title: Ilioinguinal/iliohypogastric blocks in children: where do we administer the local anesthetic without direct visualization?
abstract: BACKGROUND
  Ultrasonographic observation of peripheral nerve blocks enables direct visualization of the spread of local anesthetic around the targeted nerves. Similarly, ultrasonography may be used to determine the site of local anesthetic placement when landmark-based techniques are used. We performed a study to determine the actual location of local anesthetic when ilioinguinal/iliohypogastric nerve blocks are performed using landmark-based techniques in children in an attempt to explain a failed block.
  
  
  METHODS
  After induction of general anesthesia (1 minimum alveolar anesthetic concentration halothane and laryngeal mask airway), 62 children scheduled for inguinal surgery received an ilioinguinal/iliohypogastric nerve block based on standard anatomical landmarks. Ultrasonography was then used to determine the actual location of local anesthetic placement. The anesthesiologist performing the block was blinded to the ultrasonographic investigation. Successful blocks were recorded either when the local anesthetic surrounded the nerves or were based on clinical signs after skin incision.
  
  
  RESULTS
  In 14% of the blocks, the local anesthetic was administered correctly around the nerves resulting in successful blocks. In the remaining 86%, the local anesthetic was administered in adjacent anatomical structures (iliac muscle 18%, transverse abdominal muscle 26%, internal oblique abdominal muscle 29%, external oblique abdominal muscle 9%, subcutaneous 2%, and peritoneum 2%), and 45% of these blocks failed.
  
  
  CONCLUSIONS
  Accurate placement of local anesthetic around the ilioinguinal/iliohypogastric nerves in children is seldom possible when landmark-based techniques are used. In the majority of patients, the local anesthetic was inaccurately placed in adjacent anatomical structures with unpredictable block results.
authors.affiliation: Department of Anaesthesia and Intensive Care Medicine, Medical University of Vienna, 1090 Vienna, Austria.
authors.forename: Marion
authors.initials: M
authors.lastname: Weintraud
authors.forename: Peter
authors.initials: P
authors.lastname: Marhofer
authors.forename: Adrian
authors.initials: A
authors.lastname: Bösenberg
authors.forename: Stephan
authors.initials: S
authors.lastname: Kapral
authors.forename: Harald
authors.initials: H
authors.lastname: Willschke
authors.forename: Michael
authors.initials: M
authors.lastname: Felfernig
authors.forename: Stephan
authors.initials: S
authors.lastname: Kettner
mesh_terms: D000779:Anesthetics, Local / Q000008:administration & dosage*; D002045:Bupivacaine / Q000008:administration & dosage*; D002648:Child; D002675:Child, Preschool; D006801:Humans; D007223:Infant; D007264:Inguinal Canal / Q000000981:diagnostic imaging / Q000294:innervation* / Q000601:surgery; D009407:Nerve Block / Q000379:methods*; D010147:Pain Measurement; D017288:Pain Threshold / Q000187:drug effects; D010149:Postoperative Pain / Q000503:physiopathology / Q000517:prevention & control*; D011446:Prospective Studies; D017211:Treatment Failure; D014463:Ultrasonography
chemical_list: D000779:Anesthetics, Local; D002045:Bupivacaine