Non-Invasive Ventilator Settings for ICU Patients: Evidence-Based Guide
1. COPD Exacerbation
For acute COPD exacerbations with hypercapnic respiratory failure, use bi-level pressure support (BiPAP) with initial IPAP 10-15 cmH₂O, EPAP 4-8 cmH₂O, targeting SpO₂ 88-92%, and backup rate 10-14 breaths/min. 1
Recommended Mode
- Bi-level pressure support ventilation (BiPAP) is the preferred mode, simpler to use and validated in the majority of randomized controlled trials 2, 1
- Use Spontaneous/Timed (S/T) mode with backup rate if patient has frequent central apneas or inappropriately low respiratory rate 1
Initial Settings
- IPAP: Start at 10-15 cmH₂O 1
- EPAP: Set at 4-8 cmH₂O to offset intrinsic PEEP and improve triggering 2, 1
- Pressure difference: Maintain at least 5 cmH₂O between IPAP and EPAP 1
- Backup rate: 10-14 breaths/min, set equal to or slightly less than patient's spontaneous sleeping respiratory rate 1
- Inspiratory time: Set to achieve I:E ratio of approximately 1:2 (30% IPAP time) to allow adequate exhalation 1
- FiO₂: Titrate to maintain SpO₂ 88-92% to avoid worsening hypercapnia 1
Pathophysiologic Rationale
- EPAP eliminates exhaled air through the expiratory port, reduces rebreathing, encourages lung recruitment, and stents open the upper airway 2
- EPAP overcomes the effects of intrinsic PEEP, which is critical in COPD patients 2
- The addition of PEEP to pressure support provides greater reduction in work of breathing in acute COPD 2
- High inspiratory pressures aimed at decreasing CO₂ levels ensure NIV success in stable hypercapnic COPD 3
Monitoring and Adjustments
- Obtain arterial blood gases before initiating ventilation to guide therapy 1
- Recheck ABGs after 30-60 minutes of ventilation or if clinical deterioration occurs 1
- If pH and PaCO₂ normalize, continue with target SpO₂ 88-92% 1
- Consider intubation if worsening ABGs and/or pH in 1-2 hours, or lack of improvement after 4 hours of NIV 1
- For long-term NIV in chronic stable hypercapnic COPD, target normalization of PaCO₂ 2, 1
Contraindications and Complications
- Approximately 29% of patients do not tolerate NIV under acute circumstances 4
- Do not initiate long-term NIV during an admission for acute-on-chronic hypercapnic respiratory failure; reassess at 2-4 weeks after resolution 2
- Screen for obstructive sleep apnea before initiating long-term NIV 2
Critical Pitfalls
- Excessive oxygen therapy: Maintain SpO₂ 88-92% to prevent worsening hypercapnia 1
- Inadequate expiratory time: Ensure I:E ratio of 1:2 to prevent dynamic hyperinflation and auto-PEEP 1
- Insufficient PEEP: Titrate EPAP to 4-8 cmH₂O to offset intrinsic PEEP 1
- Delayed escalation to invasive ventilation: Monitor closely for worsening ABGs 1
2. Acute Respiratory Distress Syndrome (ARDS)
NIV should be used with extreme caution in ARDS and is generally not recommended as first-line therapy due to high failure rates and risk of delayed intubation.
Recommended Approach
- ARDS is not an ideal indication for NIV due to the severity of hypoxemia and need for lung-protective ventilation strategies 2
- If NIV is attempted in mild ARDS, use bi-level pressure support with close monitoring for failure 2
Initial Settings (If NIV Attempted)
- IPAP: 12-16 cmH₂O above PEEP 5
- EPAP: 8-12 cmH₂O to recruit underventilated lung 2
- FiO₂: Titrate to maintain SpO₂ >90% (higher target than COPD) 2
- Backup rate: 12-16 breaths/min 2
Pathophysiologic Rationale
- CPAP/EPAP increases mean airway pressure and improves ventilation to collapsed areas of lung, similar to PEEP in intubated patients 2
- Recruitment of underventilated lung is the primary mechanism 2
- However, NIV cannot reliably deliver the low tidal volumes (4-8 ml/kg) and plateau pressures <30 cmH₂O required for lung-protective ventilation 6
Monitoring and Rapid Escalation
- Intubate early if no improvement within 1-2 hours 2
- Monitor for signs of NIV failure: worsening hypoxemia, increased work of breathing, altered mental status 2
- Once intubated, use low tidal volumes (6 ml/kg predicted body weight) and target plateau pressure <30 cmH₂O 6
Critical Pitfalls
- Delayed intubation: ARDS patients who fail NIV have worse outcomes if intubation is delayed 2
- Inadequate lung protection: NIV cannot guarantee lung-protective ventilation 6
- Mask intolerance: High EPAP requirements often lead to poor mask seal and patient discomfort 2
3. Congestive Heart Failure (CHF) with Pulmonary Edema
For acute cardiogenic pulmonary edema, use CPAP at 8-12 cmH₂O as first-line therapy, or BiPAP if hypercapnia is present.
Recommended Mode
- CPAP is the preferred initial mode for pure cardiogenic pulmonary edema without hypercapnia 2
- BiPAP if patient has concurrent hypercapnia or increased work of breathing 2
Initial Settings for CPAP
Initial Settings for BiPAP (If Needed)
- IPAP: 12-15 cmH₂O 2
- EPAP: 8-10 cmH₂O 2
- Backup rate: 10-12 breaths/min 2
- FiO₂: Titrate to maintain SpO₂ >92% 2
Pathophysiologic Rationale
- CPAP permits higher inspired oxygen content than other methods of oxygen supplementation 2
- Increases mean airway pressure and improves ventilation to collapsed areas of lung 2
- CPAP unloads inspiratory muscles and reduces inspiratory work 2
- Reduces preload and afterload, improving cardiac function 2
Monitoring and Adjustments
- Monitor for rapid improvement in dyspnea, respiratory rate, and oxygenation within 30-60 minutes 2
- If no improvement or worsening, consider BiPAP or intubation 2
- Monitor blood pressure closely as positive pressure can reduce preload 2
Critical Pitfalls
- Hypotension: Positive pressure reduces venous return; monitor blood pressure closely 2
- Inadequate CPAP level: Starting too low (<8 cmH₂O) may not provide adequate benefit 2
- Delayed diuresis: NIV is adjunctive; ensure aggressive medical management continues 2
4. Pneumonia
NIV has limited role in pneumonia alone but may be considered in patients with underlying COPD or immunocompromise; use BiPAP with IPAP 12-16 cmH₂O, EPAP 5-8 cmH₂O.
Recommended Mode
- BiPAP if NIV is attempted 5
- Consider early intubation if severe hypoxemia or high work of breathing 5
Initial Settings
- IPAP: 12-16 cmH₂O above PEEP to achieve tidal volumes of 6 ml/kg predicted body weight 5
- EPAP: 5-8 cmH₂O to recruit atelectatic areas 5
- Pressure support: Typically 8-12 cmH₂O initially 5
- Backup rate: 12-14 breaths/min 5
- I:E ratio: Approximately 1:2 5
- FiO₂: Titrate to maintain SpO₂ >92% 5
Special Considerations for COPD with Pneumonia
- The combination creates competing demands: COPD requires longer expiratory times and careful PEEP titration, while pneumonia may require higher PEEP for recruitment 5
- Set initial PEEP between 4-8 cmH₂O to offset intrinsic PEEP in COPD patients 5
- Do not exceed the patient's dynamic intrinsic PEEP to avoid further hyperinflation 5
- Consider permissive hypercapnia if hemodynamically stable 5
Monitoring and Adjustments
- Recheck arterial blood gases 30-60 minutes after initiating ventilation 5
- Monitor for auto-PEEP by performing end-expiratory hold maneuver 5
- Assess plateau pressure with inspiratory hold maneuver to ensure it remains <30 cmH₂O 5
Critical Pitfalls
- Excessive oxygen therapy in COPD patients: Maintain SpO₂ 88-92% in COPD, 92-96% in non-COPD 5
- Inadequate expiratory time in COPD: Ensure I:E ratio of 1:2 or 1:3 5
- Over-application of PEEP: Do not exceed dynamic intrinsic PEEP in COPD patients 5
- Delayed intubation: Pneumonia patients have higher NIV failure rates; intubate early if not improving 5
5. Obesity Hypoventilation Syndrome (OHS)
For acute hypercapnic respiratory failure in OHS, use BiPAP with IPAP 15-20 cmH₂O, EPAP 8-12 cmH₂O, targeting normalization of PaCO₂.
Recommended Mode
- BiPAP with backup rate (Spontaneous/Timed mode) 7
- Patients with OHS often have concurrent obstructive sleep apnea requiring higher EPAP 7
Initial Settings
- IPAP: 15-20 cmH₂O (higher than COPD due to increased chest wall impedance) 7
- EPAP: 8-12 cmH₂O (higher to maintain upper airway patency and offset chest wall load) 7
- Pressure support: 10-15 cmH₂O 7
- Backup rate: 12-16 breaths/min (higher than COPD) 7
- FiO₂: Titrate to maintain SpO₂ >90% 7
Pathophysiologic Rationale
- OHS patients have reduced chest wall compliance requiring higher pressures to achieve adequate tidal volumes 7
- Many have concurrent obstructive sleep apnea requiring higher EPAP for upper airway patency 7
- Patients with BMI >30 kg/m² respond particularly well to NIV therapy 7
Monitoring and Adjustments
- Target meaningful reduction in waking PaCO₂ with inspiratory pressures in the 20-25 cmH₂O range 7
- Monitor for improvement in daytime hypercapnia and symptoms 7
- Consider polysomnography or overnight oximetry to assess for concurrent sleep apnea 7
Critical Pitfalls
- Insufficient inspiratory pressure: OHS requires higher IPAP (15-20 cmH₂O) than COPD to overcome chest wall impedance 7
- Inadequate EPAP: Many OHS patients have OSA requiring EPAP 8-12 cmH₂O 7
- Failure to address underlying obesity: NIV is supportive; weight loss is definitive therapy 7
6. Asthma Exacerbation
NIV is generally NOT recommended for acute asthma exacerbations due to high failure rates and risk of barotrauma; prioritize aggressive medical management and early intubation if needed.
Limited Role of NIV
- Asthma is not an established indication for NIV 2
- High airway resistance and dynamic hyperinflation make NIV poorly tolerated 2
- Risk of pneumothorax with positive pressure in severe bronchospasm 2
If NIV Attempted (With Extreme Caution)
- BiPAP only in mild exacerbations with patient cooperation 2
- IPAP: 8-12 cmH₂O (lower than COPD) 2
- EPAP: 3-5 cmH₂O (minimal to avoid further hyperinflation) 2
- Backup rate: 10-12 breaths/min 2
- I:E ratio: 1:3 or 1:4 to allow prolonged expiration 2
Critical Approach
- Prioritize aggressive medical management: Inhaled beta-agonists, systemic corticosteroids, magnesium sulfate 2
- Low threshold for intubation: If patient tiring, altered mental status, or worsening hypercapnia 2
- Monitor closely for pneumothorax if NIV used 2
Critical Pitfalls
- Delayed intubation: Asthma patients who fail NIV deteriorate rapidly 2
- Excessive PEEP: Worsens dynamic hyperinflation and hemodynamic compromise 2
- False reassurance: NIV should not delay definitive airway management 2
7. Post-Operative Respiratory Failure
For post-operative respiratory failure, use CPAP 8-10 cmH₂O for atelectasis/hypoxemia, or BiPAP with IPAP 12-15 cmH₂O, EPAP 5-8 cmH₂O if hypercapnia present.
Recommended Mode
- CPAP for pure hypoxemic respiratory failure due to atelectasis 2
- BiPAP if hypercapnia or increased work of breathing present 2
Initial Settings for CPAP
Initial Settings for BiPAP
- IPAP: 12-15 cmH₂O 2
- EPAP: 5-8 cmH₂O 2
- Backup rate: 10-12 breaths/min 2
- FiO₂: Titrate to maintain SpO₂ >92% 2
Pathophysiologic Rationale
- Post-operative atelectasis is common due to pain, splinting, and residual anesthetic effects 2
- CPAP recruits atelectatic lung and improves oxygenation 2
- BiPAP reduces work of breathing if patient has residual neuromuscular blockade or diaphragm dysfunction 2
Special Considerations
- Abdominal surgery patients: May benefit from prophylactic CPAP to prevent atelectasis 2
- Thoracic surgery patients: Use caution with positive pressure if recent lung resection or air leak 2
- Bariatric surgery patients: Often require higher pressures similar to OHS 7
Monitoring and Adjustments
- Monitor for improvement in oxygenation and respiratory rate within 1-2 hours 2
- If no improvement, consider chest imaging to rule out pneumothorax, pleural effusion, or pneumonia 2
- Wean CPAP/BiPAP as patient improves, typically over 24-48 hours 2
Critical Pitfalls
- Unrecognized pneumothorax: Always obtain chest X-ray before initiating NIV post-operatively 2
- Inadequate analgesia: Pain control is essential for NIV success in post-operative patients 2
- Gastric distension: Use lower pressures if possible and consider nasogastric tube if distension occurs 2
General NIV Principles Across All Conditions
Equipment Selection
- Bi-level pressure support ventilators are simpler to use, cheaper, and more flexible than other types currently available 2
- They have been used in the majority of randomized controlled trials and are recommended when setting up an acute NIV service 2
- A single model of ventilator should be used in any clinical area for ease of training and staff familiarity 2
Triggering and Cycling
- Ventilator triggering is critical to NIV success in both spontaneous and assist/control modes 2
- Trigger sensitivity and ventilator response times are generally good with modern NIV machines 2
- Some ventilators allow adjustment of cycling (switching to expiration at 20-80% of maximum inspiratory flow) 2
Monitoring Parameters
- Arterial blood gases are fundamental and should be obtained before initiating ventilation 6, 1
- Recheck ABGs 30-60 minutes after initiating or adjusting ventilation 5, 1
- Monitor respiratory rate, work of breathing, mental status, and patient-ventilator synchrony continuously 2
- Assess for auto-PEEP with end-expiratory hold maneuver in obstructive lung disease 6, 5
Newer Modalities
- Adaptive servo-ventilation has been developed to treat central and complex sleep apnea 8
- NAVA (neutrally adjusted ventilatory assist) improves trigger and cycle asynchrony 8
- Proportional assist ventilation prevents increase in respiratory rate with increased patient effort 8
- Volume-assured pressure support with autotitrating EPAP may facilitate home NIV initiation 7