Anesthesiology
-
Postoperative pain relief may be improved by reducing sensitization of nociceptive pathways caused by surgical trauma. Such a reduction may depend on the timing and efficacy of analgesia and the duration of the nociceptive block versus the duration of the nociceptive input. We examined whether a prolonged nerve block administered before a superficial burn injury could reduce local inflammation and late hyperalgesia after recovery from the block. ⋯ These data suggest that a prolonged, preemptive nerve block reduced late hyperalgesia after thermal injury, whereas the erythema and blister formation were not significantly affected.
-
Although experimental evidence indicates that preemptive intrathecal treatment with local anesthetics reduces postinjury neuronal hyperexcitability, clinical evidence indicates that preemptive treatments do not consistently reduce postoperative pain. The current study used experimental models of postinjury nociception, in which rats received subcutaneous or intraarticular injections of the irritant formalin, to evaluate the effects of peripheral inflammation, or the use of agents supplemental to anesthesia, as possible confounding influences on the effectiveness of preinjury and postinjury intrathecal local anesthetic treatments. ⋯ The current results attest to the important effects of ongoing inputs from inflamed tissue, and the use of supplemental treatments, as important confounding factors that may influence the effectiveness of preemptive spinal anesthesia for postoperative pain.
-
Randomized Controlled Trial Clinical Trial
Desflurane-mediated neurocirculatory activation in humans. Effects of concentration and rate of change on responses.
Rapid increases in the inspired concentration of desflurane have been associated with sympathetic activation, tachycardia, hypertension, and in select cases, myocardial ischemia. The current study examined the effects of the rate of change of the desflurane concentration on the sympathetic and hemodynamic responses to desflurane and sought to determine whether a finite concentration (end-tidal) of desflurane consistently initiated these responses. ⋯ There was no consistent threshold for the neurocirculatory activation associated with desflurane, and the HR and SNA thresholds generally were less than 1 MAC. The HR increase associated with desflurane was not rate- or concentration-dependent. In contrast, SNA responses were proportional to the rate of change and the concentration of desflurane.
-
Randomized Controlled Trial Clinical Trial
Prophylactic use of epidural mepivacaine/morphine, systemic diclofenac, and metamizole reduces postoperative morphine consumption after major abdominal surgery.
Surgical trauma induces nociceptive sensitization leading to amplification and prolongation of postoperative pain. While preemptive analgesic treatment with numerous agents has been successful in experimental animals, results of human studies remain conflicting. The authors used a multimodal approach for preemptive analgesia before abdominal surgery: diclofenac and metamizole inhibit prostaglandin synthesis, thus influencing peripheral sensitization; epidural local anesthetics induce conduction block, epidural opioids inhibit nociceptive synaptic transmission, and metamizole induces descending inhibition. The interaction of these drugs might suppress spinal nociceptive sensitization and postoperative analgesic demand. ⋯ A significant reduction of patient controlled analgesia requirements could be achieved by our preincisional balanced analgesia regimen compared to application before wound closure. The more distinct difference between patients receiving balanced analgesia and those in the control group is based on the analgesic action of the study substances, which lasted about 14 h.
-
Glycine and gamma-aminobutyric acid (GABA) are inhibitory neurotransmitters that appear to be important in sensory processing in the spinal dorsal horn. Intrathecal administration of strychnine (strychnine-sensitive glycine receptor antagonist) or bicuculline (GABAA antagonist) was reported to induce allodynia. Although the strychnine-induced allodynia was shown to be mediated through the N-methyl-D-aspartate (NMDA)-type glutamate receptor, it is not clear whether the bicuculline-evoked-allodynia is mediated through the glutamate receptor system or how different the allodynia induced by strychnine and bicuculline are. ⋯ These results demonstrate that both strychnine- and bicuculline-evoked allodynia were mediated through pathways that include the glutamate receptor and nitric oxide systems but in a different manner. the current study suggests that GABA and glycine may modulate responses to an innocuous tactile stimulus as inhibitory neurotransmitters at presynaptic and postsynaptic sites in the spinal cord, respectively.