Investigation of the Strategy of Preventing Post-operative Opioid-induced Hyperalgesia

The concept of Enhanced Recovery After Surgery(ERAS) has been prevalent in recent years. In the ERAS guideline, short-acting anesthetics, instead of long-acting opioid anesthetics, were recommended during surgery to decrease post-operative complication and length of hospital stay. Propofol-remifentanil based total intravenous anesthesia (TIVA) can provide quicker emergence and decreased post-operative nausea and vomiting. However, the prescription of opioid (especially remifentanil) may induce opioid-induced hyperalgesia (OIH) and increase the requirement of analgesics. Previous studies provided some strategies to prevent OIH. The purpose of this study is to investigate the effect of adding remifentanil(1 mcg/kg) after emergence and endotracheal extubation in breast cancer females receiving breast surgery under propofol-remifentanil based TIVA for the prevention of OIH.

1. After obtaining informed consent, patients will be randomized into two groups. 2. All patients receive remifentanil-propofol based TIVA and Bispectral index (BIS) monitor during breast surgery. In the end of surgery, intravenous NSAID(keto) 30mg and local anestehsia (Marcaine) infiltration around the surgical wound will be prescribed to reduce post-operative pain. 3. group R(intervention): remifentanil 1mcg/kg diluted with 0.9% saline to 50ml and drip for 30 minutes after emergence and extubation of endotracheal tube 4. group N(no intervention): 0.9% saline 50ml drip for 30 minutes after emergence and extubation of endotracheal tube 5. In post-anesthesia room: record the numerical rating scale (NRS); requirement of additional analgesics (rescue medication), blood pressure, heart rate, pulse oximeter, degree of nausea, vomiting 6. In ward: record the numerical rating scale (NRS) and total analgesics consumption