Effect of Propofol on Remifentanil-induced Postoperative Hyperalgesia in Patients Undergoing Thyroid Surgery

Effect of Propofol on Remifentanil-induced Postoperative Hyperalgesia in Patients Undergoing Thyroid Surgery

The investigators hypothesize that propofol infusion during surgery can affect the remifentanil hyperalgesia compared to sevoflurane inhalation.The outcome will be measured by a verbal numerical rating score (VNRS) and mechanical punctuating pain by electronic von frey filament.

Inclusion Criteria:

• Patients undergoing thyroidectomy
• Age 20-65
• American Society of Anesthesiologists physical status classification I or II

Exclusion Criteria:

• History of chronic pain, Regular use of analgesic, antiepileptic or antidepressive drugs
• History of drug & alcohol abuse
• Psychiatric disorder
• Use of opioids within 24hrs
• Renal disease with decreased glomerular filtrate ratio
• Neuromuscular disease, Severe cardiac disease