Spinal anaesthesia using hyperbaric 0.75% vs hyperbaric 1% bupivacaine: a double blind comparison.

Aim: The aim of this study was to compare the anesthetic effects, potency and postoperative outcome of 0.75% and 1% concentrations of hyperbaric bupivacaine in selective spinal anesthesia.

Methods: We enrolled 40 patients in a double blind fashion in 2 groups (A= 0.75% bupivacaine; B= 1% bupivacaine). Demographic data were respectively for Groups A and B: age 40.6+/-16 and 67+/-16, weight 74+/-14.4 and 68+/-10.2; sex 10M/10F and 6M/14F; ASA I-II 11/9 and 14/6. All patients received 11.25 mg bupivacaine. In all cases a 27G Whitacre needle was introduced at L1-L2, L2- L3, L3-L4 introduced with a midline approach. Time to onset and offset of sensitive and motor block, dermatomeric extension non invasive blood pressure, heart rate, ephedrine dose, deambulation time, diuresis time and request for supplemental analgesia were recorded.

Results: No statistically significant differences between the 2 groups for demographic data were found. Group B revealed a faster onset and a more adequate dermatomeric extension (4.1+/-0.8 min vs 6.5+/-1.2 min). Both concentrations guaranteed good hemodynamic stability. Motor offset times were 115.8+/-145 min and 142+/-4.8 min respectively in groups A and B. Sensitive offset times were 197.5+/-12 min and 168+/-5.2 min respectively in groups A and B. No statistically relevant differences were noticed for intraoperative Bromage, sensitive block or for postoperative motor and sensitive offset time, diuresis time and deambulation time. There are no advantages of 1% hyperbaric bupivacaine over 0.75% for selective spinal anesthesia, while several disadvantages presented shorter duration of postoperative analgesia and higher incidence of headache.