1. Hypoxemic Respiratory Failure

Impaired oxygenation from V/Q mismatch, shunt, or diffusion defects necessitates IMV when noninvasive support fails.

Diagnostic Criteria

• PaO2 <60 mmHg on room air or PaO2/FiO2 ≤300.
• Persistent tachypnea (>30 breaths/min) or signs of respiratory distress despite HFNC/NIV.
• FiO2 requirement >0.6 with inadequate PaO2.

Common Etiologies

• ARDS
• Severe pneumonia
• Cardiogenic/noncardiogenic pulmonary edema
• Sepsis-related lung injury

Pharmacologic Strategy

• Target light sedation (RASS –2 to +1).
• Multimodal analgesia: combine opioids (fentanyl, hydromorphone) with nonopioid adjuncts (acetaminophen, ketamine).
• Preferred sedatives: propofol or dexmedetomidine; avoid benzodiazepines when possible.
• Monitor with validated tools (RASS, SAS); titrate per daily sedation interruption protocols.

2. Hypercapnic Respiratory Failure

CO2 retention and acidosis from hypoventilation require IMV when NIV fails or acidosis worsens.

Diagnostic Criteria

• PaCO2 >45 mmHg with pH <7.35.
• Worsening hypercapnia despite optimal NIV settings.
• Signs of CO2 narcosis: confusion, somnolence.

Common Etiologies

• COPD exacerbations
• Neuromuscular disorders (e.g., ALS, GBS)
• Chest wall abnormalities
• Central respiratory drive depression

Pharmacologic Strategy

• Prevent over-sedation; avoid excessive respiratory drive suppression.
• Use propofol or dexmedetomidine; minimize benzodiazepines.
• Light sedation target (RASS –2 to 0).
• Employ daily spontaneous awakening and breathing trials to facilitate weaning.

3. Airway Protection

IMV secures the airway in patients at high risk for aspiration or airway compromise.

Indications

• GCS ≤8 or uncontrolled seizures (status epilepticus).
• Significant intoxication or overdose with impaired reflexes.
• Facial or airway trauma.

Rapid Sequence Induction (RSI) Agent Selection

4. Procedural Sedation and Airway Security

Deep sedation with or without paralysis ensures immobility and airway protection during high-risk procedures.

Approach

• Apply RSI principles and agents as above.
• Monitor sedation depth (RASS) and neuromuscular blockade (train-of-four) when used.
• Avoid prolonged deep sedation; resume light sedation as soon as feasible to enable weaning.

5. Evidence‐Based Sedation and Analgesia Protocols

Protocolized sedation—using validated scales, daily interruption, and light sedation targets—improves outcomes.

Core Elements

• Sedation scales: Richmond Agitation-Sedation Scale (RASS) or Sedation-Agitation Scale (SAS).
• Sedation target: light (RASS –2 to +1) unless deeper sedation is clinically indicated.
• Preferred agents: propofol or dexmedetomidine over benzodiazepines.
• Multimodal analgesia to minimize opioid exposure.
• Daily Spontaneous Awakening Trials (SAT) paired with Spontaneous Breathing Trials (SBT).

Protocol Example

1. Assess pain (e.g., CPOT) and sedation level every 4 hrs.
2. Titrate sedative infusion to RASS target.
3. Hold sedative infusion daily for SAT.
4. Conduct SBT after successful SAT; adjust support per protocol.

6. Impact of Sedation and Analgesia on Outcomes

Sedation depth and analgesia quality strongly influence delirium, ICU-acquired weakness, sleep, and overall recovery.

Key Facts

• Deep sedation is linked to increased delirium and prolonged ventilation.
• Sleep disruption contributes to delirium and longer ICU stays; implement multicomponent bundles (noise/light reduction, earplugs).
• Pain is under-assessed; robust analgesia protocols optimize comfort and limit sedative needs.

7. Areas for Future Research

Sedation strategies for prolonged mechanical ventilation and complex critical illness remain an area of active investigation.

Identified Gaps

• Optimal sedation protocols in patients requiring prolonged MV and early tracheostomy timing.
• Neuromuscular blockade dosing and monitoring guidelines in ARDS and other indications.
• PK/PD alterations in critical illness affecting sedative and analgesic dosing.