The Effects of Peripheral mu and kappa Opioid Receptor Agonists on the Thermal Injury Induced Hyperalgesia in the Rat / 대한마취과학회지

BACKGROUND: Previous reports have described that the local administration of opioid receptor agonist can attenuate the nociceptive responses induced by a variety of inflammatory states. This study evaluated the effects of mu or kappa opioid receptor agonists peripherally administered at a site of injury on the state of thermal hyperalgesia induced by mild burn injury. METHODS: Thermal injury was induced after briefly anesthetizing with halothane, by applying the left hindpaw to a hot plate (52.5 degree C) for 45 seconds. Paw withdrawal latency of the hindpaw was determined using an underglass thermal stimulus, which allowed the response latency of the injured paw to be obtained. In this work, the mu receptor agonist, morphine (10, 30, 100 microgram), or the kappa receptor agonist, U50,488H (10, 30, 100 microgram), was administered respectively at the injured site on the right hindpaw in rats. To compare the systemic effects of the drug, the same drug was administered at the normal left hindpaw site with mild burn injury. Naloxone (40 microgram/kg) was administered at the injured site or at the normal site to determine the reversibility of the opioid used. RESULTS: Mild burn injury produced thermal hyperalgesia manifested as reduced paw withdrawal latency. Administration of either morphine (10, 30, 100 microgram) or U50,488H (10, 30, 100 microgram) at the injured site attenuated hyperalgesia in a dose-dependent manner. But the administration of drugs at the normal site had no effect on hyperalgesia at the injured site. In addition, naloxone had the effect of morphine and U50,488H reversed significantly. CONCLUSIONS: These results suggest that peripheral mu or kappa opioid receptor administration at an injured site may play an important role in the hyperalgesia induced by mild burn injury.

The Effect of Incisional Infiltration of 0.5 % Bupivacaine on Postoperative Pain in Cholecystectomy Patients / 대한마취과학회지

In spite of general agreement that pain relief after upper abdominal surgery is important for the reduction of postoperative morbidity, the most widely used method remains intramuscular injection of narcotics or non-opioid analgesics with their well known disadvantages of respiratory depression, nausea, vomiting and epidural anesthesia and intercostal nerve block are invasive, so do not achieve much popularity. This double-blind prospective study, 30 patients with subcostal incision performed for cholecystectomy, reeeived 20 ml of either physiologic saline or 0.5% bupivacaine by wound infiltration at the time of closure of the incision. After operation, pain score and analgesic requirements were compared at emergence and postoperative 24 hour in each group. The results were as following: 1) Mean age of control and bupivacaine group were 45.3+/-14.9 and 53.6+/-10.3 yr respectively and mean duration of anesthesia 175+/-63 and 145+/-54 minutes respectively. 2) At emergence, mean pain score was 7.7+/-1.7 in control and 2.7+/-2.6 in bupivacaine group (p < 0.01), and at postoperative 24 hour, mean value of pain score was 6.8+/-2.1 in control and 2.31.9 in bupivacaine group(p<0.01). 3) At emergence, there were 11 patients(73%) of none to mild pain, 3(20%) of moderate pain and 1(7%) of severe pain in bupivacaine group, while 0(0%), 6(40%) and 9(60%) respectively in control group. But at postoperative 24 hour, the number of patients with none to mild, moderate and severe pain were 13(87%), 2(13%) and 0(0%) in bupivacaine group and 4(27%), 3(20%) and 8(53%) in control group respectively. 4) In experimental group, patients less than 14% needed additive analgesic, and there were no side reactions in the bupivacaine group. With above results, we suggest that pouring of 0.5% bupivacaine into incisional wound, especially in cholecystectomy patients, would be a method for postoperative pain relief.

Effect of Muscle Relaxation by Domestic Product of Metuben in Rabbit / 대한마취과학회지

The domestic product of a non-depolarizing muscle relaxant, Metuben, was studied on its effect in rabbit. Twenty four rabbits of either sex weighing 2~3kg were divided into four groups (consisting of 6 animals each) to administer Metuben in doses of 0.05 mg/kg, O.l mg/kg, 0.2 mg/ kg and 0.4 mg/kg, respectively. All animals were anesthetized with 20% urethane 5 ml/kg given intraperitoneally and 2.5% pentothal sodium 10 mg/kg intravenously. ECG was monitored by Physio-contro1(lifepak 7)model. The animal lungs were mechanically ventilated through a tracheostomy and Shinano animal respirator set to deliver a 30 ml/kg tidal volume at 30 breaths/min. This ventilatory pattern resulted in the PaCO2 values within the range of 30-40 mmHg. Twitches of the tibialis anterior muscle were elicited at 0.1 Hz, "Train of four" via the peroneal branch of the sciatic nerve, and the Myotest stimulator were applied at supramaximal voltage. Twitch recording was done via Biophysiograph. Results were as follows: 1) The effect of Metuben as a dose-dependent long lasting non-depolarizing muscle relaxant was confirmed. Their relaxant effect in rabbits were quite different from man. 2) In rabbits, Metuben showed great individual differences in its effect even with the s'ame dosage. The length of muscle relaxing activity.and the occurence of recurarization after neostigmine reverse were extremely variable suggesting its safety margin is quite narrow.