title: The superficial cervical plexus block for postoperative pain therapy in carotid artery surgery. A prospective randomised controlled trial.
abstract: OBJECTIVE
  Rapid and reliable neurological evaluation soon after carotid artery surgery is feasible with modern methods of general anesthesia, but postoperative pain therapy remains a challenge. Use of opioids can mask neurological deficits. We investigated whether superficial cervical plexus block reduced postoperative opioid consumption after carotid endarterectomy.
  
  
  METHODS
  Prospective, randomised, double-blinded, placebo controlled trial.
  
  
  METHODS
  46 patients undergoing unilateral carotid endarterectomy under general anesthesia were randomized to either superficial cervical block with ropivacaine (n=23) or placebo (n=23). A patient controlled analgesia device (PCA) delivering morphine was provided for all patients. Subjective pain levels (visual analog scale, VAS) were recorded. The primary outcome was total morphine consumption on discharge from the recovery room. Secondary outcomes included arterial pCO2 (as an indicator of central nervous effects of morphine) and patient satisfaction.
  
  
  RESULTS
  No adverse effects of the superficial cervical plexus block were reported. Four patients in the placebo group were excluded because of other drug use post-operatively. Per protocol analysis compared 23 patients in ropivacaine group and 19 patients in the placebo group. The ropivacaine group had a significant reduction in morphine consumption (3.8+/-2.0 versus 12.9+/-4.0, p<0.001), lower maximal pain scores (2.6+/-2.0 versus 5.8+/-1.6, p<0.001), and paCO2 levels (39.0+/-2.6 versus 41.9+/-3.4, p=0.008) at discharge from the recovery room. Patient satisfaction (1=very good to 6=insufficient) was substantially higher in the ropivacaine group (1.7+/-0.7 versus 3.1+/-1.2, p<00.01).
  
  
  CONCLUSIONS
  The significant and clinically relevant lower morphine consumption and pain score, as well as the substantially higher patient satisfaction demonstrate that superficial cervical plexus block provides effective pain relief for patients undergoing carotid endarterectomy.
authors.affiliation: Department of Anesthesiology, Friedrich-Alexander Universität, Erlangen, Germany. messner@gmx.li
authors.forename: M
authors.initials: M
authors.lastname: Messner
authors.forename: S
authors.initials: S
authors.lastname: Albrecht
authors.forename: W
authors.initials: W
authors.lastname: Lang
authors.forename: R
authors.initials: R
authors.lastname: Sittl
authors.forename: M
authors.initials: M
authors.lastname: Dinkel
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D000577:Amides / Q000008:administration & dosage*; D016058:Analgesia, Patient-Controlled; D000701:Analgesics, Opioid / Q000627:therapeutic use; D000779:Anesthetics, Local / Q000008:administration & dosage*; D002245:Carbon Dioxide / Q000097:blood; D002340:Carotid Artery Diseases / Q000097:blood / Q000601:surgery*; D002572:Cervical Plexus; D004311:Double-Blind Method; D016894:Endarterectomy, Carotid / Q000379:methods; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009020:Morphine / Q000627:therapeutic use; D009407:Nerve Block; D010147:Pain Measurement; D010149:Postoperative Pain / Q000517:prevention & control*; D017060:Patient Satisfaction; D011446:Prospective Studies; D000077212:Ropivacaine; D013997:Time Factors; D016896:Treatment Outcome
chemical_list: D000577:Amides; D000701:Analgesics, Opioid; D000779:Anesthetics, Local; D002245:Carbon Dioxide; D009020:Morphine; D000077212:Ropivacaine