Intubation and Mechanical Ventilation
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|Respiratory Failure
|Non invasive ventilation (NIV)
|Intubation and Mechanical Ventilation
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Mechanical Ventilation – Updated Feb 2026
ℹ️ About Mechanical Ventilation 🫁
- Supports or replaces spontaneous breathing in respiratory failure, reducing work of breathing (WOB) and improving gas exchange.
- Historical origin: Developed during 1950s polio epidemics (iron lungs → negative pressure; modern positive pressure dominant).
- Primarily invasive (endotracheal/tracheostomy) in ICU; noninvasive (NIV) first-line where possible.
✅ Benefits
- Reduces WOB → conserves energy in fatigue/shock.
- Improves oxygenation: High FiO₂ (up to 100%), PEEP recruits alveoli, prevents collapse (esp. ARDS/refractory hypoxemia).
- Enhances CO₂ removal: Adjust RR/Vt to correct hypercapnia/acidosis.
- Provides stability: Buys time for treating underlying cause (e.g., pneumonia, sepsis, trauma).
⚠️ Risks & Complications
- Barotrauma/volutrauma → pneumothorax, pneumomediastinum.
- Ventilator-associated pneumonia (VAP): >48h post-intubation; prevention: head-up 30–45°, oral care, sedation breaks.
- Ventilator-induced lung injury (VILI): Overdistension/shear; mitigated by lung-protective strategy (Vt 4–8 mL/kg PBW, Pplat <30 cmH₂O).
- Auto-PEEP/dynamic hyperinflation: Air trapping in obstructive disease → ↑ intrathoracic pressure, ↓ venous return.
- Oxygen toxicity: Prolonged FiO₂ >60% → ROS damage.
- Cardiovascular: ↓ preload (positive pressure), sedation effects → hypotension.
- Respiratory muscle atrophy: Prolonged support → difficult weaning.
- Other: Tracheal injury, sinusitis, GI bleed (stress ulcers), DVT.
🛡️ Mechanical ventilation saves lives but risks VILI/VAP. Use **lung-protective ventilation** (low Vt, limit Pplat) per ATS/ESICM guidelines.
🔄 Types of Mechanical Ventilation
- Negative Pressure Ventilation: Mimics normal breathing (e.g., iron lung, cuirass); rare today, used in some neuromuscular cases.
- Positive Pressure Ventilation: Pushes air in (invasive or NIV); standard in ICU.
🚨 Clinical Signs Indicating Need
- Dyspnoea, cyanosis, agitation, fatigue, accessory muscle use.
- Hypotension, ↑ JVP, paradoxical breathing, silent chest.
📋 Indications for Invasive Mechanical Ventilation
- Airway protection (↓ consciousness, obstruction risk, aspiration).
- Respiratory arrest or RR <8/min.
- Failure of NIV/CPAP/BiPAP/HFNC.
- Severe hypoxaemia: PaO₂ <8 kPa (<60 mmHg) or SpO₂ <90% on high FiO₂.
- Worsening hypercapnia/respiratory acidosis (PaCO₂ >8 kPa, pH <7.25).
- Secretion clearance issues (e.g., neuromuscular disease).
- Post-op major surgery, head injury (controlled PaCO₂ for ICP).
- Reduce WOB in shock/sepsis/cardiogenic failure.
🎯 Objective Criteria (Common Thresholds)
- RR >35/min.
- Vt <5 mL/kg or vital capacity <15 mL/kg.
- PaO₂ <8 kPa on FiO₂ ≥0.6.
- PaCO₂ >8 kPa with acidosis.
🛠️ Procedure & Initial Considerations
- Requires sedation/paralysis in conscious patients; RSI standard.
- May cause hypotension (positive pressure + sedation).
- Start lung-protective: Vt 6 mL/kg PBW, adjust PEEP/FiO₂ per ARDSnet tables.
🔧 Ventilation Modes Overview
- Volume-Targeted Modes (guarantee Vt; pressure varies)
- Assist-Control Volume (ACV/VCV): Fixed Vt/RR; patient-triggered breaths get full Vt.
- SIMV: Mandatory breaths (fixed Vt/RR) + spontaneous (may add PS).
- Pressure-Targeted Modes (fixed pressure; Vt varies)
- Pressure Control (PCV): Fixed inspiratory pressure/RR; used in ARDS for flow deceleration.
- Pressure Support (PSV): Augments spontaneous breaths; weaning favourite.
- BiPAP/BiLevel: Different IPAP/EPAP; NIV common.
- PEEP: End-expiratory pressure to recruit alveoli.
- Advanced/Hybrid Modes
- PRVC/APRV: Hybrid volume/pressure; auto-adjusts.
- HFOV: High-frequency oscillation for severe ARDS (limited use now).
- ECMO: Extracorporeal support for refractory cases (VV-ECMO in severe ARDS).
ℹ️ More Information
- Settings tailored to pathology (e.g., low Vt/PEEP in ARDS; higher RR in hypercapnia).
- Weaning: Daily sedation interruption + spontaneous breathing trials (SBT); tracheostomy ~7–14 days if prolonged (>10–14 days) for comfort/weaning.
- Monitor: ABGs, plateau pressure, driving pressure (<15 cmH₂O target), auto-PEEP.
📚 References (Feb 2026)
- ATS/ESICM/SCCM ARDS Guideline (2017; 2024–2025 updates on protective strategies).
- ESICM ARDS Guidelines (2023; phenotyping/respiratory support).
- StatPearls/AMBOSS Mechanical Ventilation (updated 2025–2026).
- Recent reviews (e.g., JTS CPG 2025 basics).
