Contraindications of Non-Invasive Ventilation
NIV should not be used in patients with recent facial or upper airway surgery, facial trauma/burns, fixed upper airway obstruction, or active vomiting, as these represent the strongest contraindications where NIV poses immediate risk to patient safety. 1
Absolute Contraindications (Avoid NIV)
The following conditions represent situations where NIV should be avoided due to immediate safety concerns:
- Facial trauma or burns - interferes with mask-face interface and prevents adequate seal 1
- Recent facial, upper airway, or upper gastrointestinal tract surgery - risk of anastomotic disruption and inability to achieve proper interface 1
- Fixed obstruction of the upper airway - NIV cannot overcome mechanical obstruction 1
- Active vomiting - high aspiration risk with positive pressure 1
- Cardiac or respiratory arrest - requires immediate intubation 2
Relative Contraindications (Use with Caution or Avoid Unless "Ceiling" of Care)
These conditions are associated with high NIV failure rates but may be attempted if invasive ventilation is not planned or if intubation backup is immediately available:
Airway Protection Issues
- Inability to protect the airway - increased aspiration risk with positive pressure 1
- Copious respiratory secretions - cannot be adequately cleared with NIV alone 1
- Impaired consciousness or coma - inability to cooperate and protect airway 1
- Confusion or agitation - prevents adequate mask tolerance and synchrony 1
Physiological Instability
- Life-threatening hypoxemia - may require immediate intubation for higher FiO2 and PEEP 1, 2
- Hemodynamic instability - though cardiac output changes are minimal with NIV, unstable patients may decompensate 1
- Severe co-morbidity - multiple organ dysfunction increases failure risk 1
Gastrointestinal Concerns
- Recent upper gastrointestinal surgery - risk of anastomotic leak with positive pressure 1
- Bowel obstruction - positive pressure may worsen gastric distension 1
Radiological Findings
- Focal consolidation on chest radiograph - suggests pneumonia with higher NIV failure rates 1, 2
- Undrained pneumothorax - should have intercostal drain inserted before NIV initiation in most cases 1
Critical Clinical Context
The British Thoracic Society guidelines emphasize that there are no absolute contraindications if NIV represents the "ceiling" of treatment - meaning if invasive ventilation is not appropriate but NIV would be acceptable, a trial of NIV is reasonable even in the presence of relative contraindications. 1
Important Caveats
Severe acidosis at presentation (pH < 7.25) was historically considered a contraindication outside ICUs, but recent evidence shows successful NIV treatment is possible in respiratory intermediate care units for COPD, acute cardiogenic pulmonary edema, and obesity hypoventilation syndrome patients with severe acidosis. 3
Pneumothorax management: While NIV has been used successfully with undrained pneumothorax without causing enlargement, an intercostal drain should be inserted before commencing NIV in most patients with pneumothorax. 1
Orofacial abnormalities that interfere with mask-face interface predict NIV failure due to inability to achieve adequate seal. 1, 4
When to Avoid NIV Despite Technical Feasibility
In a moribund patient with life-threatening asthma who requires urgent intubation, attempting NIV delays necessary definitive airway management and worsens outcomes - proceed directly to intubation when NIV would be difficult but invasive ventilation straightforward. 1
The key principle: Local protocols must be developed to avoid inappropriate NIV trials in patients requiring urgent intubation, as delayed intubation increases mortality risk. 1, 4