Anesthesiology
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Intrathecally administered clonidine has been reported to produce analgesia in cancer patients tolerant to intrathecal opiates. To assess the efficacy, safety, and appropriate dose of epidurally administered clonidine for the treatment of cancer pain, clonidine (range, 100-900 micrograms in 100-micrograms increments) was injected in nine patients with severe, intractable cancer pain. Clonidine produced analgesia, as measured by change in verbal pain scores, lasting more than 6 h. ⋯ Clonidine was absorbed in a dose-dependent manner into the systemic circulation, although absorption and elimination kinetics were highly variable. Following study seven patients received epidural clonidine/morphine infusions at home for periods of up to 5 months with sustained analgesia. These results suggest that epidurally administered clonidine may offer effective analgesia in patients with severe, intractable cancer pain.
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Epidurally administered clonidine has been reported to produce postoperative analgesia. To assess the efficacy, safety, and appropriate dose of epidural clonidine for postoperative analgesia, clonidine (range, 100-900 micrograms in 100-micrograms increments) was injected in 22 patients following abdominal surgery or total knee arthroplasty (TKA). Clonidine produced analgesia, as measured by change in verbal pain scores and supplemental iv morphine usage. ⋯ Oxyhemoglobin saturation, serum glucose, and arterial blood gas tensions were not altered by clonidine, whereas there was a small (28%) dose-independent decrease in serum cortisol following clonidine injection. Clonidine was absorbed in a dose-dependent manner into the systemic circulation, with plasma concentrations 0.1-3.3 ng/ml 1 h following injection. These results suggest that hemodynamic depression and short-lasting analgesia may limit the usefulness of bolus epidural clonidine analgesia in the postoperative setting.
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Nalbuphine reverses opioid-induced respiratory depression, but the effect on analgesia is unclear. The analgesic interaction between subcutaneous (sc) nalbuphine and intrathecal morphine in conscious, male, Sprague-Dawley rats implanted with chronic intrathecal catheters was investigated. Nalbuphine (10 mg/kg) injected 30 min after intrathecal morphine (4 micrograms) significantly antagonized the effect of morphine in the tail flick test. ⋯ The results indicate a complex analgesic interaction between intrathecal morphine and sc nalbuphine. The net analgesic effect during the interaction was determined by the following: 1) the doses of morphine and nalbuphine; 2) the time after nalbuphine administration; and 3) the nature of the nociceptive stimulus. At lower doses, sc nalbuphine appeared to potentiate the effect of intrathecal morphine in the noninflamed paw pressure test.
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A series of infusions of mock cerebrospinal fluid (CSF) was used to determine intracranial volume-pressure relationships in 18 anesthetized dogs. Measures of intracranial volume-pressure relationships included 1) CSF pressure prior to volume infusion (P0), 2) peak CSF pressure (Pp) caused by volume injection, 3) intracranial compliance (C, calculated as the ratio of change of intracranial volume [delta V] to change of CSF pressure [delta P]), 4) the volume-pressure response (VPR, a measure of elastance, calculated as the ratio of delta P to delta V), 5) the pressure volume index (PVI, calculated as the ratio of delta V to log Pp/P0), and 6) estimated intracranial compliance (Ce, calculated from PVI as 0.4343 PVI/P0). ⋯ Thiopental decreased P0 (by 2-3 +/- 1 cmH2O) and Pp (by 2-4 +/- 2 cmH2O), increased Ce (by 0.02-0.03 +/- 0.01 ml/cmH2O), and did not change C, VPR, or PVI. Etomidate decreased P0 (by 3-4 +/- 1 cmH2O) and Pp (by 4-6 +/- 2 cmH2O), increased Ce (by 0.03-0.04 +/- 0.01 ml/cmH2O) and did not change C, VPR, or PVI.(ABSTRACT TRUNCATED AT 250 WORDS)