title: The median effective analgesic dose (ED50) of ropivacaine in ultrasound-guided transversus abdominis plane block for analgesia in reversal of ileostomy: A double-blind up-down dose-finding study.
abstract: BACKGROUND
  The transversus abdominis plane block has become popular since it has been combined with ultrasound-guided techniques. In abdominal surgery, and especially in subumbilical surgery, it improves postoperative analgesia and reduces morphine consumption. Although it has been shown to be an effective technique, there are wide variations in reported doses and volumes of local anaesthetic used.
  
  
  OBJECTIVE
  The primary objective was to assess the median effective analgesic dose (ED50 = effective dose in 50% of patients) of ropivacaine in TAP blocks for patients undergoing reversal of ileostomy.
  
  
  METHODS
  A double-blind up-down dose-finding study.
  
  
  METHODS
  French Teaching Hospital.
  
  
  METHODS
  Twenty-six colorectal patients were included.
  
  
  METHODS
  After standardised general anaesthesia, a unilateral ultrasound-guided TAP block was performed on patients undergoing elective reversal of ileostomy using 20 ml of ropivacaine. Doses were predefined according to the up-and-down method. The first patient received a dose of 1.6 mg kg(-1). The dose adjustment interval was 0.2 ml kg(-1). The potentially toxic dose of 3 mg kg(-1) was never exceeded.
  
  
  METHODS
  The primary endpoint was pain (defined as 3 or higher on a numerical pain scale of 0 to 10) at rest 6 h after TAP block.
  
  
  RESULTS
  Out of the twenty-six patients who were included in the study, the ED50 of ropivacaine in TAP block for patients undergoing reversal of ileostomy was 2.70 mg kg(-1) [95% confidence interval (95% CI) 2.37 to 3.03 mg kg(-1)].
  
  
  CONCLUSIONS
  The ED50 of ropivacaine in TAP blocks in reversal of ileostomy is close to the toxic threshold. Anaesthesiologists should always be aware of the systemic toxicity risk and use weight-based doses when performing a TAP block.
authors.affiliation: From the CHU Rennes, Service Anesthésie et Réanimation (ML-C,CC-A,EP,YM,HB), CHU Rennes, Service Chirurgie Digestive et Hépato-biliaire, Rennes (VD), CHU Bicêtre et UMR788, Université Paris 11, Le Kremlin-Bicêtre (J-XM), and Inserm UMR 991, Université Rennes 1, Rennes, France (YM,HB).
authors.forename: Maria
authors.initials: M
authors.lastname: Lahlou-Casulli
authors.forename: Cécile
authors.initials: C
authors.lastname: Chaize-Avril
authors.forename: Emmanuel
authors.initials: E
authors.lastname: Pouliquen
authors.forename: Véronique
authors.initials: V
authors.lastname: Desfourneaux
authors.forename: Jean-Xavier
authors.initials: JX
authors.lastname: Mazoit
authors.forename: Yannick
authors.initials: Y
authors.lastname: Malledant
authors.forename: Hélène
authors.initials: H
authors.lastname: Beloeil
mesh_terms: D000009:Abdominal Muscles; D000368:Aged; D000577:Amides / Q000008:administration & dosage*; D000779:Anesthetics, Local / Q000008:administration & dosage*; D004305:Dose-Response Relationship, Drug; D004311:Double-Blind Method; D005260:Female; D006801:Humans; D007081:Ileostomy / Q000009:adverse effects / Q000379:methods*; D008297:Male; D008875:Middle Aged; D009407:Nerve Block / Q000379:methods*; D059408:Pain Management / Q000379:methods; D010147:Pain Measurement / Q000187:drug effects / Q000379:methods; D010149:Postoperative Pain / Q000209:etiology / Q000517:prevention & control; D011446:Prospective Studies; D012086:Reoperation / Q000009:adverse effects / Q000379:methods; D000077212:Ropivacaine; D016896:Treatment Outcome; D018084:Ultrasonography, Interventional / Q000379:methods*
chemical_list: D000577:Amides; D000779:Anesthetics, Local; D000077212:Ropivacaine