What would be the settings of Non-Invasive Ventilation (NIV)?

Settings for Non-Invasive Ventilation (NIV)

The optimal settings for Non-Invasive Ventilation (NIV) should include bi-level pressure support with IPAP of 15-20 cmH2O, EPAP of 3-5 cmH2O, and appropriate monitoring to ensure patient comfort and effectiveness in treating acute hypercapnic respiratory failure. 1

Ventilator Type and Mode Selection

• Bi-level pressure support ventilators are recommended when setting up an acute NIV service as they are simpler to use, more cost-effective, and have been used in most randomized controlled trials showing benefit 1
• The ventilator should have both assist-control and bi-level pressure support modes to accommodate different patient needs 1
• Essential features include pressure capability of at least 30 cmH2O, support for inspiratory flows of at least 60 L/min, sensitive flow triggers, and disconnection alarms 1
• For COPD patients, the European Respiratory Society recommends bi-level pressure support as the most effective mode of NIV 2

Initial Pressure Settings

• For patients with COPD/obesity hypoventilation syndrome/kyphoscoliosis: start with IPAP of 15 cmH2O (increase to 20 cmH2O if pH < 7.25) 1
• Set EPAP at 3-5 cmH2O initially (or higher if previously established) 1, 2
• The pressure difference between IPAP and EPAP should be at least 5 cmH2O to ensure adequate ventilation 2
• EPAP helps to offset intrinsic PEEP in COPD patients, improving trigger sensitivity and reducing work of breathing 1
• For cardiogenic pulmonary edema, CPAP at 10 cmH2O is typically used, with NIV reserved for patients who fail CPAP or develop hypercapnia 1, 3

Respiratory Rate and Timing Settings

• Set backup rate equal to or slightly less than the patient's spontaneous respiratory rate (minimum of 10 breaths/min) 2
• For COPD patients, set inspiratory time to achieve an I:E ratio of approximately 1:2 (30% IPAP time) to allow adequate time for exhalation 2
• The assist/control mode is particularly important for patients with advanced respiratory failure who may cease making spontaneous effort when "captured" 1

Oxygen Settings and Monitoring

• Target oxygen saturation of 88-92% in COPD patients to avoid worsening hypercapnia 1, 2
• Oxygen enrichment requires oxygen to be fed into the circuit or directly into the mask 1
• Continuous pulse oximetry monitoring is essential for at least 24 hours after commencing NIV 1
• Arterial blood gas analysis should be performed after 1-2 hours of NIV and again after 4-6 hours if the earlier sample showed little improvement 1

Interface Selection

• In the acute setting, a full-face mask should be used initially, potentially changing to a nasal mask after 24 hours as the patient improves 1
• A range of mask sizes should be available, and staff need training in their proper use 1
• Ensure the mask has an integral exhalation port or that an exhalation port is inserted into the ventilator circuit close to the mask 1

Common Pitfalls and Solutions

• Excessive leakage can prevent the ventilator from achieving set pressure - check mask fit and adjust as needed 1
• Patient-ventilator asynchrony may result from undetected inspiratory effort or delay in response - consider adjusting trigger sensitivity or switching to timed mode 1
• Inadequate expiratory time for COPD patients can worsen air trapping - ensure appropriate I:E ratio 2
• Rebreathing can occur with inadequate EPAP - maintain minimum EPAP of 3 cmH2O 1
• Excessive oxygen therapy can worsen hypercapnia - maintain target saturation of 88-92% 2

Red Flags Requiring Immediate Action

• pH < 7.25 despite optimal NIV settings
• Respiratory rate persistently > 25 breaths/min
• New onset confusion or patient distress 1

If these occur, check mask fit, synchronization, and exhalation port function; consider physiotherapy, bronchodilators, or anxiolytics; and evaluate the need for invasive mechanical ventilation 1.