The surgical injury results in immobilisation which again can result in impaired cardiac, respiratory and musculoskeletal system. Pain relief is a prerequisite for mobilisation and an early return to the pre-surgical level. The preferred drugs for postoperative pain management are opioids. Although opioids are known to be an effective analgesia, they have a series of side effects: nausea, vomiting, constipation, respiratory deficiency, delirium among others.