When to use Continuous Positive Airway Pressure (CPAP), Bi-level Positive Airway Pressure (BIPAP), and Non-Invasive Positive Pressure Ventilation (NIPPV) in the Intensive Care Unit (ICU)/Coronary Care Unit (CCU) setting?

Non-Invasive Ventilation in ICU/CCU: CPAP, BiPAP, and NIPPV

Non-invasive ventilation (NIV) should be used according to specific clinical indications, with CPAP preferred for hypoxemic conditions like cardiogenic pulmonary edema, and BiPAP preferred for hypercapnic respiratory failure such as COPD exacerbations. 1, 2

Basic Differences and Mechanisms

• CPAP (Continuous Positive Airway Pressure): Delivers a single constant pressure throughout the respiratory cycle, primarily used to correct hypoxemia by recruiting underventilated lung areas and improving oxygenation 2

• BiPAP (Bi-level Positive Airway Pressure): Provides two distinct pressure levels - IPAP (higher pressure during inspiration) and EPAP (lower pressure during expiration), making it more effective for patients with hypercapnic respiratory failure 2

• NIPPV (Non-Invasive Positive Pressure Ventilation): General term encompassing both CPAP and BiPAP modalities used to support breathing without endotracheal intubation 1

Clinical Indications for CPAP

• Use CPAP in patients with cardiogenic pulmonary edema who remain hypoxic despite maximal medical treatment 1, 2
• Apply CPAP in patients with chest wall trauma who remain hypoxic despite adequate regional anesthesia and high flow oxygen 1, 3
• CPAP improves oxygenation in patients with diffuse pneumonia who remain hypoxic despite maximum medical treatment 1
• CPAP is effective in patients with decompensated obstructive sleep apnea without respiratory acidosis 1, 3

Clinical Indications for BiPAP

• BiPAP should be considered in patients with acute exacerbation of COPD with persistent respiratory acidosis (pH <7.35) despite maximum medical treatment on controlled oxygen therapy 1, 3
• Use BiPAP for patients with decompensated obstructive sleep apnea if respiratory acidosis is present 1, 3
• BiPAP is indicated in acute or acute-on-chronic hypercapnic respiratory failure due to chest wall deformity or neuromuscular disease 1, 3
• BiPAP should be used when patients develop hypercapnia during CPAP treatment for pneumonia 1, 2
• BiPAP has been used successfully to wean patients from invasive ventilation when conventional weaning strategies fail 1, 3

Contraindications to NIV

• Do not use NIV in patients after recent facial or upper airway surgery, with facial abnormalities such as burns or trauma, fixed upper airway obstruction, or if the patient is vomiting 1, 3
• NIV is contraindicated in patients with inability to protect the airway, copious respiratory secretions, life-threatening hypoxemia, severe co-morbidity, confusion/agitation, or bowel obstruction 1, 3
• NIV should not be used routinely in acute asthma 1, 3
• In most patients with a pneumothorax, an intercostal drain should be inserted before commencing NIV 1

Practical Settings and Monitoring

• For CPAP in cardiogenic pulmonary edema or pneumonia, start with 10 cmH₂O, with FiO₂ 0.6, increasing to 12-15 cmH₂O if needed 1
• Target SpO₂ should be above 90% and no higher than 96% in most cases 1
• For patients with evidence of acute or chronic type 2 respiratory failure, titrate SpO₂ to 88-92% 1, 3
• Monitor patients closely after initiating NIV, with arterial blood gas analysis after 1-2 hours and again after 4-6 hours if the earlier sample showed little improvement 3
• If no improvement in respiratory function after 4-6 hours despite optimal ventilator settings, discontinue NIV and consider invasive ventilation 3

Important Clinical Considerations

• Always make a decision about tracheal intubation before commencing NIV in every patient and document this in the case notes 1, 3
• NIV may be undertaken as a therapeutic trial with a view to tracheal intubation if it fails, or as the ceiling of treatment in patients who are not candidates for intubation 1
• In chest wall trauma patients treated with CPAP or NIV, monitor in the ICU due to the risk of pneumothorax 1
• Patients with more severe acidosis should be managed in a higher dependency area, such as HDU or ICU 3
• A full-face mask should be used initially in the acute setting, changing to a nasal mask after 24 hours as the patient improves 1

Special Considerations for Cardiogenic Shock

• NIV may be considered in cardiogenic shock only after hemodynamic stabilization has been achieved, and patients must be alert and able to protect their airway 4
• Invasive mechanical ventilation is generally preferred in cardiogenic shock due to the need for airway protection in potentially deteriorating patients 4
• Maintain a low threshold for escalation to invasive mechanical ventilation if hemodynamic status deteriorates, respiratory parameters worsen, or mental status declines 4