Adjuvant Analgesic Effects of Low Dose Tramadol/Acetaminophen Combination After Open Gynaecological Surgery

Patient experience moderate to severe pain after abdominal surgery. This post-operative pain can also contribute to complications such as respiratory impairment, cardiovascular events, ileus, sleep deprivation and mood disturbance. Opioid based patient-controlled analgesia (PCA) is commonly employed but opioids have the side effects such as respiratory depression, nausea and vomiting, sedation, pruritus and urinary retention. Bowel motility can also be affected. Consequently alternative or adjunct analgesic medications without these side-effects have been investigated in order to reduce opioid consumption. Multimodal analgesia is a technique whereby a combination of analgesic drugs with different modes of action can be used to improve analgesia and decrease adverse effects by virtue of synergism. Postoperatively, with adjunctive analgesia, PCA morphine consumption as well as the side effects may be reduced. Non-steroidal anti-inflammatory drugs (NSAIDs) have been shown to be opioid sparing and decrease the adverse effects of PCA morphine. A recent review showed that acetaminophen combined with PCA could induce a significant opioid-sparing effect but the incidence of PCA morphine related side effects were not reduced. It is common nowadays to give oral analgesic supplements to post-operative patients on PCA morphine. Tramadol, an analogue of codeine, is one of the choices. However, some of the patients cannot tolerate the side effects such as nausea, drowsiness, sweating, postural hypotension and dry mouth. Combination of tramadol 37.5 mg and acetaminophen 375 mg, which has been used successfully to treat post-operative pain, may improve analgesic response with better tolerability. This study is to assess tramadol 37.5 mg and acetaminophen 375 mg combination on the efficacy of pain control, down stepping of morphine consumption and related adverse events with PCA use after open colorectal surgeries. Objectives: This study aims to compare and evaluate: * The eff