Articles: analgesics.
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Acta Anaesthesiol Scand · Feb 1988
Clinical Trial Controlled Clinical TrialEfficacy of 0.3 mg morphine intrathecally in preventing tourniquet pain during spinal anaesthesia with hyperbaric bupivacaine.
Tourniquet-induced pain is probably mediated by C-fibres. The ability of morphine to interrupt this nociceptive conduction was studied in a double-blind fashion by administering either morphine 0.3 mg or saline intrathecally along with hyperbaric bupivacaine 15 mg for spinal anaesthesia in 40 patients undergoing orthopaedic surgery on the lower extremity. The block characteristics were similar in both groups. ⋯ The remaining 12 patients in the morphine group had pain responses similar to those patients not given morphine. Intrathecal morphine provides a level of prophylaxis against tourniquet pain. However, the dosage employed here was associated with urinary and emetic side-effects.
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Parenterally administered narcotic analgesics are a critically important part of therapy for the patient with acute myocardial ischemic syndromes. These agents are very effective and, when used with appropriate caution and monitoring, are also generally safe. They not only relieve the sensation of severe pain but also reduce the effective and physiologic reaction to pain and thus reduce patient anxiety. ⋯ Thus, the hemodynamic effects of these agents may be quite different in patients with active pain during a period of acute ischemia, or in patients that are hemodynamically unstable. Hemodynamic studies during these acute settings, however, are extremely difficult to perform because the patient's acute distress mandates rapid administration of an analgesic agent prior to the institution of invasive monitoring. With these cautions relating to data interpretation in mind, it is still possible to make certain recommendations regarding the use of analgesic therapy in acute MI.(ABSTRACT TRUNCATED AT 250 WORDS)
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In the rat, the continuous intrathecal (i.t.) infusion of clonidine (0.4 microgram/hr) significantly increased the tail-flick latency (TF) and the threshold for paw pressure (PP) withdrawal for 5 days and decreased the systolic blood pressure (up to 24 mm Hg) for 7 days. The antinociceptive effect of continuous intrathecal infusion of clonidine (0.4 microgram/hr) in the tail flick and paw pressure tests was not attenuated in rats that were tolerant to morphine. The acute intrathecal administration of clonidine (2.7 micrograms) and morphine (1.0 microgram) resulted in a synergistic interaction in the tail-flick and paw pressure tests. ⋯ However, intrathecal infusion together yielded peak tail-flick and paw pressure responses comparable to that of 0.4 microgram/hr clonidine alone, without affecting systolic blood pressure. No delay in the onset of tolerance to the analgesic effect was observed with the combination as compared with clonidine (0.4 microgram/hr) alone. The data indicate that clonidine-induced spinal analgesia is independent of endogenous opioid systems linked to mu-receptors in the spinal cord, and that optimization of spinal analgesia (e.g. synergism) can be achieved during continuous intrathecal infusion without affecting cardiovascular activity.
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Patient-controlled analgesia (PCA) provides improved titration of analgesic drugs, thereby minimizing individual pharmacokinetic and pharmacodynamic differences. Patient-controlled analgesia decreases patient anxiety resulting from delays in receiving pain-relieving medication and from the slow onset of analgesic action when these drugs are administered either intramuscularly or in the extradural space. ⋯ The potential for overdose can be minimized if small bolus doses are used with a mandatory lockout interval between successive doses. Finally, studies of the cost-effectiveness of PCA therapy are important if this therapeutic approach is to achieve more widespread acceptance.