Non invasive positive pressure ventilation (NPPV)

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:  Increase Pa

Non-invasive Positive Pressure

Ventilation (NPPV) Bach Mai Hospital

Sean M Caples College of Medicine

Mayo Clinic

 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

Outline

 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

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:

 Increase PaO2

 Decrease respiratory rate

NPPV for Acute Exacerbation of

COPD- A randomized trial

Brochard et al, NEJM 1995;333:817-22

 Randomized, 5 European Centers

 Usual Care (UC) vs NPPV

 Inclusion Criteria = RR>30, PaCO2>45, pH<7.30

 Exclusion Criteria = Need For ETT, Extreme Dyspnea

Largest Trial-14 UK Hospitals

Conducted on the Wards (not ICU)

•Physiologic improvements of similar magnitude, but occur earlier with NPPV

•26 mins average nursing care burden/day on the wards

•Still, a high rate of death with NIV if more acidotic (? Better in the ICU)

Meta-Analysis NPPV in COPD Exacerbations

Keenan S, Ann Intern Med, 2003

•NPPV best for severe exacerbations of COPD (hypercapnia)

•Little evidence to support use of NPPV in milder Exacerbations (PaCO2 < 45)

 Expertise of available resources

 Fewer complicating illnesses (esp pneumonia)

 Hypercapnic Acidosis (pH ≤ 7.30)

 Prompt initiation of treatment with rapid

improvement in gas exchange and respiratory rate

 Many questions

remain- Sedation- what’s the right amount?

 Patient cooperation- how much do you need?

NPPV for Acute Exacerbation of

COPD- Determinants of success

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 gas

exchange)

 Decreases cardiac preload

 Decreases cardiac afterload

 Overcomes resistance related to upper airway edema

CPAP unloads the left ventricle and inspiratory

muscles of patients with CHF…

Naughton et al Circ 1995

CPAP May Reduce Ventricular Volumes

Mehta, AJRCCM, 2000

 Bi-Level may more effectively unload respiratory muscles Chadda, et al Crit Care Med, 2002

 Bi-Level may improve physiologic indices more rapidly Mehta, et al Crit Care Med, 1997

BiLevel CPAP

Enthusiasm for Bi-Level

tempered in 1997

p = 0.06

•More patients with chest pain were

randomized to the Bilevel group

•Higher intrathoracic pressures may occur

with BiPAP, particularly with increasing resp

rates

•Hemodynamic effects could be exaggerated

Subsequent Trials have not replicated such problems with Bi-

Level

 ER based, 38 pts (Levitt M, J Emerg Med 21(4): 2001)

 Lower intubation for BiPAP= 23.8% vs O2= 41.2%

 No difference in ABGs, pH, and AMI rate was 19% in

the BiPAP and 29.4% for O2 (NS)

 CHF & hypercapnia AJRCCM 2003 Vol 168

 More rapid relief of distress, better gas exchange, and reduced intubation rate but no mortality change

Lancet, 2006

Effect of NIPPV on the need for invasive

mechanical ventilation

NNT = 6

NNT = 7

NPPV in Hypoxemic Respiratory Failure

A heterogeneous group

1. ARDS / Acute lung injury

2. Pneumonia

L’Her, AJRCCM 2005

 How does NPPV compare with

conventional mechanical ventilation in hypoxemic respiratory failure

 Design- Randomized 64 pts to 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

Comparison of NPPV & Conventional

Mechanical Ventilation in Pts with ARF

Antonelli M, NEJM; 339: 429-435, 1998

 Conclusions-

 ICU stay and ventilator complications reduced in pts with ARF who initially try NPPV

 10/32 pts failed NPPV- age 47 vs 66 (p<.006)

 Overall gas exchange improvement similar

 If ETT is avoided, pneumonia is rare

 High mortality if NPPV then ETT(90%)

Comparison of NPPV & Conventional Mechanical Ventilation in Pts with ARF

Antonelli M, NEJM; 339: 429-435, 1998

 Do those without chronic lung disease and free of

hypercapnia respond to CPAP?

 123 Patients with acute lung injury (Pneumonia 50%)

stratified for cardiac disease Mean PaO2/FiO2~ 145

 CPAP 5 to 10 vs high flow oxygen

 After 1 hr, sig responses greater with CPAP:

 Subjective responses e.g dyspnea (P<.001)

 PaO 2 /FiO2= 203 vs 151 mmHg (P= 02)

Treatment of Hypoxemic, Non-hypercapnic ARF

with CPAP- Randomized Controlled Trial

Delclaux C; (Brochard group) JAMA 284:2352-2360 2000

 But, higher overall number of serious adverse events occurred with CPAP= 18 vs 6 (P= 01)

 Results- No differences in CPAP vs Std Care:

 Intubation rate= 34% vs 39% ( P = 53)

 Hospital 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

Treatment of Hypoxemic, Non-hypercapnic ARF with

CPAP- Randomized Controlled Trial

Delclaux C; JAMA 284:2352-2360 2000

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 ALI

initially treated with NIPPV- 25 excluded (23 DNR).

 Results:

 54 pts, 38 (70.3%) failed NIPPV, including all 19 pts that had shock

 Successful pts had:

 Lower Apache III scores (55.5 vs 81.5; p<0.01)

 Less metabolic acidosis (base deficit: 0.52 vs -4.01; p=0.02) or

 Severe hypoxemia (PaO2/FIO2: 147 vs 112; p= 0.02)

Post-operative Use of

NPPV

CPAP for Treatment of Postoperative Hypoxemia

Squadrone, JAMA 2005;293:589-595.

Randomize 209 subjects

Post-Abdominal Surgery

(Cancer and non-cancer)

Probably reverses atelectasis

Auriant, AJRCCM, 2001

Bi-Level NPPV to attain

tidal volume of

8 to 10 ml/kg

 Randomized 40 solid organ transplant pts

 NPPV pts had better gas exchange and:

 Lower intubation rate (20% vs 70%; p=0.002)

 Less fatal complications (20% vs 50%; p= 0.05)

 Lower ICU mortality (20% vs 50%; p= 0.05), but hospital mortality same

 Consider NPPV use in these types of patient

NPPV Post-op failure with Organ Transplantation

Antonelli M, JAMA; 283: 235-241, 2000

 Fever, lung infiltrates and early hypoxemic

respiratory failure

 26 NPPV vs 26 standard-treatment (oxygen)

 NPPV group:

 Reduced intubation (12 vs 20, p=0.03)

 Less serious complications (13 vs 21, p=0.02),

 Fewer ICU (10 vs 18, p=0.03) or hospital deaths (13

vs 21, p=0.02)

NPPV with Immunosuppression

Hilbert G, NEJM 344: 481-487, 2001

NPPV following extubation from conventional ventilator

(ET tube)

 When to apply NPPV after extubation

 ? Routinely- resource intensive

 ? Wait for respiratory distress—it may be too late

 ? Prevention in selected high risk patients

 Adjunct to weaning: Early extubation for

prolonged weaning failure

NPPV for Post-extubation Respiratory

Distress: Randomized Controlled Trial

Keenan SP, JAMA 287:3238-3244, 2002

 Patients- Single Center in Canada

 Mixed Medical and Surgical ICU

 Patients intubated for ≥ 48 hrs, extubated by

standard criteria (n=81)

 Randomization to standard medical therapy

alone vs NPPV (Bi-level ST) by face mask when respiratory distress develops:

RR > 30, or > than 50% from baseline, or use

of accessory muscles of respiration or abdominal paradox

NPPV for Post-extubation Respiratory Distress: Randomized Controlled Trial

 Length of ICU (11.9 vs 10.8 days)

 Hospital stay (32.2 vs 29.8 days)

 Conclusions- NPPV no benefit in unselected

patients with respiratory distress <48 hours

after planned extubation

NPPV for Post-extubation Respiratory

NPPV with Early Signs of Extubation

Failure

Esteban et al, NEJM 2004; 350:2452

 37 ICUs, 8 countries, N = 993 MV>48h

 228 dev resp distress within 48h of extubation

 Separate randomization for COPD

 Randomization (within 48h of extubation) if:

 Hypercapnia (PaCO2>45 or >20% from pre-extubation)

 Clinical signs of resp muscle fatigue or increased WOB

 Resp rate >25 (for 2 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

No diff in age, SAPS II, duration of vent (10 v 11d),

initial cause for RF or pre-extub resp variables

Higher Mortality in NPPV Failure

Average time to intubation following failure:

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

 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 4 hrs of NPPV use if signs of failure and need for re-intubation

Early NIV Averts Extubation Failure

in Pts at Risk

Early NIV Averts Extubation Failure

in Pts at Risk

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 2 – 4 hours may be detrimental

Proposed Mayo

NPPV

Algorithm

SUMMARY NPPV for ARF

 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