Transdermal Fentanyl Patch for Postoperative Analgesia After Abdominal Surgery: a Randomized Placebo-controlled Trial

Transdermal Fentanyl Patch for Postoperative Analgesia After Abdominal Surgery: a Randomized Placebo-controlled Trial

Abdominal surgery causes severe postoperative pain. Multi-modal pain therapy is usually applied but there is no perfect choice. It depends on physician's skill and situation. The best regimen is patient-controlled analgesia, but it requires an expensive equipment. Transdermal fentanyl patch, usually used in chronic pain relief, can steadily release fentanyl into blood stream for 72 hours, but it has slow onset of 12 hours.

Hypothesis: If Transdermal fentanyl patch is applied 10-12 hours before surgery, it may provide good analgesia for 72 hours.

Inclusion Criteria:

• age =>18 years
• scheduled for abdominal surgery

Exclusion Criteria:

• ASA class > 3
• Known allergy to fentanyl or morphine
• History of substance or alcohol abuse, and tolerance or dependence on opioids
• Combined epidural block
• Can't use PCA, abnormal renal / liver function