RT Book, Section
A1 Butterworth IV, John F.
A1 Mackey, David C.
A1 Wasnick, John D.
SR Print(0)
ID 1161431540
T1 Pediatric Anesthesia
T2 Morgan & Mikhail's Clinical Anesthesiology, 6e
YR 2018
FD 2018
PB McGraw-Hill Education
PP New York, NY
SN 9781259834424
LK accessanesthesiology.mhmedical.com/content.aspx?aid=1161431540
RD 2024/04/18
AB KEY  CONCEPTS  Neonates  and  infants  have  fewer  and  smaller  alveoli,  reducing  lung  compliance;  in  contrast,  their  cartilaginous  rib  cage  makes  their  chest  wall  very  compliant.  The  combination  of  these  two  characteristics  promotes  chest  wall  collapse  during  inspiration  and  relatively  low  residual  lung  volumes  at  expiration.  The  resulting  decrease  in  functional  residual  capacity  (FRC)  limits  oxygen  reserves  during  periods  of  apnea  (eg,  intubation  attempts)  and  readily  predisposes  them  to  atelectasis  and  hypoxemia.  Compared  with  older  children  and  adults,  neonates  and  infants  have  a  proportionately  larger  head  and  tongue,  narrower  nasal  passages,  an  anterior  and  cephalad  larynx,  a  longer  epiglottis,  and  a  shorter  trachea  and  neck.  These  anatomic  features  make  neonates  and  young  infants  obligate  nasal  breathers  until  about  5  months  of  age.  The  cricoid  cartilage  is  the  narrowest  point  of  the  airway  in  children  younger  than  5  years  of  age.  Cardiac  stroke  volume  is  relatively  fixed  by  the  immature,  noncompliant  left  ventricle  in  neonates  and  infants.  The  cardiac  output  is  therefore  very  sensitive  to  changes  in  heart  rate.  Thin  skin,  low  fat  content,  and  a  greater  surface  area  relative  to  weight  promote  greater  heat  loss  to  the  environment  in  neonates.  Heat  loss  can  be  made  worse  by  prolonged  exposure  to  an  inadequately  warmed  operating  room  environment,  administration  of  room-temperature  intravenous  fluid,  and  dehumidified  anesthetic  gases,  and  the  effects  of  anesthetic  agents  on  temperature  regulation.  Hypothermia  has  been  associated  with  delayed  awakening  from  anesthesia,  cardiac  arrhythmias,  respiratory  depression,  increased  pulmonary  vascular  resistance,  and  increased  susceptibility  to  anesthetics  and  other  agents.  Neonates,  infants,  and  young  children  have  relatively  greater  alveolar  ventilation  and  reduced  FRC  compared  with  older  children  and  adults.  This  greater  minute  ventilation-to-FRC  ratio  contributes  to  a  rapid  increase  in  alveolar  anesthetic  concentration  that,  combined  with  relatively  greater  blood  flow  to  the  brain,  speeds  inhalation  induction.  The  minimum  alveolar  concentration  (MAC)  for  halogenated  agents  is  greater  in  infants  than  in  neonates  and  adults.  In  contrast  to  other  agents,  no  increase  in  the  MAC  of  sevoflurane  can  be  demonstrated  between  neonates  and  infants.  Sevoflurane  appears  to  have  a  greater  therapeutic  index  than  halothane  and  is  the  preferred  agent  for  inhaled  induction  in  pediatric  anesthesia.  Children  are  more  susceptible  than  adults  to  cardiac  arrhythmias,  hyperkalemia,  rhabdomyolysis,  myoglobinemia,  masseter  spasm,  and  malignant  hyperthermia  associated  with  succinylcholine.  When  a  child  experiences  cardiac  arrest  following  administration  of  succinylcholine,  immediate  treatment  for  hyperkalemia  should  be  instituted.  Unlike  adults,  children  may  have  profound  bradycardia  and  sinus  node  arrest  following  the  first  dose  of  succinylcholine  without  atropine  pretreatment.  A  viral  infection  within  2  to  4  weeks  before  general  anesthesia  and  endotracheal  intubation  appears  to  place  the  child  at  an  increased  risk  for  perioperative  pulmonary  complications,  such  as  wheezing,  laryngospasm,  hypoxemia,  and  atelectasis.  Temperature  must  be  closely  monitored  in  pediatric  patients  because  of  their  greater  risk  for  malignant  hyperthermia  and  greater  susceptibility  for  intraoperative  hypothermia  or  hyperthermia.  Meticulous  attention  to  fluid  intake  and  loss  is  required  in  younger  pediatric  patients  because  these  patients  have  limited  margins  of  error.  A  programmable  infusion  pump  or  a  buret  with  a  microdrip  chamber  is  useful  for  accurate  ...