3. Results
REGRESSION, HEAT
After enrollment and the processes of randomization and exclusion, a total of 100 patients who underwent upper and low gastrointestinal tract oncologic open abdominal surgery in our institution were included in the study (Demographic data (age, gender, admission diagnosis, underlying medical conditions, and type of gastrointestinal surgery) are summarized in 

Accordingly, patients in the ESP group required fewer postoperative opioids (morphine) at 60 minutes to 12 hours after surgery and required additional non-opioid analgesia management at 4, 8, and 12 hours after surgery (
We also analyzed predicting factors of adequate postoperative analgesia level (defined as VAS score less than 5) on the VAS score at 60 minutes after admission to the PACU by multivariate statistical analysis. Since VAS scores within the study population were non-normally distributed outcomes, the data were analyzed using quantile regression at quantiles 0.1, 0.25, 0.5, 0.75, and 0.9. Based on the results of quantile regression analysis, patients in the ESP group were considered a significantly relevant predictor with negative regression coefficients for Q10, Q25, Q50, Q75, and Q90 (−2.478CHF(critical heat flux), 