RASS Score Calculator — Richmond Agitation-Sedation Scale

About

The Richmond Agitation-Sedation Scale (RASS) was developed by a multidisciplinary team of critical care physicians, nurses, and pharmacists at Virginia Commonwealth University, with the original validation study published by Sessler et al. in the American Journal of Respiratory and Critical Care Medicine in 2002. The scale emerged from a need for a standardized, reliable tool to assess level of sedation and agitation in critically ill patients, addressing limitations of earlier scales like the Ramsay Sedation Scale. RASS is a 10-level ordinal scale ranging from +4 (combative, posing immediate danger to staff) through 0 (alert and calm) to -5 (unarousable, no response to voice or physical stimulation). The scale has demonstrated excellent inter-rater reliability (weighted kappa > 0.90) across diverse ICU populations and nursing shifts, and it has been validated against other sedation measures and neurophysiologic monitoring. The Society of Critical Care Medicine's Clinical Practice Guidelines for the Prevention and Management of Pain, Agitation/Sedation, Delirium, Immobility, and Sleep Disruption (PADIS) in Adult ICU Patients, published in 2018, explicitly recommend RASS as the preferred sedation assessment tool in mechanically ventilated patients. RASS is also a prerequisite for delirium assessment using the Confusion Assessment Method for the ICU (CAM-ICU), as CAM-ICU cannot be performed in patients with RASS -4 or -5. The scale is now the most widely used sedation assessment instrument in ICUs globally, integrated into sedation protocols, daily interruption bundles, and quality improvement initiatives aimed at reducing oversedation, ventilator days, and ICU length of stay.

Formula

RASS: +4 Combative → 0 Alert & Calm → -5 Unarousable

RASS is a single ordinal scale that follows a structured, stepwise assessment protocol. The assessment begins by observing the patient at rest without stimulation. If the patient is fully alert and shows any degree of agitation or restlessness, the clinician scores from 0 (alert and calm) upward to +4 (combative) based on observed behavior. A score of +1 is given for restless or anxious but non-aggressive movements; +2 for frequent non-purposeful movement or pulling at tubes; +3 for very agitated behavior such as attempting to remove catheters or striking staff; and +4 for overtly combative or violent behavior posing immediate danger. If the patient is not fully alert, the clinician proceeds to step two: verbal stimulation. The patient is called by name in a normal voice, and if necessary, with a louder command to open eyes. Response to verbal stimulation yields scores of -1 (drowsy but awakens to voice with sustained consciousness for more than 10 seconds), -2 (awakens briefly to voice with eye opening for less than 10 seconds), or -3 (any movement or eye opening to voice but without sustained eye contact). If there is no response to verbal stimulation, step three involves physical stimulation: gentle shaking of the shoulder followed by rubbing the sternum if needed. Response only to physical stimulation yields -4 (movement to physical stimulation but no response to voice), while no response to any stimulation yields -5 (unarousable). The structured protocol ensures consistency across different assessors. The target RASS range depends on the clinical context: for most mechanically ventilated patients, the PADIS guidelines recommend targeting RASS 0 to -1 (light sedation). For patients with severe ARDS or elevated intracranial pressure, deeper sedation (RASS -2 to -4) may be appropriate. Light sedation targets (RASS 0 to +1) are appropriate for post-operative patients undergoing rapid weaning.

Score Interpretation

RASS is the most widely used sedation assessment instrument in ICUs worldwide and is formally recommended by the Society of Critical Care Medicine's PADIS (Pain, Agitation/Sedation, Delirium, Immobility, and Sleep Disruption) guidelines published in Critical Care Medicine in 2018. The guidelines recommend routine monitoring of sedation with a validated tool such as RASS at least every 4 hours and whenever sedation is adjusted. The target RASS score should be individualized based on patient-specific factors: for most mechanically ventilated patients, a target of RASS 0 to -1 (light sedation) is recommended as it is associated with reduced duration of mechanical ventilation, shorter ICU length of stay, decreased incidence of delirium, and lower rates of tracheostomy. Light sedation targets (RASS 0 to +1) are appropriate for patients undergoing daily sedation interruption or rapid weaning protocols. Deeper sedation targets (RASS -2 to -4) may be indicated for patients with severe ARDS requiring lung-protective ventilation with neuromuscular blockade, those with elevated intracranial pressure, status epilepticus, or refractory hypoxemia. The implementation of nurse-driven sedation protocols with explicit RASS targets has been shown to reduce total sedative exposure, decrease variability in sedation practice, and improve clinical outcomes. Daily sedation interruption (DSI), also known as a "sedation vacation," involves holding sedative infusions until the patient reaches RASS 0 to -1 or demonstrates awakening. DSI guided by RASS has been demonstrated in randomized trials to reduce duration of mechanical ventilation and ICU stay. RASS also serves as the first step in delirium screening — CAM-ICU can only be performed when RASS is -3 or higher. An RASS of -4 or -5 precludes delirium assessment and should prompt evaluation of sedation depth.

Reference Ranges