When should a patient be put on Non-Invasive Ventilation (NIV)?

Indications for Non-Invasive Ventilation (NIV)

NIV should be initiated in patients with acute exacerbation of COPD who develop respiratory acidosis (pH <7.35) despite maximum medical treatment on controlled oxygen therapy, as this reduces mortality, need for intubation, and treatment failure. 1, 2

Primary Indications for NIV

• NIV is indicated in acute or acute-on-chronic hypercapnic respiratory failure due to chest wall deformity or neuromuscular disease 1
• Continuous positive airway pressure (CPAP) should be used in patients with cardiogenic pulmonary edema who remain hypoxic despite maximal medical treatment, with NIV reserved for patients in whom CPAP is unsuccessful 1, 3
• NIV (bi-level pressure support) should be used for patients with decompensated obstructive sleep apnea if respiratory acidosis is present 1
• NIV has been shown effective for weaning patients from invasive ventilation and should be used when conventional weaning strategies fail 1

Secondary Indications for NIV

• A trial of NIV may be undertaken in patients with respiratory acidosis (pH <7.35) secondary to acute exacerbation of bronchiectasis, though excessive secretions may limit effectiveness 1
• NIV can be used as an alternative to tracheal intubation in patients with diffuse pneumonia who become hypercapnic after remaining hypoxic despite maximum medical treatment 1
• NIV has been used successfully in various conditions including acute respiratory distress syndrome, postoperative and post-transplantation respiratory failure 1, 4
• NIV may be considered in patients with tracheobronchomalacia who develop hypercapnic respiratory failure 5

Contraindications for NIV

• NIV should not be used in patients after recent facial or upper airway surgery, with facial abnormalities such as burns or trauma, fixed upper airway obstruction, or if vomiting 1
• Other contraindications include recent upper gastrointestinal surgery, inability to protect the airway, copious respiratory secretions, life-threatening hypoxemia, severe comorbidity, confusion/agitation, or bowel obstruction 1
• NIV should not be used routinely in acute asthma 1
• In patients with pneumothorax, an intercostal drain should be inserted before commencing NIV 1

Setting and Monitoring Requirements

• Patients with more severe acidosis (pH <7.30) should be managed in a higher dependency area such as HDU or ICU 1
• Arterial blood gas analysis should be measured in most patients after 1-2 hours of NIV and after 4-6 hours if the earlier sample showed little improvement 1
• If there is no improvement in PaCO2 and pH after 4-6 hours despite optimal ventilator settings, NIV should be discontinued and invasive ventilation considered 1, 6
• Oxygen saturation should be monitored continuously for at least 24 hours after commencing NIV, with supplementary oxygen administered to maintain saturations between 85% and 90% 1

Special Considerations

• A decision about tracheal intubation should be made before commencing NIV in every patient and documented in the case notes 1, 7
• Patients with conditions where the role of NIV is not yet clearly established (pneumonia, ARDS, asthma) should only receive NIV in an HDU or ICU where facilities for immediate tracheal intubation are available 1
• In chest wall trauma, CPAP should be used for patients who remain hypoxic despite adequate regional anesthesia and high-flow oxygen, with monitoring in the ICU due to pneumothorax risk 1
• Bi-level pressure support ventilators are recommended when setting up an acute NIV service due to their simplicity, cost-effectiveness, and flexibility 1, 8