What are the indications for Non-Invasive Ventilation (NIV)?

Indications for Non-Invasive Ventilation (NIV)

Primary Indications

NIV should be used in patients with acute exacerbation of COPD who have persistent respiratory acidosis (pH <7.35, H+ >45 nmol/l) despite maximal medical treatment and controlled oxygen therapy. 1 This represents the strongest evidence-based indication, with demonstrated reductions in intubation rates, hospital-acquired pneumonia, ICU length of stay, and mortality. 1, 2, 3

COPD Exacerbation

• Initiate NIV when arterial blood gas shows pH <7.35 (particularly pH 7.25-7.35) with hypercapnia after optimal medical therapy. 1, 4
• Measure arterial blood gases in all patients with acute breathlessness to identify candidates. 1
• Repeat blood gas measurement after initial medical treatment, as many patients improve without NIV. 1
• This indication carries Grade A evidence with clear mortality benefit. 1, 3

Cardiogenic Pulmonary Edema

• Use NIV when patients with cardiogenic pulmonary edema remain hypoxic despite maximal medical treatment and CPAP has failed. 1, 4
• CPAP should be tried first; reserve NIV (bilevel pressure support) for CPAP non-responders. 1, 4
• This carries Grade B evidence. 1

Hypercapnic Respiratory Failure from Restrictive Disorders

• NIV is indicated for acute or acute-on-chronic hypercapnic respiratory failure due to chest wall deformity (scoliosis, thoracoplasty) or neuromuscular disease. 1, 4
• Maintain low threshold for measuring blood gases in these patients, as they may lack significant breathlessness despite respiratory failure. 1
• This carries Grade C evidence. 1

Immunocompromised Patients

• NIV should be used in immunocompromised patients with acute respiratory failure to avoid intubation-related complications. 4, 2, 3
• This indication carries Grade A evidence due to reduced rates of ventilator-associated pneumonia. 3

Weaning and Post-Extubation

• Use NIV to facilitate weaning in patients with hypercapnic respiratory failure, particularly COPD patients. 1, 4, 3
• NIV can prevent post-extubation failure in selected patients. 3
• This carries Grade A evidence. 3

Decompensated Obstructive Sleep Apnea

• Use NIV (bilevel pressure support) for decompensated OSA when respiratory acidosis is present; use CPAP if no acidosis. 1
• This carries Grade C evidence. 1

Absolute Contraindications

NIV is contraindicated in patients with impaired consciousness, severe hypoxemia unresponsive to initial therapy, or copious respiratory secretions. 1, 4

• Impaired consciousness prevents airway protection and cooperation. 1
• Severe hypoxemia typically requires intubation for higher FiO2 and PEEP. 1, 4
• Copious secretions cannot be adequately cleared with NIV. 1, 4

Conditional or Limited Indications

Chest Wall Trauma

• Use CPAP (not NIV routinely) for chest wall trauma patients who remain hypoxic despite adequate regional anesthesia and high-flow oxygen. 1
• Monitor in ICU due to pneumothorax risk. 1
• CPAP carries Grade C evidence; NIV should not be used routinely (Grade D). 1

Pneumonia with Hypoxemia

• Trials of CPAP or NIV in acute pneumonia with refractory hypoxemia should only occur in HDU or ICU settings, as most patients will require intubation. 1
• NIV has high failure rates (30-50%) in hypoxemic respiratory failure without hypercapnia. 3
• This carries Grade D evidence. 1

Acute Asthma

• There is insufficient evidence to support NIV in acute asthma exacerbation. 2

Critical Pre-Treatment Decision

Before starting NIV, document whether the patient is a candidate for intubation if NIV fails, or if NIV represents the ceiling of treatment. 1 This decision must be verified with senior medical staff and clearly documented. 1

Initial Settings and Monitoring

Starting Parameters

• Begin with IPAP 8-12 cmH2O and EPAP 3-5 cmH2O. 4
• Start FiO2 at 40% and titrate to maintain SpO2 >92% (or 85-90% in COPD to avoid CO2 retention). 4

Interface Selection

• Use a full-face mask initially in acute settings, switching to nasal mask after 24 hours as the patient improves. 1
• Have multiple mask sizes and types available. 1

Monitoring for Success or Failure

• Obtain arterial blood gases at 1-2 hours to assess PaO2, PaCO2, and pH improvement. 4
• Expect improvement by 4-6 hours; lack of progress indicates likely NIV failure. 1
• Deteriorating consciousness level requires immediate consideration of intubation. 4

Common Pitfalls

• Do not use NIV as a substitute for intubation when invasive ventilation is clearly more appropriate. 1
• Do not give excessive oxygen in COPD patients; target SpO2 85-90% to prevent worsening hypercapnia. 1
• Check for mask leaks, circuit problems, and patient-ventilator asynchrony if treatment fails. 1
• Ensure optimal medical treatment is given concurrently; NIV is not a replacement for bronchodilators, diuretics, or other disease-specific therapy. 1