Orris

The role of anaesthesia in the ICU. Make a detailed note with valid & latest references/guidelines

Reading File
Finding Sources
Finding Sources
Searching PubMed

anaesthesia intensive care unit sedation analgesia

Searching the Web

anaesthesia role ICU 2024 2025 guidelines sedation analgesia critical care

Finding Sources
Finding Sources
Searching PubMed

sedation analgesia delirium ICU PADIS guidelines 2025

Searching PubMed

propofol dexmedetomidine sedation mechanical ventilation ICU

Reading Web Page

https://www.aacn.org/blog/key-takeaways-2025-update-padis-gu…

Finding Sources
Finding Sources
Searching PubMed

analgesia opioid pain management ICU critical care

Searching PubMed

neuromuscular blockade ARDS mechanical ventilation ICU

Reading File
Reading File
Searching PubMed

general anaesthesia airway management ICU intubation

Searching PubMed

regional anaesthesia nerve block perioperative ICU outcome

Reading File
Searching PubMed

inhalational anaesthesia ICU sevoflurane isoflurane AnaConDa

Reading Article

PMID: 39207913

I now have comprehensive data from multiple sources. Let me compile the detailed note.

The Role of Anaesthesia in the Intensive Care Unit (ICU)

1. Introduction

Anaesthesia and critical care medicine have always been deeply intertwined disciplines. In most countries, intensivists are trained anaesthesiologists who apply their expertise in pharmacology, physiology, airway management, and monitoring to the care of the critically ill. Within the ICU, anaesthetic principles govern a wide range of interventions - from sedation and analgesia during mechanical ventilation to procedural anaesthesia at the bedside, airway management, neuromuscular blockade, and increasingly, inhaled sedation. The modern approach is anchored in the ABCDEF bundle and the 2025 PADIS (Pain, Agitation/Sedation, Delirium, Immobility, and Sleep Disruption) guidelines from the Society of Critical Care Medicine (SCCM).

2. Airway Management and Intubation

The anaesthesiologist's most fundamental competency - securing and maintaining the airway - is exercised daily in the ICU. Tracheal intubation in critically ill patients carries significantly higher risk than in the elective surgical setting, owing to physiological derangement (hypoxia, haemodynamic instability, full stomach), limited preparation time, and unpredictable anatomy.
Rapid Sequence Induction (RSI) is the standard technique for emergency intubation in the ICU. The induction agents most used are:
  • Ketamine (1-2 mg/kg IV): preferred in haemodynamically unstable patients; bronchodilator; increases heart rate and blood pressure via sympathomimetic effects. - Goldman-Cecil Medicine
  • Propofol (1-2.5 mg/kg IV): rapid onset, but causes dose-dependent hypotension; best avoided in haemodynamic compromise.
  • Etomidate (0.3 mg/kg IV): minimal haemodynamic effects; however, adrenocortical suppression (even with a single dose) remains a concern in septic patients.
Succinylcholine (1.5 mg/kg) or rocuronium (1.2 mg/kg) is used as a neuromuscular blocker to facilitate intubation. With sugammadex available for reversal, rocuronium has become preferred in many ICUs.
Apnoeic oxygenation during laryngoscopy (15 L/min via nasal cannula while apnoeic) prolongs the safe apnoea time and is supported by meta-analytic evidence. A 2024 systematic review (PMID: 38030551) confirmed benefit in paediatric patients; similar physiological principles apply in adults.
Post-intubation, a 2024 systematic review in Critical Care (PMID: 38720332) demonstrated that non-invasive respiratory support (NIV/CPAP/HFNO) after extubation significantly reduces re-intubation rates in post-operative ICU patients.

3. Sedation in the ICU

3.1 Goals and Principles

Sedation in the ICU aims to:
  • Reduce anxiety, agitation, and distress
  • Facilitate tolerance of invasive interventions (endotracheal tube, mechanical ventilation, invasive lines)
  • Prevent patient self-harm and unplanned extubation
  • Reduce oxygen demand in critically ill patients
The key paradigm shift over the past decade is from deep sedation toward light, targeted sedation ("analgesia-first" or "analgosedation"). Evidence consistently shows that deep sedation is associated with prolonged mechanical ventilation, ICU delirium, post-ICU cognitive impairment, and increased mortality. - Fishman's Pulmonary Diseases and Disorders

3.2 Sedation Assessment Tools

Two validated scales are used routinely:
ScaleRangeTarget in most ICU patients
Richmond Agitation-Sedation Scale (RASS)-5 to +4-1 to 0 (light sedation)
Riker Sedation-Agitation Scale (SAS)1-73-4 (sedated-calm)
  • Fishman's Pulmonary Diseases and Disorders
The RASS has been validated for use in adult ICU patients (Sessler et al., Am J Respir Crit Care Med, 2002).

3.3 Sedation Strategies

Targeted light sedation (RASS -1 to 0) is preferred over deep sedation in all mechanically ventilated adults except those with specific indications (raised ICP, refractory hypoxaemia, status epilepticus).
Daily Sedation Interruption (DSI) / "Sedation Holiday": Holding sedatives each day (when safe) allows titration to the minimum necessary dose. Two landmark RCTs (Kress et al., NEJM 2000; Girard et al., Lancet 2008) demonstrated that DSI, especially when paired with daily spontaneous breathing trials ("Wake-Up and Breathe"), significantly reduces ventilator days, ICU/hospital LOS, and 1-year mortality. - Fishman's Pulmonary Diseases and Disorders
Analgesia-First (Analgosedation): Treating pain before layering on sedative drugs prevents the syndrome of painful-but-sedated patients. This approach reduces total benzodiazepine and sedative requirements. The SCCM PADIS guidelines strongly endorse this strategy.

4. Sedative Agents: Pharmacology and Clinical Use

4.1 Propofol

  • Mechanism: GABA-A receptor agonist
  • Half-life: ~40 minutes (though context-sensitive)
  • Dose: Infusion 5-80 mcg/kg/min
  • Advantages: Rapid titration, antiemetic, anticonvulsant, enables quick neurological assessment
  • Adverse effects: Hypotension, respiratory depression, hypertriglyceridaemia, pancreatitis, and the rare but life-threatening Propofol Infusion Syndrome (PRIS) - characterised by metabolic acidosis, rhabdomyolysis, renal failure, cardiac failure - particularly with high doses (>5 mg/kg/h) for >48 hours
  • Fishman's Pulmonary Diseases and Disorders

4.2 Dexmedetomidine

  • Mechanism: Highly selective central alpha-2 agonist
  • Dose: 0.2-1.5 mcg/kg/h (no loading dose recommended in ICU)
  • Advantages: Induces cooperative, arousable sedation mimicking natural sleep; provides analgesia and sympatholysis; does not cause respiratory depression; reduces delirium duration; facilitates earlier extubation
  • Adverse effects: Bradycardia (especially with loading dose), hypotension; not suitable for deep sedation
The 2025 PADIS guideline update (SCCM) conditionally recommends dexmedetomidine over propofol to maintain light sedation in mechanically ventilated adults, citing reduced delirium and improved time at target sedation level despite a higher risk of bradycardia. This is a landmark 2025 update to prior guidelines.
The A2B RCT (Walsh et al., JAMA, July 2025, PMID: 40388916) - a large, multicenter Phase III pragmatic RCT - compared dexmedetomidine/clonidine-based sedation vs. propofol in critically ill patients, providing the highest-quality contemporary evidence for this comparison.
A 2025 meta-analysis (PMID: 41140695) showed dexmedetomidine is superior to propofol for reducing delirium in septic shock patients, with improved ICU outcomes.
Goldman-Cecil Medicine notes: "Dexmedetomidine appears to have significant advantages over benzodiazepines because it can provide more comfort with a similar safety profile and decrease the time that critical care patients spend on ventilators."

4.3 Benzodiazepines (Midazolam, Lorazepam)

DrugHalf-lifeIV Dose (infusion)Key Concerns
Midazolam3 h0.04-0.2 mg/kg/hAccumulates in renal/hepatic failure; prolonged sedation
Lorazepam8 h0.01-0.1 mg/kg/hPropylene glycol toxicity with prolonged infusion; nephrotoxicity
Both the 2018 PADIS and 2025 PADIS update recommend against routine benzodiazepine use for sedation due to increased delirium incidence and prolonged mechanical ventilation. Benzodiazepines remain indicated for:
  • Alcohol/benzodiazepine withdrawal
  • Status epilepticus
  • Situations where specific anxiolysis is required
  • Fishman's Pulmonary Diseases and Disorders; Fischer's Mastery of Surgery

4.4 Ketamine

  • Mechanism: NMDA receptor antagonist + AMPA receptor activation; provides analgesia, dissociative anaesthesia, bronchodilation
  • Properties: Haemodynamically stimulating (increases BP, HR, CO via sympathomimesis); preserves airway reflexes and spontaneous respiration at analgesic doses; bronchial smooth muscle relaxant
  • Use in ICU: Analgosedation adjunct, haemodynamically unstable patients, severe bronchospasm, procedural sedation, refractory pain
The 2025 Rapid Practice Guideline (Saudi Critical Care Society/Scandinavian SAIM, Anesthesia & Analgesia, PMID: 39207913) based on 17 RCTs (n=898) and 9 observational studies (n=1934) provides two conditional recommendations:
  1. Against ketamine monotherapy for analgo-sedation when other agents are available
  2. Ketamine as an adjunct to standard sedatives (opioids, propofol, dexmedetomidine) is conditionally suggested - it may slightly reduce mechanical ventilation duration and opioid requirements
A 2026 meta-analysis (PMID: 41578281) with GRADE assessment confirmed continuous ketamine infusion in surgical ICU patients may reduce opioid consumption without significant adverse effects.

4.5 Remimazolam (Emerging Agent)

A water-soluble benzodiazepine with rapid organ-independent metabolism by tissue esterases. A 2026 RCT (PMID: 41935116) in mechanically ventilated oncology patients found remimazolam non-inferior to propofol for long-term sedation. Its reversibility with flumazenil adds a safety advantage.

4.6 Inhaled Sedation

The AnaConDa (Anaesthetic Conserving Device) system allows delivery of volatile anaesthetics (sevoflurane, isoflurane) via ICU ventilators without an anaesthetic machine. A 2025 systematic review and meta-analysis (PMID: 39972505) found inhaled sedation to be safe and effective, associated with:
  • Faster awakening and earlier extubation
  • Reduced opioid consumption
  • Potential cardioprotective effects (ischaemic preconditioning)
  • Bronchodilatory properties (useful in severe asthma/COPD)
Goldman-Cecil Medicine notes: "All inhalational agents... cause dose-dependent cardiovascular depression." Inhalational sedation in the ICU remains most used in Europe; widespread adoption is limited by cost, infrastructure, and environmental concerns (global warming potential of volatile agents).

5. Analgesia in the ICU

5.1 Principles

The SCCM endorses an "Analgesia-First" approach: pain should be assessed and treated before initiating sedation. Uncontrolled pain is the leading driver of agitation in the ICU.
Pain assessment tools for ICU patients:
  • Numeric Rating Scale (NRS: 0-10) for self-reporting patients
  • Behavioural Pain Scale (BPS) or Critical Care Pain Observation Tool (CPOT) for intubated/non-verbal patients

5.2 Opioids

Opioids remain the cornerstone of analgesia in mechanically ventilated ICU patients:
  • Fentanyl: Short-acting, preferred in haemodynamic instability and renal failure; infusion 25-100 mcg/h
  • Morphine: IV boluses or infusion; histamine release; accumulation in renal failure
  • Hydromorphone: 5-7x more potent than morphine; less histamine release
  • Remifentanil: Ultra-short acting (esterase-metabolised); excellent for rapid neurological assessment but withdrawal on discontinuation
  • Methadone: A 2025 systematic review (PMID: 40767695) confirmed methadone facilitates opioid weaning and reduces withdrawal in ICU patients on prolonged mechanical ventilation.

5.3 Non-Opioid Analgesic Adjuncts (Multimodal Analgesia)

Reducing opioid requirements is a primary goal (opioid-sparing strategy):
  • Paracetamol (acetaminophen): IV 1g q6h; safe, effective first-line adjunct
  • NSAIDs (ibuprofen, ketorolac): Opioid-sparing; use caution - renal impairment, GI bleeding, coagulopathy risk
  • Ketamine (sub-anaesthetic dose): NMDA antagonism reduces opioid tolerance and hyperalgesia; adjunct role supported by 2025/2026 guidelines
  • Alpha-2 agonists (dexmedetomidine, clonidine): Analgesic in addition to sedative
  • Gabapentinoids: Limited ICU evidence; used adjunctively in neuropathic pain
  • Regional nerve blocks: Erector spinae plane (ESP) block, epidural, paravertebral blocks - reduce opioid requirements post-operatively and in rib fracture patients. A 2024 systematic review (PMID: 38341301) confirmed ESP block reduces opioid requirements and pain scores in cardiac surgery patients.

6. Delirium in the ICU: The Anaesthesiologist's Role

ICU delirium occurs in 30-80% of mechanically ventilated patients and is associated with prolonged ICU stay, long-term cognitive impairment, and increased mortality.
Assessment tools:
  • Confusion Assessment Method for the ICU (CAM-ICU): Most widely validated; high sensitivity and specificity
  • Intensive Care Delirium Screening Checklist (ICDSC)
Prevention (pharmacological):
  • Avoid benzodiazepines (strongest risk factor for delirium)
  • Prefer dexmedetomidine or propofol for sedation - Goldman-Cecil Medicine; Fishman's Pulmonary Diseases and Disorders
  • Light sedation / daily awakening trials
  • Adequate analgesia, orientation interventions, sleep hygiene, early mobilisation (ABCDEF bundle)
Treatment: The 2025 PADIS update provides a significant clarification: the panel does not recommend antipsychotics (haloperidol or atypical agents) for delirium treatment, as current evidence shows minimal or no effect on ICU/hospital LOS. This overturns prior common practice.
A 2025 systematic meta-review (PMID: 41469920) on pharmacological interventions for ICU delirium confirmed insufficient evidence for routine antipsychotic use.
Non-pharmacological approaches (early mobility, reorientation, sleep promotion, family involvement, hearing/vision aids) are the most evidence-based interventions.

7. Neuromuscular Blockade (NMB) in the ICU

NMB agents are used in the ICU for:
  1. Facilitating tracheal intubation (RSI) - as above
  2. ARDS management: Cisatracurium infusion (48h) to improve oxygenation, reduce ventilator-induced lung injury (VILI), and improve synchrony. The ACURASYS trial showed survival benefit; the subsequent ROSE trial (2019) did not replicate this, creating ongoing controversy.
  3. Status epilepticus
  4. Tetanus
  5. Refractory ICP elevation
  6. Shivering during targeted temperature management
A 2026 network meta-analysis (PMID: 41781628) on therapeutic interventions combined with lung-protective ventilation in ARDS confirmed the benefit of neuromuscular blockade in selected severe ARDS (P/F <150 mmHg).
Monitoring: Train-of-Four (TOF) monitoring is mandatory during NMB infusions to prevent overdose and to assess reversal.
Reversal:
  • Sugammadex: encapsulates rocuronium/vecuronium; enables rapid, reliable reversal independent of cholinesterase
  • Neostigmine + glycopyrrolate: anticholinesterase-based reversal for benzylisoquinoliniums and residual NMB from aminosteroids

8. Procedural Anaesthesia/Sedation in the ICU

The ICU requires anaesthetic expertise for numerous bedside procedures:
  • Tracheostomy (surgical or percutaneous dilational): Requires sedation, analgesia, and often NMB
  • Bronchoscopy: Topical anaesthesia + IV sedation (propofol ± remifentanil); HFNO during procedure to maintain oxygenation
  • Cardioversion: Short anaesthesia with propofol or etomidate
  • Chest drain insertion, arterial/central line placement
  • Lumbar puncture, joint aspiration
  • Renal replacement therapy (RRT) catheter insertion
  • Endoscopy (upper/lower GI), PEG insertion
Monitoring requirements follow ASA minimum standards: SpO2, ETCO2 (capnography), ECG, NIBP, temperature.

9. Perioperative Liaison and Post-Surgical ICU Care

The anaesthesiologist's role in the ICU extends beyond the operating theatre:
  • Post-cardiac surgery ICU: Complex sedation and weaning protocols; management of haemodynamic instability, arrhythmias, and coagulopathy. A 2024 systematic review (PMID: 39004790) compared sedation strategies (propofol, dexmedetomidine, midazolam) in post-cardiac surgical ICU patients.
  • Enhanced Recovery After Surgery (ERAS): Anaesthesiologists design multimodal analgesia protocols (thoracic epidural, paravertebral block, wound infiltration) to reduce ICU admission rates and length of stay.
  • Fast-track extubation: Early extubation in selected cardiac and thoracic surgical patients to reduce ventilator-associated complications. A 2025 systematic review (PMID: 40012055) compared extubation protocols in cardiac surgery.

10. Anxiety Management in the ICU (2025 PADIS Addition)

For the first time, the 2025 PADIS focused update addresses anxiety as a distinct entity separate from agitation:
  • Use validated tools to assess anxiety (though no single tool is strongly recommended yet)
  • Non-pharmacological interventions are preferred: music therapy, virtual reality, reorientation, presence of family
  • Evidence is insufficient to recommend benzodiazepines specifically for anxiety (though they are anxiolytic); non-pharmacological measures show potential
  • Anxiety is one of the most distressing ICU experiences reported by survivors, with effects persisting post-discharge

11. Sleep in the ICU

Sleep disruption is near-universal in ICU patients and impairs recovery, immunity, and cognition. The anaesthesiologist-intensivist's role:
  • Cluster care to allow undisturbed sleep periods
  • Reduce nocturnal noise and light
  • Melatonin may improve sleep quality (limited evidence)
  • Dexmedetomidine promotes electroencephalographically similar "natural sleep" compared to propofol or benzodiazepines - Goldman-Cecil Medicine

12. Immobility and Early Mobilisation

The 2025 PADIS update reinforces that early progressive mobility (early physical and occupational therapy, passive range-of-motion, ambulation) reduces delirium, ICU-acquired weakness, and ICU LOS. Achieving safe mobilisation requires coordinating sedation reduction (SAT: spontaneous awakening trial) with physiotherapy.

13. The ABCDEF Bundle

The anaesthesiologist-intensivist operationalises all of the above through the ABCDEF bundle:
LetterComponent
AAssess, prevent, manage Pain (analgesia-first)
BBoth SAT and SBT (spontaneous awakening + breathing trials)
CChoice of analgesia and sedation (light sedation, avoid benzodiazepines)
DDelirium: assess, prevent, manage
EEarly mobility and Exercise
FFamily engagement and empowerment
Bundle implementation is associated with significant reductions in delirium, coma-free days, ventilator days, and ICU/hospital LOS.

14. Special Situations

Traumatic Brain Injury (TBI)

  • Propofol preferred for rapid neurological assessment; reduces ICP via cerebral vasoconstriction and CMR reduction
  • Maintain CPP 60-70 mmHg, ICP <20 mmHg
  • Dexmedetomidine useful for awake-cooperative periods; avoid hypotension

Hepatic Failure

  • Avoid benzodiazepines (accumulation, encephalopathy)
  • Propofol titrated carefully; dexmedetomidine is metabolised hepatically but can still be used cautiously

Renal Failure

  • Avoid morphine (active metabolite accumulation)
  • Fentanyl, hydromorphone, and remifentanil are safer
  • Lorazepam accumulates propylene glycol carrier in renal failure

Status Asthmaticus / Severe Bronchospasm

  • Ketamine is the induction agent of choice (bronchodilator)
  • Inhaled anaesthetics (sevoflurane) provide profound bronchodilation in refractory cases

15. Current Controversies and Future Directions

  1. Dexmedetomidine vs. propofol: The A2B RCT (JAMA, 2025) provides the strongest contemporary data; results are awaited by many guidelines committees.
  2. Volatile anaesthetic sedation in ICU: Growing interest; AnaConDa systems expanding use; pending large RCTs.
  3. Remimazolam as a propofol alternative: Non-inferior, reversible; expanding evidence base (2026 RCT).
  4. AI-assisted closed-loop sedation: Automated propofol delivery systems (e.g., CLOSED loop systems) - early stage.
  5. ARDS neuromuscular blockade: Ongoing controversy post-ROSE trial; subgroup analysis suggests benefit in severe ARDS.
  6. Post-ICU syndrome (PICS): Long-term cognitive, psychological, and physical sequelae of ICU care - sedation and delirium management during ICU stay are the most modifiable risk factors.

References

  1. SCCM PADIS 2025 Focused Update - Society of Critical Care Medicine. Key Takeaways from the 2025 Focused Update to the PADIS Guidelines. Crit Care Med 2025. Available from: AACN summary
  2. Amer M, Hylander Møller M et al. Ketamine Analgo-sedation for Mechanically Ventilated Critically Ill Adults: A Rapid Practice Guideline. Anesth Analg 2025; doi:10.1213/ANE.0000000000007173. PMID: 39207913
  3. Walsh TS, Parker RA, Aitken LM et al. Dexmedetomidine- or Clonidine-Based Sedation Compared With Propofol in Critically Ill Patients: The A2B RCT. JAMA 2025 Jul 1. PMID: 40388916
  4. Gao X, Li Z et al. Is dexmedetomidine superior to propofol for sedation in critically ill patients with septic shock? A systematic review and meta-analysis. Front Med (Lausanne) 2025. PMID: 41140695
  5. Yuan F, Liu D. Sedation management in mechanically ventilated ICU patients: Meta-analysis review. Acta Pharm 2026. PMID: 41493968
  6. Feng F, Kang H, Yang Z et al. Safety and effectiveness of inhaled sedation in critically ill patients: a systematic review and meta-analysis. Syst Rev 2025 Feb. PMID: 39972505
  7. Alzmmam AI et al. Continuous ketamine infusion for surgical patients in the ICU: a systematic review and meta-analysis with GRADE assessment. Crit Care 2026. PMID: 41578281
  8. L Jones K, Kundakci B, Booth A. Systematic meta-review of interventions to prevent and manage delirium in the ICU: Part 1 - Pharmacological interventions. Crit Care 2025. PMID: 41469920
  9. Aoyama H, Uchida K et al. Effect of therapeutic interventions combined with lung-protective ventilation on long-term mortality in ARDS: network meta-analysis. Can J Anaesth 2026. PMID: 41781628
  10. Pereira SM, Abbott M et al. Methadone for critically ill patients under mechanical ventilation: a systematic review. Crit Care Sci 2025. PMID: 40767695
  11. Hu Q, Liu X, Xiang Y et al. Comparing different postoperative sedation strategies after cardiac surgery: systematic review and network meta-analysis. Basic Clin Pharmacol Toxicol 2024. PMID: 39004790
  12. Greene JJ, Chao S, Tsui BCH et al. Clinical Outcomes of Erector Spinae Plane Block for Midline Sternotomy in Cardiac Surgery: Systematic Review and Meta-Analysis. J Cardiothorac Vasc Anesth 2024. PMID: 38341301
  13. Pettenuzzo T, Boscolo A et al. Effects of non-invasive respiratory support in post-operative patients: systematic review and network meta-analysis. Crit Care 2024. PMID: 38720332
  14. Luo RY, Fan YY, Wang MT et al. Different extubation protocols for adult cardiac surgery: systematic review and network meta-analysis. BMC Anesthesiol 2025. PMID: 40012055
  15. Goldman-Cecil Medicine, International Edition (2-Volume Set). ISBN: 9780323930345 - Sections on Ketamine, Dexmedetomidine, Volatile Anaesthetics.
  16. Fishman's Pulmonary Diseases and Disorders (2-Volume Set). ISBN: 9781260473940 - Chapter 151: Sedation and Analgesia in the Critically Ill, including RASS/SAS tables, sedative agent pharmacology, daily awakening trials.
  17. Fischer's Mastery of Surgery, 8th ed. ISBN: 9781975176433 - Recommendations on propofol/dexmedetomidine over benzodiazepines for ICU sedation.
Key 2025/2026 Guideline Updates to Remember:
  • The 2025 SCCM PADIS update now recommends dexmedetomidine over propofol for light sedation in mechanically ventilated adults.
  • Antipsychotics (haloperidol) are no longer recommended for ICU delirium treatment (insufficient evidence for benefit).
  • Anxiety is now a distinct PADIS domain - use non-pharmacological interventions first.
  • Ketamine adjunct use (not monotherapy) is conditionally supported for analgosedation in mechanically ventilated patients (2025 Practice Guideline).
  • The A2B RCT (JAMA 2025) provides the highest-quality contemporary RCT evidence for dexmedetomidine vs. propofol.
This is a shared conversation. Sign in to Orris to start your own chat.