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NON-INVASIVE VENTILATION IN ACUTE RESPIRATORY FAILURE

NON-INVASIVE VENTILATION IN ACUTE RESPIRATORY FAILURE. Virginia Chung, MD Chief, Pulmonary & Critical Care Medicine Jacobi Medical Center January 30, 2013. OUTLINE. Acute respiratory failure Definitions, Pathophysiology NIPPV / NIV / BPAP / BiPAP vs CPAP

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NON-INVASIVE VENTILATION IN ACUTE RESPIRATORY FAILURE

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  1. NON-INVASIVE VENTILATION IN ACUTE RESPIRATORY FAILURE Virginia Chung, MD Chief, Pulmonary & Critical Care Medicine Jacobi Medical Center January 30, 2013

  2. OUTLINE • Acute respiratory failure • Definitions, Pathophysiology • NIPPV / NIV / BPAP / BiPAP vs CPAP • Indications / Contraindications • Use of NIV in: • COPD, Severe Asthma, CAP, ARDS, APE/CHF, DNI/DNR • Summary of Recommendations

  3. BACKGROUND • Respiratory failure is a syndrome where the respiratory system fails in one or both of its gas exchange functions: oxygen uptake and carbon dioxide elimination. • Respiratory failure may be acute or chronic. • While acute respiratory failure (ARF) is characterized by life-threatening derangements in ABGs and acid-base status, manifestations of chronic respiratory failure are less dramatic and may not be as readily apparent.

  4. CLASSIFICATION • Respiratory failure can be classified as HYPOXEMIC or HYPERCAPNIC and may be ACUTE or CHRONIC. • TYPE I: Hypoxemic Respiratory Failure is characterized by a PaO2 < 60 mmHg with a normal or low PaCO2. Most common form of respiratory failure Can be associated with virtually all acute diseases of the lung Examples: pulmonary edema, pneumonia, ARDS, PE

  5. CLASSIFICATION • TYPE II : Hypercapnic respiratory failure is characterized by a PaCO2 of > 50 mmHg. Hypoxemia is common in patients with Type II failure who are breathing room air. pH depends on the serum bicarbonate level, which, in turn, is dependent on the duration of the hypercapnia Examples: opiate overdose, neuromuscular disease, status asthmaticus, severe COPD.

  6. Acute vs. Chronic Hypercapnic Respiratory Failure • Acute hypercapnic respiratory failure develops over minutes to hours; therefore, pH < 7.3. • Chronic hypercapnic respiratory failure develops over several days or longer, allowing time for renal compensation and an increase in serum bicarbonate concentration; pH is only slightly decreased.

  7. PATHOPHYSIOLOGY • Hypoxemic Respiratory Failure • Hypoxemia can be caused by any one of these four mechanisms: Ventilation-Perfusion (V/Q) mismatch, Shunt, Diffusion Impairment, and Hypoventilation. • V/Q mismatch is the most important and common mechanism. Areas of low ventilation relative to perfusion (low V/Q units) lead to hypoxemia. • Shunts can be intracardiac or intrapulmonary.

  8. Causes of Hypoxemic Respiratory Failure Pneumonia Cardiogenic Pulmonary Edema (CHF) Non-cardiogenic Pulmonary Edema (ARDS, seizure) Pulmonary Fibrosis (IPF, sarcoidosis) COPD / Asthma Pneumothorax Pulmonary Embolism Pulmonary Arterial Hypertension (Primary, Scleroderma) Pneumoconiosis (Coal-workers)

  9. Causes of Hypoxemic Respiratory Failure Hypersensitivity Pneumonitis Congenital Heart Disease Bronchiectasis Fat Embolism Syndrome Kyphoscoliosis Obesity Massive Pleural Effusions Pulmonary Hemorrhage

  10. Causes of Hypercapnic Respiratory Failure COPD Status Asthmaticus Drug Overdose Poisonings Myasthenia gravis Guillain-Barre Head and Cervical Cord Injury Poliomyelitis Polyneuropathy Primary Alveolar Hypoventilation Obesity Hypoventilation Syndrome Severe Pulmonary Edema Severe ARDS Myxedema Tetanus

  11. SUMMARY • Two types of acute respiratory failure: • Type I : Hypoxemic , where PaO2 < 60 mmHg • Type II : Hypercapnic , where PaCO2 > 50 mmHg NB* : for status asthmaticus, PaCO2 > 40 mmHg signifies hypercapnic respiratory failure. • V/Q mismatch is the most common mechanism for both types of respiratory failure. • Many conditions can cause both hypoxemia and hypercapnia : e.g., COPD, Obesity, ARDS, severe pulmonary edema, neuromuscular disorders. • Avoid worsening hypercapnia by judiciously giving the patient supplemental oxygen. • Some patients may require NIPPV or mechanical ventilation.

  12. NIPPV / NIV / BPAP/ BiPAP

  13. BiPAP Graphics

  14. BENEFITS OF NIV • Symptomatic relief of dyspnea • Correction of gas exchange • Improve lung mechanics • Facilitate sleep • Correct mental status • Pre-oxygenate for intubation • Prevent ETI • Avoid complications of ETI • VAP • Sepsis/shock • Tracheostomy • GI bleed • DVT • Decrease mortality associated with respiratory failure • Use NIV in the place of IMV • Assist DNI patients with respiratory failure

  15. PHYSIOLOGIC MECHANSIMS • Unload respiratory muscles inspiratory cycle: hyperinflation >> respiratory muscle shortening/disadvantage Decreased compliance of respiratory system • NIPPV = augments respiratory effort, Increases Vt, decreases RR • Overcome intrinsic peep intrinsic peep>> difficulty in generating pressure gradient for flow • CPAP • Stent open lower airway expiratory cycle • CPAP to reduce obstruction • Stent open upper airway • CPAP

  16. PHYSIOLOGIC MECHANSIMS • Reduce CO2 production • NIPPV • Improve gas exchange by decreasing atelectasis • CPAP/NIP • Reduce negative intra-thoracic pressure swings • CPAP • Redistribute pulmonary edema • CPAP/NIPPV • Increase CO by decreasing effective LV afterload • CPAP

  17. Contraindications for NIV Absolute contraindications: • Coma • Cardiac arrest • Respiratory arrest • Any condition requiring immediate intubation Other contraindications (rare exceptions) • Cardiac instability (shock+need for vasopressors, ventricular dysrhythmias, complicated AMI) • GI bleeding – intractable emesis, uncontrolled bleeding

  18. Contraindications for NIV • Inability to protect airway • impaired cough or swallowing • poor clearance of secretions • depressed sensorium and lethargy • Status epilepticus • Potential for upper airway obstruction • Extensive head / neck tumors • Any other tumor with extrinsic airway compromise • Angioedema or anaphylaxis causing airway compromise

  19. Candidates for NIV • Patient cooperative (excludes agitated, belligerent, comatose patients) • Dyspnea (moderate to severe, short of respiratory failure / agonal breathing) • Tachypnea (rr> 24 /min) • Increased work of breathing (+accessory muscle use, pursed lip breathing) • Hypercapnic respiratory acidosis (pH range 7.10 – 7.35) • Hypoxemia (PaO2/FiO2 < 200 mm Hg, best in rapidly reversible causes for hypoxemia)

  20. Suitable Clinical Conditions for NIV Most patients with : • COPD • Cardiogenic pulmonary edema Selected patients with : • CAP + COPD • Asthma / CF • Decompensated OSA/OHS, cor pulmonale • ARDS • Immunocompromised state / mild PCP • Neuromuscular respiratory failure • DNI +/- DNR status • Post extubation COPD / post –op respiratory failure

  21. NIV: utilization classification • mandatory ventilation • Alternative to intubation • severe ARF, meet criteria for IMV • Failed medical treatment • Trials: NIV vs IMV after failed MT • Primary outcome: mortality • supportive ventilation • Prevent intubation • mild-to-moderate ARF/does not meet criteria for IMV • Trials: NIV+MT vs MT • Primary outcome: intubation

  22. NIV: utilization classification • prophylactic ventilation • To prevent ARF in patients • no substantial impairment of gas exchange • Trials: NIV+MT vs MT • Primary outcome: Blood gas values, FEV1, etc • other purpose ventilation • bronchodilation • Pre-oxygenation • Facilitate sleep

  23. INCLUSION CRITERIA NON-INVASIVE VENTILATION FOR ACUTE EXACERBATIONS OF COPDBROCHARD, MANCEBO, WYSOCKI: NEJM, 1995 SUPPORTIVE VENTILATION RCT COPD with exacerbation of dyspnea > two days and at least two of the following: RR>30 PaO2 < 45 mm Hg pH < 7.35 after > 10 min on RA • EXCLUSION CRITERIA RR< 12 breaths, sedative drugs within the previous 12 hours CNS disorder unrelated to hypercapnic encephalopathy or hypoxemia Cardiac arrest (within the previous five days) Cardiogenic pulmonary edema Asthma

  24. NON-INVASIVE VENTILATION FOR ACUTE EXACERBATIONS OF COPDBROCHARD, MANCEBO, WYSOCKI: NEJM, 1995 SUPPORTIVE VENTILATION RCT kyphoscoliosis as the cause of chronic respiratory failure neuromuscular disorder as the cause of chronic respiratory failure Upper airway obstruction, facial deformity, tracheotomy need for immediate intubation = a clear cause of decompensation requiring specific treatment (e.g., peritonitis, septic shock, AMI) pulmonary thromboembolism pneumothorax, hemoptysis severe pneumonia recent surgery or trauma

  25. Primary outcome: need for intubationSecondary outcomes: LOS hosp, complications, length of MV, in hosp mortality Standard treatment arm • `O2 via NC up to 5 liters for target sat > 90% • Medications: SQH, antibiotics, bronchodilators, IV corticosteroids or aminophylline NIPPV treatment arm: • same as above and • BIPAP at least 6 hours/day, NC for at least 2 hours/day • IP=20, EP=0, flow cycled, PAC if patient is apneic

  26. Primary outcome: need for intubationSecondary outcomes: LOS hosp, complications, length of MV, in hosp mortality Major Criteria for intubation: • respiratory arrest, pauses with LOC, gasping, requiring sedation, HR<50 with lethargy, SPB<70 Minor Criteria for intubation: • RR> 35 and > on admission, pH < 7.3 and < admission, PaO2<45 despite O2, worsening MS One Major Criteria or 2 Minor Criteria after one hour of RX would be indication for intubation. In the NIPPV group if 2 minor criteria met off NIV, they can be placed back on it. But if problem persisted then intubation performed

  27. NIV for acute exacerbations COPD Brochard, NEJM, 1995

  28. Primary outcome: need for intubation • 85 patients total • 42 standard rx (ST) group  31 intubated (74%) • 43 NIPPV rx group  11 intubated (26%) • ARR = 48%, NNT= 2 • Major criteria for intubation met by 10/31 (ST) and 8/11 (NIPPV) • At 1 hour: • NIPPV group: • improved encephalopathy, rr, PaO2, pH • Standard group: • worsening enceph, PaCO2, pH

  29. Encephalopathy score • 1= mild asterixis, • 2= marked asterixis, mild confusion, sleepy during the day • 3= major confusion with daytime sleepiness or agitation

  30. Primary outcome: need for intubation Need for intubation was associated with: • Higher SAP scores • Higher encephalopathy scores on admission. • On admission prior to randomization: • ST 1.6 • NIPPV 1.8 • At one hour: • the scores worsened in ST  1.9 • improved in NIPPV  1.5 (and 0.8 at 12h) • Results: • ST group  no ETI = 0.7; +ETI = 1.9 • NIPPV group  no ETI = 1.6; +ETI = 2.5

  31. NON-INVASIVE VENTILATION FOR ACUTE EXACERBATIONS OF COPDBROCHARD, MANCEBO, WYSOCKI: NEJM, 1995 SUPPORTIVE VENTILATION RCT Success probably related to rapid improvement in encephalopathy • Mortality: ST 29% (32% intubated) • NIPPV: 9% (25% intubated) • Complications in ST 48%, NIPPV 16% • NIPPV group: average NIPPV = 4 days; average MV = 25 days • ST group: average MV =17 d • LOS: ST 35 days, NIPPV 23 days

  32. Noninvasive positive pressure ventilation in acute respiratory failure due to COPD vs other causes:Ritesh Agarwal, Rajesh Gupta, Ashutosh N Aggarwal, Dheeraj Gupta SUPPORTIVE VENTILATION: Both hypoxic and hypercapnic patients responded to NIV: • COPD patients improved their PCO2 and pH • PNA/ARDS patients improved their PAO2 • Avoided ETI in 87% of COPD patients and 61% all other etiologies • Mortality:12% in COPD, 18% other etiologies

  33. Non-invasive positive pressure ventilation in acute respiratory failure due to COPD vs other causes:R Agarwal, R Gupta, A N Aggarwal, D Gupta: Supportive ventilation MIXED POPULATION STUDY • Primary outcome: NIPPV failure defined as inability to stabilize or improve in 60 min • gas exchange • dyspnea • mental status

  34. Noninvasive positive pressure ventilation in acute respiratory failure due to COPD vs other causes:Ritesh Agarwal, Rajesh Gupta, Ashutosh N Aggarwal, Dheeraj Gupta Etiology is the only independent predictor of outcome: STUDIES WITH MIXED POPULATIONS ARE VIRTUALLY MEANINGLESS NIPPV failure rate is very high in Pneumonia, ARDS: • transient improvement in RR, HR and blood gas parameter does occur • the underlying process such as sepsis or pneumonia is not affected by NIPPV • improvement with antibiotics and other supportive measures takes at least 24- 48 hours which can cause late NIPPV failure despite an improvement in the first few hours

  35. RECOMMENDED ALGORITHMNoninvasive ventilation in acute exacerbations of COPDM.W. Elliott, Eur Respir Rev 2005

  36. Factors for NIV Failure NIPPV failure: likely to need intubation • APACHE 2 score higher than 29 • Higher PaCO2 on admission (>85) • Lower pH( 7.2 or less) leads to higher intubation rates but not worse outcomes • Failure to reduce PaCO2 in 1-2 hours • often related to air leak/poor interface • Hypercapnic encephalopathy • Asynchrony, copious secretions Despite higher ETI in the likely to fail group this did not lead to higher mortality from trial of NIV

  37. SEVERE ACUTE ASTHMA • Increased WOB secondary to • inspiratory cycle: hyperinflation • expiratory cycle: airway obstruction • Increased CO2 production secondary to increased WOB • Decreased CO2 elimination • Mucus plugging resulting in atelectasis and hypoxemia • Rational for BPAP/CPAP: unload respiratory muscles during inspiration and reduce obstruction with CPAP: airway stenting • Improve gas exchange by eliminating atelectasis, distribute BD’s

  38. A Pilot Prospective, Randomized, Placebo-Controlled Trial of Bilevel Positive Airway Pressure in Acute Asthmatic Attack, Arie Soroksky, MD, Chest 2003 PROPHYLACTIC Ventilation • Patients in ED • Nasal BPAP at EPAP 5, IPAP 8-15 • pH both groups 7.4, PCO2= 34 • FEV1 • 37%  57% pred in NIV group • 34%  44% pred in control • Also significant improvement in ED d/c rates, RR

  39. A Prospective RCT on the Efficacy of Noninvasive Ventilation in Severe Acute Asthma: Dheeraj Gupta MD DM, 2010 SUPPORTIVE Ventilation • Clearly not the most severe status asthmaticus group but initial FEV1= 23% pred and RR 37, P/F ratio < 300 and normocapnea • 25 pt in each arm treated in a respiratory ICU • Does not show significant statistical differences in improvement of FEV1, RR, or P/F ratio between the two groups • + trend toward a quicker reversal of bronchial obstruction= 50% improvement in (FEV1) at 4 hours of treatment (64% vs 86%)

  40. A Prospective RCT on the Efficacy of Noninvasive Ventilation in Severe Acute Asthma: Dheeraj Gupta MD DM, 2010 SUPPORTIVE Ventilation • Shorter ICU stay (median 10 h vs 24 h) and hospital stay (median 38 h vs 54 h) • Lower doses of BD were used in NIV group • 4 pts in med arm had treatment failure but improved with NIV (masking potential benefit of NIV arm or need for intubation) (no one in the ST group was intubated) • 2 patients on NIV required IMV for respiratory fatigue, hypoxia, and agitation • There was no mortality in either group

  41. Noninvasive Positive Pressure Ventilation in Status Asthmaticus, Meduri, G: Chest 1996 • MANDATORY VENTILATION • 17 patients with severe asthma exacerbation, not improved with medical management, and not immediately intubated in ED. • Average pH 7.25, PCO2 67 • 2 required intubation due to rising PCO2 • There were no controls

  42. Non-invasive mechanical ventilation during status asthmaticus: M.M. Fernandez 2001 MANDATORY VENTILATION • Retrospective Observational Cohort Study • Status defined as: • hr > 140/min, +dyspnea, +accessory muscle use, • rr >35/min, pulsus paradoxus >18 mmHg, PEF <100 l/min, • hypercapnia • 14 medically managed patients improved and did not need MV or NIMV • 5/11 MV patients intubated in ED • NIMVnot started until patients arrived in ICU • 22 pts were started on NIMV (CPAP 7 and BIPAP 10/5) because their PCO2 was rising (53  63) • 3 were later intubated, 1/3 died of VAP, no other complications were noted

  43. Non-invasive mechanical ventilation during Status Asthmaticus: M.M. Fernandez • RR declined more slowly than in the MV • both PCO2 and RR did not improve at tx to ICU but improved rapidly after NIV initiation • All blood gases eventually normalized • P/F ratio: • MV 212 improved to 285 • NIV 261 improved to 292 • Medical group 314 improved to 324 • Overall: • some improved with med therapy • severe cases required intubation • moderate cases were not harmed by NIV

  44. SUMMARY of RESULTS: NIV for ASTHMA • Some patients need to be intubated immediately: • NIV is Contraindicated: • CAC • hemodynamic or electrical instability • life threatening hypoxemia • AMS • Severe respiratory acidosis is a relative contraindication • “Mandatory Ventilation” Has no RCT associated with it. • Meduri and Fernandez retrospective studies show that a trial of NIV can correct impaired gas exchange (pH 7.2, 7.25) without increasing risk to patient.

  45. SUMMARY of RESULTS: NIV for ASTHMA • “Supportive Ventilation” one RCT • Did not show significant differences in improvement of FEV1, RR, or P/F ratio • Did show decreased ICU and hospital los, Intubation rates ? increased • “Prophylactic Ventilation” oneRCT • Significant differences in improvement of FEV1 and rr • “Inhaler ventilation/ bronchodilator delivery” • Some significant improvement in FEV1 with or without BD’s

  46. Non-invasive pressure support ventilation in severe CAP,Jolliet, Intensive care medicine, 2001, Observational study: SUPPORTIVE VENTILATION • Oxygenation and RR improved in all • Drager: PS 15/PEEP5 • Only 5 pts wore NIV continuously • Effects of NIV dissipated 30m post d/c • Likely effect of NIV: recruitment, reduction in dyspnea, RR, WOB, oxygen consumption, improved gas mixing on inspiration. • 16/24 were intubated • Mortality IMV= 8/16, NIV only 0/8 • Difference on admission between groups only in average age ETI 55, NIV only 37 • COPD, APE, restrictive lung dz patients were excluded.

  47. NIV for PNA SUMMARY of FINDINGS • 4 trials: observational, supportive RCT x 2, mandatory RCT x 1 • Supportive ventilation 1 RCT • Decreased mortality and intubation rates for PNA + COPD • Increased mortality for non- COPD patients • Supportive ventilation 2 RCT • Decreased mortality and intubation rates • Decreased HAP, septic shock • Supportive ventilation 3 observational • Decreased mortality in patients not requiring intubation 0/8 vs 8/16 • ETI patients 16/24 were older • Mandatory Ventilation • 8/8 patients in the NIV arm were intubated • Mortality trended toward better in NIV group

  48. Observational case-control study of non-invasive ventilation in patients with ARDS, Domenighetti, G Mandatory Ventilation • 24 patients with ARDS: matched for age SAP score, P/F and pH • 12 placed on NIV, • 12 immediately ETI NIV failed in 4/12 patients secondary to distant organ failures. NIV success patients had: • reduced cumulative time on ventilation ; reduced los in ICU After the first 60h of ventilation: • PaO2: NIV= 146 +/- 52 mmHg vs ETI= 109 +/- 34 mmHg; p = 0.05 ICU mortality rate did not differ significantly between the groups but tended to be higher in the NIV group.

  49. NIV for ARDS/ALI • No RCT dedicated to ARDS/ALI • Other trials: • Ferrer: • intubation rates NIV 6/7, control 8/8 • mortality rates NIV 71%, control 88% • Antonelli: Multicenter Survey: • SAPS > 34 and P/F < 175 after 1 hour NIV associated with need for ETI • Sameer Rana: ALI: cohort study: predictors of failure • Shock but not sepsis, lactic acidosis • Severe hypoxemia PaO2/FiO2 < 147 • Higher Vt, minute ventilation causing lung injury • Patients who failed had a higher mortality than predicted by APACHE score

  50. Cardiogenic pulmonary edema • The Rational: effects of CPAP/PS • augmentation of cardiac output and oxygen delivery • improved functional residual capacity • improved respiratory mechanics • decreased left ventricular afterload

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