Non-invasive Positive Pressure Ventilation (NPPV) Bach Mai Hospital Sean M Caples College of Medicine Mayo Clinic Outline  “NPPV” = BiLevel and/or CPAP  Historical Overview  Rationale for use of NPPV, physiology Outline  Review of important studies in selected clinical situations COPD exacerbation  Acute cardiogenic pulmonary edema  Hypoxic resp failure/ARDS/lung injury  Post-operative setting  Extubation failure   Proposed Algorithm History  Negative pressure ventilation (Iron Lung)  Invasive ventilation with polio epidemic  IPPB-intermittent positive pressure breathing by mouthpiece to deliver aerosol medications  Sullivan-CPAP for obstructive sleep apnea 1981 Why Use NPPV ? Avoid the complications of endotracheal intubation: Acute placement of the tube: trauma, aspiration, hypotension Nosocomial infection: VAP-ventilator associated pneumonia, sinusitis Post-extubation: hoarseness, tracheal stenosis, vocal cord dysfunction Patient Factors: Allows swallowing and speech NPPV for Acute Respiratory Failure at Mayo Clinic From Peter Gay, MD NPPV: Mechanisms of Action in Acute Respiratory Failure  Respiratory Muscle Unloading resulting in: Decrease PaCO2  Increase PaO2  Decrease respiratory rate  NPPV for Acute Exacerbation of COPD- A randomized trial Brochard et al, NEJM 1995;333:817-22  Randomized, European Centers     Usual Care (UC) vs NPPV Inclusion Criteria = RR>30, PaCO2>45, pH45 or >20% from pre-extubation)  Clinical signs of resp muscle fatigue or increased WOB  Resp rate >25 (for hours)  Resp acidosis: pH < 7.30 with PaCO2 > 50  Hypoxemia: SpO2 < 90% or PaO2 < 80 on FiO2 > 0.50 NPPV with Early Signs of Extubation Failure % of pts No diff in age, SAPS II, duration of vent (10 v 11d), initial cause for RF or pre-extub resp variables * * Esteban et al, NEJM 2004; 350:2452 Higher Mortality in NPPV Failure Average time to intubation following failure: NPPV: 12 hours Standard: 2.5 hours May NPPV Be Detrimental?  Very few COPD patients (13%)  Relatively mild respiratory failure at time of randomization: RR 29, pH 7.39, PaCO2 46, PaO2 79  Delay in definitive treatment (whether NPPV or intubation) may be costly NPPV to Prevent Respiratory Failure after Extubation Early NIV Averts Extubation Failure in Pts at Risk M Ferrer, AJRCCM Vol 173: 164-170, (2006)  Hypothesis: Identify “at-risk” patients before extubation and apply NPPV prophylactically (age > 65, cardiogenic edema, high Apache)  Upon extubation: Supplemental oxygen or immediate BiPAP for 24 hrs  No more than hrs of NPPV use if signs of failure and need for re-intubation Early NIV Averts Extubation Failure in Pts at Risk M Ferrer, AJRCCM Vol 173: 164-170, (2006) NPPV to Prevent Extubation Failure: Recommendations •Routine (self-extubated)- No •Overt, severe post-extubation failure; unstable cardiac/other medical problems- No •In Post-operative patients or Selected High Risk Patients - Possibly Delay of reintubation, if needed, beyond – hours may be detrimental Proposed Mayo NPPV Algorithm SUMMARY NPPV for ARF  NPPV benefit for COPD exacerbation, CHF  NPPV vs endotracheal intubation:  Reduces complications, especially nosocomial pneumonia for many causes of ARF  Absolute efficacy for hypoxic ARF or CAP without COPD is less clear  NPPV probably beneficial for selected patients for failed extubation [...]... Effect of NIPPV on the need for invasive mechanical ventilation NNT = 6 NNT = 7 NPPV in Hypoxemic Respiratory Failure A heterogeneous group 1 2 3 ARDS / Acute lung injury Pneumonia Trauma L’Her, AJRCCM 2005 Comparison of NPPV & Conventional Mechanical Ventilation in Pts with ARF Antonelli M, NEJM; 339: 429-435, 1998  How does NPPV compare with conventional mechanical ventilation in hypoxemic respiratory... rapid improvement in gas exchange and respiratory rate Many questions remain  Sedation- what’s the right amount? Patient cooperation- how much do you need? Mehta S, Hill NS, State of the Art: Noninvasive Ventilation AJRCCM 163:540-77, 2001 NPPV (CPAP or Bi-Level) for Acute Cardiogenic Pulmonary Edema Mechanisms of Action  Opens flooded/collapsed alveoli     (↑ functional residual capacity, improves... Bi-Level NPPV or endotracheal intubation  Non- COPD pts with Hypoxic ARF Comparison of NPPV & Conventional Mechanical Ventilation in Pts with ARF Antonelli M, NEJM; 339: 429-435, 1998 RESULTS % ICU Mortality ICU Stay (days) %Serious complications %ETT rel pneum/sinus ETT 47 16+17 66 31 NPPV 28 9+7 38 3 p< 0.19 0.04 0.02 0.003 Comparison of NPPV & Conventional Mechanical Ventilation in Pts with ARF Antonelli... mortality= 31% vs 30% (P= 89)  ICU length of stay= 6.5 vs 6.0 days (P= 43) Conclusion- Despite early physiologic improvements, CPAP did not improve outcomes in patients with hypoxia alone Failure of non- invasive ventilation in patients with acute lung injury: observational cohort study Rana S, Gay P, Buck C, Hubmayr R, Gajic O, Crit Care 2006  Design:   Observational cohort study of 79 cons pts with... try NPPV  10/32 pts failed NPPV- age 47 vs 66 (p