[Low concentration/high volume is more effective than high concentration/low volume for postoperative continuous epidural analgesia with the combination of bupivacaine and fentanyl].

In 40 females undergoing gynecologic laparotomy, lumbar epidural analgesia using a disposable infusion pump was continued for postoperative 48 hours. Then the analgesic effect of epidural bupivacaine (4.8 mg.kg-1) plus fentanyl (12 micrograms.kg-1) diluted with normal saline was prospectively compared between the two groups; high concentration/low volume group (HC/LV, 96 ml of total volume and 2 ml.h-1 of infusion rate, n = 20) versus low concentration/high volume group (LC/HV, 240 ml of total volume and 5 ml.h-1 of infusion rate, n = 20). On postoperative day 1, LC/HV group showed the significantly lower visual analog scale and verbal pain score at rest than HC/LV group (P < 0.05). No significant differences in the incidence of side effects were observed between the groups. These results suggest that when the equivalent dose is given, the volume rather than the concentration of the solution is important for postoperative continuous epidural analgesia with the combination of bupivacaine and fentanyl.

[A case of prolonged apnea probably caused by vecuronium potentiated with hypermagnesemia].

A 73-year-old female weighing 41 kg who had undergone ilecolostomy under general anesthesia showed extremely prolonged apnea. Despite only 7 mg of vecuronium, she needed postoperative mechanical ventilation for more than 24 hours. A postoperative examination revealed hypermagnesemia, which probably potentiated the effect of vecuronium. Her hypermagnesemia might be caused by chronic renal failure with hypocalcemia and administration of magnesium sulfate as a cathartic. Plasma magnesium concentration should be measured perioperatively in all surgical cases.