Spinal anesthesia for endoscopic urological surgery--low dose vs. varying doses of hyperbaric bupivacaine.

Background And Objective: The aim of this study is to compare the efficiency of low dose vs. varying doses of hyperbaric bupivacaine in spinal anesthesia for endoscopic urological procedures.

Methods: Sixty consecutive patients were studied in a randomized prospective manner. They received either of 5 (Gr I), 7.5 (Gr II) or 10 mg (Gr III) of hyperbaric bupivacaine 0.5% combined with 25 microg of fentanyl, through a 25-gauge W hitacre spinal needle placed in the L3-L4 interspace. Characteristics of sensory and motor block, dose of ephedrine required, secondary effects, the patients, and the surgeons satisfaction, were noted.

Results: The maximum number of blocked segments was 14 +/- 1 (Gr I), 15 +/- 2 (Gr II) and 16 +/- 2 (Gr III). Time to T12 regression was significantly shorter for Gr I (53 +/- 13 min) than for Gr II (69 +/- 20 min) or Gr III (94 +/- 14 min). Bromage 3 block was not found in Gr I compared to 4 patients in Gr II and 15 patients in Gr III. The duration of motor block was shorter in Gr 1(51 +/- 18 min) than in Gr II (86 +/- 19 min) and in Gr III (138 +/- 21 min). Ephedrine was used for 16 patients in Gr III (9.8 +/- 12.2 mg), 5 patients in Gr II (3.7 +/- 7.8 mg) and 2 patients in Gr I (0.5 +/- 1.5 mg). The difference is statistically significant between Gr III and the other groups.

Conclusions: These results suggest that the use of a low dose of bupivacaine (5 mg) added to fentanyl (25 microg) for endoscopic urological surgery, resulted in short-acting sensory block, without motor block and a lower incidence of cardiovascular side effects, as compared to either of 7.5 or 10 mg bupivacaine with 25 microg fentanyl.