To view the full text, please login as a subscribed user or purchase a subscription. Click here to view the full text on ScienceDirect. Fig 1 Mean cold pain intensity ratings and analgesia nociception index (ANI) values. (a) Mean cold pain intensity ratings (Numerical Rating Scale [NRS], 0–10) with 95% confidence intervals (CI) during the cold pressor test (CPT). In Group 6, the non-linear increase of NRS values was significantly slower compared with the other groups.