

marked• Medications prior to propofol to

decrease pain:• Lidocaine, fentanyl, ketamine,

and nitrous oxide inhalation.43

Intravenous Agents

• Ketamine• It is the only intravenous agent that

offers both potent hypnosis and analgesia.

• Other unique aspects• preserves airway reflexes• maintains respiratory drive• increases endogenous

catecholamine release resulting in a small amount of bronchodilation

Intravenous Agents

• Induction doses of 1 mg/kg of ketamine intravenously yields effective analgesia and sedation with rapid onset.

• Intramuscular doses of 3 to 4 mg/kg result in a similar state, appropriate for minor procedures such as intravenous starts or fracture manipulation.

• Side effects:• Diplopia, disturbing dreams, nausea

and vomiting• Midazolam (0.025 to 0.50mg/kg) is

used to decrease these side effects

Intravenous Agents

• Opioids• important elements of balanced

anesthesia and sedation in children.

• Usual recommended doses include fentanyl, 5 to 1 µg/kg; morphine, 0.10 mg/kg; sufentanil, 1 µg/kg; and alfentanil, 50 to 100 µg/kg. Remifentanil has also been shown to be an effective part of anesthesia and sedation protocols for a variety of procedures at 0.25 to 1.0 µg/kg/min

Intravenous Agents

• Newborns and infants < 6 months• susceptible to depression of

central respiratory effort because of the immature blood–brain barrier and increased levels of free drug.

• Newborns after 6 months of age• no more susceptible to central

depression from opioids than adults given equivalent doses.

• Careful monitoring is necessary and providers must be prepared in giving muscle relaxants if the need arises.

Intravenous Agents

• Muscle Relaxants• Succinylcholine • Given in a dose of 1.5 to 2.0 mg/kg • Produces excellent intubating

conditions (reliably) in 60 seconds. Recovery occurs in 6 to 7 minutes.

• Succinylcholine can also be given intramuscularly at 4 mg/kg in emergencies when intravenous access is not available.

Intravenous Agents

• Absolutely contraindicated in a variety of patients, particularly in those with muscular dystrophy, recent burn injury, spinal cord transaction, and/or immobilization, as well as any child with a family history of malignant hyperthermia because of the risk of rhabdomyolysis, hyperkalemia, masseter spasm, and malignant hyperthermia.

Intravenous Agents

• Pancuronium has a vagolytic effect. On the other hand, it is dependent on renal excretion and therefore may have a markedly extended duration of action in neonates when glomerular filtration rate is relatively decreased.

• Rocuronium has the lowest potency and the fastest onset of action of the currently available nondepolarizing relaxants (60 seconds for a 1-mg/kg dose) and is therefore the logical choice for rapid-sequence intubation.

Intravenous Agents

• Atracurium and cis-atracurium are popular nondepolarizing muscle relaxants for children

• Muscle twitches should be monitored and reversal agents (i.e., neostigmine, 0.05 mg/kg, with 0.015 mg/kg of atropine or 0.01 mg/kg of glycopyrrolate) administered if residual weakness is detected.

• Clinical signs of adequate strength for ventilation in this age group include the ability to flex hips.

Dosage Onset Duration Cardio effects

Cost consideration

Atracurium 500 Intermediate

Intermediate

Rare hypotension

Intermediate

Mild erythema common

Cis-atrac 80-200 Slow to intermediate

Intermediate to long

Absent Inexpensive

Mivacurium 250-400 Intermediate

Short Rare hypotension

Intermediate

Mild erythema common

Pancuronium 100 Intermediate

Intermediate – long

Tachycardia, occasional hypertension

Inexpensive Effect prolonged in renal failure

Rocuronium 500 – 1200

Rapid Intermediate

Slight increase in HR

Intermediate

Deltoid injection facilitates tracheal intubation

Vecuronium 100-400 Intermediate (rapid with large doses)

Intermediate (long with doses > 150 ug/kg)

Absent Intermediate

• Antiemetics• postoperative nausea and vomiting

(PONV) rate can be twice as high as in adults

• All of the antiemetics used in adults including phenothiazines, antihistamines, anticholinergics, benzamides, butyrophenones and 5-HT3 antagonists have been used in children

• The most effective prophylaxis strategy in children at moderate or high risk for PONV is to use combination therapy that includes a 5-HT3 antagonist (odansetron 0.05 to 0.15 mg/kg) and a second drug such as low-dose dexamethasone (0.15 to 1 mg/kg).

Fluid and Blood Product Management

• Maintenance Fluid Requirements for Pediatric Patients

Weight(kg) Hourly Fluid 24-hr Fluid

<10 4ml/kg 100ml/kg

11-20 40ml + 2ml/kg >10kg

1000ml+50ml/kg >10kg

>20 60ml + 1ml/kg > 20kg

1500ml +20ml/kg >20

• In general, blood volume is estimated at • 100 mL/kg for the preterm infant, • 90 mL/kg for the term infant, • 80 mg/kg for the child 3 to 12 months of

age, and • 70 mg/kg for the patient older than 1

year. • These estimates of blood volume can be

used in calculating the individual patient's blood volume by multiplying the child's weight by the estimated blood volume (EBV) per kilogram:

• Packed red blood cells have a hematocrit between 55 and 70%. On the average, 1 mL/kg of packed red blood cells increases the hematocrit by 1.5%. Units of blood can be subdivided into pediatric packs of 50 to 100 mL; thus, the remainder of a single unit is not wasted.

Airway Management

• Appropriate airway management remains the single most important aspect of delivering safe pediatric anesthesia. At any age, operative cases can be performed with face mask, LMA, or endotracheal tube placement.

Airway Management

• As a general rule, endotracheal tubes are preferred for premature infants and most neonates in maintaining general anesthesia because of the slightly greater difficulty of providing effective face mask ventilation and the risk of filling the stomach with air while providing mask ventilation.

Airway Management

• Cases in which recent oral intake or pathology (such as pyloric stenosis or intestinal obstruction) raise the probability that the stomach contains food or acid (and therefore risk aspiration injury) are best managed with a rapid-sequence induction and intubation regardless of age.

• LMAs and other pharyngeal airways come in a range of sizes that can be employed in infants, toddlers, and older children for almost any procedure that does not involve opening the abdomen or thoracic cavity.

Airway Management

• Although their use is standard for lower extremity, inguinal, cutaneous, or eye procedures, the application this airway for oral procedures such as tonsillectomy/adenoidectomy varies from center to center.

• Because the narrowest portion of the pediatric airway is at the level of the cricoid cartilage (and is therefore round), uncuffed tubes can be used and will create a functional seal when appropriately sized.68

Airway Management

• Several formulas have been used for tube selection in children older than age 1 year, the most common being (16 + age)/4 or variations thereof. One may also estimate the size by comparing the size of the fifth digit or the opening of a nare.

• Once the tube is in place, it should be checked to determine at what pressure air can escape around the tube. Air should leak out at no lower than approximately 10 cm H2O (to allow adequate ventilation) and no higher than 25 to 30 cm H2O (to minimize risk of postextubation croup).

Airway Management

• Cuffed tubes can also be safely used in infants and young children by selecting a tube 0.5 mm smaller in internal diameter than the uncuffed choice

• Intubation in children can be safely accomplished after inhaled induction with or without the use of muscle relaxant. Intubating conditions after 3 minutes of 8% sevoflurane or a dose of propofol and opiate may produce acceptable views of the larynx.

Monitoring

• The pediatric patient should be monitored continuously with precordial or esophageal stethoscope.

• Allows the anesthesiologist to detect changes in the rate, quality, and intensity of the heart sounds.

• Pulse oximetry, capnography, blood pressure (measured appropriately sized cuffs), temperature, and electrocardiogram should also be monitored routinely in children as in adults.

Pain Management and Regional Anesthesia

• The most common oral analgesic used in children continues to be acetaminophen. This medication has been shown to be safe and efficacious in neonates as well as older children.

• Doses of 10 to 15 mg/kg orally every 4 hours or 30 to 40 mg/kg rectally as a loading dose followed by 10 to 15 mg/kg every 6 hours, with a maximum dose of 90 mg/24 hr, produce therapeutic plasma levels with good analgesia.

Regional Anesthesia

• Regional anesthetic techniques (e.g., spinal and epidural) may be used as the sole anesthetic in premature infants at risk for postoperative apnea undergoing abdominal or lower extremity procedures.

• Simple techniques such as ilioinguinal–iliohypogastric nerve block, ring block of the penis, or caudal block can be very useful for common pediatric surgical procedures

Regional Anesthesia

• The most commonly used form of regional anesthesia in children is the caudal block.

• This technique can provide postoperative analgesia following a wide variety of lower abdominal and genitourinary surgical procedures. For single-dose administration (outpatient surgeries) bupivacaine, 0.25 to 0.175%100 solution, or ropivacaine, 0.2 to 0.175%,101 at a dose of 1 mL/kg is commonly used.

Regional Anesthesia

• Postoperative analgesia typically lasts 4 to 6 hours and is not associated with a motor paralysis at these concentrations. This route can be used for either a single-dose injection or for catheter advancement for continuous infusion.

• Spinal anesthesia may be used for procedures involving surgical dermatomes below T6.103 It is important to note that the dural sac migrates cephalad during the first year of life and in a neonate it is at S3 while over the age of 1 year it is at the S1 level.

Postanesthesia Care

• Hypothermia is a common perioperative problem, particularly in infants and young children.

• The inability to regulate body temperature under general anesthesia, cold large operating rooms, and continued heat loss are major reasons for hypothermia.

• More significant hypothermia can result in increased oxygen consumption, cardiovascular manifestations of hypothermia, prolonged metabolism, and excretion of anesthetic drugs and delayed wound healing.

• Special attention should be paid to the treatment of pain and nausea and vomiting in the PACU.

• Pretreatment with ondansetron, 0.15 mg/kg; droperidol, 0.075 mg/kg; or metoclopramide, 0.15 mg/kg, has been very successful in reducing nausea and vomiting for patients at higher risk, such as those undergoing tonsillectomy or strabismus repair.

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Pediatric Anesthesia