Ch. 19: Non-Invasive Ventilation Notes

Non-Invasive Ventilation

• One of the earliest forms of mechanical ventilation.
• Types:
  • Negative pressure ventilation.
  • Positive pressure ventilation.

History and Use

• Before 1960s: Non-invasive ventilation was the standard.
• Later: Invasive ventilation became standard due to perceived higher survival rates.
• Current: Improved non-invasive methods show early NIPPV can reduce the need for invasive ventilation.

Negative Pressure Ventilation

• Peaked in 1950s during Polio epidemic.
• Mechanism: Intermittent negative pressure increases lung volumes.

Abdominal Displacement Ventilation

• Alternative during the polio epidemic.
• Rocking Bed and Pneumobelt.

Positive Pressure Ventilation

• Early use: Bag and mask for resuscitation (1780).
• Later: IPPV used for acute respiratory failure, especially with COPD and Asthma.

NIPPV

• IPPB: Became a method for delivering aerosolized medications.
• CPAP (1980s): Effective for OSAS (obstructive sleep apnea syndrome).
  • Low continuous pressure prevents airway collapse.

Goals of NPPV

• Based on specific pathology, setting, and illness severity.
• Acute Care: Can be lifesaving in acute respiratory failure.
• Benefit: Avoidance of intubation.

Acute Care Applications

• Acute exacerbation of COPD
• Asthma
• Hypoxemic Respiratory Failure/ARDS: PaO2/FIO2 < 200, RR > 35
• Community-Acquired Pneumonia
• Cardiogenic Pulmonary Edema

Chronic or Homecare Applications

• OSAS
• Nocturnal hypoventilation syndrome
• Restrictive disorders
• Chronic neuromuscular conditions
• Chronic stable COPD

Equipment Selection

• Acute Care Ventilators
• Home Care Ventilators: Portable pressure-targeted Ventilators (BIPAP/CPAP) machines

Patient Interface Selection

• Types:
  • Nasal Interfaces
  • Full-face (Oronasal) Interface
  • Total Face and Helmet Interfaces
  • Oral Interfaces

Patient Interface: Nasal Masks

• Advantages: easy to fit quickly, less risk of claustrophobia, lower risk of aspiration, patient can cough and speak, less mechanical dead space.
• Disadvantages: Mouth Leaks, Eye and facial skin irritation, Ulceration over bridge of nose, Oral and nasal dryness, nasal congestion, Increased resistance through nasal passages.

Patient Interface: Full-Face (Oronasal) Masks

• Advantages: Reduces air leakage through mouth, Less airway resistance.
• Disadvantages: Increased risk for aspiration especially at pressures greater than 20 cm H_2O, Increased risk for asphyxia, Increased dead space, Claustrophobia, Difficult to secure and fit, Facial irritation/ulceration, Must remove to speak or expectorate secretions

Total Face Mask and Helmet

• Total Face Mask: Seals perimeter of the face and does not obstruct vision, Air circulates throughout entire mask making breathing more comfortable Decreases the incidence of pressure sores, Same concerns as full-face mask.
• Helmet: Transparent PVC cylinder that fits over patient’s entire head Secured by metal ring, silicone collar and straps under each armpit. Not currently FDA approved for use in U.S.

Patient Interface Selection – Considerations

• Emergency/Critical Care: Full-face mask is recommended( high shortness of breath). However, patient must be observed for potential risk of aspiration.
• Chronic or Homecare: Nasal mask, nasal prongs or pillows.

Setup and Preparation

• Patient sitting up or at least Semi-fowler’s position.
• Explain NIV to patient, procedure, goals, possible complications.
• Determine correct mask type for patient. Use sizing template to choose correct mask size.
• Setup and attach mask to ventilator, turn on vent and adjust settings. Hold or allow patient to hold mask gently to face while adjusting straps. Adjust straps evenly and avoid over-tightening.
• Talk to and encourage patient. Patient refusal or non-compliance is a contraindication. Monitor vital signs and obtain ABG within 1 hour.

Improving Oxygenation

• Increase FIO_2
• Increase CPAP or EPAP
• If on BIPAP, increase IPAP to maintain pressure support.

Improving Ventilation

• In BIPAP, delta-P or change in pressure supports spontaneous ventilation. To increase ventilatory support, increase the IPAP.
• Patient’s respiratory rate is important.

NIV Failure

• Worsening pH and PaCO2
• Persistent tachypnea (>30 breaths/min)
• Hemodynamic instability
• Worsening hypoxemia
• Decreased level of consciousness
• Inability to clear secretions
• Inability to tolerate interface

CPAP/NIV Weaning and Discontinuation

• Criteria for CPAP: FIO2 has been titrated to 50% or less with SPO2 > 93%.
• Criteria for BIPAP: FIO2 has been titrated, vital signs and PaCO2 values are consistently within normal limits.
• Transition to nasal O_2.