If the individual patient's pain is assessed and the amount of analgesic needed after surgery is predicted, appropriate injection of pain control and excessive injection of narcotic analgesic can be prevented. Therefore, investigators try to evaluate the relation intraoperative nociception response with postoperative pain score.

In similar anesthetic depth(End tidal sevoflurane 3%) , changes of surgical pleth index values for stimulus of skin incision are thought to reflect the individual nociception characteristics.

Patients who undergoing upper abdominal laparotomy surgery usually experience severe postoperative pain. Previous studies were reported that preoperative pain, young age, high-dose remifentanil, and depression were associated with severe postoperative pain.

However, anesthesia-related studies were either retrospective studies or injected with anesthetic agents in excess of clinical doses to differentiate between groups. There is no objective indicator for prediction severe postoperative pain.The purpose of this study was to investigate the relationship between intraoperative pain response and postoperative pain on standardized surveillance devices.

To maintain the depth of anesthesia, an EEG monitoring device bispectral index (BIS) is used. Also, surgical pleth index (SPI, GE healthcare, Freiburg, Germany) is a noninvasive pain-analgesia balance monitoring device that is commercially available to evaluate the state of pain during general anesthesia. SPI = 100- (0.3 * heart beat interval + 0.7 * photoplethysmographic pulse wave amplitude) is automatically and continuously calculated from the waveform of peripheral oxygen saturation.

In similar anesthetic depth(End tidal sevoflurane 3%) , changes of SPI values for stimulus of skin incision are thought to reflect the individual nociception characteristics. The investigators hypothesized the higher analgesics consumption can predict with high SPI response following incisional stimuli.

Thus, investigators try to evaluate the comparison of two groups ( high fentanyl consumption group vs. low fentanyl consumption group) with intraoperative SPI value (incision and before aurosal) and hemodynamic parameters under End tidal sevoflurane 3%(anesthesia depth, hemodynamically stable and appropriate anesthetic depth based on previous studies were confirmed at the time of skin incision). And the characteristics and emotional status of patients in two groups are compared.

Inclusion Criteria:

-undergoing laparotomy gastrectomy

Exclusion Criteria:

• cardiac arrythmia
• allergic history for drugs
• renal failure (Cr> 1.5 mg/dl)

the 20-80 year old patients who undergoing lapatotomy gastrectomy at samsung medical center