The patients will be transferred to the recovery area for monitoring for at least 30 minutes postoperatively. The vital signs including blood pressure, pulse and SpO2 and the Ramsay sedation score (RSS) will be assessed every 5 minutes. Pain score (NRS) will be recorded every 15 minutes. The patients will be sent back to general ward when the parameters are normal. P deletion test will be done from postoperative hour 2 in the general ward until the performance is at least the same as that before operation. Mini-mental test will be done at 2 hours postoperatively. Hourly blood pressure, pulse, SpO2 and pain score (NRS) will be performed for 4 hours. Pain score (NRS) will be assessed 4 hourly afterward. Quality of recovery will be assessed after operation with Chinese QoR. Serum IL-6 and TNF-α will be taken at postoperative 6th hour and 16th hour. Paracetamol 1 g three times daily and tramadol 50mg three times daily as required will be prescribed postoperatively.