Healthcare & Clinical
RASS Sedation Depth & CAM-ICU Delirium Screening Logic Formula
Pair the Richmond Agitation-Sedation Scale (RASS -5 to +4) arousal gate (RASS >= -3) with Wes Ely’s validated 4-feature Confusion Assessment Method for the ICU (CAM-ICU: Feature 1 AND Feature 2 AND [Feature 3 OR Feature 4]).
Catch hypoactive "quiet" ICU delirium that bedside observation misses 70% of the time!
Critical-care nurses perform paired sedation-delirium checks every shift using Sessler’s Richmond Agitation-Sedation Scale (RASS, -5 unarousable to +4 combative) followed immediately by Wes Ely’s Confusion Assessment Method for the ICU (CAM-ICU)! Step 1 checks arousal: if RASS is -4 (deep sedation, movement to physical stimulation only) or -5 (unarousable coma), delirium cannot be assessed ("Unable to Assess — Comatose/Deeply Sedated, Reassess Later").
Whenever RASS >= -3, CAM-ICU evaluates four features: Feature 1 (Acute onset OR fluctuating mental status course over 24h), Feature 2 (Inattention: > 2 errors on the 10-letter SAVEAHAART auditory squeeze test), Feature 3 (Altered level of consciousness: current RASS <> 0!), and Feature 4 (Disorganized thinking: > 1 error on 4 yes/no questions + command). CAM-ICU is Positive if and only if Feature 1 AND Feature 2 AND (Feature 3 OR Feature 4)—capturing both agitated hyperactive delirium (RASS +1 to +4) and lethal hypoactive delirium (RASS -1 to -3, or RASS 0 with Feature 4 positive)!
| RASS & CAM-ICU Step | Bedside Rule | Clinical ICU Output |
|---|---|---|
| Step 1: Arousal Gate (RASS -5 to +4) | RASS <= -4 (Deep Sedation / Coma) | "Unable to Assess (RASS -4/-5)" |
| CAM-ICU Positive Delirium | RASS >= -3 AND F1=1 AND F2(>2 err) AND (RASS<>0 OR F4>1 err) | "CAM-ICU Positive (Hypoactive or Hyperactive)" |
| CAM-ICU Negative | RASS >= -3 with F1=0, F2<=2 errors, or (RASS=0 and F4<=1) | "CAM-ICU Negative (No Delirium)" |
CAM-ICU Screening Result With Automatic RASS Arousal Gate & Feature 3 Derivation
Derives Feature 3 automatically from current RASS <> 0 (B2), evaluates Feature 2 as SAVEAHAART errors > 2 (B4 > 2), and Feature 4 as thinking errors > 1 (B5 > 1).
=IF(OR(B2 < -5, B2 > 4, B4 < 0, B4 > 10, B5 < 0, B5 > 5), "Invalid RASS/CAM Inputs", IF(B2 <= -4, "Unable to Assess (Coma/Deep Sedation RASS -4/-5)", IF(AND(B3 = 1, B4 > 2, OR(B2 <> 0, B5 > 1)), IF(B2 > 0, "CAM-ICU Positive (Hyperactive Delirium)", "CAM-ICU Positive (Hypoactive / Quiet Delirium)"), "CAM-ICU Negative (No Delirium)")))Count of Positive CAM-ICU Features (0 to 4)
Counts how many of Features 1–4 are positive for nursing flowsheet documentation.
=IF(B3 = 1, 1, 0) + IF(B4 > 2, 1, 0) + IF(B2 <> 0, 1, 0) + IF(B5 > 1, 1, 0)Try the example
Use the original values or change them to test your understanding.