An Introduction to Pediatric Anesthesia

Rae Brown, M.D.

Professor, Department of Anesthesiology

UK HealthCare

An Introduction to Pediatric Anesthesia:

Managing Infants and Children During the Perioperative Period

The perioperative care of children is often challenging but may actually be

fun. Children are remarkably resilient and routinely respond positively to

attention, affection, and kindness. Doing the best that you can do for a

child usually means thinking about life from their perspective and trying to

eliminate the stresses that they will encounter.

Under the best of circumstances children come to us attached to parents.

Parents have their own perceptions about the perioperative experience

and their own anxieties sometimes based on their own history. The anxieties

that parents bring with them are usually sensed by the child and may

dramatically affect the interaction that you have. Anything that can be

done to allay the anxiety of the parent should improve the interaction that

you can have with the child. Because most parents will have some

knowledge of the problems attendant to anesthetizing a child, a calm,

competent, caring clinician will attenuate some of the parent’s anxiety. It is

well to note that parents place the care of their most treasured possession

in our hands when they allow us to take their child to the operating room. In

many ways, we must earn their respect and trust.

Children come in different sizes, shapes, and developmental levels. They

respond variously to the stresses of the operating room based on the level

of development, age, their experience with medical care providers, and

the reactions of the people around them. The developmental level of a

child may, or may not be correlated with their chronological age. Thus, a

ten year old child with spina bifida that has had many surgical procedures

may totally dissimilate prior to going off to the operating room after

Rae Brown, M.D.

Professor, Department of Anesthesiology

UK HealthCare

seeming to be remarkably mature when first interviewed. Many times we

are put in the circumstance of having to accept the child at the

developmental level that they are passing through at the time rather than

the level that we would like them to reside in.

A part of the mystique of caring for various sizes of children – preemie to

young adult – is that the attendant physiology and pharmacology in any

particular patient will vary widely from patient to patient. Remarkably, some

rules are consistent across the group. First, all patients respond aversely to

the pain that is produced during a surgical procedure. Second, the care of

patients requires attention to detail and vigilance. Third, every patient

deserves to have the close attention of a caring physician

Every anesthesiologist will, at some point, be called upon to manage the

anesthetic care of a child. Training programs for anesthesiology in the

United States are obligated to include pediatric anesthesia as an integral

part of their curriculum. The safe management of children during the

perioperative period should be a basic part of the continuing medical

training for active practitioners. The information that follows represents a

small part of the knowledge base that a practicing anesthesiologist should

be familiar with and should review and update over the course of training

and practice.

A Child Has Surgery

Children that present for surgery are more different than they are alike. Any

two children may have remarkably similar ages, physical and physiological

characteristics; yet differ dramatically in their psychosocial level,

temperament, and ability to tolerate a change in their normal daily

activities. The myriad combinations of physical disease, social setting,

parental support, and development taken together make the practice of

Rae Brown, M.D.

Professor, Department of Anesthesiology

UK HealthCare

pediatric anesthesia interesting and unique in anesthesiology and

medicine. In addition, most children are fun to be around and you can

hardly ever blame a child for abusing their bodies or having a hand in the

development of disease.

Introduction

In order to have a common understanding of the broad range of patients

that are included when one discusses pediatrics, one must commit to

memory the standard definitions descriptive of the age range of the child.

These definitions are important:

Definitions

1. Preterm Infants that are born before 37 weeks post conception are

considered premature. These patients are in general at the highest

perioperative risk.

2. Neonate – An infant from birth to four weeks of age

3. Infant – A baby from birth to one year of age

4. Child – Something that keeps you up at night, no matter what their age

is.

5. Gestational Age – This is the age of the fetus since conception. The

normal gestational age at birth is nine months or 40 weeks. Post dates

infants are born after 42 weeks post conception

6. Post Conceptual Age – The infant’s age, in weeks and days, since

conception (e.g. 34 wks, 3 days PCA). This can be judged in a number of

ways; not all of the methods will provide clinicians with the same answer.

Rae Brown, M.D.

Professor, Department of Anesthesiology

UK HealthCare

Obstetricians can judge the age by measuring the bi-parietal diameter,

by measuring the length, or by asking the mom about the date of her last

menstrual period. The best way to determine the possible gestational age

is to examine the infant when they are born in order to assess the

development of the child.

7. Post dates – Born after the presumed estimated date of confinement.

Most use 42 weeks PCA as the time to begin calling the infant post

dates. These infants risk outliving the productive life of the placenta

and may require emergent delivery in order to reduce the risk of

neurological injury. Many meconium aspiration episodes relate to post

dates babies.

8. Small for gestational age (SGA) – A fetus that is stressed in utero will not

grow normally and therefore will be smaller than appropriate for a

given gestational age.

A mother may have chronic hypertension or untreated preeclampsia,

both of which affect the ability to pass oxygenated blood, glucose, or

other necessary nutrients across the placenta. A normal baby usually

weighs about 3500 grams at the end of a forty week gestation; SGA

infants may weigh 2500 grams or less. They are identified, not only for their

small size but by the lack of body fat usually seen in a healthy baby. These

infants are usually below the 10th percentile for age and are at risk for a

variety of metabolic abnormalities at birth including hypoglycemia,

hypocalcemia, and hypothermia.

9. Large for gestational age (LGA) Infants whose mothers have untreated

gestational diabetes are usually LGA. These infants are at or above the

90th percentile for age and length. Other than maternal diabetes, other

causes of LGA include excessive weight gain in the mother, Beckwith –

Wiedemann Syndrome, and Sotos Syndrome (cerebral gigantism).

Rae Brown, M.D.

Professor, Department of Anesthesiology

UK HealthCare

Important Skills for the Pediatric Anesthesiologist

There are skills intrinsic to the management of children that must be

acquired by residents prior to independent practice. These skills, once they

have been learned, will make the difference between the enjoyment and

dread of the care of children. I have listed many, but not all of these skills

below. Use this list as a take off point for discussion with the attending in the

operating room.

1. The ability to do a mask induction on an infant or child - A part of

learning this skill set is losing the anxiety, which often attends

anesthetizing someone without an IV. Some of learning this skill is

dealing with something small. This is not difficult. Place the mask on the

face. Use a non-pungent potent agent in oxygen. Keep your fingers on

the mandible and out of the airway. When the infant is still, put an oral

airway in to prevent obstruction by the tongue. Control the airway by

first applying continuous positive airway pressure and then by

incrementally increasing the positive pressure ventilation that is applied.

The goal should be to push the infant through the second stage of

anesthesia as quickly as possible to avoid the development of

laryngospasm. Allowing the infant to breathe spontaneously, even on

8% sevoflurane will not be adequate to place an IV. Control ventilation

if you are trying to attain sufficient depth of anesthesia to place an

endotracheal tube without muscle relaxants. A shoulder role sufficient

to place the infant's airway in the sniffing position can be very helpful.

Be gentle. It's a baby.

2. The ability to establish rapid intravascular access - Look in places where

there are veins - the saphenous, the cubital fossa, the dorsum of the

hand. Look for the best vein before you poke the kid. Retract the skin

Rae Brown, M.D.

Professor, Department of Anesthesiology

UK HealthCare

before the cannula goes through. Use a small catheter for a small vein.

Go slowly.

3. The ability to assess volume loss in infants - Think about how long it has

been since the infant had anything to drink. We say NPO after five am,

but in reality it may have been twelve hours or more since the baby

had any fluids. When was the last wet diaper? Is the baby perky or

somnolent? Are the mucous membranes wet? Remember that potent

inhalational agents severely depress the myocardium and this

especially reduces cardiac output in dehydrated infants. Be very

careful.

4. The ability to talk to parents - Try to think about what you would feel like

if your baby had to go to the operating room and you were putting the

baby's safety in the hands of a complete stranger. Then sit down and

calmly talk to the parents about their child and their worries. Play with

the baby. Establish rapport. Talk to the parents about your or your

attending's wealth of experience. Be calm.

5. The ability to assess the airway of an infant - All infants have tough

airways because of the small mouth, large tongue and large occiput

problem. But some have a small chin, a small mouth or a very large

tongue. These children can be a real problem if you don't recognize this

until the muscle relaxants are given. A good rule of thumb is to look up

any syndrome that you are unfamiliar with before it becomes a

Wednesday Morning Conference.

6. The ability to recognize a sick child - Sick kids look sick. They are listless,

somnolent and glassy eyed. They may be mottled or have cold

extremities. Their skin will often have a doughy consistency. These infants

and children respond poorly to the administration of potent anesthetic

Rae Brown, M.D.

Professor, Department of Anesthesiology

UK HealthCare

agents. Extreme caution should be exercised in the conduct of this

child’s care. In other words low doses administered slowly. Often these

children are dehydrated. It makes sense to assess the need for

rehydration in a sick child prior to administering an anesthetic.

7. The ability to manage the pain of surgery in an infant - Infants and

children suffer after painful procedures to the same extent as adults.

There are many ways to safely control the pain of surgery without

added risk. Become familiar with simple blocks that effectively ablate

pain after common procedures in children. Discuss the

pharmacokinetics and pharmacodynamics of analgesics in infants and

older children.

8. The ability to recognize common postoperative problems of infants and

children – Laryngospasm, croup and apnea are the three most

common life-threatening postoperative problems in infants. These can

all be predicted with a remarkable degree of certainty by the clinical

situation.

Laryngospasm rarely occurs in patients with dry airways in which a nonpungent

agent has been used. Sevoflurane is very forgiving. In a patient

that is somnolent, has a wet airway or has been exposed to Desflurane

the risk of airway obstruction is great after removal of an endotracheal

tube.

Croup is an inflammatory response secondary to a superimposed

infectious process or the placement of a large endotracheal tube in a

small airway. Croup is tolerated well by children older than three and

not at all by infants. This scenario of airway obstruction and respiratory

failure can be eliminated by using a small endotracheal tube and leak

testing after every intubation in children less than three. Get your

attending to demonstrate a leak test if you are uncertain.

Apnea and/or periodic breathing are uncommon in infants greater

Rae Brown, M.D.

Professor, Department of Anesthesiology

UK HealthCare

than three kgs and fairly common in infants less than 1500 grams. Be on

the look out!

9. The ability to resuscitate a newborn infant in the delivery room- The

ability to oxygenate and ventilate the depressed newborn is key to

improving survival. In this regard the effective use of the bag-valvemask

can be life saving. It is uncommon for newborn infants to fail to

respond to adequate delivery of 100% oxygen. If this fails consider longstanding

acidosis, volume depletion secondary to blood loss, or a

central nervous system catastrophe.

10. The ability to recognize and treat common life threatening problems in

newborns- The common life threatening problems in the delivery room

include diaphragmatic hernias, severe meconium aspiration,

gastroschisis and omphalocoele. Fortunately, with the use of preterm

echo, it is rare for these diagnoses to be made in the delivery room.

Because the diagnosis is not in doubt plans can be made for airway

management and other emergent care before the delivery.

Meconium aspiration represents the end result of stress and hypoxia in a

just delivered infant. Aspirated meconium may produce severe airway

obstruction and air trapping sometimes leading to respiratory

compromise and death. Meconium can be suctioned out of the airway

prior to the first breath. This procedure is probably warranted if an infant

has had a long hypoxic period or has a large amount of thick

meconium in the amniotic fluid. Infants that are vigorous at birth or have

thin, non-particulate "pea-soup" meconium do not require direct

laryngoscopy before the first breath.

Rae Brown, M.D.

Professor, Department of Anesthesiology

UK HealthCare

Important Clinical Pearls for the Management of Infants and

Children in the Perioperative Period

Or

What I Have Learned in Thirty Years of Taking Care of Kids

1. When placing a caudal block in a child:

a. Use a dilute solution of a long acting local anesthetic- usually .25%

Bupivacaine or .2% Ropivacaine

b. Adding epinephrine increases the risk of prolonged lower

extremity weakness in children that are old enough to walk. It also

increases the likelihood of urinary retention prolonging the time

spent in the PACU before discharge

c. One mg per kg of anesthetic solution will usually give the child a

T10 block; this is not high enough for an umbilical hernia repair. 1.2

mi. will usually give a T6 block. This level is variably effective in

providing analgesia at the level of the umbilicus. If the

concentration of bupivacaine is greater than 0.25%, then the risk

of toxicity rises with the volume of local anesthetic over 1cc/kg

d. Identify the topographic anatomy before the needle is place

through the skin. Then, remember the topographic anatomy

before you stick the needle in

e. Always aspirate before you inject and always fractionate the

dose. Always, always, always aspirate before you inject. Besides

that, aspirate before you inject.

2. When performing a mask induction on an infant:

a. Have all of the equipment that you need at hand before you

start.

b. Always induce with 100% oxygen and a mild volatile agent. Not

Desflurane

c. Expect hypoxemia!

Rae Brown, M.D.

Professor, Department of Anesthesiology

UK HealthCare

d. When the infant is quiet, begin to follow the respiratory pattern of

the child and provide positive pressure, first as end expiratory

pressure, then as PPV. The goal is to get the infant through stage 2

of anesthesia as rapidly as possible to reduce the risk of

laryngospasm.

3. When setting up an IV line for an infant put 25cc/kg of Ringers in the

buretrol. That is the amount that will go into the baby while you are not

paying attention. Because most infants are volume contracted prior to

an operative procedure, this bolus represents an appropriate initial

volume expansion and will reduce the risk of hypotension. This fluid

should never contain glucose.

4. Positive pressure ventilation with 8% Sevoflurane will produce

hypotension in most infants.

5. The forced air warming blanket should be prewarmed before the infant

comes into the room. Forced air under the infant and plastic covering

the infant is a fine way to maintain temperature homeostasis.

6. Glucose containing solutions should never be used as volume

expanders in infants.

7. A rolled up washcloth under the shoulders may be required to put the

infant in a sniffing position; appropriate for airway management.

8. Infants with pyloric stenosis are always under resuscitated; no matter

what the electrolytes say. The serum electrolytes of the child that has

been vomiting for a long period will correct long before the hydrogen

ion concentration in the CSF corrects. If an infant with a diagnosis of

pyloric stenosis presents with a systemic acidosis they are either very ill or

Rae Brown, M.D.

Professor, Department of Anesthesiology

UK HealthCare

they have some other medical or surgical problem. There are so many

reasons for the body to get rid of potassium when an infant has been

vomiting that hypokalemia should be expected and hyperkalemia

indicates severe disease or the wrong diagnosis.

9. The rectal loading dose of acetaminophen in an infant is 40 mg/kg.

Acetaminophen given per rectum has a reduced and variable uptake.

Giving the child an initial dose of 15 mg/kg per rectum will never reach

10. Always draw up medications in a 1cc syringe if your patient is less than 5

kg. This reduces the possibility of a massive overdose of the drug that

you are giving.

11. "Malignant hyperthermia" should be called "malignant hypercarbia".

Elevations in temperature may be the last thing to occur after

elevations in ETCO2 arrhythmias and tachycardia.

12. Positive pressure ventilation with rates greater than 30, in infants

increases the mean intrathoracic pressure and reduces the filling of the

right heart. This will reduce cardiac output and is very effective in

producing hypotension.

13. Parents want to know that the person managing their child is

competent and professional. They are often less anxious if you take

some time to understand the infant or child. Sit down with the child or

play with the infant.

Sometimes fear looks like anger in parents. Remember that they are

scared!

14. Infants have a larger volume of distribution than older children and

adults. This increases the initial dose required of most drugs. It also

Rae Brown, M.D.

Professor, Department of Anesthesiology

UK HealthCare

reduces the rate of clearance of the drug. This becomes a special

problem if the drug has active metabolites like morphine.

15. If you induce an infant and the heart rate drops below 100, think about

the amount of oxygen that you are giving and the percentage of

potent agent that is being administered. The most common cause of

bradycardia is hypoxemia. Positive pressure ventilation with 8%

sevoflurane dramatically reduces cardiac output.

16. If an infant's heart rate drops below 60, start chest compressions. The

neonatal heart depends on a rapid heart rate to create an appropriate

cardiac output.

17. Newborns, premature infants, and infants with pyloric stenosis are very

sensitive to general anesthetic agents, narcotics, and sedatives. Many

will be profoundly sedated by doses of drugs that one would not

predict would be a problem. Treatment of these infants with central

nervous system stimulants such as caffeine, validated as safe in the

premature infant is effective in allowing these infants to maintain an

awake state and normal respiratory drive during the postoperative

period.

18. When a neurosurgeon takes the cranium off of a baby in order to treat

craniosynostosis, almost all will entrain air. Some of these infants may

develop hemodynamic disturbances - often profound. Precordial

doppler is a reasonable method of making the diagnosis. Because of

the large third space and blood loss, the central venous pressure is

often low predisposing to the air.

19. The onset of desaturation in an apneic child is related to the child's age.

After preoxygenation, change from saturation of 100% to 90% occurred

Rae Brown, M.D.

Professor, Department of Anesthesiology

UK HealthCare

within 90 seconds in infants and within 160 seconds in two year olds.

Adolescents dropped to 90% saturation in an average of 380 seconds.

All of these children had normal pulmonary function.

20. Evidence-based neonatal resuscitation in the delivery room:

a. Oxygen vs. room air resuscitation - Data strongly suggest that

room air will suffice for most infants during brief resuscitation. If

prolonged and vigorous resuscitation is required, especially in the

face of positive pressure ventilation, short-term use of oxygen in

the lowest concentration possible to produce saturations of 90 -

95% is appropriate.

b. Routine suctioning of the oropharynx and trachea, even in the

face of meconium aspiration pneumonia, is unsupported by

currently available evidence.

c. Body temperature can best be maintained in the delivery room

by placing the infant in a plastic occlusive wrap.

d. Compromised neonates may have hyperthermia at birth

especially in the face of maternal chorioamnionitis. Elevated

temperature is associated with higher neonatal morbidity and

mortality.

e. The best indicator of effective ventilation is a rapid increase in

heart rate to more than 100 beats per minute.

f. When initiating ventilation, the provider should try to avoid

volutrauma or barotrauma, especially in the premature infant.

g. There is no evidence that high dose intravenous epinephrine is

any more effective than standard dose. (.01 - .03 mg/kg)

h. Higher doses of epinephrine may be required if the drug is given

per an EIT - though the best dose is unknown. (A reasonable dose

is 0.1 mg/kg)

i. Intravenous sodium bicarbonate may be required after a

prolonged resuscitation once ventilation is reestablished. This

Rae Brown, M.D.

Professor, Department of Anesthesiology

UK HealthCare

should be based on blood gas analysis, if at all possible.

j. The routine use of post resuscitation hypothermia in neonates that

have suspected or proven asphyxia is not supported by current

evidence.

k. Glucose levels should be monitored closely with a goal of

maintaining glucose in the normal range. Both hyperglycemia

and hypoglycemia produce injury in newborns

21. Children with intracranial mass lesions will usually tolerate a mask

induction with concurrent hyperventilation. Exceptions to this rule are

readily apparent in that the children will be symptomatic - somnolent

vomiting, cranial nerve palsies - and/or have mid line shift on CT scan.

22. Medical Management of Pediatric Patients:

a. If a child is not growing, then they are ill. If a child has congenital

heart disease, diabetes, or asthma and is not following some

growth curve, then the therapy is not completely effective- e.g.

For the child with congenital heart disease, growth failure implies

hypoxemia or continuing CHF or both.

b. Seizure disorders- Anticonvulsants can have a significant impact

on the metabolism of anesthetic drugs. Most of the

anticonvulsants are metabolized by the cytochrome P450 system.

This hepatic system increases in functional capacity in response to

induction and other drugs, such as muscle relaxants, have

profound reduction in their Beta elimination half - life

c. Asthma - Fifteen percent of children in the United States will

wheeze at some point in their lives. Children that reside in homes

where cigarettes or pipes are used are at increased risk.

Premature infants, especially those that have had RSV

bronchiolitis are also at high risk. Use of beta-adrenergic agents is

common. Systemic steroids should be avoided unless

Rae Brown, M.D.

Professor, Department of Anesthesiology

UK HealthCare

bronchospasm is very severe.

23. How do we manage a child with congenital heart disease?

a. Questions: Is the child blue at rest? Does he turn blue when he

cries? Does the child lose consciousness? Does the child sweat

when he nurses? Are the eyes puffy in the morning? Does the

child stop playing and squat?

b. Rules about the physical exam:

1. You can't auscultate a crying child.

2. Examine the heart first.

3. Start by ignoring the murmur.

4. Most systolic murmurs will be benign.

5. All pansystolic murmurs are pathological.

6. The louder the murmur, the smaller the shunt.

7. All diastolic murmurs are pathological.

8. Children develop biventricular failure.

9. All murmurs that radiate are pathological.

10. Take upper and lower extremity BP in a child with a murmur.

24. Always sit down in the presence of a parent or a child. Don't tower over

them. Take your time and get to know the child and the parent. You

can only do that if you take the time to pull up a chair and sit down.

25. Play with the child. Give them a toy, your stethoscope, your phone.

Show them something. The best time to do this is as you are talking to

the parents. In doing this you form a relationship with the child and show

the parents that you feel comfortable with children. This observation is

important in allaying some of the anxieties and fears that the child and

the parents may have.

Rae Brown, M.D.

Professor, Department of Anesthesiology

UK HealthCare

26. Always talk to the surgeon about the surgical approach before you put

an infant to sleep. The special physiology attendant to neonates makes

this a requirement as intrathoracic or intraabdominal pressures shift and

create ventilatory issues. Strategies for managing the consequences of

the surgeon's trespass are a part of the training of a good

anesthesiologist, but often these are employed too late to be

completely effective.

27. Learn to swaddle a baby and make that a part of your pre operating

room or pre recovery room routine. It keeps the babies nice and warm

and it shows the folks that are watching you that you know what you

are doing.

28. Your knowledge of child development will be a big help to you in

understanding how the child is going to tolerate going to the operating

room with a stranger. From about age one to three, little can be done

to calm a child if they are leaving a parent. These kids will require

premedication in most circumstances. After age six, unless a child has

been chronically ill or has had multiple surgical procedures, there is

often no need for premeds.

29. Taking care of an infant in the operating room is about paying attention

to detail. Concern about the temperature, the postoperative pain

control, appropriate fluid management and knowledge about the risks

of continued variability in respiratory control are critical to the outcome

of the procedure. If, for example, attention is not paid to the nurse that

is prepping the patient, the infant may rest in a puddle of cold fluid

throughout the procedure. Hypothermia in infants is not well tolerated.

30. The relationship between neonatologists and pediatric anesthesiologists

is sometimes difficult. Both desperately want to provide the best possible

Rae Brown, M.D.

Professor, Department of Anesthesiology

UK HealthCare

care for the infant. Both see the infant from their own unique

perspective. The problem with this interaction is not that anyone is trying

to harm the baby, or that anyone is necessarily wrong. The problem is

that the operating room is not the intensive care nursery. The infant in

the operating room is met with stressors such as cold, blood loss, an

open abdomen and/or chest as well as an acute rise in autonomic

tone that produces hyperglycemia, tachycardia, and hypertension.

These changing conditions challenge the most experienced of us and

require rapid responses that would rarely be required while the infant is

in the nursery.

31. Infants and small children are at high risk for significant physical abuse.

Kentucky leads the nation; unfortunately, during the current economic

downturn there is depression, angst, and anger in those without jobs.

This does not excuse abusing your child, but is simply a head's up to look

at the children that you take care of with an eye toward patterns of

injury that may be questionable.

32. Infants are funny. When they are awake, they are usually upset about

something: hunger, a wet diaper - something. When they are asleep,

they are peaceful. Healthy babies have a lot of muscle tone, look

toward voices, and respond when touched. Infants that are healthy

have warm extremities and are pink. If you press on a toe the red color,

capillary refill returns almost immediately. Healthy babies look healthy.

33. Sick babies are different from healthy babies. They will often have an

abnormal, irregular breathing pattern; sometimes with significant

respiratory pauses. Sick babies often have diminished tone and

prolonged capillary refill. Babies that are septic will often grunt when

they breathe, creating a kind of auto peep. They may guard their

abdomen if touched and their color may be grey rather than pink a

rosy.

Rae Brown, M.D.

Professor, Department of Anesthesiology

UK HealthCare

34. Many people make the mistake of thinking that a baby that is not

fussing is a "good" baby. Many times these infants are tightly swaddled

and the lack of crying is viewed as a positive thing. Sometimes these

babies are very sick, as opposed to very good. In order to make to

make the diagnosis you must look at the baby to evaluate color, tone,

and breathing pattern. Sick babies look sick. They will show you that

they have a problem, but you have to look.