Regional anesthesia and pain medicine
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Reg Anesth Pain Med · Mar 1999
Multicenter Study Comparative Study Clinical Trial Controlled Clinical TrialRopivacaine 0.25% and 0.5%, but not 0.125%, provide effective wound infiltration analgesia after outpatient hernia repair, but with sustained plasma drug levels.
Ropivacaine is a long-acting local anesthetic similar to bupivacaine, but with lower cardiac toxicity and intrinsic vasoconstrictive properties that may reduce the risk and extent of systemic plasma absorption. Plasma levels and risks are associated with the total dose used and the extent of absorption, with lower doses potentially representing less risk. Although both 0.5% and 0.75% ropivacaine provide adequate analgesia for wound infiltration after hernia repair, the efficacy of lower doses and the early systemic absorption have not been reported. ⋯ Ropivacaine 0.25% and 0.5% is adequate for pain relief after outpatient hernia repair, whereas the 0.125% solution is no more effective than saline. Prolonged systemic absorption from peripheral injection may be associated with prolonged elevations of plasma concentrations, which potentially could be associated with unexpectedly high plasma levels if repeated injections are performed in the perioperative period with higher concentrations or doses.
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Reg Anesth Pain Med · Mar 1999
Randomized Controlled Trial Comparative Study Clinical TrialContinuous spinal anesthesia: a comparative study of standard microcatheter and Spinocath.
This prospective, randomized study evaluated the advantages and disadvantages of a new subarachnoid catheter. ⋯ Spinocath insertion required 6.3 +/- 3.2 minutes in group 1 versus 3.9 +/- 1.2 minutes in group 2 (P < .01) with similar difficulties with catheter introduction. Perception of dural puncture was better in group 1 (P < .05). There were significant intergroup differences in time to free flow of CSF through the catheter. In group 2, correct catheter positioning had to be confirmed by aspiration in 80% of cases (P < .05). At the end of surgery, the catheters were removed, and there were no significant differences between groups. The anesthetic blocks were similar with both systems. Patient opinion of the technique did not differ between groups, and regression analysis did not show any differences between groups or correlation to any incident during performance of the technique. Globally, the anesthesiologists participating in the study considered both systems to be easy to use and adequate for continuous spinal anesthesia. With respect to the advantage afforded by a directional needle in orientating the catheter within the spinal canal, the Spinocath system-with a longer technique performance time than the standard approach-involves a success rate and incidence of technical problems similar to that of the conventional technique.
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Reg Anesth Pain Med · Mar 1999
An investigation of the neurophysiologic mechanisms of tourniquet-related pain: changes in spontaneous activity and receptive field size in spinal dorsal horn neurons.
Several theories have been proposed for the pain resulting from the nerve compression and ischemia associated with maintaining the inflation of a pneumatic tourniquet on an extremity. This investigation observes changes in the spontaneous activity and receptive field (RF) size of spinal dorsal horn neurons during tourniquet-related nerve compression and ischemia. ⋯ The results of this study indicate that nerve compression and ischemia results in block of input to LTM neurons having RFs distal to the tourniquet cuff and an increase in spontaneous activity and expansion of the RFs of NRs, especially those with RFs located proximal to the tourniquet. Increases in spontaneous firing activity and expansion of the RFs of nociresponsive dorsal horn neurons receiving input from primary afferent nociceptors proximal to the tourniquet may explain, in part, the neurophysiologic mechanism of tourniquet-related pain.