What is the Richmond Agitation‑Sedation Scale (RASS) and how is it used to assess consciousness in adult intensive‑care patients?

What is RASS?

The Richmond Agitation-Sedation Scale (RASS) is a 10-point scale ranging from +4 (combative) to -5 (unarousable) that provides the most valid and reliable assessment of sedation depth and agitation in adult ICU patients. 1, 2

Scale Structure and Scoring

• RASS uses discrete numerical scores from +4 to -5, with positive scores indicating agitation, zero indicating calm and alert, and negative scores indicating sedation 1, 2
• The scale defines specific levels:
  • +4 = Combative (overtly combative or violent)
  • +3 = Very agitated (pulls or removes tubes/catheters, aggressive)
  • +2 = Agitated (frequent non-purposeful movement, fights ventilator)
  • +1 = Restless (anxious but movements not aggressive or vigorous)
  • 0 = Alert and calm
  • -1 = Drowsy (not fully alert, sustained awakening to voice)
  • -2 = Light sedation (briefly awakens to voice, eye contact <10 seconds)
  • -3 = Moderate sedation (movement or eye opening to voice, no eye contact)
  • -4 = Deep sedation (no response to voice, movement to physical stimulation)
  • -5 = Unarousable (no response to voice or physical stimulation) 1

Psychometric Properties and Validation

• RASS demonstrates excellent inter-rater reliability (r = 0.956) across diverse ICU populations, including medical, surgical, cardiac surgery, coronary, and neuroscience ICUs 3, 2
• The scale shows high correlation with visual analog scales (r = 0.93) and moderate-to-high correlation with objective measures like EEG and bispectral index 1, 4
• RASS achieves superior inter-rater agreement (weighted κ = 0.879) compared to older scales like Ramsay (weighted κ = 0.449), making it more reliable for clinical decision-making 5
• The scale maintains validity in both ventilated and non-ventilated patients, and in those with or without sedative medications 3

Clinical Application and Target Goals

• The Society of Critical Care Medicine recommends targeting RASS -2 to 0 (light sedation to awake and calm) for most mechanically ventilated adult ICU patients, as this reduces duration of mechanical ventilation and ICU length of stay 1, 2, 4
• RASS should be assessed at least every 4 hours per shift to guide sedation titration 1
• When patients are under-sedated (RASS >0), assess and treat pain first using validated pain scales, then administer sedatives as needed, preferring non-benzodiazepines unless treating alcohol or benzodiazepine withdrawal 1, 2
• When patients are over-sedated (RASS <-2), hold sedative medications immediately until target is reached, then restart at 50% of the previous dose 1, 2

Treatment Adjustment Algorithm Based on RASS

For RASS >0 (agitated):

• Assess pain using BPS or CPOT for non-communicative patients 1
• Treat pain with IV opioids first 1, 4
• If agitation persists after adequate analgesia, administer sedatives (propofol or dexmedetomidine preferred over benzodiazepines) 1, 2

For RASS -2 to 0 (target range):

• Continue current sedation strategy 1, 2
• Reassess regularly to maintain this light sedation level 2

For RASS <-2 (over-sedated):

• Stop sedative infusions immediately 1, 2
• Wait until patient reaches RASS -2 to 0 1
• Restart sedatives at 50% of prior dose 1, 2

For RASS -3 to -5 (deep sedation):

• Reserve only for specific indications: severe ARDS with refractory patient-ventilator asynchrony, intracranial hypertension, status epilepticus, neuromuscular blockade requirement, or profound hemodynamic instability 2, 4
• Reassess need for deep sedation daily 2, 4

Advantages Over Other Scales

• RASS is described by ICU nurses as logical, easy to administer, and readily recalled, facilitating consistent bedside implementation 3, 6
• The scale demonstrates excellent internal consistency (Cronbach α = 0.989) compared to Ramsay scale (α = 0.828) 5
• RASS provides better discrimination between sedation levels than older instruments, enabling more precise titration of sedative medications 1, 2

Critical Pitfalls to Avoid

• Never rely on objective brain function monitors (BIS, entropy, PSI) as the primary sedation assessment method in non-paralyzed patients, as they are inadequate substitutes for RASS scoring 2, 4
• Never use RASS in neonates or infants under 2 months, as it lacks validation in this population and does not account for developmental differences in pain and sedation responses 7
• Do not use daily sedation interruption as justification for maintaining deep sedation (RASS <-3) during the remainder of the day when not clinically indicated 4
• Always assess and treat pain before escalating sedation for agitation, as pain is frequently the underlying cause of apparent agitation 2, 4
• Avoid benzodiazepines as first-line sedatives unless specifically treating alcohol or benzodiazepine withdrawal, as they increase delirium risk and prolong mechanical ventilation 2, 4

Implementation Considerations

• Formal education on why and how to use RASS is essential for successful implementation and consistent application across ICU staff 6, 8
• Visual management tools and reminder cards improve compliance with RASS-based sedation protocols 6
• RASS facilitates interprofessional communication by providing a standardized language for discussing sedation goals 8