cyclic-gmp and Pain--Postoperative

Fentanyl is a short-acting synthetic opioid with spinal analgesic properties and dose-dependent side-effects. The analgesic effect of opioids is mediated in part through activation of inhibitory descending pain pathways involving nitric oxide (as a central neurotransmitter) through the NO-cGMP system. This NO-cGMP pathway plays an important role in spinal nociception. The aim of the study was to evaluate the effect of transdermal nitroglycerine on the analgesic action of intrathecal fentanyl in patients undergoing abdominal hysterectomy. Patients (n=120) were randomised into one of four groups. All received 3 ml bupivacaine 0.5% plus 0.5 ml of an intrathecal test drug. Twenty minutes after lumbar puncture, a transdermal patch of either nitroglycerine or placebo was applied. Group B received spinal bupivacaine plus saline 0.5 ml and a placebo patch. Group B-N received bupivacaine plus saline 0.5 ml and a nitroglycerine patch. Group F received bupivacaine plus fentanyl 25 microg and a placebo patch. Group F-N received bupivacaine plus fentanyl 25 microg and a nitroglycerine patch. The duration of effective analgesia was longer in group FN (363.53 +/- 34.09 min) compared from the other groups (P < 0.001). The times to two-segment regression in group F-N and group F were 132.87 +/- 31.2 min and 126.40 +/- 26.81 min respectively. The visual analog scale pain score at the time of the first rescue analgesic was similar in all groups. We conclude that nitroglycerine does not result in postoperative analgesia but enhances the analgesic effect of intrathecal fentanyl.

Topics: Administration, Cutaneous; Adult; Anesthetics, Local; Bupivacaine; Cyclic GMP; Double-Blind Method; Female; Fentanyl; Humans; Hysterectomy; Injections, Spinal; Middle Aged; Nitric Oxide; Nitroglycerin; Pain, Postoperative

Pain-alleviating effects of epidural spinal cord stimulation (ESCS) were assessed in patients with chronic intractable pain including cancer pain, and some aspects concerning its mechanisms were discussed. The temporary ESCS with percutaneously inserted electrodes was employed in 105 patients, and the implantable systems for long-term use in 19 patients. The ESCS had satisfactory effects especially in patients suffering from cancer pain, causalgia, facial and nape pain. The conditioning stimuli applied to the cervical dorsal cord exhibited interactions with the segmentally evoked spinal cord potential (SCP). The N1 wave of the SCP was inhibited up to 120 ms, while the P2 wave was facilitated for more than 100 ms, suggesting that the presynaptic inhibitory action at the dorsal horn is responsible for mechanism of the ESCS. CSF concentration of norepinephrine was significantly decreased by the ESCS therapy, indicating the existence of the relationship between norepinephrinergic descending inhibitory system and the ESCS in pain-alleviating mechanism.

Topics: Adult; Aged; Cerebral Palsy; Cyclic GMP; Electric Stimulation Therapy; Electrodes, Implanted; Female; Humans; Male; Middle Aged; Neoplasms; Neuralgia; Norepinephrine; Pain, Intractable; Pain, Postoperative; Spinal Cord; Spinal Cord Diseases; Spinal Cord Injuries