9.2 ICU Delirium: Risk Factors, Screening (CAM-ICU/ICDSC), Non-Pharmacological Bundles, and Medical Management

9.2 ICU Delirium: Risk Factors, Screening (CAM-ICU/ICDSC), Non-Pharmacological Bundles, and Medical Management

Core Knowledge: Delirium is an acute, fluctuating organic brain dysfunction characterized by disturbances in attention, awareness, and baseline cognition. In the burn intensive care unit, delirium affects up to 50% to 70% of critically ill patients. Far from being an expected, benign consequence of critical illness, delirium is an independent predictor of 6-month mortality, prolonged mechanical ventilation, profound long-term cognitive impairment, and catastrophic surgical failure resulting from patients tearing off dressings and avulsing skin autografts.

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1. Pathophysiology and Burn-Specific Delirium Risk Factors

The pathogenesis of burn delirium is multifactorial, involving neuroinflammation, microglial activation, blood-brain barrier (BBB) hyperpermeability, neurotransmitter dysregulation (acetylcholine deficiency and excess dopamine/glutamate), and cerebral microvascular hypoperfusion.

                         NEUROBIOLOGY OF BURN ICU DELIRIUM
  ┌────────────────────────────────────────────────────────────────────────┐
  │ Major Burn Trauma (≥20% TBSA) / Sepsis / Inhalation Injury / Shock     │
  │                                   │                                    │
  │                                   ▼                                    │
  │ Massive Systemic Cytokine Surge: Circulating TNF-α, IL-1β, IL-6, IL-8  │
  │                                   │                                    │
  │                                   ▼                                    │
  │ Breakdown of Blood-Brain Barrier (BBB) & Direct Microglial Activation  │
  │                                   │                                    │
  │                                   ▼                                    │
  │ Central Neurotransmitter Imbalance: Acetylcholine Depletion & Dopamine │
  │ Excess ──► Cortical Network Breakdown & Severe Bioenergetic Failure    │
  │                                   │                                    │
  │                                   ▼                                    │
  │        ACUTE ORGANIC BRAIN DYSFUNCTION (ICU DELIRIUM)                  │
  └────────────────────────────────────────────────────────────────────────┘

Multifactorial Delirium Risk Matrix in Burn Patients:

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2. Clinical Motoric Subtypes of Delirium

Delirium is categorized into three clinical subtypes based on psychomotor activity. Recognizing the subtype is vital because clinical presentation dictates diagnostic vigilance and management.

                         MOTORIC SUBTYPES OF ICU DELIRIUM
  ┌────────────────────────────────────────────────────────────────────────┐
  │ 1. HYPOACTIVE DELIRIUM ("Quiet Delirium") — Most Common (~50–60%)      │
  │    • Presentation: Lethargic, flat affect, withdrawn, staring, delayed │
  │      verbal responses, decreased spontaneous motor activity.           │
  │    • Clinical Pitfall: Frequently missed; misdiagnosed as depression,  │
  │      fatigue, or 'good ICU sleep'. CARRIES THE HIGHEST MORTALITY.      │
  ├────────────────────────────────────────────────────────────────────────┤
  │ 2. HYPERACTIVE DELIRIUM — (~10–15%)                                    │
  │    • Presentation: Agitated, combative, paranoid, restless, climbing   │
  │      out of bed, pulling invasive lines/tubes, visual hallucinations.  │
  │    • Clinical Impact: Immediate danger to self, graft avulsion risk.   │
  ├────────────────────────────────────────────────────────────────────────┤
  │ 3. MIXED DELIRIUM — (~25–35%)                                          │
  │    • Presentation: Rapid, unpredictable fluctuations between          │
  │      hyperactive combativeness and hypoactive lethargy within 24 hours. │
  └────────────────────────────────────────────────────────────────────────┘

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3. Validated Delirium Screening Tools: CAM-ICU & ICDSC

Bedside nursing screening must be conducted routinely at least every 8 to 12 hours (every shift) and with any acute change in mental status. The two gold-standard, validated screening tools are the Confusion Assessment Method for the ICU (CAM-ICU) and the Intensive Care Delirium Screening Checklist (ICDSC).

                   CAM-ICU ASSESSMENT ALGORITHM AT THE BEDSIDE
  ┌────────────────────────────────────────────────────────────────────────┐
  │ STEP 1: Assess Level of Consciousness (RASS)                           │
  │ • If RASS is -4 (deep sedation) or -5 (unarousable): STOP. Patient is  │
  │   UNTOUCHABLE / UNABLE TO ASSESS (UTA). Re-evaluate when lighter.      │
  │ • If RASS is ≥ -3 (-3 to +4): PROCEED to Step 2.                       │
  └───────────────────────────────────┬────────────────────────────────────┘
                                      │
                                      ▼
  ┌────────────────────────────────────────────────────────────────────────┐
  │ STEP 2: Evaluate Feature 1 — Acute Change or Fluctuating Course        │
  │ • Is there an acute change from baseline mental status? OR             │
  │ • Has the patient's mental status or RASS fluctuated in past 24 hours? │
  └───────────────────────────────────┬────────────────────────────────────┘
                                      │ YES (Required)
                                      ▼
  ┌────────────────────────────────────────────────────────────────────────┐
  │ STEP 3: Evaluate Feature 2 — Inattention                               │
  │ • Squeeze hand on letter 'A' in 'S-A-V-E-A-H-A-A-R-T' (10 letters)     │
  │ • Errors > 2 (Missed 'A' or squeezed on non-'A')?                      │
  └───────────────────────────────────┬────────────────────────────────────┘
                                      │ YES (Required: >2 Errors)
                                      ▼
                  ┌───────────────────┴───────────────────┐
                  │                                       │
                  ▼                                       ▼
  ┌───────────────────────────────┐       ┌────────────────────────────────┐
  │ Feature 3: Altered Level of   │       │ Feature 4: Disorganized        │
  │ Consciousness                 │  OR   │ Thinking                       │
  │ • Is current RASS anything    │       │ • 4 logic questions + command  │
  │   other than 0 (Alert/Calm)?  │       │ • Errors > 1?                  │
  └───────────────┬───────────────┘       └────────────────┬───────────────┘
                  │                                        │
                  └───────────────────┬────────────────────┘
                                      │ EITHER Feature 3 OR Feature 4 POSITIVE
                                      ▼
                     ┌──────────────────────────────────┐
                     │     CAM-ICU POSITIVE (DELIRIUM)  │
                     │  [Feature 1 + 2 + (3 OR 4)]      │
                     └──────────────────────────────────┘

CAM-ICU Feature Breakdown:

1. Feature 1: Acute Onset or Fluctuating Course: Evidence of a sudden change in mental status from baseline or fluctuation over the previous 24 hours (e.g., fluctuating RASS scores).
2. Feature 2: Inattention (Auditory / Visual Testing): Read the 10-letter sequence "S-A-V-E-A-H-A-A-R-T" (or "A-B-A-D-A-B-A-A-Y-T"). Instruct the patient to squeeze your hand every time they hear the letter "A". An error is scored if the patient fails to squeeze on "A" or squeezes on another letter. $>2\text{ errors}$ indicates inattention.
3. Feature 3: Altered Level of Consciousness: Evaluated directly by the patient's current RASS score. Any score other than 0 (Alert and Calm) is positive (i.e., $-3, -2, -1, +1, +2, +3, +4$).
4. Feature 4: Disorganized Thinking: Administer 4 simple binary logic questions and a 2-step command:
   • 1. Will a stone float on water?
   • 2. Are there fish in the sea?
   • 3. Does one pound weigh more than two pounds?
   • 4. Can you use a hammer to pound a nail?
   • Command: "Hold up this many fingers" (examiner demonstrates 2 fingers), then "Now do the same with the other hand" (without demonstrating).
   • $>1\text{ error}$ indicates disorganized thinking.

Intensive Care Delirium Screening Checklist (ICDSC):

An 8-item observational screening tool scored from 0 to 8 over a 24-hour shift:

• Items: (1) Altered consciousness, (2) Inattention, (3) Disorientation, (4) Hallucinations/delusions, (5) Psychomotor agitation/retardation, (6) Inappropriate speech/mood, (7) Sleep-wake cycle disturbance, (8) Symptom fluctuation.
• Scoring: $\ge 4\text{ points}$ = Clinical Delirium; 1 to 3 points = Subsyndromal Delirium (warrants early intervention).

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4. The ABCDEF (PADIS) Bundle in Burn Care

The implementation of the evidence-based ABCDEF Bundle reduces delirium occurrence by up to 50%, shortens mechanical ventilation duration, decreases ICU readmission rates, and improves long-term survival.

                         THE ABCDEF CARE BUNDLE IN BURNS
  ┌───┬───────────────────────────────────┬────────────────────────────────────────┐
  │ A │ Assess, Prevent, and Manage Pain  │ Prioritize IV opioids/ketamine/multimod│
  ├───┼───────────────────────────────────┼────────────────────────────────────────┤
  │ B │ Both SAT and SBT Daily            │ Spontaneous Awakening & Breathing trials│
  ├───┼───────────────────────────────────┼────────────────────────────────────────┤
  │ C │ Choice of Analgesia and Sedation  │ Light sedation; AVOID BENZODIAZEPINES  │
  ├───┼───────────────────────────────────┼────────────────────────────────────────┤
  │ D │ Delirium: Assess, Prevent, Manage │ Screen q8-12h with CAM-ICU / ICDSC     │
  ├───┼───────────────────────────────────┼────────────────────────────────────────┤
  │ E │ Early Mobility and Exercise       │ Physical/Occupational therapy on Day 1 │
  ├───┼───────────────────────────────────┼────────────────────────────────────────┤
  │ F │ Family Engagement and Empowerment │ Reorientation, photos, familiar voices │
  └───┴───────────────────────────────────┴────────────────────────────────────────┘

Burn-Specific Execution Details:

• A (Pain Management): Routine pain scoring with CPOT/BPS; preemptive procedural analgesia prior to wound debridement and dressing changes.
• B (SAT / SBT Coordination): Daily cessation of sedatives ("sedation vacation") paired with ventilator weaning trials as soon as hemodynamic stability and airway parameters permit.
• C (Sedation Choice): Prefer non-benzodiazepine agents (dexmedetomidine or propofol). Benzodiazepines (midazolam/lorazepam) are independent risk factors for delirium and must be avoided except for alcohol withdrawal.
• D (Delirium Prevention & Environmental Management):
  • Reorientation: Position large-print clocks, updated calendars, and communication whiteboards in direct visual line.
  • Sensory Aids: Promptly replace patient's personal hearing aids and eyeglasses.
  • Restraint Reduction: Remove physical restraints as early as possible; restraints exacerbate hyperactive combativeness.
• E (Early Mobility): Progressive physical rehabilitation starting within 24 hours of admission—in-bed active/passive range of motion, dangling at the edge of the bed, transfer to cardiac chair, and standing/ambulation with ventilator support.
• F (Family Engagement): Involve family members in daily care rounds, reorientation protocols, reading familiar books, and playing preferred music.

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5. Pharmacological Management of Severe Delirium and QTc Surveillance

[!IMPORTANT] Clinical trials demonstrate that antipsychotic medications do NOT decrease the duration of delirium, shorten ICU stay, or reduce mortality. Antipsychotics must NEVER be used for routine delirium prophylaxis or for treating quiet, hypoactive delirium. They are indicated strictly as short-term rescue therapy for severe, intractable agitation, distressing hallucinations, or violent behavior that endangers patient safety or surgical graft integrity.

Pharmacological Options for Severe Refractory Delirium:

1. Atypical Antipsychotics (Second-Generation):
   • Quetiapine (Seroquel): 25 to 50 mg PO/NG every 12 hours (titrated up to 100–200 mg BID). Preferred in burn patients due to mild sedative properties and lower incidence of extrapyramidal symptoms.
   • Olanzapine (Zyprexa): 2.5 to 10 mg PO/IM/sublingual daily. Effective for severe agitation and concomitant nausea.
2. Typical Antipsychotics (First-Generation):
   • Haloperidol (Haldol): 0.5 to 2.5 mg IV/IM every 4 to 6 hours PRN for acute, dangerous combativeness. Has minimal active hemodynamic suppression but carries higher extrapyramidal risk.
3. Alpha-2 Agonists for Hyperactive Agitation:
   • Dexmedetomidine (Precedex): Highly effective in weaning mechanically ventilated patients who fail extubation trials purely due to hyperactive, hyperadrenergic delirium.

                      CARDIAC SAFETY PROTOCOL: QTC SURVEILLANCE
  ┌────────────────────────────────────────────────────────────────────────┐
  │ Baseline 12-Lead ECG Prior to Initiating Any Antipsychotic Agent       │
  │                                   │                                    │
  │                                   ▼                                    │
  │ Calculate Bazett Corrected QT Interval: QTc = QT / sqrt(RR interval)   │
  │ • Normal QTc: Men < 450 ms; Women < 460 ms                             │
  │ • Borderline / Caution: QTc 460–500 ms                                 │
  │ • HIGH RISK / CONTRAINDICATED: Baseline QTc > 500 ms                   │
  │                                   │                                    │
  │                                   ▼                                    │
  │ Daily ECG & Continuous Telemetry Monitoring During Pharmacotherapy     │
  │                                   │                                    │
  │                                   ▼                                    │
  │ HOLD / DISCONTINUE ANTIPSYCHOTIC IF:                                   │
  │ [1] Absolute QTc exceeds 500 ms                                        │
  │ [2] QTc increases by >60 ms above patient's baseline                   │
  │ [3] Occurrence of polymorphic ventricular ectopic beats                │
  │                                   │                                    │
  │                                   ▼                                    │
  │ PREVENT TORSADES DE POINTES: Maintain K+ > 4.0 mEq/L & Mg2+ > 2.0 mg/dL│
  └────────────────────────────────────────────────────────────────────────┘