title: The effects of three different approaches on the onset time of sciatic nerve blocks with 0.75% ropivacaine.
abstract: We studied three different injection techniques of sciatic nerve block in terms of block onset time and efficacy with 0.75% ropivacaine. A total of 75 patients undergoing foot surgery were randomly allocated to receive sciatic nerve blockade by means of the classic posterior approach (group classic; n = 25), a modified subgluteus posterior approach (group subgluteus; n = 25), or a lateral popliteal approach (group popliteal; n = 25). All blocks were performed with the use of a nerve stimulator (stimulation frequency, 2 Hz; intensity, 2-0.5 mA) and 30 mL of 0.75% ropivacaine. Onset of nerve block was defined as complete loss of pinprick sensation in the sciatic nerve distribution with concomitant inability to perform plantar or dorsal flexion of the foot. In the three groups, an appropriate sciatic stimulation was elicited at <0.5 mA. The failure rate was similar in the three groups (group popliteal: 4% versus group classic: 4% versus group subgluteus: 8%). The onset of nerve block was slower in group popliteal (25 +/- 5 min) compared with group classic (16 +/- 4 min) and group subgluteus (17 +/- 4 min; P < 0.001). There was no significant difference in the onset of nerve block between group classic and group subgluteus. No differences in the degree of pain measured at the first postoperative administration of pain medication were observed among the three groups. We conclude that the three approaches resulted in clinically acceptable anesthesia in the distribution of the sciatic nerve. The subgluteus and classic posterior approaches generated a significantly faster onset of anesthesia than the lateral popliteal approach.
  
  
  CONCLUSIONS
  Comparing three different approaches to the sciatic nerve with 0.75% ropivacaine, the classic and subgluteal approaches exhibited a faster onset time of sensory and motor blockade than the lateral popliteal approach.
authors.affiliation: *Department of Anesthesiology and †Clinical Epidemiology Unit, Hospital Clínico Universitario de Santiago, Santiago de Compostela, Spain; ‡Department of Anesthesiology, Universidad de Santiago de Compostela, Spain; and §Department of Anesthesiology, Yale University School of Medicine, New Haven, Connecticut.
authors.forename: Manuel
authors.initials: M
authors.lastname: Taboada
authors.forename: Julián
authors.initials: J
authors.lastname: Álvarez
authors.forename: Joaquín
authors.initials: J
authors.lastname: Cortés
authors.forename: Jaime
authors.initials: J
authors.lastname: Rodríguez
authors.forename: Susana
authors.initials: S
authors.lastname: Rabanal
authors.forename: Francisco
authors.initials: F
authors.lastname: Gude
authors.forename: Alexander
authors.initials: A
authors.lastname: Atanassoff
authors.forename: Peter G
authors.initials: PG
authors.lastname: Atanassoff
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000577:Amides / Q000008:administration & dosage; D000779:Anesthetics, Local / Q000008:administration & dosage; D000842:Ankle / Q000601:surgery; D001794:Blood Pressure / Q000187:drug effects; D004311:Double-Blind Method; D004558:Electric Stimulation; D005260:Female; D005528:Foot / Q000601:surgery; D006339:Heart Rate / Q000187:drug effects; D006801:Humans; D008297:Male; D008875:Middle Aged; D009407:Nerve Block; D010092:Oximetry; D011446:Prospective Studies; D012018:Reflex / Q000187:drug effects; D000077212:Ropivacaine; D012584:Sciatic Nerve; D013997:Time Factors
chemical_list: D000577:Amides; D000779:Anesthetics, Local; D000077212:Ropivacaine