pediatric anestesia

7/30/2019 Pediatric Anestesia

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CHAPTER 44

PEDIATRIC ANESTHESIA

JOSEPH P. CRAVERO AND LINDA JO RICE

Preanesthetic Evaluation and Preparation

Minimal Laboratory Evaluation

Preoperative Fasting Period

Preanesthetic Medications

Anesthetic Agents

Potent Inhalation Agents

Intravenous Agents SedativeHypnotics

Airway Management

Pediatric Breathing Circuits

Intravenous Fluid Therapy

Postanesthetic Care

Monitoring

Analgesia

Subglottic Edema (Postextubation Croup)Conclusion

Chapter References

The provision of safe anesthesia for the pediatric patient requires a clear understanding of

the psychological, physiologic, and pharmacologic differences between a premature

infant and an adolescent, as well as between a newborn and a toddler. A thorough

understanding of these differences must be applied to each pediatric patient presenting for

surgery.

Dalam menetapkan ketentuan untuk dapat melaksanakan suatu tindakan anesstesi

yang aman pada pasien pediatric memerlukan pemahaman yang menyeluruh tentang

keadaan psikologis, fisiologik, dan farmakologik yang membedakannya antara infant


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prematur dengan orang dewasa, demikian juga halnya dengan bayi yang baru lahir

(newborn) dengan anak kecil yang baru belajar berjalan (toddler). Pemahaman yang

seksama akan perbedaan-perbedaan tadi akan berguna dalam penerapannya pada pasien

pediatric yang memerlukan tindakan pembedahan dengan pemberian anestesi.

This chapter presents an overview of the important issues in pediatric anesthesia. There

are many specialized pediatric anesthesia texts that expand on topics introduced

here.1,2,3,4,5 and 6 In addition, neonatal anesthesia, pediatric pharmacology, equipment,

and other general topics are covered elsewhere in this text.

During the first several months of life, an infant experiences rapid growth, organ

maturation, and neurologic development. In the first 3 months of life, circulatory and

ventilatory adaptation are completed and thermoregulation is altered to a more adult state.

The sizes of body fluid compartments approach adult values. Skeletal muscle mass and

hepatic enzyme systems are developing and renal function is maturing (Table 44-1). Over

the next 18 months, the infant is physically transformed to a miniature adult.

Psychological maturation (which continues through adolescence) is a much more gradual

process7 (Table 44-2).

Selama beberapa bulan awal dari kehidupan, seorang infant akan mengalami

perkembangan yang pesat, penyempurnaan atau maturasi organorgan, serta

perkembangan neurologist. Pada 3 bulan awal kehidupan, penyesuaian dari system

sirkulasi dan ventilasi sudah sempurna sedangkan fungsi termoregulasi sudah mengalami

perubahan sehingga mencapai tingkatan yang menyerupai orang dewasa. Kemudian

ukuran ukuran dari kompartemen cairan tubuh juga hampir mendekati komposisi orang

dewasa. Massa dari otot skelet dan sistem enzim hepatik terus berkembang sedangkan

fungsi ginjal mulai sempurna. Setelah melewati usia 18 bulan, secara fisik dapat

dikatakan bahwa infant merupakan miniatur dari orang dewasa. Sedangkan

perkembangan psikologis merupakan suatu proses yang terjadi secara bertahap.

Table 44-1. BODY COMPOSITION DURING GROWTH


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Table 44-2. SPECIFIC ANXIETIES OF PEDIATRIC PATIENTS

PREANESTHETIC EVALUATION AND PREPARATION

The preoperative visit and preparation of the child for surgery is more important than the

choice of premedication. During this brief period, the anesthesiologist evaluates the

medical condition of the child, integrating this information with the planned surgical

procedures. The history should begin with a review of the perinatal period and seek

information regarding history of a recent or intercurrent upper respiratory infection.8 The

pediatric anesthesiologist should be aware of the increasing prevalence of reactive airway

disease in pediatric patients; routine or as-needed use of nebulized bronchodilators

occurs in up to 10% of pediatric patients, especially during high-risk times of the year.

Evaluasi dan Persiapan Pre-Anestesi

Pemeriksaan dan persiapan yang dilakukan sebelum operasi pada anak yang akan

menjalani pembedahan sebenarnya memiliki nilai yang lebih penting daripada pemilihan

obat obatan pada saat premedikasi. Selama periode ini seorang anestesiologis dapat

mengevaluasi kondisi medis anak, dan kemudian mengintegrasikan informasi yang

diperoleh tadi dengan rencana tindakan pembedahan. Penting untuk mengetahui riwayat

anak sejak periode perinatal dan digali informasi mengenai adanya riwayat menderita

infeksi pada saluran nafas atas belakangan ini atau yang bersifat hilang timbul.

Anestesiologis harus mewaspadai peningkatan prevalennsi dari penyakit pernafasan yang

reaktif, penggunaan bronkodilator baik secara rutin maupun sewaktu-waktu terjadi pada

lebih daari 10% pada pasien pediatrik.


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The possibility of loose teeth should be evaluated in school-age children. The

anesthesiologist should recall that congenital anomalies frequently present in

combination rather than as single entities. Other medical problems should be assessed

and pediatric caregivers consulted as appropriate to ascertain that the child is in the best

possible physiologic state before surgery.9,10 and 11

Kemungkinan terjadinya kehilangan gigi akibat gigi yang rapuh juga harus

dievaluasi pada anak-anak usia sekolah. Adanya kelainan congenital juga perlu diketahui,

dimana bila terdapat keadaan ini penting untuk diingat bahwa sseringakali kelainan ini

bersifat kombinasi dengan kelainan lainnya dan jarang hanya berupa kelainan tunggal.

Masalah medis lainnya juga perlu dinilai untuk selanjutnya diberikan perawatan yang

sesuai sehingga sebelum tindakan pembedahan tercapai keadaan fisiologis yang

optimum.

In addition, the anesthesiologist must assess the psychological makeup of the child and

family. He or she should establish rapport with the child and reassure the parents. In

addition, the anesthesiologist must realize that the entire family is undergoing the

psychological stress of the child's surgery, in addition to the feelings of guilt,

helplessness, and inconvenience that even outpatient surgery may cause. Parental

anxieties concerning both the anesthesia and surgical procedure are transmitted to even

very young children. Both realistic concerns and misconceptions (How do they put the

eye back in its socket after they fix the muscles?) can be addressed during the

preoperative interview.

Sebagai tambahan, anestesiologis juga harus memperhatikan kondisi psikologis

baik pada anak maupun keluarganya. Penting untuk menjalin hubungan yang baik dengan

anak dan keluarga. Perlu diingat juga bahwa meskipun anak tersebut yang akan menjalani

pembedahan namun seluruh anggota keluarga dapat mengalami stress psikologi karena

perasaan bersalah, ketidakmampuan untuk membantu atau terhadap efek yang

dtitimbulkan dari pembedahan tadi. Kecemasan pada orangtua baik terhadap tindakan

bedah atau anestesi dapat ikut mempengaruhi anak. Sehingga pada saat dilakukan pre-


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operasi ini dapat diberikan penjelasan terhadap hal - hal yang sebelumnya belum

dipahami.

Anesthesia and surgery represent an enormous time of stress for the child. The reasons

for the stress are many, but include primarily (1) separation from parents, (2) strange

surroundings, (3) painful procedures, (4) frightening procedures, and (5) survival. Coping

with this stress and pain requires honest and consistent communication between the child

and his or her parents, all physicians involved in the anesthesia and surgery, and all other

staff involved in the child's care. The more information the parents and child have, the

more easily they will cope with the period leading up to surgery and hospitalization.

Presurgical programs, including written literature, videotapes, or hospital tours, have

been shown to decrease preoperative anxiety in both the patient and the family.12

Unfortunately, the stress caused by mask induction of anesthesia and postoperative care

is not necessarily ameliorated by these interventions.

Tindakan pembedahan maupun anestesi dapat menimbulkan stress yang tinggi

pada anak. Terdapat beragam alasan terhadap timbulnya kecemasan tadi, diantaranya:

keadaan terpisah dari orangtuanya, keberadaannya di lingkungan yang dianggap asing,

prosedur tindakan yang akan menimbulkan rasa sakit sehingga anak merasa takut, atau

keadaan setelah tindakan. Untuk mengatasi hal ini diperlukan komunikasi yang baik

antara anak dan orangtuanya, serta dengan tenaga medis yang berperan dalam

penbedahan, anestesi, dan perawatannya. Ssemakin jelas informasi yang diperoleh anak

dan keluarga maka semakin mudah untuk mengatasi masalah pada periode sebelum

operasi.


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Many institutions have adopted policies that allow parents to participate actively in the

anesthetic induction.13,14 and 15 Very young children benefit most from parental

reassurance and a hypnotic voice, whereas older children and adolescents benefit from

choices and ability to maintain some control over their environment.16 Although many

parents prefer to be with their child during the stressful and somewhat frightening time of

anesthesia induction, not all parents and not all children benefit from this opportunity. In

fact, one prospective, randomized study found that only certain personality types of

children and parents had improvement in anxiety levels at the time of induction when

parents were allowed to be present.17

Banyak institusi yang menganut kebijakan dimana orangtua pasien diperkenankan

untuk ikut hadir saat dilakukan induksi anestesi. Keuntungan yang didapat dari hal

tersebut adalah anak mendapat dukungan yang menentramkan hati dan turut berperan

sebagaai hipnotik. Sedangkan pada anak yang lebih dewasa berperan untuk menetapkan

pilihan dan menjaganya selama berada di lingkungan yang baru. Walaupun banyak orang

tua yang memilih untuk ikut menemani anaknya selama induksi anestesi, namun tidak

semua anak atau orang tua dapat memperoleh keuntungan dari hal tersebut. Fakta yang

diperoleh dari suatu randomized study bahwa keuntungan untuk mengurangi kecemasan

dengan diperkenankannya orangtua untuk menemani anaknya selama induksi anestesi

hanya berlaku pada kepribadian tertentu.

Parents can become quite emotional if their child continues to struggle even in their

presence, and again when the child lies quietly, not moving, at the end of induction.

Parents who have been questioned after such an experience express the need for a great

deal of education about what to expect and how they can help their child. In addition,

institutions that have such a program emphasize the need for an escort to provide support

(and be certain that the parent leaves the operating room or induction room).

Orangtua dapat menjadi emosional saat anaknya menghadapi tindakan, begitu

pula saat anak hanya tenang dan tidak bergerak karena berada dalam pengaruh anestesi.

Orang tua yang sudah mengalami hal tersebut mengungkapkan pentingnya diberikan

pengertian dan pemahaman tentang tindakan yang akan dilakukan.


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A consistent policy for age and medical status of children who are eligible to have

parental accompaniment is also important, as is the recognition that the final decision

always rests in the hands of the anesthesiologist responsible for the safe care of that child

during that anesthetic. Other children, even preschoolers, may benefit from the

opportunity to exhibit independence and bravery.

Adanya kebijakan yang konsisten tentang usia dan kondisi medis anak untuk

memenuhi persyaratan untuk memperbolehkan kehaddiran orangtuanya sangat penting,

dimana hal ini tergantung dari keputusan anestesiologis yang bertanggungjawab terhadap

keselamatan anak selama tindakan anestesi.

Preoperative sedation has been studied carefully with respect to effect on stress and

postoperative behaviors. The most complete and recent information suggests that

adequate preoperative sedation (midazolam 0.5 mg kg1 orally) decreases anxiety for

parents and children in the immediate presurgical time frame and at the time of mask

induction. Preoperative sedation has been found to be superior to parental presence for

decreasing anxiety during induction of anesthesia and increasing cooperation with

inhalation induction.18

Sedasi yang diberikan pre-operasi telah dipelajari secara seksama dan keuntungan

yang diperoleh terhadap stress dan keadaan anak sesudak operasi. Data-data

menunjukkan bahwa sedasi pre-operasi yang adekuat (midazolam 0.5 mg /kgBB per

oral) dapat menurunkan kecemasan anak saat periode waktu prabedah maupun saat

dilakukan induksi.Sedasi pre-operasi juga diketahui lebih berperan dibandingkan

kehadiran orangtua dalam hal menurunkan kecemasan, keuntungan lain yang dapat

diperoleh yaitu pasien tersebut menjadi lebih kooperatif saat dilakukan induksi inhalasi.


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In addition, children who are sedated before coming to the operating room may have

fewer stress-related behavioral changes in the immediate postoperative time compared

with groups of patients who receive no sedation. Almost all of these behaviors extinguish

by 2 weeks after the operation, however, and much of this work was performed on first-

time surgical patients. Further studies are needed to clarify the role of sedation with

respect to postoperative behavior changes.19

Anak yang diberikan sedasi sebelum masuk ke ruang operasi menunjukkan stres

yang lebih sedikit dimana hal ini berhubungan dengan perilaku anak setelah operasi bila

dibandingkan dengan kelomppok pasien yang tidak diberikan sedasi. Namun demikian

kebanyakan perilaku tadi akan hilang dalam waktu 2 minggu sesudah operasi, walaupun

ini merupakan operasi yang pertama kali.


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Minimal Laboratory Evaluation

As with adults, preoperative laboratory evaluation is guided by the medical history.20

Most children require no laboratory evaluation, and can be spared the psychological and

physical pain of venipuncture. Determination of electrolytes or other chemistries should

be limited to those children who have a clinical history consistent with a significant

probability of abnormalities. Many institutions still require preoperative hematocrits for

infants younger than 2 months of age, largely because the frequency of postoperative

apnea and bradycardia in newborns has been shown to increase with anemia. Outside of

this subgroup, there is little evidence that testing for hematocrit levels is helpful in the

management of routine pediatric outpatients.21

EVALUASI LABORATORIUM MINIMAL

Sseperti halnya pada orang dewasa maka evaluasi laboratorium pre-operasi

dilakukan berdasarkan riwayat kesehatan pasien. Umumnya, kebanyakan pasien anak

tidak perlu dilakukan pemeriksaan laboratorium, sebab hal terssebut dapat mempengaruhi

psikologis dan nyeri secara fisik akibat suntikan. Pemeriksaan elektrolit dan kimia

lainnya dibatasi pada anak yang memang memiliki riwayat kelainan dan secara klinis

juga menunjukkan adanya kelainan yang signifikan. Masih banyak institusi rumah sakit

yang melakukan pemeriksaan hematokrit pada infant yang berusia kurang dari 2 tahun

karena kejadian apneu dan bradikaardia post-operatif pada newborn diketahui meningkat

dengan terdapatnya anemia.

There is controversy as to what constitutes the minimal acceptable hemoglobin value for

elective pediatric surgery. The arbitrary value of 10 g dl1 (the nadir of hemoglobin in a

healthy term infant) has been cited for infants older than 3 months, with higher values for

the younger infants, depending on gestational age and general health status. Children

whose hemoglobin values are less than this arbitrary standard should have the cause of

their anemia investigated and corrected.

Terdapat kontroversi mengenai nilai minimal hemoglobin yang dapat diterima

untuk diterapkan pada pembedahan anak yang elektif . Batasan nilai 10 gr/dl disebutkan

berlaku untuk infant yang berusia lebih dari 3 bulan, dan batasan nilai tadi meningkat


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pada infant yang lebih muda, disamping itu tergantung pula dari usia kehamilan dan

status kesehatan secara umum. Pada anak dengan nilai hemoglobin lebih rendah dari

batasan tadi, maka harus dicari penyebab anemia tersebut dan kemudian dilakukan

koreksi.

A decision to proceed with anesthesia and surgery should include an assessment of the

surgical procedure and the possibility of blood loss. Elective major surgery in which

blood loss is anticipated, but transfusion is not usually required, should be postponed

until the anemia is corrected. A decision to proceed with major surgery in which blood

transfusion is planned, as well as brief minor surgery with little anticipated blood loss,

might be appropriate in a child with iron-deficiency anemia.

Keputusan untuk melakukan tindakan pembedahn dan anestesi seharusnya juga

berdasarkan penilaian terhadap prosedur pembedahan yang dilakukan dan resiko

kemungkinan kehilangan darah. Pembedahan mayor yang elektif dimana kehilangan

darah ini sudah diantisipasi tidak selalu memerlukan transfuse, dan dapat ditunda sampai

anemia tadi dikoreksi. Keputusan mengerjakan pembedahan mayor dapat pula dengan

rencana transfusi darah, pada pembedahan minor dengan perkiraan kehilangan darah

yang tidak banyak transfuse ini mungkin tepat untuk dilaksanakan bila terdapat keadaan

anemia defisiensi besi.

Transfusion to raise a hemoglobin value to an arbitrary number to perform elective

surgery is rarely justified. Even in premature infants, where apnea is correlated with

anemia, appropriate supervision in the postoperative period and perioperative caffeine to

treat apnea is preferred over the risks of transfusion.

Tindakan transfusi dengan tujuan meningkatkan kadar hemoglobin untuk mecapai

batasan yang diperlukan pada pelaksanaan pembedahan yang elektif jarang dikerjakan.

Bahkan pada infant premature dimana kejadian apneu berhubungan dengan anemia,

tindakan pengawasan yang tepat selama perioperatif dan post-operatif untuk mengatasi

apneu lebih dipilih jika mengingat resiko yang ditimbulkan dari transfusi.


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Patients with sickle cell anemia or other hemoglobinopathies require special preoperative

preparation. Debate continues as to the exact need for preoperative transfusion to a target

hemoglobin level, or to a given percentage of hemoglobin A.22 This is reviewed in the

standard texts mentioned previously.1,2,3,4,5 and 6

Pada pasien yang menderita sickle cell anemia atau hemoglobinopati lainnya

memerlukan persiapan pre-operasi yang berbeda. Masih menjadi perdebatan mengenai

tujuan daari transfuse yang dilakukan untuk mencapai suatu nilai target hemoglobin atau

memberikan persentase hemoglobin yang cukup.

Preoperative Fasting Period

Evidence is accumulating that children allowed clear fluids until 2 hours before surgery

have similar gastric contents as those fasted for more than 4 hours.23,24 In fact, Cot et

al25 have demonstrated that up to 76% of children have sufficient volume of acid gastric

contents at time of induction to cause chemical pneumonitis regardless of their fasting

status. In spite of this, the best estimates of aspiration in pediatric patients place the

incidence at a relatively rare 1 in 500010,000.26

The exact length of time that a child must not eat or drink various foods and liquids

before surgery has not been completely settled. A survey of pediatric anesthesia

fellowship programs found significant variation in recommendations for restriction of

breast feeding, formula feeding, and solids.27 Various experts recommend 2- or 4-hour

restriction of breast feeding, 4- or 6-hour restriction of formula feeding, and 6-hour or

after midnight restrictions on solids. In spite of the lack of complete agreement among

pediatric anesthesiologists, an American Academy of Pediatrics/American Society of

Anesthesiologists task force has set recommendations that advise restriction of clear

fluids for 2 hours, breast milk for 4 hours, formula or light meals for 6 hours, and fatty

solid meals for 8 hours.

When counseling parents, recommendations need to be unambiguous. Clear liquids

should be specifically listed and the time that they should stop should be noted. Many

pediatric institutions have chosen to make the absolutely nothing by mouth (NPO) time 4


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hours before scheduled surgery, although it is recognized that 2 hours is sufficient for

gastric emptying of clear fluids. The longer fasting times allow for flexibility in patient

scheduling; should an earlier surgical case be canceled, the next child can be safely

moved up. Of course, gastric emptying after trauma is delayed in children as well as

adults, and even a prolonged fast may not result in significant gastric emptying.

If these details of feeding and fasting are not clearly defined with stated hours, infants

and children are likely to go without fluids for protracted times.28,29 Because young

children do not understand the need for fasting, they should still be scheduled early in the

day, or at least at a specified time to minimize their discomfort and that of the parents,

who must keep them away from the wat er fountain. Anesthesiologists should be alert to

delays and make sure that the child's fluid restriction is modified if a long delay is

anticipated.

Preanesthetic Medications

Preanesthetic sedation is usually used to decrease apprehensiveness and stress for

pediatric surgical patients and their families. Preoperative anxiolytics may also greatly

improve cooperation with mask induction of anesthesia. The large number of studies in

this area have produced approximately the same results: all sedatives are effective in a

large percentage of patients if administered in a timely fashion. Other preanesthetic

medications may be administered to prevent vagal reflexes or dry oral secretions in a

child with an anticipated difficult airway. In some cases, premedications can serve to

reduce gastric volume and acidity in a child with increased risk of vomiting.

Because of children's exaggerated psychological response to needles, other routes of

administration are almost always preferable. Some children simply refuse to cooperate at

all with preanesthetic medication, and for them the only sure method of administration is

intramuscular or intravenous. Although it is desirable to provide anxiolysis for the child

who is to undergo anesthesia and surgery, the respiratory cost of this state may

sometimes be excessive, particularly in patients who have predisposing factors that

increase the respiratory effects of sedation. An example of such a patient would be an

obese 3-year-old with sleep apnea coming for a tonsillectomy. In addition, although a

heavily sedated and unresponsive child will have no memory of the surgery, he or she


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may also undergo prolonged emergence from anesthesia and experience postoperative

respiratory depression, especially after short surgical procedures.

Oral

By far the most popular oral premedication at this time is midazolam, in a dose of 0.5

0.75 mg kg 1. Midazolam is first and foremost an anxiolytic; the child's eyes are

usually open and he is aware of the environment, but nothing seems to disturb him. The

effects of this medication peak approximately 30 minutes after administration, and last

approximately 30 minutes.30,31 An oral syrup preparation is now available in a

concentration of 2 mg ml1 that is palatable to all but the most uncooperative of

patients.

Serious side effects after oral midazolam are uncommon. However, loss of balance and

head control occurs in as many as 20% of children receiving oral midazolam.

Consequently, strict adult supervision is necessary in children who receive this drug.

Dysphoria has also been notedin these patients, the drug has the opposite effect to that

desired. The crying and disorientation that ensue usually abate with the drug effect.

As mentioned in the Preoperative Preparation section of this chapter, midazolam has been

shown in one study to be superior to parental presence in decreasing perioperative stress

for patients and families. It has been shown to increase cooperation with induction of

anesthesia and has also been suggested to decrease the incidence of adverse behavioral

changes that may occur in the 2 weeks after a surgical intervention.18 Further studies are

required to confirm these findings.

Oral ketamine has also been used as a sedation medication. One study evaluated doses of

56 mg kg1 for children 16 years of age.32 Maximal sedation occurred within 20

minutes. Nystagmus occurred in 60% of children, and increased oral secretions in 33%,

but there were no emergence phenomena in any child at these doses. Nausea and

vomiting rates were slightly increased in children who received oral ketamine. Discharge

from the day surgery unit was slightly delayed compared with children sedated with

midazolam. Although effective, this drug is probably best reserved for patients who

would benefit from the tachycardia and increased blood pressure that usually accompany

its administration.


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Oral transmucosal fentanyl represents the first commercial attempt to deliver medication

to children by the transmucosal oral route.33 It is available in 200-, 300-, and 400-mg

strengths; onset is 1020 minutes, with a duration of action of 30 minutes. The current

dosage recommendation is 1015 mg kg1. Intense supervision is required to ensure the

medication is absorbed by the transmucosal route and not chewed and swallowed. In

addition, difficulties with perioperative emesis and arterial oxygen desaturation have

been reported.34 One advantage of oral transmucosal fentanyl is its postoperative

analgesic properties. The dose indicated previously offers similar pain control as that

provided by 2 mg kg1 given iv. However, safe use of this medication does require

more intensive nursing care than do the other oral sedatives commonly in use.

Nasal

Although this route of administration also bypasses the dreaded shot, any parent who

has administered nose drops to a child recognizes that lack of cooperation may also

defeat this mode of administration. Most clinicians have found this mode of drug

administration no better than intramuscular injection, and consequently its use has never

been widespread. Rapid absorption as well as avoidance of first-pass hepatic metabolism

of medications are advantages of this route of administration. This route should be

reserved for the rare patient who refuses oral medication and has a contraindication to

intramuscular injection.

When required, midazolam (for intravenous use) can be administered undiluted (5 mg

ml1) by dropper or syringe to the nose in a dose of 0.2 mg kg1. Clinical effects of

midazolam are evident in 10 minutes, and these children are conscious but glassy-eyed,

just as with oral administration.35 Drawbacks of this form of administration are the

intense stinging of nose drops on the nasal mucosa and the undisguised bitterness of the

medication that reaches the oral cavity.

The use of sufentanil and other sedatives intranasally has largely been abandoned because

of untoward side effects.

Rectal

Both methohexital and thiopental have been used in rectal formulations in a dose of 25

mg kg1. Onset of sedation requires approximately 10 minutes. Respiratory depression

and oxygen desaturation may occur because of variable absorption of the medication in


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the rectum. Care must be taken that the medication is not expelled immediately on

placement. In spite of these drawbacks, there are a number of institutions that report a

high success rate in infants and toddlers with this type of preoperative sedative.

Intramuscular

Parenteral administration of sedation may be the only alternative in a child who refuses to

cooperate with other modalities. Injection should be accomplished with a very small

gauge needle or a CO2-powered needleless injection system. When done quickly,

intramuscular injection can be less upsetting than the other modes of delivery mentioned

previously.

Intramuscular midazolam in a dose of 0.3 mg kg1 provides anxiolysis in 510 minutes

and dissipates in 2530 minutes.

Ketamine in an intramuscular dose of 34 mg kg1 provides a quiet, breathing, yet

minimally responsive patient in approximately 5 minutes. Analgesia for intravenous

placement is more than adequate. Previous studies have shown that smaller doses of 23

mg kg1 provide sedation without prolonging hospital stay even after brief

procedures.36

A combination of intramuscular morphine 0.050.1 mg kgkg1, atropine 0.02 mg kg

1, and pentobarbital 4 mg kg1 is still used in children presenting for repair of

congenital heart disease in some institutions. Although mixtures such as this are effective

in experienced hands, they also markedly increase the chance of medication errors and

respiratory depression. The use of these combinations is no longer widespread.

ANESTHETIC AGENTS

The choices of anesthetic drugs for infants and children are not strikingly different from

those for adults. There are few specific contraindications to any of the commonly used

drugs on the basis of age alone. Selection of drugs and techniques should be based on the

anesthesiologist's experiences, preferences, and skill. Nitrous oxide in combination with

potent inhalation agents or intravenous drugs is frequently used to induce and maintain

anesthesia in pediatric patients; muscle relaxants and local anesthetics are also common

adjuncts to anesthesia.

Potent Inhalation Agents


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Mask induction of general anesthesia is the most common induction technique in the

United States. Although in general very safe, it can be complicated by breath-holding,

laryngospasm, dysrhythmias, and distention of the stomach by anesthetic gases (both

from crying and from difficulty in ventilation). Difficulty in maintaining a mask fit may

also occur, particularly in a struggling infant.

Although very young infants may interpret the mask as a nipple and attempt to suck as

they breathe, increasing the concentrations of anesthetic agents, toddlers and preschool

children usually fight the claustrophobic feeling of a tight mask fit. Older children may

be persuaded to assist in holding the mask if they have chosen this induction over a

shot. Halothane and sevoflurane are the only agents available for reliable and safe

inhaled induction of anesthesia. The incidence of bradycardia, hypotension, and cardiac

arrest during inhalation induction of anesthesia is higher in infants younger than 1 year of

age than in older children and adults.37 This greater propensity for untoward events from

potent inhalational agents may be attributed to age-related differences in uptake,

anesthetic requirements, and sensitivity of the cardiovascular system.38 Uptake of

inhalational anesthetics is faster in infants and small children than in adults because of the

much greater ratio of alveolar ventilation to functional residual capacity and the altered

distribution of cardiac output. The high inspired concentrations (overpressure) used early

in induction can lead to very high tissue concentrations of anesthetic early in induction

and result in severe cardiac depression.39 The incidence of severe myocardial depression

is similar with equipotent concentrations of both halothane and sevoflurane.40,41 Mask

anesthesia induction in this age group must be accompanied by vigilant monitoring of

blood pressure and pulse. Early administration of muscle relaxants to facilitate intubation

in young infants may be more prudent than attempting endotracheal intubation under

deep volatile anesthesia alone.

Although intracardiac shunts can, in theory, alter the uptake of anesthetic agents and

affect the speed of induction, this is rarely clinically evident. A right-to-left shunt slows

the induction of anesthesia because anesthetic concentration in the arterial blood

increases more slowly. A left-to-right shunt should have the opposite effect; volatile

agent induction is speeded up because the rate of anesthetic transfer from the lungs to the


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arterial blood is increased. In practice, decreased delivery of anesthetic to the target

tissues largely negates the increased uptake.

The minimum alveolar concentration (MAC) of anesthetic required in pediatric patients

differs with age, usually in an inverse relationship (Fig. 44-1). Two- to 3-month-old

infants actually have the highest anesthetic requirements.

Figure 44-1. The minimum alveolar concentration (MAC) of isoflurane and

postconceptual age. (Data from Le Dez KM, Lerman J: The minimum alveolar

concentration [MAC] of isoflurane in preterm neonates. Anesthesiology 67:301, 1987.)

Halothane has a long history of efficacy as an inhaled agent for pediatric anesthesia. It

has the least noxious smell of the older agents and is very well accepted by most patients.

In terms of emergence characteristics (in spite of a higher bloodgas partition

coefficient), studies of time to awakening have shown little clinical difference between

halothane and isoflurane.42 Although there has been some concern regarding

sensitization of the myocardium to catecholamines, there is little problem in the absence

of hypercarbia or light anesthesia.43 Up to 10 mg kg1 of epinephrine may be used with

minimal risk of cardiac dysrhythmia in normocarbic pediatric patients.

Halothane can cause myocardial depression. This effect is exaggerated in young children,

and in those who are relatively hypovolemic. Addition of muscle relaxants to a lighter

halothane anesthetic (in conjunction with regional anesthetic techniques or opioids) can

ameliorate this effect.

Isoflurane has a long track record as a safe and efficacious agent for maintenance of

anesthesia in infants and children. Like halothane, it decreases blood pressure in pediatric

patients. Although the myocardial depression in children may be less than that caused by

halothane in equipotent doses, isoflurane reduces peripheral vascular resistance, whereas

halothane does not. (In neonates, equal myocardial depression has been demonstrated

with both drugs.44) The major disadvantage of isoflurane is its pungent odor and high

incidence of laryngospasm when this agent is used for inhaled induction of anesthesia. It

should not be used for inhaled induction of anesthesia.


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Desflurane has also been used as a maintenance anesthetic in pediatric patients of all

ages. Unfortunately, an unacceptable incidence of coughing, increased secretions, and

laryngospasm preclude its use as a mask induction agent.45 Although desflurane appears

to be associated with faster initial awakening when used as a maintenance anesthetic

agent in pediatric patients, studies have shown no difference between halothane and

desflurane in time to discharge after ambulatory surgery.46

Sevoflurane is now well established as an excellent choice for inhaled induction of

anesthesia of anesthesia in pediatric patients. Its low blood-gas solubility allows rapid

induction and emergence from anesthesia. There appears to be a relatively low level of

myocardial depression even when given at maximum vaporizer output for induction of

anesthesia. Numerous studies have documented a decreased incidence of dysrhythmias

compared with halothane. However, some confusion is apparent in studies citing

sevoflurane's superiority over other potent inhalational agents; in many studies, higher

MACs of halothane are compared with lower MACs of sevoflurane.40,41

The nonpungent smell of sevoflurane allows smooth mask induction.47,48 Its safety and

efficacy have been well established in hundreds of studies from around the world. In spite

of its excellent clinical track record, concerns about the possible accumulation of toxic

metabolites in a rebreathing circuit at low fresh gas flows remain to be worked out; at this

time, flows of 2 l min1 or greater are recommended. Sevoflurane is also relatively

expensive compared with the other inhalation agents. In addition, the one advantage of

any agent with low solubility (i.e., rapid awakening) is accompanied by a high rate of

postoperative excitement.49,50 Close attention to postoperative analgesia is imperative

when either desflurane or sevoflurane is used.

Intravenous Agents SedativeHypnotics

Sedativehypnotic medications are often used after intravenous placement in pediatric

patients (after mask induction) to facilitate deepening of anesthesia. Older children

frequently undergo intravenous induction rather than mask inhalational anesthesia

induction. Application of EMLA (eutectic mixture of local anesthetics) cream or

iontophoresis of lidocaine can increase cooperation and patient comfort during venous

cannulation, particularly in children who must undergo frequent needle procedures.51,52

Propofol, thiopental, methohexital, and ketamine have been used extensively for


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anesthetic induction in pediatric patients; there is much less experience with etomidate.

Children usually require larger doses of these drugs (on a per kilogram basis) to achieve

obtundation than adults. Pediatric patients receiving antiseizure medications require even

larger doses than their nonmedicated counterparts to achieve the same effect.

Propofol's chemistry and pharmacokinetics are reviewed elsewhere in this text. Induction

doses of 2.53 mg kg1 are required in children younger than 2 years of age, whereas

older children need doses of 2.02.5 mg kg1.53 The major drawback with use of this

drug (aside from the requirement for intravenous access) is pain on administration. This

pain is enhanced if the drug is injected into a small vein. The injection of intravenous

lidocaine 0.21 mg kg1 immediately before propofol injection can reduce this pain, as

can administration through a small-gauge (2227) catheter in a large antecubital vein. As

in adults, a modest reduction in systolic blood pressure usually accompanies bolus

administration. Propofol may be used for induction or maintenance of anesthesia. When

used for maintenance of anesthesia (150200 mg kg1 min1), propofol is associated

with decreased postoperative vomiting.53 In addition, propofol infusions can be very

useful for sedation during magnetic resonance imaging as well as other minimally

invasive procedures where patient cooperation is essential.54

OpioidsFentany lmg kg1 or morphine 0.050.1 mg kg1 are often used as adjuncts to nitrous

oxidevolatile agent anesthetics. Sufentanil 12 mg kg1 or alfentanil 50100 mg kg

1 have also been successfully used in pediatric patients. In addition to blunting

hemodynamic responses to intubation and decreasing required MAC for inhaled agents,

these doses of fentanyl and morphine also provide postoperative analgesia. The ultra

short-acting opioid remifentanil has been successfully used in children for both general

anesthesia and sedation.55 No postoperative analgesia is provided, and further experience

is required to prove its cost effectiveness and safety.

The issue of sensitivity to the respiratory depressant effects of opioids and at what age it

decreases has yet to be resolved. It is apparent that altered pharmacokinetics and

immaturity of the bloodbrain barrier may alter disposition of these drugs in very young

children. Morphine is the least lipophilic of the opioid class; a greater proportion of any


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blood concentration may be able to cross the immature bloodbrain barrier of the neonate

or young infant compared with adults. Therefore, this medication should be administered

with caution in infants younger than 6 months of age.

Bradycardia and chest wall rigidity are two other potential difficulties associated with

opioid anesthesia. Early administration of a vagolytic agent or muscle relaxant should be

considered in all infants when using these medications.

Muscle Relaxants

Succinylcholine has a long history of use in children. Since 1990, the drug has received

much attention because of the severity of its possible complications.56 Reports of

rhabdomyolysis, hyperkalemia, masseter spasm, and malignant hyperthermia have caused

the U.S. Food and Drug Administration to label this drug relatively contraindicated in

pediatric patients.

The hydrophilic nature of succinylcholine and its rapid redistribution into the

extracellular fluid volume mandate higher doses in infants (2 mg kg1) than in older

patients. Optimal intubating conditions are achieved within 1 minute when administered

iv. Reliable muscle relaxation is also achieved within 12 minutes after intramuscular

administration of 45 mg kg1; this route may be life saving if laryngospasm occurs

before establishment of intravenous access.

Atropine is frequently administered before or with succinylcholine to prevent potential

associated dysrhythmias such as marked bradycardia or sinus arrest, especially with

repeat dosing. Although both of these cardiac dysrhythmias may occur at any age, they

are more frequent in young pediatric patients.

Succinylcholine administration has also been associated with spasm of the masseter

muscles. There is an association of masseter spasm with malignant hyperthermia, and

some debate remains as to the appropriate action when masseter spasm occurs.57 At the

very least, extreme vigilance for signs of malignant hyperthermia is warranted whenever

masseter spasm occurs. Malignant hyperthermia is evidenced by high end-tidal carbon

dioxide along with tachycardia and hypertension. Treatment with cooling measures and

dantrolene must be initiated immediately to avoid serious morbidity and mortality.

Although malignant hyperthermia remains the most dreaded consequence of

succinylcholine administration, another life-threatening complication has been


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reported.58 Succinylcholine-induced hyperkalemic cardiac arrest has been reported in

children with previously undiagnosed myopathies. Hyperkalemic cardiac arrest is

heralded by tall, peaked T waves on the electrocardiogram, proceeding swiftly to bizarre,

wide-complex tachydysrhythmias, ventricular tachycardia, and possible ventricular

fibrillation. In addition to immediate cardiopulmonary resuscitation efforts, calcium and

bicarbonate administration can be life saving in this situation.

In spite of the aforementioned catastrophes, airway-related complications are a far more

frequent cause of serious morbidity in pediatric patients undergoing anesthesia. Although

use of succinylcholine should probably be limited to patients with a full stomach or

laryngospasm, it remains the drug of choice when rapid onset of muscle relaxation is

essential.

All of the nondepolarizing muscle relaxants used in adults are effective for pediatric

patients as well. Neonates have a significantly larger volume of distribution for these

drugs than older children and adults.59 In addition, infants appear relatively sensitive to

nondepolarizing muscle relaxants. The recommended effective doses for nondepolarizing

muscle relaxants (reviewed elsewhere in this text) are similar in children and adults, but

the duration of action tends to be slightly longer in pediatric patients. Selection of muscle

relaxant should be done with an understanding of side effects and desired duration of

effect. Rocuronium has the fastest onset of action in this class (6090 seconds for a 1 mg

kg1 dose); however, the variability of onset time in pediatric patients has left its use as

a reliable rapid-sequence drug uncertain. Although intramuscular administration of

rocuronium provides rapid onset of muscle relaxation, intubating conditions are

inadequate.60 Thus, succinylcholine remains the only reliable intramuscular muscle

relaxant.

The new, rapid-onset agent rapacuronium is being evaluated in children. Early reports

indicate that the same profiles of hemodynamic stability and rapid onset noted in adults

are evident in pediatric patients. Higher doses administered intramuscularly provided

optimum intubating conditions much less rapidly than succinylcholine, although faster

than rocuronium.61

Antagonism of neuromuscular blockade should be carefully considered in all neonates

and small infants, even if they have recovered clinically. Any increase in the work of


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breathing may cause fatigue and respiratory failure, particularly if concomitant opioid

administration occurs. In general, if an infant or child can vigorously flex at the hips,

adequate muscle strength is present for spontaneous respiration.

Antinausea Medications

Nausea and vomiting are among the most frequent causes for unanticipated hospital

admission in pediatric ambulatory surgery patients. This is a particular problem in

children undergoing tonsillectomy, strabismus surgery, or orchiopexy.

The same medications have been shown to be effective in children as in adults.

Droperidol in doses of 2070 mg kg1 has been successfully used; however, some

studies report a delay in discharge at higher doses.62 Metoclopramide has also been used

in doses of 0.15 mg kg1, whereas ondansetron at doses of 0.050.15 mg kg1 has

also proven useful.63 Use of propofol as a primary anesthetic decreases nausea and

vomiting after surgeries associated with a high rate of nausea; use of propofol solely as

an induction agent does not decrease nausea and vomiting.64 Many studies have

demonstrated that the use of high doses of dexamethasone decreases nausea and vomiting

after tonsillectomy and other procedures.65,66

What is lacking in pediatric, as in adult patients, is a clear costbenefit analysis showing

a hierarchy of use of these various medications as either prophylactic or rescue

medications.67 It is clear, however, that in addition to pharmacologic intervention, the

simple policy of not requiring children to drink fluids before discharge itself decreases

vomiting.68 It is also clear that administration of even a single dose of opioid increases

nausea and vomiting. Optimal use of nonsteroidal anti-inflammatory drugs (NSAIDs),

acetaminophen, and regional analgesia techniques can help avoid this annoying

complication.69

AIRWAY MANAGEMENT

Attention to appropriate management of the airway in pediatric patients remains the

single most important aspect of pediatric anesthesia. Many pediatric anesthetics in older

infants and children are conducted by face mask or (more often) laryngeal mask airway

(LMA). Most pediatric anesthesiologists still believe that endotracheal intubation is

particularly valuable in young infants and neonates. Mask ventilation is technically more

difficult in young infants, and sizing/securing an LMA can be uncertain. In addition,


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these infants are more sensitive to the myocardial depressant effects of volatile

anesthetics and often benefit from the use of muscle relaxants as part of the anesthetic

technique.

Laryngeal mask airways are available in sizes for all patients, including newborns.70

Their use has become ubiquitous in outpatient pediatric anesthesia. The LMA is now a

standard airway for lower extremity and genito-urinary surgery. More recently, it has

been incorporated into tonsillectomy and adenoidectomy procedures as well as eye

muscle surgery.71,72 In addition, the LMA has proven useful in assisting airway

management in infants and children with difficult airways, particularly those for whom

conventional mask ventilation may be difficult.73 As in older patients, the use of LMAs

is not without problems; oxygen desaturation and difficulty in placement as well as

aspiration around the device can occur.

Tracheal intubation in infants and children is not more difficult than in the adult, but the

anesthesiologist must be familiar with the anatomic differences of the pediatric airway as

well as the specialized equipment required. Trauma can be minimized by gentle airway

manipulation at a sufficiently deep plane of anesthesia or after adequate muscle

relaxation. The most common morbidity associated with endotracheal intubation

(postextubation croup) has been associated with tight endotracheal tube fit. An air leak at

2025 cm H2O pressure or lower has been shown to decrease the risk of postextubation

croup; use of a cuffed endotracheal tube usually requires a half-size decrease in tube

diameter to provide the same leak as an uncuffed tube, but its use is by no means

contraindicated.

Several formulas have been used for endotracheal tube selection; for children older than 1

year of age, (age/4) + 4.5, or French size + 18/4 are two of the more popular formulas.

Appropriate size has also been correlated with the tip of the child's fifth finger. It is

important to have endotracheal tube sizes above and below the estimated size, and to

begin with the smaller tube if an estimated size falls between available tubes. If an air

leak is present at too low a pressure, replacement of a smaller tube with one a half-size

larger causes less trauma than the reverse.

PEDIATRIC BREATHING CIRCUITS


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Much has been written about the advantages and disadvantages of various anesthesia

circuits for use in pediatric patients (see Chapter 22). Pediatric circuit design has been

directed to the physiology of the neonate and ways of reducing the work of breathing

while preventing rebreathing. Nonrebreathing circuits minimize the work of breathing

because they have no valves to be opened by the patient's respiratory effort. In addition,

because the total volume of the circuit is less, the partial pressure of inhaled agent

increases faster. Compression and compliance volumes are also decreased compared with

a standard breathing circuit.

A number of combinations of the simple T-piece tubing, reservoir bag, and sites of fresh

gas entry and overflow are possible. Mapleson classified the various combinations into

five types (Fig. 44-2). The Jackson Rees modification is functionally identical to the

Mapleson D, as are coaxial systems. Carbon dioxide is removed most effectively in the D

configuration when controlled ventilation is used, whereas spontaneous ventilation is

most effective in the A system.

Figure 44-2. Mapleson classification (AE) of some rebreathing systems. VFG is the

fresh gas flow. (From Mushin WW, Jones PL: Physics for the Anaesthetist, 4th ed, p 375.

Boston, Blackwell Scientific, 1987.)

Circle breathing systems can also be used very effectively in infants and children. Newer

anesthesia machines use valves with much less resistance than older models. In addition,

most neonates and small infants (for whom resistance would be the biggest problem) are

ventilated mechanically during surgery, making work of breathing a nonissue. Dead

space in these systems is no more than that of the Mapleson circuits.74,75

MONITORING


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Monitoring decisions for pediatric patients are similar to those in adults. The pediatric

patient should be monitored continuously with precordial or esophageal stethoscope. This

simple device allows the anesthesiologist to detect changes in the rate, quality, and

intensity of the heart sounds, which is helpful in evaluating the depth of anesthesia when

potent inhalational agents are used. Pulse oximetry, capnometry, blood pressure

(measured noninvasively with appropriately sized cuffs), temperature, and

electrocardiogram should also be monitored routinely in children as in adults. More

invasive or sophisticated monitoring should be used in appropriate circumstances.

INTRAVENOUS FLUID THERAPY

Fluid therapy is divided into three portions: deficit, maintenance, and third-space/blood

replacement. Fortunately, modern fasting guidelines have greatly reduced the fluid deficit

that pediatric surgical patients must replace. It is, however, important to elicit when the

child last took fluid, and an estimate of how much the child drank.

An understanding of intravenous fluid management in the pediatric patient must consider

the high metabolic demands and the high ratio of body surface area to weight that

children have.76 The basis for calculating maintenance fluid need derives from the fact

that daily fluid requirements depend directly on metabolic demand; 100 ml of water is

required for each 100 calories of expended energy. Relating this to weight produces the

hourly fluid requirements, as seen in Table 44-3.

Table 44-3. MAINTENANCE FLUID REQUIREMENTS FOR PEDIATRIC

PATIENTS (LEAN BODY MASS)

There is a trend to provide maintenance fluids, as well as deficit fluids with a balanced

salt solution, with or without glucose. The optimum fluid to avoid hypoglycemia and

hyperglycemia is dextrose 2.5% in lactated Ringer's solution; however, this fluid is not


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commercially available.28 Even though symptomatic hypoglycemia is very rare in

children beyond the infant age, it is important to monitor blood glucose if it is not

included in the intravenous therapy for infants. Another approach might be to provide 5%

dextrose in 0.45% normal saline (D5 0.45 NS) for maintenance, piggybacked into a

balanced salt solution for the deficit and third-space fluid. This double-iv fluid system

may be quite costly because it does require a second intravenous administration setup.

The fluid deficit incurred during fasting should be replaced during anesthesia.

Vasodilation from anesthetic agents may cause hypotension, even in patients who are not

significantly hypovolemic. Aggressive intravenous hydration improves patient well-

being. As mentioned earlier, aggressive hydration in the perioperative period combined

with no requirement for oral intake before discharge decreases both postoperative nausea

and vomiting and time to discharge home in pediatric outpatients.77

Assuming a healthy infant is in water and electrolyte balance at the time oral feeding

stopped, the fluid deficit at the start of anesthesia can be calculated by multiplying the

infant's hourly maintenance fluid requirement by the number of hours since the last oral

intake. This deficit may be replaced by giving half of the calculated volume during the

first hour of anesthesia, and the other half over the next 2 hours in addition to

intraoperative maintenance fluids. An alternative formula for short surgical cases is to

administer 20 mg kg1 of deficit fluid, plus 5 mg kg1 of maintenance fluid in the first

hour, followed by maintenance fluid for the rest of the brief procedure. It is important not

to give large amounts of hypotonic solutions or dextrose in water (D5W) because these

hypotonic solutions can result in hyponatremia.78

Replacement of third-space intraoperative losses and blood is administered in a fashion

similar to that in adult patients. The magnitude of third-space loss varies with the surgical

procedure, and is highest in infants undergoing intestinal surgery. Evaporative losses are

also highest in these procedures. Estimated third-space loss during intra-abdominal

surgery varies from 6 to 15 ml kg1 h1, whereas in intrathoracic surgery it is less (47

ml kg1 h1). Lactated Ringer's solution is frequently used to replace these third-space

losses. In cases of massive volume replacement, some advocate the use of 5% albumin.

The end point of fluid therapy is sustained adequate blood pressure, tissue perfusion, and

urine volume (0.51 ml kg1 h1). Because baroreceptor reflexes are blunted by


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volatile anesthetic agents, pulse rate often is not an accurate reflection of decreased

intravascular volume.

All blood loss should be replaced in some way. Accurate measurement and calculation of

acceptable blood loss in the infant are vital to any replacement plan. The concept of the

maximum allowable blood loss (MABL) takes into account the effects of patient age,

weight, and starting hematocrit on blood volume. In general, blood volume is

approximately 100120 ml kg1 for the preterm infant, 90 ml kg1 for the term infant,

80 mg kg1 for the child 312 months of age, and 70 mg kg1 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:

Therefore, if an infant weighs 6 kg and has a starting hematocrit of 32%, and if clinical

judgment estimates the desired postoperative hematocrit to be 25%, the calculation would

be:

This MABL would be replaced with 3 ml of lactated Ringer's per milliliter of blood loss

(118 3 = 354 ml). If blood loss remains less than MABL, no further blood loss is

anticipated in the perioperative period, and hemodynamics remain stable, there is no need

for blood transfusion. If significant perioperative blood loss occurs or is anticipated,

discussion of potential transfusion needs with the surgeon is important.

As mentioned earlier, the incidence of apnea is higher in neonates and premature infants

with hematocrits below 30%. A discussion with the surgeon and neonatologist may be

helpful regarding transfusion management for surgical procedures for which significant

perioperative blood loss is anticipated in these tiny patients.

Packed red blood cells have a hematocrit between 55 and 65%. On the average, 1 ml

kg1 of packed red blood cells increases the hematocrit by 1.5%. Units of blood can be

subdivided into pediatric packs of 50100 ml; thus, the remainder of a single unit is not

wasted.


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Rapid administration of citrated blood products can result in hypocalcemia as well as

hypothermia. Fresh frozen plasma contains the greatest amount of citrate per unit volume

of any blood product; rapid administration of fresh frozen plasma causes the greatest

decrease in ionized calcium. Although under most circumstances, mobilization of

calcium and hepatic metabolism of citrate are sufficiently rapid to prevent precipitous

decreases in ionized calcium, infants have smaller stores of calcium. Infusion of fresh

frozen plasma at a rate of 12.5 ml kg1 min1 may be associated with transient

decreases in ionized calcium and decreased arterial blood pressure.

POSTANESTHETIC CARE

Monitoring

Continued monitoring of vital signs is important in infants and children, just as in adults.

Pulse oximetry, pulse rate, and noninvasive blood pressure measurement should continue

in the postanesthesia care unit, just as in older patients. Administration of supplemental

oxygen may be guided by pulse oximetry.

Analgesia

It is the responsibility of the adult to provide analgesia, not the responsibility of the child

to request pain relief. Pain assessment in pediatric patients is complicated by children's

changing but relatively limited cognitive ability to understand measurement instructions

or to articulate descriptions of their pain.79 Children's responses are also affected by their

developing behavioral repertoire and their constantly changing psychology.

Children older than 46 years of age can self-report pain. Younger children are usually

assessed using a behavioral or physiologicbehavioral scale. Pain in children is much

more difficult to assess than in adults because discrimination between pain and distress

may be very challenging, particularly in the younger pediatric patient. Selecting a

consistent means of pain assessment, performing that assessment at regular intervals,

intervening, and reassessing are probably more important than which tool is selected. The

prevailing philosophy among pediatric anesthesiologists is as follows: if I were having

the procedure/surgery that this child is undergoing, would I require pain medication? If

the answer is yes, the child is assessed, pain medication is administered, and a

reassessment is made. If the reassessment shows a decrease of pain behaviors, pain


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management is considered successful, and continued evaluations are planned. If pain

behaviors persist, the child receives additional pain treatment.

In addition, it is recognized that the emotional component of pain is very strong in

children. Nonpharmacologic methods of pain management are also important. Although

the most important of these is minimal separation from parents, other methods such as

reassurance, cuddling, stroking, and distraction should also be used.

Nonopioid analgesics, usually acetaminophen or an NSAID, act at peripheral sites of

injury by inhibiting prostaglandin synthesis and decreasing activation of primary afferent

nerve injuries. These analgesics are useful for the treatment of mild to moderate

discomfort (such as in many ambulatory procedures). When given in appropriate doses,

all of these medications reduce the need for opioids in more severe pain conditions by

approximately 30%.

The most common oral analgesic used in pediatric patients continues to be

acetaminophen. This medication has been shown to be safe and efficacious in neonates as

well as older children, with similar pharmacodynamics and pharmacokinetics in all but

the youngest age groups.80 Doses of 15 mg kg1 orally every 4 hours or 3040 mg

kg1 rectally as a loading dose followed by 1520 mg kg1 every 6 hours, with a

maximum dose of 90 mg 24 h1, produce therapeutic plasma levels with good

analgesia.81 Acetaminophen should be administered only for a few consecutive days to

reduce the risk of hepatic toxicity. Although rectal administration is less convenient and

absorption more erratic than oral doses, acetaminophen suppositories can be inserted after

induction of anesthesia to achieve effective blood levels in approximately 90 minutes.

Ketorolac has been shown to be an effective and safe analgesic for pediatric patients.82

Because a child often denies pain rather than submit to an intramuscular injection,

intravenous administration of ketorolac has become very popularin spite of the fact that

it is an off-label use of the drug. Intramuscular doses of 0.75 mg kg1 provide highly

effective postoperative analgesia, as does an intravenous dose of 1 mg kg1 as a loading

dose, with 0.5 mg kg1 administered every 6 hours thereafter.

As with other NSAIDs, ketorolac should be avoided in patients with pre-existing

nephropathy or bleeding diathesis. Attention to fluid balance is also important; acute

renal failure can occur with the use of NSAIDs in dehydrated patients after even one


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dose. Gastritis does not appear to be a problem. Although the bleeding time is not

increased after administration of this drug, there is an increasing tendency to avoid its

administration in surgical procedures that place a large stress on platelet and clotting

mechanisms, such as tonsillectomy and adenoidectomy.

Ibuprofen is the most popular NSAID given orally to children. It comes in several

palatable preparations. When given in the recommended oral dose of 10 mg kg1 it has

similar analgesic effects as acetaminophen or ketorolac. Gastrointestinal side effects are

uncommon.

Codeine can be administered orally or parenterally, and provides effective control of mild

to moderate postoperative pain. The bioavailability of codeine after oral administration is

approximately 60%. Orally administered codeine (0.51 mg kg1) is often combined

with acetaminophen (10 mg kg1). This combination reduces the overall codeine

requirement, thus limiting dose-dependent side effects. Although available, this

medication is rarely used in its intravenous form because it has no advantage over

morphine, and may be associated with a higher incidence of nausea and vomiting.

Oxycodone (0.2 mg kg1) is available only as a tablet, and is also often combined with

acetaminophen or an NSAID. This agent appears to cause less nausea than codeine at

equipotent doses.

As mentioned in the Opioids section of this chapter, all of the intravenous opioids used in

adult patients can be successfully used in the pain management of children. Doses need to

be reduced for neonates and infants younger than 46 months of age. Patient-controlled

analgesia with opioids is used very effectively in children. The developmental level of the

child must be considered, but most 5-year-olds and almost all 6-year-olds can be taught

to use patient-controlled analgesia for postoperative pain control.

Regional anesthetic techniques have been shown to be particularly useful in pediatric

ambulatory surgery procedures. They are most often used as adjuncts to general

anesthesia, decreasing volatile agent requirement and providing postoperative analgesia.

Simple techniques such as ilioinguinaliliohypogastric nerve block, ring block of the

penis, or caudal block can be very useful for common pediatric surgical

procedures.82,83,84 and 85 Direct local infiltration of surgical wounds can also be very

helpful. Strict attention must be paid to the dose of local anesthetic, the dose of


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epinephrine (if used), and the technique of administration. More sophisticated techniques

such as continuous caudal or epidural analgesia using combinations of opioids and local

anesthetics are useful for inpatients after thoracic, abdominal, or lower extremity

procedures. These regional techniques usually are used in combination with general

anesthesia (catheters are placed after the child is induced) and the regional block is

maintained for postoperative pain control.86 Meticulous attention to technique and close

monitoring of the child must take place when these continuous infusions are used.

Subglottic Edema (Postextubation Croup)

Subglottic edema after extubation usually manifests itself by arrival in the postanesthesia

care unit, and if not, within 2 to 4 hours. In most cases, a barky cough and stertorous

respirations are observed. With severe croup, there may be suprasternal retractions,

tachypnea, labored respirations, and arterial oxygen desaturation.87

Mild cases require little therapy other than high concentrations of humidified oxygen.

Racemic epinephrine (0.5 ml of a 2% solution diluted to a volume of 24 ml)

administered by nebulizer is the next step. If this treatment is used, the child should be

observed for 4 hours before discharge so that an evaluation of respiratory status

postepinephrine effect can be made. If a second treatment is required, the child should be

admitted for overnight observation and treatment.

Even if racemic epinephrine is not used, if there is any doubt as to the child's fitness for

discharge, admission is the prudent course. Although their efficacy is unproven, systemic

steroids are often administered in severe cases of postextubation croup.

CONCLUSION

Children are not just little adults. However, most principles of adult anesthesia are also

applicable in pediatric patients. A thorough understanding of the differences is crucial to

the skilled administration of anesthesia to this challenging group of patients. The smaller

the child, the less margin of reserve is present. The smile on the face of a child who is

comfortable in her mother's arms in the postanesthesia care unit is one of the greatest

rewards any practitioner can receive.

pediatric anestesia

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