NIV Basics

• CPAP = PEEP only
  • PEEP contributes towards oxygenation alone
  • same pressure for inspiration and for expiration (IPAP = EPAP)
• BiPAP = PEEP + delta = IPAP and EPAP
  • higher pressure for inspiration and lower baseline pressure (PEEP) for expiration
  • once again, the PEEP contributes to the oxygenation
  • the delta (IPAP - EPAP) contributes to the ventilation
  • BiPAP 10/5 provides the same ventilation as 15/10
• if you need to improve oxygenation, increase the PEEP, e.g. PEEP 5 to 10 or 10/5 to 15/10
• if you need to improve ventilation, then increase the delta (IPAP - EPAP), e.g. 10/5 to 15/5

NIV Guidelines for acute respiratory failure

Recommendations & Evidence

Strong Recommendations For NIV

1. BiPAP in Chronic obstructive pulmonary disease (COPD)-related acute or acute-on-chronic respiratory acidosis (pH <= 7.35, PaCO2 > 45 and RR > 20-24) despite standard medical therapy.
   1. No significant decrease in mortality in patients who are not acidotic. Focus should be on optimal medical therapy and titration of oxygen to 88-92%.
   2. Improvement of pH or RR from 7.25-7.35 to normal range is usually seen in the first 1-4 h after NIV initiation, and is a good predictor of sucess. BiPAP reduces dyspnea, need for immediate intubation, ICU admission, hospital LOS, and improves survival. When compared to first line intubation, BiPAP has similar mortality but decreases VAP/tracheostomy.
2. CPAP/BiPAP for cardiogenic pulmonary edema (excluding acute MI or cardiogenic shock)
   1. decreases LV afterload, increases RV afterload and decreases RV preload
   2. NIV decreases the need for intubation, reduces in-hospital mortality

Conditional Recommendations For NIV

1. Immunocompromised patients
2. Post-surgical patients (supra-diaphragmatic and abdominal/pelvic surgery)
3. Palliative cancer/terminal illness patients
4. Chest trauma patients
5. Prevention of respiratory failure post-exubation (See below)

No Recommendations For/Against NIV

1. acute asthma - Unable to make a recommendation on NIV in ARF due to asthma due to uncertainty of evidence.
2. influenza and other pandemic viral respiratory illnesses
3. De novo ARF - Unable to make a recommendation on NIV in de novo ARF due to uncertainty of evidence.

NIV for extubation and ventilator liberation

Risk Factors for Extubation Failure

1. Lung comorbidity
2. Cardiac comorbidity

3. Age > 65

4. 3/3 has >30% risk of extubation failure

5. 2/3 has >20% risk of extubation failure
6. For these above patients, we should be routinely extubating to NIV to decrease risk of respiratory failure. Consider doing this for 1/3 risk factors as well.

Guideline Recommendations

1. Prevention of respiratory failure post-extubation
   • conditional recommendation to USE to prevent in high-risk patients and NOT USE in non-high-risk patients
   • in unselected patients, NIV provides no benefit post-extubation compared with standard oxygen therapy
   • small studies demonstrate ICU mortality and 90-day mortality benefit when high-risk (Age, pulmonary, cardiac conditions) patients are randomized to NIV vs standard therapy post extubation
2. Treatment of established respiratory failure post-extubation
   • conditional recommendation to NOT use NIV for treatment of established post-extubation respiratory failure
   • increases ICU mortality, probably by delaying intubation when intubation is actually indicated
3. Facilitating weaning from invasive ventilation
   • conditional recommendation to USE to facilitate weaning from mechanical ventilation in patients with hypercapnic respiratory failure
   • no recommendations for hypoxemic patients

# References 1. Rochwerg B, Brochard L, Elliott MW, et al. Official ERS/ATS clinical practice guidelines: noninvasive ventilation for acute respiratory failure. European Respiratory Journal. 2017;50(2). doi:10.1183/13993003.02426-2016 2. Burns KE, Adhikari NK, Keenan SP, Meade MO. Noninvasive positive pressure ventilation as a weaning strategy for intubated adults with respiratory failure. Cochrane Database of Systematic Reviews. 2010;(8). doi:10.1002/14651858.CD004127.pub2 3. Ornico SR, Lobo SM, Sanches HS, et al. Noninvasive ventilation immediately after extubation improves weaning outcome after acute respiratory failure: a randomized controlled trial. Crit Care. 2013;17(2):R39. doi:10.1186/cc12549