What is Non-Invasive Positive Pressure Ventilation (NIPPV)?

Non-Invasive Positive Pressure Ventilation (NIPPV)

Non-Invasive Positive Pressure Ventilation (NIPPV) is a ventilatory support technique that delivers mechanical ventilation through a face or nasal mask without requiring endotracheal intubation, primarily used to treat acute hypercapnic respiratory failure, particularly in COPD exacerbations. 1

Definition and Mechanism

NIPPV (also commonly abbreviated as NIV) refers to the delivery of positive pressure ventilation through a non-invasive interface such as:

• Face masks
• Nasal masks
• Nasal pillows
• Helmet devices

Unlike invasive mechanical ventilation, NIPPV does not require an artificial airway (endotracheal tube or tracheostomy), making it more comfortable and associated with fewer complications.

NIPPV works by:

• Reducing the work of breathing
• Improving alveolar ventilation
• Decreasing PaCO₂ levels
• Supporting respiratory muscles
• Counteracting intrinsic PEEP in COPD patients
• Improving oxygenation by recruiting collapsed alveoli

Types of NIPPV

1. Bi-level Positive Airway Pressure (BiPAP):

   • Provides two levels of pressure: higher inspiratory positive airway pressure (IPAP) and lower expiratory positive airway pressure (EPAP)
   • Typical initial settings include IPAP of 10-12 cmH₂O and EPAP of 4-5 cmH₂O 2
   • Pressure support (difference between IPAP and EPAP) typically 6-8 cmH₂O

2. Continuous Positive Airway Pressure (CPAP):

   • Delivers constant pressure throughout the respiratory cycle
   • Not technically ventilation but often grouped with NIV modalities
   • Primarily used for cardiogenic pulmonary edema and obstructive sleep apnea

Primary Indications

NIPPV is particularly indicated in:

• COPD exacerbations with respiratory acidosis (pH 7.25-7.35) 1, 3
• Hypercapnic respiratory failure secondary to:
  • Chest wall deformity (scoliosis, thoracoplasty)
  • Neuromuscular diseases 1
• Cardiogenic pulmonary edema unresponsive to CPAP 1
• Weaning from invasive mechanical ventilation 1
• Persistent hypercapnia 2-4 weeks after an acute exacerbation of COPD 2
• Immunocompromised patients with acute respiratory failure 4

Contraindications

NIPPV should not be used in patients with:

• Impaired consciousness 1
• Severe hypoxemia 1
• Copious respiratory secretions 1
• Hemodynamic instability
• Recent facial or upper airway surgery
• Inability to protect the airway
• Vomiting or high aspiration risk

Monitoring and Adjustment

Proper monitoring during NIPPV includes:

• Continuous SpO₂ monitoring
• Regular assessment of arterial blood gases
• Monitoring of respiratory rate and work of breathing
• Target oxygen saturation of 88-92% to prevent worsening hypercapnia 2
• Assessment for signs of NIV failure:
  • Deteriorating PaCO₂ and pH after 1-2 hours
  • No improvement in PaCO₂ and pH by 4-6 hours
  • Worsening consciousness level 2

Benefits of NIPPV

Research has demonstrated that NIPPV:

• Decreases mortality (RR 0.52) 3
• Reduces need for intubation (RR 0.41) 3
• Decreases treatment failure (RR 0.48) 3
• Provides rapid improvement in pH, PaCO₂, and respiratory rate 3, 5
• Reduces complications associated with treatment 3
• Shortens hospital length of stay by approximately 3.24 days 3

Physiological Effects

NIPPV improves gas exchange primarily by:

• Increasing alveolar ventilation through an efficient breathing pattern 5
• Decreasing breathing frequency (from 26 to 19 breaths/min) 5
• Increasing tidal volume (from 311 to 520 ml) 5
• Increasing minute ventilation 5

Implementation Requirements

For successful NIPPV implementation, hospitals need:

• A committed consultant/physician
• Trained nursing staff on a respiratory ward, HDU, or ICU
• ICU backup for patients who do not improve on NIPPV
• Appropriate non-invasive ventilators and mask selection 1, 2

Long-Term NIPPV

Consider home NIPPV for:

• Patients who still need NIPPV more than one week after an acute episode
• Patients with three or more episodes of acute hypercapnic respiratory failure in the previous year 2
• Stable hypercapnic COPD patients (when titrated with high-intensity settings) 6

NIPPV has revolutionized the management of acute respiratory failure, particularly in COPD exacerbations, by providing effective ventilatory support while avoiding the complications associated with invasive mechanical ventilation.