Advances in postoperative pain management
Management of postoperative pain still depends on the administration of opioids and these drugs are associated with adverse effects eg sedation, nausea and vomiting. Local anaesthetics and NSAIDs are not associated with these adverse effects. Five RCTs have been undertaken: three on the administration of local anaesthetics, and two on NSAIDs. Two models of surgery have been used. As an example of an invasive standardised surgical procedure associated with severe pain, I have studied patients undergoing total abdominal hysterectomy (TAH). I also studied patients undergoing laparoscopy as an example of a minimally invasive technique that is associated with moderate pain. In patients who had TAH, I found that a combination of intraperiotoneal and incisional bupivacaine with epinephrine was associated with significant morphine sparing analgesia. Patients experienced significantly less pain on movement with this technique compared with placebo. Furthermore, in patients having laparoscopic cholecystectomy, I found that intraperitoneal administration of levobupivacine with epinephrine was associated with significantly lower total abdominal pain on inspiration, compared with placebo. However, I was not able to demonstrate significant differences in rescue morphine consumption or adverse effects between the two treatment groups. In another RCT, I did not find that administration of local anaesthetics via the transcervical route during laparoscopic sterilisation was useful for analgesia. I also examined how NSAIDs may be useful for postoperative analgesia. After TAH, rectal diclofenac was found to reduce morphine consumption, improve postoperative analgesia and was associated with reduced sedation and nausea. In another RCT of similar design, I found that iv parecoxib was associated with significant reductions in morphine consumption and pain scores on sitting, compared with placebo. The results of the investigations described in this thesis show that local anaesthetics and NSAIDs are useful as analgesic adjuncts after major and minimally invasive surgery.