J Korean Pain Soc.
1999 May;12(1):59-63.
Effective Dosage of Intrathecal Morphine for Postoperative Pain Control of Perianal Surgery
- Affiliations
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- 1Department of Anesthesiology, St. Benedict Hospital, Pusan, Korea.
Abstract
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BACKGROUND: Contraction of anal sphincter muscle produces severe pain in perianal surgery
post- operatively. Recent reports have indicated that effective and prolonged pain relief
can be obtained by the injection of small doses of morphine into the subarachnoid space.
We attempted to use this technique for perianal surgery and investigated postoperative pain
control and its side effects.
METHODS
Forty five patients scheduled for hemorrhoidectomy and anal fistulectomy were studied
to determine the minimal effective dose of intrathecal morphine for postoperative analgesia.
In order to control the pain, 7 mg of 0.5% hyperbaric bupivacaine with 0.05 mg (group I),
0.1 mg (group II) and 0.15 mg (group lII) of morphine hydrochloride was injected with
a 25 gauge spinal needle into the subarachnoid space. We estimated the duration of analgesia
until the pain score attained to above 3 in 10 cm VAS (visual analogue scale) and incidence
of itching, nausea and vomiting by percentage, headache, backpain and respiratory depression
by positive and negative. We also checked the time of self-voiding.
RESULTS
The mean time of analgesia was 10.3+/-1.54, 19.7+/-2.22 and 20.3+/-2.29 hours in group I, II
and III respectively. Urinary retention of group I, II and III after block persisted for an
average of 20.3+/-2.31, 21.2+/-2.51 and 23.3+/-3.74 hours. Nausea and vomiting were observed 33%,
53%, 67% and itching was observed 53%, 67%, 80% in group I, II and III respectively and
respiratory depression did not occur in all groups. CONCLUSIONS: It is not necessary to
use more than 0.1mg of intrathecal morphine in perianal surgery because analgesia is not
prolonged and side effects are increased.