[Spinal anesthesia with hyperbaric tetracaine and bupivacaine: velocity of spread, analgesic effect and motor blockade in various positions and injection volumes].

The effect of Trendelenburg position (5 degrees head-down) for 60 or 45 s on the spread of hyperbaric 0.5% tetracaine and 0.5% bupivacaine (3 or 4 ml) was studied in 80 patients scheduled for urological surgery. The mean spread of analgesia was faster (p less than 0.05) and greater (p less than 0.05) in patients tilted head-down for 45 s receiving 4 ml tetracaine than in those with 3 ml tetracaine and 60 s Trendelenburg position. With bupivacaine corresponding results of both volumes, 3 or 4 ml, were similar. Tetracaine compared with bupivacaine showed a faster cephalad spread with 4 ml (p less than 0.05) but not with 3 ml. The onset time of motor blockade in all groups was short (less than 10 min) and complete (Bromage III). The results prove that 4 ml of 0.5% tetracaine with 5% Trendelenburg position for 45 s ensure a rapid and safe spread of analgesia with adequate motor blockade for transurethral surgery.