Interventional sedation analysis (ISA) is a medical procedure that facilitates the execution of potentially painful or anxiety-inducing diagnostic and therapeutic interventions in specific patient populations. The effectiveness of ISA is assessed by monitoring the depth of sedation achieved in patients
1,2. Numerous scales have been developed to monitor sedation depth, with the most commonly used being the Ramsay Sedation Scale (RSS), Michigan University Sedation Scale (MUSS), and Brussels Sedation Scale (BSS). Among these, the RSS remains the most widely utilized in clinical practice today
3. However, the application of these scales in clinical settings poses challenges, as their reliability depends heavily on the subjective interpretation of the evaluator. Additionally, these scales require the administration of painful or verbal stimuli at specific moments, which limits their ability to provide continuous and objective measurements
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The Ramsay Sedation Scale (RSS) was first introduced by Ramsay and colleagues in 1974 as a straightforward scoring system, which continues to be a predominant tool in intensive care units 5.The RSS is applicable not only in intensive care settings but also across various clinical scenarios where sedative and analgesic medications are administered 6. The scale consists of six levels: Level 1-patient is awake but anxious, agitated, or restless; Level 2-patient is awake, cooperative, oriented, and calm; Level 3-patient is asleep but responds to commands; Level 4-patient exhibits a brisk response to glabellar tap or loud auditory stimulus; Level 5-patient shows a sluggish response to such stimuli; and Level 6-patient exhibits no response to glabellar tap or loud auditory stimulus 7. The target sedation level for most clinical scenarios is typically Level 2. It remains one of the most widely utilized clinical evaluation methods to this day 8.
The University of Michigan Sedation Scale (MUSS) was developed to provide a simple and rapid method for assessing and documenting the depth of sedation in patients receiving sedative agents for diagnostic or therapeutic procedures. The scale ranges from 0 to 4: Level 0-patient is awake and alert; Level 1-patient responds to minimal verbal stimuli; Level 2-patient responds to moderate tactile stimuli; Level 3-patient requires deeper physical stimuli for arousal; and Level 4-patient does not respond to any stimuli. The MUSS was designed to be easy to use, reproducible, and objective 9.
The Brussels Sedation Scale (BSS) was primarily developed for use in intensive care settings, aiming to provide a simple, repeatable, and objective method for assessing sedation depth. The scale includes five levels, but unlike the RSS, it inverts the order: higher numerical values correspond to lighter levels of sedation. This approach is believed to be easier to apply and is conceptually similar to the Glasgow Coma Scale (GCS), where lower scores indicate deeper levels of unconsciousness. On the BSS, Level 1 corresponds to a patient who cannot be awakened and only responds to painful stimuli, such as trapezius muscle compression; Level 2 indicates a patient who does not respond to verbal stimuli but reacts to pain; Level 3 is for patients who respond to verbal commands; Level 4 indicates the patient is awake and alert; and Level 5 corresponds to a state of agitation 10.
The Bispectral Index (BIS) ranges from 0, which represents isoelectric EEG, to 100, indicating an awake brain. Following the administration of sedative and analgesic agents, a patient’s level of consciousness transitions through various stages, which are reflected in the BIS score. The BIS value decreases from 100, with a BIS of 60 indicating a reduced likelihood of consciousness, while values below 40 are indicative of deep hypnosis approaching an isoelectric EEG. The BIS value, which starts at 100 indicating an awake state of consciousness, gradually decreases as sedation deepens. A BIS value of 60 is associated with a significantly reduced likelihood of consciousness, while values below 40 are indicative of deep hypnosis, nearing an isoelectric EEG. BIS values within the range of 40 to 60 are considered to provide an effective hypnotic state suitable for general anesthesia, ensuring a rapid recovery. The Bispectral Index (BIS), derived from electroencephalography (EEG) signals, is widely regarded as a quantitative measure of anesthetic depth. This index is generated by advanced computational algorithms that analyze cerebral electrical activity, allowing for continuous and objective monitoring of sedation depth. The BIS technique facilitates the precise assessment of sedative and hypnotic effects of anesthetic agents, making it a valuable tool in clinical settings. Numerous studies have demonstrated the utility of EEG monitoring, particularly in intensive care units and operating rooms, for assessing sedation depth. Furthermore, in cases where general anesthesia is not administered but sedation is required, BIS monitoring has been reported as an effective alternative for determining anesthetic depth during procedures such as endoscopy, bronchoscopy, central catheter insertion, and dental interventions. It also serves as an alternative to traditional sleep staging systems in sleep studies 11-14. This study aims to evaluate the correlation between the clinically subjective scales RSS, MUSS, and BSS and BIS monitoring in patients undergoing Interventional Sedation and Analgesia (ISA).
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