Nociception-Level (NOL) for the Assessment of Pain in Patient Unable to Self-Report

Inclusion Criteria: * Male and female, Age \> 18 years old. * Spontaneously breathing or mechanically ventilated * Any patient who is unable to express his/her own level of personal pain by using visual scales according to the hospital standard * Written informed consent provided by the participant (if they have capacity) or guardian (if they do not have capacity) or a written proxy informed consent from a legally authorized representative empowered to make health-related decisions for the potential study participant. Exclusion Criteria: * A patient whose staff or research team believes that his or her participation in the research will cause suffering to the patient. * Unstable condition preventing planned routine procedures of care, and conditions precluding the use of PMD-200: absence of sinus cardiac rhythm.