Anesthesia and analgesia
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Anesthesia and analgesia · Jul 2003
Peripheral antihyperalgesic and analgesic actions of ketamine and amitriptyline in a model of mild thermal injury in the rat.
In this study, we examined antihyperalgesic and analgesic actions after local peripheral administration of ketamine and amitriptyline in a rat model of mild thermal injury. Exposure of the hindpaw to 52 degrees C for 45 s under anesthesia produced a subsequent thermal hyperalgesia lasting at least 2 h. The local peripheral administration of ketamine (100-1000 nmol) 15 min before the thermal injury produced an antihyperalgesic effect when injected into the ipsilateral paw, whereas amitriptyline produced both antihyperalgesic (300 nmol) and analgesic (1000 nmol) effects. Administered after the thermal injury, ketamine had no effect, whereas amitriptyline retained its analgesic but not its antihyperalgesic effect. Amitriptyline (300 and 1000 nmol) produced an analgesic action when administered into the normal nonsensitized hindpaw. Both drugs increase paw volume, particularly at larger doses; biogenic amines are not involved in the action of amitriptyline, as was shown previously for ketamine. These results indicate that (a) ketamine produces antihyperalgesia, but not analgesia, when administered locally with a mild thermal injury model; (b) amitriptyline produces both antihyperalgesia and analgesia when administered locally; and (c) the increase in paw volume produced by these drugs occurs by different mechanisms. ⋯ This study examines the pain-relieving properties of the local peripheral administration of ketamine and amitriptyline, two drugs in current clinical use, in a thermal injury model of hyperalgesia and demonstrates both antihyperalgesic and analgesic properties. These observations provide support for their potential use as local (e.g., topical) analgesics.
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Anesthesia and analgesia · Jul 2003
Randomized Controlled Trial Comparative Study Clinical TrialA comparison of intrathecal opioid and intravenous analgesia for the incidence of cardiovascular, respiratory, and renal complications after abdominal aortic surgery.
Major surgery evokes a stress response that can produce deleterious consequences, especially in a population at high risk for those complications. We tested the hypothesis that decreasing or eliminating one of the sources of stress by providing intense analgesia in the immediate postoperative period via application of neuraxial opioids would decrease major nonsurgical complications. Two-hundred-seventeen patients scheduled to undergo abdominal aortic surgery were randomly allocated to receive either general anesthesia alone (control) or general anesthesia combined with intrathecal opioid (1 micro g/kg sufentanil with 8 micro g/kg preservative-free morphine injected at the L4-5 interspace). Postoperative care was identical in the two groups, including patient-controlled analgesia. Each patient provided an assessment of postoperative pain using a visual analog scale. Postopera-tive complications were recorded according to criteria established a priori. The administration of intrathecal opioid provided more intense analgesia than patient-controlled analgesia during the first 24 h postoperatively (P < 0.05). There was no difference between groups for the incidence of combined major cardiovascular, respiratory, and renal complications (P > 0.05) or mortality (P > 0.05). The incidence of myocardial damage or infarction, as defined by abnormal plasma concentration of troponin I, did not differ between the two groups (P > 0.05). In patients undergoing major abdominal vascular surgery, decrease of one contributor to postoperative stress, by provision of intense analgesia for the intraoperative and initial postoperative period, via application of neuraxial opioid, does not alter the combined major cardiovascular, respiratory, and renal complication rate. ⋯ Provision of intense analgesia for the initial postoperative period after major abdominal vascular surgery, via the administration of neuraxial opioid, does not alter the combined incidence of major cardiovascular, respiratory, and renal complications.