Non Invasive Ventilation

Introduction to Non-Invasive Ventilation

• Presenter: San Fernando, Emergency Physician in South West Sydney.

• Focus: Non-Invasive Ventilation (NIV) in emergency medicine, specifically CPAP and BiPAP.

Reasons for Using Non-Invasive Ventilation

• Ventilatory Failure:

  • Patients experience respiratory difficulty and become fatigued or weak, unable to handle respiratory challenges.

  • The forces opposing ventilation surpass the respiratory effort of the patient.

• Failure of Gas Exchange:

  • Occurs when alveoli are compromised due to substances like pus, phlegm, fluid, or blood.

  • Gas exchange between the alveoli and bloodstream is disrupted.

  • Often, both ventilatory failure and gas exchange failure are present.

Mechanism of Action of Non-Invasive Ventilation

• NIV can help mitigate further pulmonary complications by:

  • Keeping airways open and preventing collapse, particularly during expiration.

  • Enhancing alveolar ventilation and reducing the work of breathing.

  • Offering beneficial effects on cardiac function.

Application of CPAP and BiPAP

• CPAP (Continuous Positive Airway Pressure):

  • Best suited for treating hypoxia, which is low oxygen supply.

  • Example: Used in acute pulmonary edema, especially cardiogenic types.

  • Mechanism: Improves movement of alveolar fluid into interstitium, increases surfactant production, and recruits collapsed alveoli.

  • Recommended in isolation without hypercapnia.

• BiPAP (Bilevel Positive Airway Pressure):

  • Designed for hypercapnia (high CO2 levels).

  • Provides both inspiratory and expiratory pressures, helping to reduce the work of breathing.

  • Comprises inspiratory pressure and an expiratory pressure, where the difference defines pressure support.

  • Particularly effective for COPD exacerbations, addressing both hypoxia and hypercapnia simultaneously.

Case Study Example

• Hypothetical Patient: 68-year-old man with acute pulmonary edema.

  • Symptoms: Shortness of breath, high respiratory rate (40), sweating, oxygen saturation at 90% despite supplemental oxygen.

  • Initial treatment: Established on CPAP (5-10 cm H2O, FiO2 at 40%).

• Initial Blood Gas Results:

  • PaO2: 55, PaCO2: 72, indicating both hypoxia and hypercapnia.

  • Transitioned to BiPAP (initial IPAP 12 cm H2O, EPAP 6 cm H2O).

  • Adjusted FiO2 to 22%.

  • Improvement in O2 saturation and reduction in work of breathing observed.

Adjustments to Treatment

• One hour later, patient appears to tire despite improved oxygenation.

  • Repeat arterial blood gas indicates an elevated CO2 (75).

  • Correct response: Increase pressure support by adjusting IPAP and EPAP.

  • Increase IPAP to 15 cm H2O and decrease EPAP to 5 cm H2O, achieving an increased pressure support of 10 cm H2O.

Conclusion

• Summary of treatment approach:

  • CPAP is used for hypoxia.

  • BiPAP is utilized for hypercapnia, leveraging pressure support to minimize the work of breathing.

  • Emphasis on continuous assessment and adjustment of ventilation settings.

Closing

• Thank you for watching; stay tuned for more emergency medicine insights.