Background and Aims Analgesia Nociception Index (ANI) is a new method used to measure acute pain while the patient is unconscious. ANI detection principle is monitoring heart rate variability by using electrocardiography. Technology uses algorithms analyzing R-R complexes and breathing rate therefore assesses patient condition and his sympathetic and parasympathetic nervous systems activity. This innovative technology allows doctors to create an individual technique for dosing analgesic drugs to every patient.

This pilot study aimed to determine the usefulness of ANI for pain intensity during shoulder arthroscopic surgery.

Methods The pilot study was conducted in “Hospital of Traumatology and Orthopaedics” after Ethics Committee approval on August 2021. All twelve patients were under general anesthesia and were divided into two groups – with and without plexus brachialis block. ANI was monitored all the surgery time - from ET intubation till extubation.

Results In controlgroup “Block after surgery” the median of ANI values at surgery 15th minute were lower (56.5) compared with a group “Block before surgery” (69). Mean ANI values in control group were (54.17) meanwhile in group ”Block before surgery” were (67.67)-which means analgesia without plecus brachialis block were poorer – and ANI effectively detected that. ANI values at group with block before surgery 95% CI [52.39–82.94]) and (95% CI [37.46–70.87]) in group with block after surgery.

Conclusions In the pilot study tendency is observed that ANI technology at pain detection works effectively and could be potentially useful tool for measurement of acute pain. The study will continue because much broader study is needed to get statistically significant results.