Postoperative analgesia after peripheral nerve block for pediatric surgery: Clinical efficacy and chemical stability of lidocaine alone versus lidocaine Plus Ketorolac
Dj. Reinhart et al., Postoperative analgesia after peripheral nerve block for pediatric surgery: Clinical efficacy and chemical stability of lidocaine alone versus lidocaine Plus Ketorolac, REG ANES PA, 25(5), 2000, pp. 506-513
Background and Objectives: The purpose of this study was to determine wheth
er the addition of ketorolac tromethamine to local anesthesia for ankle blo
ck alters the quality or duration of analgesia after pediatric surgery. The
second aim was to determine the chemical stability of ketorolac tromethami
ne when added to local anesthetic solutions.
Methods: The study design was double-blinded, placebo-controlled, and rando
mized. Seventy-nine American Society of Anesthesiologists (ASA) class I or
17 patients scheduled for bunionectomy or hammer toe repair, or both were r
andomized to 1 of 4 groups. Group L received plain 1.73% lidocaine for thei
r ankle block. Group It received 1.73% lidocaine with ketorolac (4 mg/mL) a
dded to the local solution. Group Kiv received 1.73% plain lidocaine for an
kle block and 20 mg of ketorolac intravenously. Group E received 1.73% lido
caine with .67% ethanol added. The final concentration of lidocaine for all
groups was 1.73%. The block performed in each patient was a 5-point ankle
block. Beginning at 1 hour after the completion of the block and every 30 m
inutes thereafter, visual analogue stale (VAS) and verbal pain scores were
recorded. The time from performance of the block to the initial pain and ti
me to the first oral pain meditation intake were also recorded. The lime an
d amount of postoperative oral analgesics in the first 9 hours after the bl
ock were recorded. Adverse events were also recorded for each group.
Results: There were significantly lower overall VAS and verbal pain scores
for group K compared with groups E and L and group Kiv compared with group
E. Group It also had a significantly longer time to the first reported pain
and first oral pain medications than groups E and L, but not with Group Ki
v. The same group had significantly fewer average doses of pain medications
postoperatively than Groups E and L. Group E had significantly shorter tim
es to first report of pain and first pain medications and higher mean dose
of postoperative oral analgesics than group K and Group Kiv. There were no
untoward side effects reported from any group. Chemical analysis by gas chr
omatography (GC) and capillary electrophoresis (CE) showed no significant c
hange in composition of the solutions when ketorolac was mixed with lidocai
ne and/or bupivacaine and stored at 37 degrees C for 1 week.
Conclusions: The addition of ketorolac to Lidocaine for ankle block contrib
uted to longer duration and better quality analgesia after foot surgery com
pared with plain 1.73% lidocaine or 1.73% lidocaine plus intravenous ketoro
lac. The ethanol vehicle is unlikely responsible far the analgesic effects
of ketorolac. Ketorolac retains its chemical stability when placed in local
solutions of lidocaine or bupivacaine.