1. The study sample comprised 82 patients who underwent breast cancer surgery between 2015 and 2016 in our institution. |
2. Patients were excluded if they met our exclusion criteria. |
3. We then selected 20 patients who had no pain after surgery immediately upon admission to the post-anesthesia care unit (PACU) (with “no pain” defined as a Numerical Rating Scale (NRS) value between 0 and 2). |
4. These 20 patients were divided into two groups: Group A (n = 16) had no pain upon admission to PACU and remained pain free upon discharge from PACU (12 h after surgery); group B (n = 4) had no pain immediately upon admission to PACU and experienced increasing pain 1 h after surgery while in PACU, requiring analgesic therapy. |
5. NRS was measured immediately upon arrival in PACU, then 1 and 2 h after surgery. |
6. Heart rate variability (HRV) was measured upon arrival in PACU and then 2 h after surgery. |
7. These 20 patients (both group A (n = 16) and group B (n = 4) remained in PACU for 12 h after surgery. |