title: Ultrasound versus anatomical landmarks for caudal epidural anesthesia in pediatric patients.
abstract: BACKGROUND
  Caudal block is easily performed because the landmarks are superficial. However, the sacral hiatus is small and shallow in pediatric patients. In the present study, we evaluated under general anesthesia whether the distance between the bilateral superolateral sacral crests increased with growth, whether an equilateral triangle was formed between the apex of the sacral hiatus and the bilateral superolateral sacral crests, and whether expansion of the epidural space could be confirmed by ultrasound.
  
  
  METHODS
  This prospective observational study included 282 children who were ASA I-II. Under general anesthesia, each patient was placed in the lateral bent knees position, and the attending anesthesiologist drew an equilateral triangle and measured the distance between the bilateral superolateral sacral crests along a line forming the base of the triangle. Then the sacral hiatus was identified by ultrasound. Differences of the distance between the anatomical landmarks measured by the anesthetist and by ultrasound were evaluated.
  
  
  RESULTS
  Two patients were excluded because the superolateral sacral crests and sacral hiatus could not be palpated. The base of the triangle increased in proportion to age up to 10 years old, with a significant correlation between age and the length of the base (Spearman's r value = 0.97). The triangle was not an equilateral triangle under 7 years old. The sacral hiatus could be identified by ultrasound and we could confirm expansion of the epidural space in all patients.
  
  
  CONCLUSIONS
  We observed a correlation between age and the length of the triangle base in children under 10 years old. Although detection of the anatomical landmarks by palpation differed from identification by ultrasound in pediatric patients, performing ultrasound is important. Epinephrine should be added to the anesthetic to avoid complications.
  
  
  BACKGROUND
  Current Controlled Trials UMIN000017898 . Registered 14 June 2015. Date of protocol fixation was 1(st) December, 2008 and Anticipated trial start date was 5(th) January, 2009.
authors.affiliation: Department of Anesthesia and Critical Care, Tokyo Women's Medical University, Tokyo, Japan. yukako1@rg8.so-net.ne.jp.
authors.forename: Yukako
authors.initials: Y
authors.lastname: Abukawa
authors.affiliation: Department of Anesthesia and Critical Care, Tokyo Women's Medical University, Tokyo, Japan.|Kanagawa Children's Medical Center, 4-1124-2 Mutsukawa, Minami-ku, Yokohama, Kanagawa, 232-0066, Japan.
authors.forename: Koichi
authors.initials: K
authors.lastname: Hiroki
authors.affiliation: Department of Anesthesia and Critical Care, Tokyo Women's Medical University, Tokyo, Japan.
authors.forename: Nobutada
authors.initials: N
authors.lastname: Morioka
authors.affiliation: Department of Anesthesia and Critical Care, Tokyo Women's Medical University, Tokyo, Japan.
authors.forename: Hiroko
authors.initials: H
authors.lastname: Iwakiri
authors.affiliation: Department of Anesthesia and Critical Care, Tokyo Women's Medical University, Tokyo, Japan.
authors.forename: Tomoko
authors.initials: T
authors.lastname: Fukada
authors.affiliation: Department of Anesthesia and Critical Care, Tokyo Women's Medical University, Tokyo, Japan.
authors.forename: Hideyuki
authors.initials: H
authors.lastname: Higuchi
authors.affiliation: Department of Anesthesia and Critical Care, Tokyo Women's Medical University, Tokyo, Japan.
authors.forename: Makoto
authors.initials: M
authors.lastname: Ozaki
mesh_terms: D000367:Age Factors; D000763:Anesthesia, Caudal / Q000379:methods*; D000767:Anesthesia, Epidural / Q000379:methods*; D002648:Child; D002675:Child, Preschool; D004824:Epidural Space / Q000033:anatomy & histology* / Q000000981:diagnostic imaging; D004837:Epinephrine / Q000008:administration & dosage; D005260:Female; D006801:Humans; D007223:Infant; D008297:Male; D011446:Prospective Studies; D012447:Sacrum / Q000033:anatomy & histology* / Q000000981:diagnostic imaging; D018084:Ultrasonography, Interventional
chemical_list: D004837:Epinephrine