Sedation in icu 5 marks anesthesia residency

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Sedation in the ICU

(5 marks - Anesthesia Residency)

1. Goals of ICU Sedation

The primary goal is to provide patient comfort and safety while minimizing adverse effects. An ideally sedated patient:

Tolerates endotracheal tube and mechanical ventilation (improves oxygenation, reduces ventilator-induced lung injury)
Does not dislodge catheters, monitoring lines, or self-extubate
Can participate in early mobilization and physiotherapy
Is protected from the sympathoadrenal stress response to injury

The key principle is "analgesia-first" - pain should be treated before sedation is added, as many ICU patients are agitated primarily due to inadequately treated pain.

Barash, Cullen & Stoelting's Clinical Anesthesia, 9e, p. 4857
Fischer's Mastery of Surgery, 8th e, p. 457

2. Assessment of Sedation - Scoring Scales

Validated scales must be used before and after every intervention.

Richmond Agitation-Sedation Scale (RASS) - Most Widely Used

Score	Label	Description
+4	Combative	Overtly combative, violent, immediate danger to staff
+3	Very agitated	Pulls/removes tubes or catheters, aggressive
+2	Agitated	Frequent non-purposeful movement, fights ventilator
+1	Restless	Anxious but movements not aggressive
0	Alert and calm	Spontaneously attentive
-1	Drowsy	Not fully alert, sustained eye opening >10 sec
-2	Light sedation	Briefly awakens, eye opening <10 sec
-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

Target RASS: -2 to +1 for most ICU patients. Scores below -2 are associated with longer ICU stay and prolonged time to extubation; scores above +1 are associated with self-harm and self-extubation.

Other scales: Ramsay Sedation Scale (RSS), Sedation-Agitation Scale (SAS).

Fischer's Mastery of Surgery, 8th e, p. 458-459

3. Sedative Agents in the ICU

Drug	Mechanism	Typical Dose	Half-life	Key Features / Adverse Effects
Propofol	GABA-A agonist	5-50 mcg/kg/min infusion	Short	Drug of choice for short-term sedation; shorter MV duration vs. BZDs; can cause hypotension, hypertriglyceridemia, propofol infusion syndrome (PRIS) at high doses
Midazolam	GABA-A agonist (BZD)	Bolus 1-5 mg; infusion	3-11 hr	Deep sedation + amnesia; hemodynamically stable; associated with more delirium and prolonged MV; drug of choice for alcohol withdrawal; active metabolites accumulate in renal failure
Dexmedetomidine	Alpha-2 agonist (central)	0.2-0.7 mcg/kg/hr	Short	Sedation without respiratory depression; analgesic-sparing; preserves arousability ("cooperative sedation"); cannot reliably produce deep sedation; bradycardia and hypotension are limiting adverse effects; not appropriate as sole agent in paralyzed patients
Ketamine	NMDA antagonist	1-2 mcg/kg/hr (adjunct)	Moderate	Opioid-sparing analgesic adjunct; preserves airway reflexes; may increase ICP (caution)

Key comparison - Propofol vs. Dexmedetomidine vs. Benzodiazepines:

Propofol and dexmedetomidine are associated with shorter duration of mechanical ventilation and less delirium than benzodiazepines
Benzodiazepine infusions should be reserved for specific indications requiring deep sedation (RASS -4 to -5): status epilepticus, severe ARDS, refractory intracranial hypertension, alcohol withdrawal
Propofol is most commonly used, equally efficacious but less expensive than dexmedetomidine, and more reliably produces deep sedation
Barash, Cullen & Stoelting's Clinical Anesthesia, 9e, p. 4858
Fischer's Mastery of Surgery, 8th e, p. 459-462

4. Analgesic Agents

Analgesia-first (analgo-sedation) strategy is preferred. Common opioids:

Fentanyl - preferred in hemodynamic instability; short-acting
Morphine - avoid in renal failure (active metabolite morphine-6-glucuronide accumulates)
Hydromorphone - alternative in renal impairment

Non-opioid adjuncts (opioid-sparing strategy):

Acetaminophen (IV/enteral)
Low-dose ketamine infusion
NSAIDs (use cautiously - renal and GI effects)
Gabapentin / Pregabalin (neuropathic pain)
Regional anesthesia (especially for extremity trauma/surgery)

5. Daily Sedation Interruption (DSI) / Spontaneous Awakening Trial (SAT)

Protocolized daily sedation holds are standard of care:

Reduces total drug exposure
Shortens duration of mechanical ventilation
Decreases ICU length of stay
Reduces mortality

The "ABCDEF Bundle" (also called the "Liberation Bundle") integrates:

A - Assess, Prevent, and Manage Pain
B - Both SAT (Spontaneous Awakening Trial) and SBT (Spontaneous Breathing Trial)
C - Choice of analgesia and sedation (lightest effective)
D - Delirium: Assess, Prevent, and Manage
E - Early Mobility and Exercise
F - Family Engagement and Empowerment

Exceptions to DSI (where deep sedation is maintained continuously): severe ARDS, refractory ICP, status epilepticus, therapeutic hypothermia after cardiac arrest.

Barash, Cullen & Stoelting's Clinical Anesthesia, 9e, p. 4859
Fischer's Mastery of Surgery, 8th e, p. 465

6. ICU Delirium - A Major Complication of Over-Sedation

Definition: Acute brain dysfunction characterized by:

Acute onset and fluctuating course
Inattention
Altered level of consciousness
Disorganized thinking

Epidemiology: Present in up to 66% of ICU patients. Each day of delirium increases mortality by 10%; 60-day mortality triples and hospital stay doubles with delirium.

Diagnosis: CAM-ICU (Confusion Assessment Method for the ICU) - validated tool with high sensitivity and specificity. Positive CAM-ICU = delirium. Cannot be assessed in comatose patients (RASS -4 to -5).

Risk factors:

Premorbid: age, prior dementia, alcohol use, frailty
On admission: sepsis, AKI, liver dysfunction, surgery
Intra-ICU: deep sedation, immobility, sleep deprivation, polypharmacy, restraints

Management of delirium:

Non-pharmacologic (first-line): sleep-wake cycle normalization, early mobilization, minimizing disruptions, family involvement, sensory aids (glasses, hearing aids)
Pharmacologic: Antipsychotics (haloperidol, quetiapine) for agitation - no proven mortality benefit but reduce agitation safely; avoid benzodiazepines (worsen delirium) except in alcohol withdrawal

Post-Intensive Care Syndrome (PICS): Over half of ICU survivors suffer long-term cognitive impairment; PICS-F affects families of ICU patients.

Fischer's Mastery of Surgery, 8th e, p. 466-472
Barash, Cullen & Stoelting's Clinical Anesthesia, 9e, p. 4859

Quick Summary Table for Exam

Feature	Propofol	Dexmedetomidine	Midazolam
Mechanism	GABA-A	Alpha-2 agonist	GABA-A
Deep sedation	Yes	No	Yes
Amnesia	Yes	No	Yes
Respiratory depression	Yes	Minimal	Yes
Hemodynamics	Hypotension	Bradycardia/Hypotension	Stable
Delirium risk	Low	Lowest	High
Cost	Low	Higher	Low
Special concern	PRIS (high dose/long duration)	Cannot use as sole agent with paralysis	Avoid in renal failure; prolongs MV

Key exam points:

Prefer propofol or dexmedetomidine over benzodiazepines for most ICU patients
RASS target -2 to +1 for most mechanically ventilated patients
Daily sedation interruption is mandatory unless contraindicated
CAM-ICU is the standard delirium screening tool
Analgo-sedation (analgesia-first) is the modern approach - treat pain before adding sedatives
Propofol infusion syndrome (PRIS): metabolic acidosis + rhabdomyolysis + cardiac failure - occurs with >4 mg/kg/hr for >48 hours; monitor triglycerides and CK

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