| IntroductionStress and emotional reaction of children caused by postoperative noxious stimulation are very strong, which affects children postoperative healing seriously. Therefore, postoperative analgesia is necessary to children. Recently a new method of treating postoperative pain is pre - emptive analgesia, which seeks to prevent or diminish pain before it is caused. The present studies suggest that peptides and amino-acids especially NMDA released by spinal neuron lead to the central nervous pain when acute pain occurs. This study evaluates outcomes of preemptive a small dose of ketamine wich is a NMDA receptor antagonist, and the effect to caudal morphine analgesia.MethodThis is a randomized, double - blinded controlled study. Sixty ASA physical status I and II patients, aged 4 - 10 yr, scheduled for elective lower abdominal surgery were enrolled. Exclusion criteria included patients with respiratory and cardiovascular diseases. A total of sixty patients were randomly assigned into one of four groups, 15 patients in each group. Group SL received IM normal saline 1ml and caudal 1% lidocaine. Group KL received IM ketamine 2mg/kg andcaudal l%lidocaine. Group SML received IM normal saline 1ml and caudal morphine 0. 02mg/kg + 1% lidocaine. Group KML received IM ketamine 2mg/kg and caudal morphine 0. 02mg/kg + 1% lidocaine. Caudal infused volume was 0.7 ml/kg but the maximal volume was 20ml. Ketamine and normal saline were given to patients before they entered operation room. Anesthesia induction was performed with 2.5mg/kg propofol. Then patients received IV propofol at 10mg/kg. h and inhaled the gas mixture of isoflurane and oxygen. Caudal block was performed when alveolar concen tration reached 1. 3 MAC reached 1.3. Onset of caudal block was confirmed with relaxation of anus. Recorded data included age, weight, anesthesia duration, operation duration, time from IM ketamine to incision and time from caudal block to incision. Blood pressure, heart rate, pulse oxygen saturation, VAS and OPS for pain at2, 4, 8, 12, 24h after operation and side effect including nausea, vomiting, pruritus and urinary retention were recorded by the same follower.Statistical analysis was performed with the program SPSS 10. 0. Quantitative data were presented as mean \SD, compared by using a-nalysis of variance. Qualitative data were presented as percentage and compared by using Chi - squared test. P values < 0. 05 were confirmed significant, and P values <0. 01 were confirmed very significant.ResultsThere were no significant differences in age, weight, preoperativeblood pressure and pulse, operative duration, anesthesia duration, IM-incision time, or block -incision time among the four groups. TheVAS and OPS for pain at 2, 4, 8, 12 and 24 h postoperatively were significantly lower in Group KML and Group SML as compared with Group SL ( P <0. 01) , whereas the VAS and OPS at 2, 4h postoperatively in Group KL were lower than those in Group SL ( P < 0. 05). The VAS and OPS at 2, 4, 8 , 12 and 24h postoperatively were significantly lower in Group KML and Group SML as compared with Group KL ( P < 0. 01) . The VAS and OPS at 4, 8 , 12, 24h postoperatively in Group KML were lower than those in Group SML (P <0. 05). HR and MAP postoperatively among the four groups increased, but there were no clinical significance. Pruritus and urinary retention occurred in Group KML and SML, but there were no significant difference a-mong groups.DiscussionThis investigate found that small dose ketamine pre - operation could decrease VAS value and OPS value obviously in 2h and 4h, thus releave over - pain. But it was impossible to deprive pain. Small dose morphine in caudal duct did better. In acute pain stimulation , injury stimulation could transmit through C fiber, thus influence the sensory transmission in spinal cord . The dorsal cord neuron sensory area was enlarged. In result, pain hypersensitivity prolonged and automatory pain happened, The transmitor maybe P sabstance, neuron peptide , and positive amino acid . It...
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