8.3 ICU Delirium, Cognitive Dysfunction & Behavioral Emergencies

8.3 ICU Delirium, Cognitive Dysfunction & Behavioral Emergencies

Clinical Scenario: A 71-year-old male on post-operative day 3 following emergent repair of a ruptured abdominal aortic aneurysm remains in the surgical ICU. The nurse reports that the patient is 'unusually calm and cooperative,' sleeping between checks and taking 15 seconds to answer questions with slow, one-word responses. Vital signs: BP 128/72 mmHg, HR 68 bpm, RR 14 breaths/min, and SpO2 96% on 2 L/min nasal cannula. RASS score is $-1$. On examination, he makes five errors (missed 'A' responses or squeezes on other letters) during the SAVEAHAART vigilance test. When asked simple cognitive questions, he answers incorrectly.

Delirium Epidemiology & Clinical Subtypes

ICU delirium is an acute, fluctuating syndrome of cognitive dysfunction characterized by altered mental status, inattention, and disorganized thinking. It affects up to 60% to 80% of mechanically ventilated and 20% to 50% of non-ventilated ICU patients:

• Outcomes: Longer delirium is associated with worse outcomes, including persistent cognitive impairment.
• ICU Stay: Associated with prolonged mechanical ventilation and high institutionalization rates.
• Long-Term Cognitive Impairment: In BRAIN-ICU at 12 months, about one-third scored comparably to moderate TBI and one-quarter to mild Alzheimer disease. These cognitive-test comparisons do not diagnose neurodegenerative dementia.

Validated Bedside Diagnostics: RASS & CAM-ICU

PADIS recommends regular assessment with a validated tool. SCCM’s ICU Liberation Bundle suggests screening at least once per shift and with mental status changes.

Richmond Agitation-Sedation Scale (RASS)

The RASS evaluates arousal and agitation:

• $+4$ (Combative) to $+1$ (Restless).
• $0$ (Alert and Calm): Optimal baseline target.
• $-1$ (Drowsy): Eye contact $\ge 10$ seconds after verbal stimulation.
• $-2$ (Light Sedation): Eye contact $<10$ seconds.
• $-3$ (Moderate Sedation): Movement or eye opening to voice, but no eye contact.
• $-4$ (Deep Sedation) and $-5$ (Unarousable): Defer CAM-ICU and reassess when arousal improves.

CAM-ICU Algorithm

1. Feature 1: Acute Onset or Fluctuating Course: Change from baseline mental status or fluctuation in the past 24 hours. (If YES, proceed to Feature 2).
2. Feature 2: Inattention (The Hallmark): Tested via letter vigilance (S-A-V-E-A-H-A-A-R-T); patient squeezes on 'A'.
   • Errors $\le 2$: CAM-ICU Negative.
   • Errors $>2$: Inattention confirmed; proceed to Feature 3.
3. Feature 3: Altered Level of Consciousness: Current RASS score.
   • If current RASS is anything other than $0$ (e.g. $-3, -2, -1, +1, +2$): CAM-ICU is POSITIVE.
   • If current RASS is $0$: Proceed to Feature 4.
4. Feature 4: Disorganized Thinking: 4 questions ('Will a stone float on water?', 'Do fish live in sea?') and 1 command ('Hold up 2 fingers').
   • Errors $>1$: CAM-ICU is POSITIVE.
   • Errors $\le 1$: CAM-ICU is Negative.

The ABCDEF Liberation Bundle

The SCCM ABCDEF bundle is an evidence-based framework reducing delirium and mortality:

Environmental & Non-Pharmacologic Strategies

Use multicomponent non-pharmacologic prevention; routine antipsychotic prophylaxis is not recommended. The 2025 PADIS update conditionally suggests melatonin, with low-certainty evidence:

• Circadian Restoration: Provide daylight cues, reduce light and avoid unnecessary noise at night, and cluster nonurgent care when feasible.
• Sensory Optimization: Provide eyeglasses, hearing aids, and dentures promptly.
• Cognitive Reorientation: Clocks, whiteboards with names/dates, and frequent verbal reorientation.
• Early Device Removal: Promptly remove restraints, urinary catheters, and central lines.

Pharmacologic Considerations & Safety Parameters

Benzodiazepine Harm

Benzodiazepine exposure is a modifiable delirium risk. Minimize avoidable use while treating specific indications such as alcohol or sedative withdrawal and status epilepticus.

Targeted Antipsychotics & QTc Surveillance

The 2025 PADIS update could not recommend for or against antipsychotics for delirium treatment. MIND-USA found no improvement in delirium/coma-free days; AID-ICU found no significant improvement in days alive/out of hospital at 90 days, although secondary 90-day mortality favored haloperidol. These results do not justify routine prophylaxis.

• Indications: Reserved strictly for severe, distressing hallucinations or agitation threatening patient safety (unplanned extubation).
• Agents: Quetiapine (25–50 mg PO q12h; aids sleep), Olanzapine (2.5–10 mg PO/IM daily; low EPS risk), and Haloperidol (0.5–2.5 mg IV/IM q4–6h PRN).

Suicidal Ideation and Immediate Safety

A positive suicide screen requires a direct, private safety assessment of current thoughts, plan, intent, access to means, prior attempts and protective supports. Ask plainly; a calm appearance does not exclude risk. Current suicidal thoughts on adult inpatient assessment require immediate safety precautions, removal of dangerous items, continuous observation and urgent mental-health evaluation; do not leave the patient alone. A nonacute positive screen still needs assessment and a disposition plan, but does not automatically require identical precautions. Collaborate on a written safety plan, warning signs, coping strategies, support contacts and restriction of lethal means. A promise or “no-suicide contract” is not a substitute for assessment or protection.

Behavioral Emergencies, De-escalation & Restraints

1. Verbal De-escalation: Calm posture, simple sentences, validating distress.
2. Search for Reversible Drivers (THINK): Toxic drugs/withdrawal, Hypoxemia/hypercapnia, Infection/immobilization, Non-pharmacologic needs (retention, pain), K+/electrolytes.
3. Restraints as Last Resort: Use the least restrictive effective measure and stop as soon as safe; never order PRN. For violent/self-destructive behavior, federal adult orders last at most four hours, with a one-hour face-to-face evaluation; after 24 hours, the responsible physician or authorized licensed practitioner must see and assess the patient before a new order. Nonviolent renewal and monitoring intervals follow hospital policy. Apply stricter state requirements and document reassessment, circulation, skin, respiratory safety and basic needs.