title: A comparison of the onset time of complete blockade of the sciatic nerve in the application of ropivacaine and its equal volumes mixture with lidocaine: a double-blind randomized study.
abstract: BACKGROUND
  The purpose of the current study is to create a new mixture of local anesthetics-one with a short time of block development and short action term (5 ml of 1% lidocaine solution) and another with a longer time of anesthesia development and a long analgetic effect (5 ml of 0.75% ropivacaine)-for use during surgical operations on extremities. The primary end point was the development of the complete sensory block of the sciatic nerve.
  
  
  METHODS
  Sixty blocks of sciatic nerve were used in a double-blind randomized research, under ultrasonic guidance, using an electric stimulator with the peripheral nerves. Sixty patients were divided into 3 equal groups. In the first group, a sciatic nerve block was performed with 5 ml of 0.75% ropivacaine solution (37.5 mg); in the second group, 10 ml of 0.75% ropivacaine solution (75 mg) was used and, in the third group, a mixture of 5 ml of 0.75% ropivacaine (as above) and 5 ml of 1% lidocaine solution (50 mg) was used. The assessment of the time required for developing sensory and motor blocks was carried out from the beginning of local anesthetic solution injection in the fascial sheath of the sciatic nerve.
  
  
  RESULTS
  Demographic data of patients were identical in the three sample groups. The time required for achieving a complete motor and sensory block was reduced due to the mix of the 1% lidocaine solution with the 0.75% ropivacaine solution. The time required for achieving a complete sensory block in groups treated with 5 and 10 ml ropivacaine was 45 (40-48) and 30 (28-30) min, respectively, in contrast with 12 (10-13) min when the mixture of anesthetics was applied (P < 0.01). There was no difference in analgesic duration in the postoperative period among groups at P > 0.05.
  
  
  CONCLUSIONS
  The mixture of 5 ml of 1% lidocaine with 5 ml of 0.75% ropivacaine leads to a reduction in the time required for the development of complete sensory and motor blocks of the sciatic nerve, without reducing postoperative analgesia time.
authors.affiliation: Department of Anesthesiology Intensive Care, Mogilev Regional Hospital, Mogilev, Republic of Belarus.
authors.forename: Piacherski
authors.initials: P
authors.lastname: Valery
authors.forename: Marochkov
authors.initials: M
authors.lastname: Aliaksei
keywords: EMLA; Lidocaine; Ropivacaine; Sciatic nerve; Ultrasonography
references.citation: Anesth Analg. 2006 Feb;102(2):593-7
references.pmid: 16428568
references.citation: Br J Anaesth. 1990 Nov;65(5):648-53
references.pmid: 2248843
references.citation: Anesth Analg. 1998 Sep;87(3):597-600
references.pmid: 9728836
references.citation: Br J Anaesth. 2010 Feb;104(2):239-44
references.pmid: 20034967
references.citation: Reg Anesth Pain Med. 2012 Jul-Aug;37(4):410-4
references.pmid: 22609646
references.citation: Anesth Analg. 2001 Jul;93(1):187-91
references.pmid: 11429363
references.citation: Br J Anaesth. 2008 Oct;101(4):549-56
references.pmid: 18682410
references.citation: Anesth Analg. 1999 Sep;89(3):739-42
references.pmid: 10475316
references.citation: Anesth Analg. 2011 Oct;113(4):951-5
references.pmid: 21821517
references.citation: Anaesthesist. 2011 Nov;60(11):1014-26
references.pmid: 22083099
references.citation: Anesth Analg. 2010 Oct;111(4):1059-64
references.pmid: 20705778
references.citation: Br J Anaesth. 2005 Jan;94(1):7-17
references.pmid: 15277302
references.citation: Anesthesiology. 2009 Nov;111(5):1128-34
references.pmid: 19809282
references.citation: Anesth Analg. 2009 Feb;108(2):641-9
references.pmid: 19151302
references.citation: Anesth Analg. 2008 Dec;107(6):2085-8
references.pmid: 19020163
references.citation: Anesth Analg. 2012 May;114(5):1121-7
references.pmid: 22366843
references.citation: Anesth Analg. 2005 Apr;100(4):976-981
references.pmid: 15781509