Part 2: Agitation and Sedation Assessment and Management

Sedation Assessment

Routine, validated sedation assessment is the foundation of optimal sedation management. Sedation depth should be assessed at least every 2–4 hours and more frequently during titration (every 15–30 minutes). The two recommended scales are the Richmond Agitation-Sedation Scale (RASS) and the Sedation-Agitation Scale (SAS).^{1 2}

Richmond Agitation-Sedation Scale (RASS) — Complete Scoring Table

The RASS is a 10-point scale ranging from −5 (unarousable) to +4 (combative). It is the most widely used and validated sedation assessment tool in the ICU, with excellent interrater reliability (weighted kappa 0.91–0.94) across physicians, nurses, and other providers.^{1 3}

RASS Assessment Protocol (Step-by-Step):

1. Observe the patient for 30 seconds without stimulation

   • If the patient is alert, restless, agitated, or combative → score +1 to +4
   • If the patient is calm and alert → score 0

2. If not alert, use verbal stimulation — say the patient’s name and ask them to open their eyes and look at you

   • Eye contact sustained > 10 seconds → score −1
   • Eye contact sustained < 10 seconds → score −2
   • Movement but no eye contact → score −3

3. If no response to verbal stimulation, use physical stimulation — apply sternal rub or trapezius squeeze

   • Any movement to physical stimulation → score −4
   • No response to physical stimulation → score −5

Sedation-Agitation Scale (SAS) — Complete Scoring Table

The SAS is a 7-point scale ranging from 1 (unarousable) to 7 (dangerous agitation). It has good interrater reliability (weighted kappa 0.92) and correlates well with RASS.^{1 4}

RASS-to-SAS Correlation

Choosing a Sedation Target

The 2018 guidelines strongly recommend targeting light sedation (RASS 0 to −2, SAS 3–4) for most mechanically ventilated ICU patients, unless there is a specific clinical indication for deeper sedation.^{1 2}

Evidence for Light Sedation

Indications for Deeper Sedation (RASS −3 to −5)

Recommendation: Reassess the need for deep sedation at least daily and lighten sedation as soon as clinically feasible.¹

Sedative and Analgesic Agents for Sedation

Agent Selection Principles

The 2018 guidelines recommend:^{1 2}

1. Analgesia-first approach — treat pain before adding sedation
2. Prefer non-benzodiazepine agents (propofol or dexmedetomidine) over benzodiazepines for sedation in mechanically ventilated adults (conditional recommendation)
3. Avoid benzodiazepines as first-line sedation — associated with increased delirium, prolonged ventilation, and longer ICU stay
4. Use the minimum effective dose for the shortest duration

Propofol

Propofol Infusion Syndrome (PRIS)

PRIS is a rare but potentially fatal complication of propofol infusion. Incidence is estimated at 1–4% when doses exceed 70 mcg/kg/min for more than 48 hours.⁷

Risk factors:

• High infusion rates (> 70 mcg/kg/min or > 4.2 mg/kg/h)
• Duration > 48 hours
• Concomitant catecholamine or corticosteroid use
• Critical illness with high catecholamine state
• Traumatic brain injury
• Pediatric patients (higher susceptibility)
• Low carbohydrate intake

Clinical features of PRIS (diagnosis requires ≥ 2 of the following):

PRIS prevention:

• Limit propofol to ≤ 70 mcg/kg/min (4.2 mg/kg/h)
• Limit duration when possible; consider alternatives for prolonged sedation (> 48–72 h)
• Ensure adequate carbohydrate intake (≥ 6–8 mg/kg/min glucose)
• Monitor triglycerides, CK, and lactate every 24–48 hours
• Monitor for unexplained metabolic acidosis

PRIS management:

• Immediately discontinue propofol
• Aggressive IV fluid resuscitation
• Hemodynamic support (vasopressors, inotropes)
• Correct hyperkalemia, acidosis, and electrolyte abnormalities
• Consider renal replacement therapy for refractory acidosis, hyperkalemia, or rhabdomyolysis-related AKI
• Switch to alternative sedation (dexmedetomidine, midazolam, ketamine)
• Mortality: 18–33% even with early recognition and treatment

Dexmedetomidine

Key trial evidence:

Midazolam

Ketamine for Sedation

Sedative Agent Comparison Summary

Sedative Selection Algorithm

Is the patient intubated and expected to require sedation > 72 hours?
├── YES → Dexmedetomidine (if light sedation target achievable)
│         OR Propofol (monitor for PRIS, TG q 24–48 h)
│         Consider ketamine as adjunct to reduce doses of either
│         AVOID midazolam as routine infusion
│
└── NO (< 72 hours expected)
    ├── Light sedation needed (RASS 0 to −2)?
    │   → Dexmedetomidine or propofol (either first-line)
    │
    ├── Deep sedation needed (RASS −3 to −5)?
    │   → Propofol first-line (achieves deeper sedation)
    │   → Add ketamine if hemodynamically unstable
    │   → Midazolam ONLY if propofol contraindicated AND dexmedetomidine inadequate
    │
    └── Hemodynamically unstable?
        → Ketamine (sympathomimetic)
        → Midazolam (less hemodynamic depression than propofol)
        → Dexmedetomidine with caution (avoid loading dose)
        → Propofol at low dose with vasopressor support

Daily Sedation Interruption — Spontaneous Awakening Trials (SAT)

Rationale

Daily sedation interruption (also known as spontaneous awakening trial, or SAT) involves temporarily stopping all sedative and analgesic infusions each day to reassess the patient’s neurologic status, pain, agitation, and need for continued sedation. When paired with a spontaneous breathing trial (SBT), the “wake up and breathe” protocol significantly improves outcomes.^{5 12}

SAT Safety Screen

Before initiating an SAT, a safety screen must be passed. The SAT is contraindicated if any of the following are present:

SAT Protocol

1. Pass the safety screen (see above)
2. Stop all continuous sedative and analgesic infusions at a designated time each morning (typically 06:00–08:00)
3. Observe for up to 4 hours (or until patient meets failure criteria)
4. Assess for wakefulness: patient is considered awake if they open eyes to voice, follow simple commands, or have RASS ≥ −1
5. If patient tolerates the SAT: proceed immediately to an SBT (spontaneous breathing trial)
6. If the SAT fails (see criteria below): restart sedation at half the previous rate and titrate to the targeted RASS

SAT Failure Criteria

Restart sedation at 50% of the prior rate if any of the following occur:

Paired SAT-SBT Protocol (“Wake Up and Breathe”)

The landmark ABC Trial demonstrated that pairing daily SAT with SBT, compared to SBT alone, resulted in:¹²

• 3.1 more ventilator-free days (14.7 vs. 11.6 days; p = 0.02)
• 4 fewer ICU days
• Reduced 1-year mortality (HR 0.68, 95% CI 0.50–0.92; p = 0.01)
• No increase in self-extubation

Coordinated SAT + SBT Protocol:

Step 1: SAT Safety Screen → PASS
Step 2: Stop all sedative/analgesic infusions
Step 3: Wait for patient to awaken (RASS ≥ −1)
   → If SAT fails → Restart at 50% dose, reassess next day
   → If SAT passes → Proceed to Step 4
Step 4: SBT Safety Screen → PASS
Step 5: SBT (T-piece, CPAP 5, or PSV 5–8 / PEEP 5 for 30–120 min)
   → If SBT fails → Return to prior ventilator settings; sedation PRN
   → If SBT passes → Assess for extubation readiness
Step 6: Evaluate for extubation
   → Positive cuff leak (if applicable)
   → Ability to protect airway
   → Manageable secretions
   → Extubate

Nurse-Driven Sedation Protocol

Nurse-driven sedation protocols empower bedside nurses to titrate sedation to achieve and maintain a physician-ordered RASS target. Implementation of nurse-driven sedation protocols has been associated with reduced duration of mechanical ventilation, shorter ICU stays, and decreased sedative use.^{1 13}

Example Nurse-Driven Sedation Protocol

Prerequisites:

• Physician order specifying: target RASS, preferred sedative agent, initial infusion rate, and titration parameters
• Pain assessed and treated first (BPS < 5 or CPOT < 3)

Assessment schedule:

• RASS every 2 hours (minimum)
• RASS every 15–30 minutes during active titration
• BPS/CPOT/NRS at each RASS assessment

Titration rules (propofol example):

Titration rules (dexmedetomidine example):

Sedation-Related Adverse Events and Management

Neuromuscular Blocking Agents (NMBA) — Considerations

NMBAs are occasionally required in the ICU for specific indications. When NMBAs are used, adequate sedation and analgesia must be assured because the patient cannot communicate distress. The following principles apply:^{1 14}

Common NMBA Dosing in the ICU

References