We compared intrathecal ropivacaine to bupivacaine in patients scheduled fo
r transurethral resection of bladder or prostate. Doses of ropivacaine and
bupivacaine were chosen according to a 3:2 ratio found robe equipotent in o
rthopedic surgery. One hundred patients were randomly assigned to blindly r
eceive either 10 mg of isobaric bupivacaine (0.2%, n = 50) or 15 mg of isob
aric ropivacaine (0.3%, n = 50) over 30 s through a 27-gauge Quincke needle
at the L2-3 level in the sitting position. Onset and offset times for sens
ory and motor blockades and mean arterial blood pressure were recorded. Pai
n at surgical site requiring supplemental analgesics was recorded. Cephalad
spread of sensory blocks was higher with bupivacaine (median level, cold T
-4 and pinprick T-7) than with ropivacaine (cold T-6 and pinprick T-9) (P <
0.001). Eight patients in Group Ropivacaine received IV alfentanil (P <0.01
). Onset time (mean +/- SD) to T-10 anesthesia and offset time at L2 were n
ot different (bupivacaine = 13 +/- 8 min, 127 +/- 41 min; ropivacaine = 11
+/- 7 min, 105 +/- 29 min). Complete motor blockade occurred in 43 patients
with bupivacaine and in 41 patients with ropivacaine (not significant). To
tal duration of motor blockade was not different. No difference in hemodyna
mic effects was detected between groups. No patient reported back pain. We
conclude that 15 mg of intrathecal ropivacaine provided similar motor and h
emodynamic effects but less potent anesthesia than 10 mg of bupivacaine for
endoscopic urological surgery.