title: Ultrasound-guided carotid sheath block for carotid endarterectomy: a case series of the spread of injectate.
abstract: BACKGROUND
  We aimed to show the spread of local anesthetic following an ultrasound-guided, double-injection technique of a carotid sheath block before carotid endarterectomy.
  
  
  METHODS
  The study included 15 patients scheduled for elective carotid endarterectomy. The carotid sheath block was performed after ultrasound-guided localization of the carotid bifurcation (level C4-C6) at the posterior border of the sternocleidomastoid muscle. A mix of 7.5 mL ropivacaine 0.75%, 7.5 mL prilocaine1% and 3 mL iopromidum was injected at the base of the carotid bifurcation. An additional 15 mL of the mixture was administered subcutaneously at the surgical incision line. Thirty minutes after the block, a computed tomography scan of the head, neck region and upper thorax was performed to reconstruct a 3-D distribution of the injectate.
  
  
  RESULTS
  All patients achieved C2-C4 dermatomal sensory blockade. None required conversion to general anesthesia. The injectate spread ranged from the vertebral body of C1 to the vertebral body of T3. The mean volume of distribution was 97±13 mL, the craniocaudal spread 138±19 mm, dorsoventral 57±8 mm and coronal 53±8 mm. The mean carotid artery circumference contact was 252°±77, with four patients (27%) presenting with a ring formation (360°) around the carotid artery.
  
  
  CONCLUSIONS
  Ultrasound-guided carotid sheath block provided an extensive spread of local anesthetic. A complete ring formation of local anesthetic around the artery does not seem necessary for a successful anesthesia. The resulting nerve blockade thus appears sufficient for surgery, with minor risks compared to blind methods.
authors.affiliation: Department of Anesthesiology and Intensive Care, Kantonsspital, Lucerne, Switzerland.
authors.forename: Mattias
authors.initials: M
authors.lastname: Casutt
authors.affiliation: Department of Anesthesiology and Intensive Care, Kantonsspital, Lucerne, Switzerland.
authors.forename: Ivo
authors.initials: I
authors.lastname: Breitenmoser
authors.affiliation: Department of Radiology, Kantonsspital, Lucerne, Switzerland.
authors.forename: Lennart
authors.initials: L
authors.lastname: Werner
authors.affiliation: Department of Surgery, Kantonsspital, Lucerne, Switzerland.
authors.forename: Robert
authors.initials: R
authors.lastname: Seelos
authors.affiliation: Department of Anesthesiology and Intensive Care, Kantonsspital, Lucerne, Switzerland.
authors.forename: Christoph
authors.initials: C
authors.lastname: Konrad
keywords: carotid endarterectomy; carotid sheath block; cervical plexus block; spread of local anesthetic; three-dimensional reconstruction; ultrasonic controlled