Pain
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Gender differences in pain modulation are evident but data are rare with regard to perioperative regional analgesia. The aim of the present analysis was to assess gender-related differences in pain ratings, analgesic consumption, and adverse events in a large group of patients treated with patient-controlled epidural analgesia (PCEA) after major surgery. Data from 14,988 adult patients (6506 women; 8482 men) receiving a PCEA between January 1998 and December 2009 were examined. ⋯ Furthermore, motor blockade was greater in females compared to males (P=0.000). In patients treated with PCEA, gender differences in numeric rating scale scores exist but are not clinically relevant. However, reduced total PCEA consumption in women might be a consequence of an increased incidence of motor blockade and vomiting; the latter point towards an opioid-free PCEA solution in female patients at high risk for vomiting.
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Impairment of spinal GABAergic inhibition is demonstrated to contribute to pathologic chronic pain states. We investigated spinal and peripheral GABAergic regulation of incisional pain in rats. We found that intrathecal but not peripheral administration of muscimol (GABA-A receptor agonist) and baclofen (GABA-B receptor agonist) reduced mechanical and thermal hyperalgesia after plantar incision in rats. ⋯ However, expression of GABA-A receptor subunits α2 and α3 and GABA-B receptor subunits within the dorsal horn of the spinal cord were unchanged after incision, indicating that receptor expression cannot explain a possible modulation of GABAergic inhibition after incision. Thus, other mechanisms need to be considered. In conclusion, GABA-A and GABA-B receptors are promising targets for postoperative, incisional pain in humans.