Nociception Level Index variations in ICU: curarized vs non-curarized patients. A pilot study

Abstract

Abstract Purpose Pain is a major physiological stressor that can worsen critical medical conditions in many ways. Currently, there is no reliable monitoring tool is available for pain monitoring in the deeply sedated ± curarized critically ill patients. This study aims to assess the effectiveness of the multiparameter nociception index (NOL®) in the critical care setting. We compared NOL with traditionally used neurovegetative signs and examined its correlation with sedation depth measured by bispectral index (BIS®) EEG monitoring. Methods This prospective monocentric cohort study was conducted in a general medical surgical ICU, including patients who required moderate to deep levels of sedation with or without continuous neuromuscular blockade. The performance of NOL was evaluated both in the entire studied population, as well as in two subgroups: curarized and non-curarized patients. Results NOL demonstrated greater accuracy than all other indicators in pain detection in the overall population. In the non-curare subgroup, all indices correctly recognized painful stimulation, while in the patients subjected to NMBA infusion, only NOL properly identified nociception. In the former group, EEG’s relation to nociception was on the border of statistical significance, whereas in the latter BIS showed no correlation with NOL. Conclusion NOL emerges as a promising device for pain assessment in the critical care setting and exhibits its best performance precisely in the clinical context where reliable pain assessment methods are most lacking. Our study demonstrates its feasibility in a mixed surgical and medical ICU population. Furthermore, our research confirms the distinction between sedation and analgesia, highlighting the necessity for distinct monitoring instruments to accurately assess them.