title: [Hypobaric 0.15% bupivacaine versus hyperbaric 0.5% bupivacaine for posterior (dorsal) spinal block in outpatient anorectal surgery.].
abstract: OBJECTIVE
  The aim of this study was to study low dose hypobaric 0.15% bupivacaine and hyperbaric 0.5% bupivacaine in outpatient anorectal surgical procedures.
  
  
  METHODS
  Two groups of 50 patients, physical status ASA I and II, undergoing anorectal surgical procedures in a jackknife position, received 6 mg of hypobaric 0.15% bupivacaine in the surgical position (Group 1) or 6 mg of hyperbaric 0.5% bupivacaine in the sitting position for 5 minutes, after which they were placed in a jackknife position (Group 2). Sensitive and motor blockade, time of first urination, ambulation, complications, and the need for analgesics were evaluated. Patients were followed until the third postoperative day and questioned whether they experienced post-puncture headache or temporary neurological symptoms, and until the 30th day and questioned about permanent neurological complications. The test t Student, Mood's median, and Fisher Exact test were used for statistical analysis, and a p < 0.05 was considered significant.
  
  
  RESULTS
  Every patient in Group 1 presented selective blockade of the posterior sacral nerve roots, while patients in Group 2 experienced blockade of the anterior and posterior nerve roots. Blockade was significantly higher in Group 1. Motor blockade was significantly less severe in Group 1. Forty-nine patients in Group 1 transferred to the stretcher unassisted while only 40 patients in Group 2 were able to do so. Recovery in Group 1 occurred in 105 +/- 25 minutes and in 95 +/- 15 minutes in Group 2, and this difference was not statistically significant. There were no hemodynamic changes, nausea or vomiting, urine retention, or post-puncture headache.
  
  
  CONCLUSIONS
  Anorectal surgical procedures under spinal block with low dose bupivacaine, hyperbaric or hypobaric, can be safely done.
authors.affiliation: Instituto de Anestesia Regional, Hospital de Base, FAMERP.
authors.forename: Luiz Eduardo
authors.initials: LE
authors.lastname: Imbelloni
authors.forename: Eneida Maria
authors.initials: EM
authors.lastname: Vieira
authors.forename: M A
authors.initials: MA
authors.lastname: Gouveia
authors.forename: João Gomes
authors.initials: JG
authors.lastname: Netinho
authors.forename: José Antonio
authors.initials: JA
authors.lastname: Cordeiro