Regional anesthesia and pain medicine
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Reg Anesth Pain Med · Mar 1999
Case ReportsAnxiety, vocalization, and agitation following peripheral nerve block with ropivacaine.
Central nervous system (CNS) and cardiovascular toxicity are potential side effects of local anesthetics. However, ropivacaine has been reported to be less CNS toxic than bupivacaine in human volunteers. ⋯ This case report shows that ropivacaine may cause CNS toxicity that differs from classical signs of local anesthetic-induced toxicity. This effect might be related to the unique structure of ropivacaine, which is formulated in an S-enantiomer preparation. It has been shown that S-enantiomers bind differently to receptors in both the CNS and cardiovascular systems. This property may account for the disinhibition of select neural pathways that are specifically involved in mediation of anxiety and aggression.
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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.