A. Introduction to Non-Invasive Ventilation (NIV)

This lesson provides an in-depth overview of Non-Invasive Ventilation (NIV), including Continuous Positive Airway Pressure (CPAP) and Bi-level Positive Airway Pressure (BiPAP). We will cover the principles, indications, contraindications, application, settings, modes, a step-by-step guide, and management of NIV.

B. Understanding Non-Invasive Ventilation (NIV)

Non-invasive ventilation (NIV) is a method of providing ventilatory support without endotracheal intubation. It involves using a mask or other interface to deliver positive pressure to the patient’s airways.

• NIV supports the patient’s breathing, reduces the work of breathing, and improves gas exchange.
• It helps to avoid the complications associated with intubation and mechanical ventilation.

C. Continuous Positive Airway Pressure (CPAP)

CPAP delivers a single, continuous level of positive airway pressure during both inspiration and expiration.

• Mechanism of Action: CPAP increases and stabilizes the pressure in the upper airway, preventing collapse and improving oxygenation.
• Common Uses:
  • Obstructive Sleep Apnea (OSA)
  • Cardiogenic Pulmonary Edema
  • Pre-oxygenation before intubation

D. Bi-level Positive Airway Pressure (BiPAP)

BiPAP delivers two levels of positive airway pressure:

• Inspiratory Positive Airway Pressure (IPAP): Higher pressure during inhalation.
• Expiratory Positive Airway Pressure (EPAP): Lower pressure during exhalation.

BiPAP provides both ventilatory support (IPAP) and oxygenation support (EPAP).

• Common Uses:
  • Chronic Obstructive Pulmonary Disease (COPD) exacerbation
  • Acute respiratory failure
  • Neuromuscular diseases

E. Indications for NIV

NIV is indicated for a variety of conditions, including:

• Acute respiratory failure
• COPD exacerbation
• Cardiogenic pulmonary edema
• Pneumonia
• Asthma exacerbation
• Neuromuscular diseases
• Obstructive sleep apnea

The specific type of NIV (CPAP or BiPAP) and the settings are tailored to the patient’s condition.

F. Contraindications to NIV

While NIV is a valuable tool, there are certain contraindications:

• Absolute Contraindications:
  • Respiratory arrest
  • Inability to protect the airway
  • Severe hemodynamic instability
  • Facial trauma or burns that interfere with mask fit
  • Upper airway obstruction (fixed)
• Relative Contraindications:
  • Decreased level of consciousness
  • Copious secretions
  • High risk of aspiration
  • Recent facial or upper airway surgery
  • Claustrophobia

The decision to use NIV should be made carefully, weighing the risks and benefits for each patient.

G. Equipment and Setup

Successful NIV requires proper equipment and setup:

• NIV Ventilator (CPAP or BiPAP machine)
• Appropriate size and type of mask (nasal, oronasal, full face)
• Tubing
• Humidifier (often recommended for patient comfort and secretion management)
• Oxygen source and delivery system (if needed)
• Monitoring equipment (pulse oximetry, etc.)

Proper mask fitting is crucial to ensure effective ventilation and patient comfort.

H. NIV Settings and Modes

Understanding NIV settings and modes is crucial for effective therapy.

Modes of NIV

• CPAP (Continuous Positive Airway Pressure):
  • Delivers a constant level of pressure throughout the respiratory cycle.
  • Primary effect is to increase functional residual capacity (FRC) and improve oxygenation.
• BiPAP (Bi-level Positive Airway Pressure):
  • Provides two pressure levels: IPAP and EPAP.
  • Spontaneous (S): Patient-triggered breaths, with pressure support.
  • Timed (T): Machine-triggered breaths at a set rate.
  • Spontaneous/Timed (S/T): A combination of patient-triggered and machine-triggered breaths.

Key NIV Settings

• Inspiratory Positive Airway Pressure (IPAP):
  • The pressure delivered during inspiration.
  • Affects tidal volume and ventilation.
• Expiratory Positive Airway Pressure (EPAP):
  • The pressure maintained during expiration.
  • Improves oxygenation by preventing alveolar collapse.
• FiO2 (Fraction of Inspired Oxygen): The concentration of oxygen delivered to the patient.
• Respiratory Rate (Backup Rate):
  • For BiPAP S/T mode, the minimum number of breaths the ventilator will deliver per minute.
  • Ensures a minimum level of ventilation.
• Inspiratory Time (I-time): The duration of the inspiratory phase.
• Ramp Time: The time it takes for the ventilator to reach the set IPAP.

I. Step-by-Step Guide to Initiating NIV

Here is a step-by-step guide to initiating NIV:

1. Patient Assessment:
   • Evaluate the patient’s respiratory status, including respiratory rate, work of breathing, and oxygen saturation.
   • Assess the patient’s level of consciousness and ability to protect their airway.
   • Determine the appropriate NIV mode (CPAP or BiPAP) and settings based on the patient’s condition.
2. Equipment Setup:
   • Ensure the NIV ventilator is functioning correctly.
   • Select the appropriate size and type of mask (nasal, oronasal, or full-face).
   • Connect the mask to the ventilator tubing.
   • If needed, connect the oxygen source and adjust the FiO2.
   • Set up the humidifier, if required.
3. Patient Preparation:
   • Explain the procedure to the patient, providing reassurance and addressing any concerns.
   • Position the patient upright or in a semi-Fowler’s position to optimize lung expansion.
4. Mask Fitting:
   • Fit the mask on the patient’s face, ensuring a good seal while avoiding excessive pressure.
   • Adjust the head straps to secure the mask in place.
   • Check for air leaks and adjust the mask as needed.
5. Initial Settings:
   • Start with low initial pressure settings:
     • For CPAP: Start with 5-8 cm H2O.
     • For BiPAP: Start with IPAP 10-12 cm H2O and EPAP 4-5 cm H2O.
   • Set the FiO2 to the desired level.
   • For BiPAP S/T mode, set an initial respiratory rate (e.g., 12-16 breaths/min).
6. Titration and Monitoring:
   • Gradually increase the pressure settings as tolerated by the patient, while closely monitoring their response.
   • Assess the patient’s:
     • Respiratory rate and effort
     • Oxygen saturation (SpO2)
     • Level of consciousness
     • Heart rate and blood pressure
     • Tidal volume (if available)
     • Patient comfort and mask seal
   • Adjust settings to achieve the desired clinical response:
     • Increase IPAP to improve ventilation and decrease respiratory rate.
     • Increase EPAP to improve oxygenation.
     • Adjust FiO2 to maintain target SpO2.
7. Ongoing Management:
   • Continue to monitor the patient closely and adjust settings as needed.
   • Provide regular oral care and skin care.
   • Ensure adequate humidification.
   • Address any complications or issues that may arise.

J. Monitoring and Assessment During NIV

Close monitoring is essential during NIV:

• Vital signs (heart rate, blood pressure, respiratory rate)
• Oxygen saturation (SpO2)
• Level of consciousness
• Respiratory effort and pattern
• Mask seal and patient comfort
• Gas exchange (ABGs if necessary)
• Signs of improvement or deterioration

Regularly assess for complications and adjust the NIV settings as needed.

K. Weaning from NIV

Weaning from NIV should be considered when the patient’s condition improves.

Criteria for weaning:

• Improved respiratory status
• Stable vital signs
• Adequate level of consciousness
• Improved gas exchange
• Ability to maintain spontaneous ventilation

The weaning process involves gradually decreasing the ventilatory support (pressure settings) while closely monitoring the patient’s response.