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electrophysiological monitoring, mechanical ventilation, intensive care unit, sedation, bispectral index
Background: Adequate sedation is required for smooth ventilation of patients on invasive mechanical ventilation. Under sedation may result in prolonged stress mobilization and patient harm, whereas over sedation obscures neurologic abnormalities and increases mortality and morbidity. In instances such as deep sedation/analgesia, the Bispectral Index (BIS) may be used as an auxiliary to clinical assessment of sedation to assist in determining depth of sedation. Determining the correlation between clinical and BIS measurements of sedation will assist in determining the appropriate role of BIS in intensive care unit (ICU). The aim of the present study to monitor depth of sedation of patients in ICU using Riker Sedation Agitation Scale (RSAS) and to assess the correlation between RSAS & BIS.
Methods: The present observational study was conducted from May 2022 to April 2023. 47 cases that required mechanical ventilation and sedation with a baseline intact brain function were enrolled as per inclusion-exclusion criteria. Patients of either of 18 years or older who required mechanical ventilation and sedation with a baseline intact brain function and willing to participate were included in the study. Patients with age less than 18 years, diagnosed or suspected condition that resulted in a decreased level of consciousness or reduced blood flow/oxygen supply of the brain, i.e., prolong seizure activity, encephalopathic state, hypoxemia with PaO2 less than 55 mm Hg, altering level of consciousness, and severe ischemic or hemorrhagic stroke were excluded from study. Patients with clinical states such as drug overdose producing alterations in level of consciousness, severe anemia impairing consciousness, and severe alkalotic/ acidotic states, patients with birth injuries impairing neurologic function such as cerebral palsy were not included in study. The BIS and RSAS measurement was done before initiation of sedation & in 4-hour intervals after initiation of sedation up to 24 hours.
Results: At all the periods of observation correlation between BIS and RSAS were highly significant and level of correlation was strong to very strong/perfect.
Conclusion: BIS monitoring may play an additional function in sedation assessment in cases where the clinical assessment is ambiguous. BIS results must be taken with caution, however, because electromyography activity and other variables appear to confuse BIS scores. Additional research is required to determine the clinical utility of BIS monitoring in ICU practice.
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