What are the guidelines for using noninvasive ventilation (NIV) in patients with respiratory failure?

Guidelines for Noninvasive Ventilation in Respiratory Failure

Noninvasive ventilation (NIV) should be considered first-line therapy in patients with acute exacerbation of COPD who have respiratory acidosis (pH <7.35) despite maximum medical treatment on controlled oxygen therapy. 1

Primary Indications for NIV

NIV is strongly indicated in several specific clinical scenarios:

• COPD Exacerbation: For patients with acute exacerbation of COPD with respiratory acidosis (pH <7.35) despite maximum medical treatment and controlled oxygen therapy (Grade A evidence) 1
• Cardiogenic Pulmonary Edema: CPAP has been shown to be effective in patients who remain hypoxic despite maximal medical treatment; NIV should be reserved for patients in whom CPAP is unsuccessful (Grade B evidence) 1
• Neuromuscular Disease/Chest Wall Deformity: NIV is indicated in acute or acute-on-chronic hypercapnic respiratory failure due to these conditions (Grade C evidence) 1
• Weaning from Invasive Ventilation: NIV should be used when conventional weaning strategies fail (Grade B evidence) 1
• High-Risk Post-Extubation: NIV should be used to prevent post-extubation respiratory failure in high-risk patients (conditional recommendation) 1

Contraindications

NIV should be avoided in patients with:

• Recent facial or upper airway surgery
• Facial abnormalities (burns, trauma)
• Fixed upper airway obstruction
• Active vomiting 1

Relative contraindications include:

• Recent upper gastrointestinal surgery
• Inability to protect the airway
• Copious respiratory secretions
• Life-threatening hypoxemia
• Severe co-morbidity
• Confusion/agitation
• Bowel obstruction 1

Setting and Equipment

Location

• NIV can be provided in ICU, high dependency unit (HDU), or respiratory ward
• Each hospital should have a designated area with appropriately trained staff 1
• Patients with more severe acidosis (pH <7.30) should be managed in HDU or ICU 1
• Patients with conditions where NIV efficacy is not well-established (pneumonia, ARDS, asthma) should only receive NIV in HDU or ICU with immediate intubation capabilities 1

Equipment

• Bi-level pressure support ventilators are recommended when setting up an acute NIV service (Grade C evidence) 1
• Volume-controlled ventilators should be available in comprehensive NIV services 1
• A selection of different sizes of nasal masks, full-face masks, and nasal pillows should be available 1
• In acute settings, full-face masks should be used initially, with potential transition to nasal masks after 24 hours as the patient improves 1

Monitoring and Management

Initial Assessment

• Before starting NIV, a decision about tracheal intubation should be made for every patient (whether NIV is a trial with intubation as backup, or the ceiling of treatment) 1
• This decision should be verified with senior medical staff and documented 1

Ongoing Monitoring

• Clinical evaluation should include: patient comfort, conscious level, chest wall motion, accessory muscle recruitment, coordination with ventilator, respiratory rate, and heart rate 1
• Arterial blood gas analysis should be performed after 1-2 hours of NIV and after 4-6 hours if earlier sample showed little improvement 1
• If no improvement in PaCO2 and pH despite optimal ventilator settings, NIV should be discontinued and invasive ventilation considered 1
• Oxygen saturation should be monitored continuously for at least 24 hours with supplementary oxygen to maintain saturations between 85-90% 1

Treatment Duration

• Patients who benefit from NIV should be ventilated for as much as possible during the first 24 hours or until improving 1
• Breaks should be provided for medications, physiotherapy, meals, etc. 1

Special Considerations

Post-Extubation

• NIV should be used to prevent respiratory failure in high-risk post-extubation patients (>65 years with cardiac or respiratory disease) 1
• NIV should NOT be used in the treatment of established post-extubation respiratory failure, as it may increase mortality by delaying intubation 1

Pneumothorax

• In most patients with pneumothorax, an intercostal drain should be inserted before commencing NIV 1

Chest Wall Trauma

• CPAP should be used in patients with chest wall trauma who remain hypoxic despite adequate regional anesthesia and high-flow oxygen 1
• NIV should not be used routinely in chest trauma 1
• These patients should be monitored in ICU due to pneumothorax risk 1

Treatment Failure

Signs of treatment failure include:

• Deterioration in patient's condition
• Failure to improve arterial blood gases
• Development of new complications (pneumothorax, sputum retention)
• Intolerance or poor synchronization with the ventilator
• Deteriorating consciousness level 1

Service Organization

• A named consultant (usually respiratory physician) with appropriate training should have overall responsibility for the NIV service 1
• Clear protocols should be established for on-call staff regarding NIV indications, initiation, and supervision 1
• All patients who have received NIV for acute hypercapnic respiratory failure should undergo spirometric testing and arterial blood gas analysis before discharge 1
• Patients with spinal cord lesions, neuromuscular disease, chest wall deformity, or morbid obesity who develop acute hypercapnic respiratory failure should be referred to centers providing long-term home ventilation 1

NIV has revolutionized the management of acute respiratory failure, reducing mortality and the need for intubation in selected patients when applied appropriately and with proper monitoring.