RT Book, Section
A1 Karmakar, Manoj
A1 Vandepitte, Catherine
A2 Hadzic, Admir
SR Print(0)
ID 55904999
T1 Chapter 43. Introduction
T2 Hadzic's Peripheral Nerve Blocks and Anatomy for Ultrasound-Guided Regional Anesthesia, 2e
YR 2012
FD 2012
PB The McGraw-Hill Companies
PP New York, NY
SN 978-0-07-154963-9
LK accessanesthesiology.mhmedical.com/content.aspx?aid=55904999
RD 2024/04/24
AB Central  neuraxial  blocks  (CNBs),  which  include  spinal,  epidural,  combined  spinal  epidural  (CSE),  and  caudal  epidural  injections,  are  commonly  practiced  regional  anesthesia  techniques  in  the  perioperative  period,  for  obstetric  anesthesia  and  analgesia,  as  well  as  for  managing  chronic  pain.1  Traditionally,  CNBs  are  performed  using  surface  anatomic  landmarks,  operator  tactile  sensation  (loss  of  resistance)  during  needle  advancement,  and/or  visualizing  the  free  flow  of  cerebrospinal  fluid.  Although  anatomic  landmarks  are  fortuitous  because  spinous  processes  provide  a  relatively  reliable  surface  landmark  in  many  patients,  they  are  not  always  easily  recognized  or  reliable  signs  in  patients  with  obesity,2  edema,  underlying  spinal  deformity,  or  after  back  surgery.  Even  in  the  absence  of  spine  abnormalities,  data  suggest  that  a  clinical  estimate  of  a  specific  intervertebral  space  based  on  the  surface  anatomy  may  not  be  accurate  in  many  patients.3,4  In  other  words,  a  clinical  estimate  of  an  intervertebral  space  often  results  in  needle  placement  one  or  two  spinal  levels  higher  than  intended.3,5,6  This  estimation  error  has  been  attributed  as  a  cause  of  injury  of  the  conus  medullaris  or  spinal  cord  after  spinal  anesthesia.5,7  The  difficulty  of  identifying  the  correct  level  is  particularly  present  in  patients  with  obesity  and  when  accessing  intervertebral  space  in  the  upper  spinal  levels.3,5,7  Therefore,  the  Tuffier's  line,  a  surface  anatomic  landmark  that  is  used  ubiquitously  during  CNB,  is  not  a  consistent  landmark.6  Moreover,  because  of  the  blind  nature  of  the  landmark-based  techniques,  it  is  not  possible  for  the  operator  to  predict  the  ease  or  difficulty  of  needle  placement  prior  to  skin  puncture.  In  a  study  of  300  spinal  anesthetics,  15%  of  attempts  were  judged  to  be  technically  difficult,  and  10%  required  more  than  five  attempts.8  In  another  study  including  202  patients  who  were  under  50  years  of  age,  failed  CNB  was  reported  in  5%  of  cases.9  Thus  the  need  to  establish  a  more  reliable  method  to  identify  the  spinal  levels  and  needle  advancement  toward  the  neuraxis  continues  to  inspire  clinical  and  imaging  studies.