Types Of NIV

CPAP (Continuous Positive Airway Pressure)

Mechanism:

• CPAP delivers continuous positive airway pressure during both inspiration and expiration.
• It helps maintain the airways open, especially in conditions where airway collapse or fluid accumulation is a concern.

 

Indications:    

i. Acute Pulmonary Edema (APO/AHF):

• Improves oxygenation by increasing functional residual capacity (FRC) and reducing pulmonary edema.

ii. Sleep Apnea:

• Keeps the upper airways open by providing continuous airway pressure.

iii. Hypoxemic Respiratory Failure (e.g., pneumonia, ARDS):

• Prevents alveolar collapse, improving oxygenation.

 

Initial Settings:

PEEP:

• 5-10 cmH2O (can titrate up to 20 cmH2O depending on the patient’s condition)

FiO2:

• Titrated to maintain SpO2 > 92% (or 88-92% in COPD)

 

Advantages:

• Increases oxygenation
• Decreases the work of breathing
• Improves cardiac function in patients with left ventricular failure (due to decreased preload and afterload)
• Can reduce the need for intubation

 

Limitations:

• Does not improve ventilation (no ventilatory support)
• Not suitable for patients with high CO2 retention (Type II respiratory failure)

 

 

BiPAP (Bilevel Positive Airway Pressure)

Mechanism:

BiPAP delivers two levels of positive airway pressure:

• IPAP (Inspiratory Positive Airway Pressure): Assists with ventilation during inspiration.
• EPAP (Expiratory Positive Airway Pressure): Keeps airways open during expiration, preventing alveolar collapse, similar to CPAP.

 

Indications:    

i. Acute Exacerbation of COPD:

• BiPAP improves ventilation by reducing CO2 levels and assisting with breathing in hypercapnic patients.

ii. Neuromuscular Diseases:

• Assists weakened respiratory muscles by providing inspiratory pressure support.

iii. Obesity Hypoventilation Syndrome:

• Helps ventilate the lungs and offload CO2.

iv. Weaning from Mechanical Ventilation:

• Can be used to prevent post-extubation respiratory failure.

 

Initial Settings:

IPAP:

• Initial settings between 10-15 cmH2O (adjust to achieve adequate tidal volumes of 6-8 mL/kg ideal body weight)

EPAP:

• Initial settings between 4-5 cmH2O (adjust based on oxygenation needs)

FiO2:

• Adjust to maintain SpO2 > 92% (or 88-92% in COPD)

 

Advantages:

• Improves both oxygenation and ventilation
• Decreases work of breathing by providing inspiratory support
• Ideal for Type II respiratory failure (hypercapnic respiratory failure)

 

Limitations:

• Requires a cooperative patient to tolerate the mask and pressures
• Limited effectiveness in patients with excessive secretions or those at risk of aspiration

 

 

Signs of NIV Failure:

• Worsening respiratory distress

• Rising PaCO2 despite NIV

• Decreasing mental status 

• Hemodynamic instability

• Inability to maintain SpO2 despite maximum settings

 

 

When to Escalate Care

If the patient shows signs of NIV failure, such as persistent hypercapnia, worsening hypoxemia, or hemodynamic instability, consider endotracheal intubation.