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NIV in Acute Settings
Gamal Rabie Agmy ,MD ,FCCP Professor of Chest Diseases, Assiut University
Rationale for ventilatory assistance
Respiratory load
Respiratory muscles
capacity
Alveolar hypoventilation
PaO2 and PaCO2
Abnormal
ventilatory drive
Mechanical ventilation unloads the
respiratory muscles
Respiratory load Respiratory muscles
Mechanical
ventilation
Severe
Mild To
moderate
Not established
COPD
exacerbation
Post-extubation
COPD
exacerbation
Hypoxemic
Post-extubation
COPD
Exacerbation
Hypoxemic
Weaning
DNI order
Meaning of NIV use
ARF Severity
TO PREVENT TO AVOID
ETI ALTERNATIVE
to ETI
300 250 200 150 100 50
Low Tidal Volume Ventilation
Higher PEEP
HFO
Prone Positioning
ECMO
Low – Moderate PEEP
Neuromuscular Blockade
PaO2/FiO2
Increasing Severity of Lung Injury
Mild ARDS Moderate ARDS Severe ARDS In
creasin
g I
nte
nsit
y o
f In
terven
tio
n
NIV
ECCO2-R
iNO
The case of ARDS
Ventilators for NIV: Not all are useful in each indication
Standard interfaces
Facial masks
advantages:
– sufficient ventilation also during mouth breathing
– sufficient ventilation in patients with limited co-operation
disadvantages:
– coughing is difficult
– skin lesions (bridge of the nose)
Nasal masks
advantages:
– better comfort
– good seal
– coughing is possible
– communication is possible
disadvantages:
– effective in nose breathing only
– good co-operation is necessary
Standard interfaces
Nasal prong/nasal pillow systems
for patients with
claustrophobia
for patients with allergies
against straps
for low to moderate
pressures only
(< 20 cmH2O)
Standard interfaces
total-face masks
• Safe interface for acute respiratory insufficiency with high pressures
• well tolerated by the patients
Standard interfaces
helmet
• well tolerated by the patient
• no direct contact to the skin of
the face
• large dead space
• may influence the triggering of
the patient; use with CPAP
• very noisy
Standard interfaces
mouthpieces
• simple and cheap
• short-interval alternative
interface for long-term
ventilated patients
Custom-made masks
• for long-term ventilation
• if standard masks are not
tolerated
Standard interfaces
Physiologic evaluation of three
different interfaces
cohort: 26 stable patients with hypercapnic COPD or interstitial lung disease.
intervention: three 30 minute tests in two ventilatory modes with
facial mask / nasal mask / nasal prongs Conclusions: NIPPV was effective with all interfaces. patients„ tolerance: nasal mask > facial mask or nasal prongs pCO2 reduction: facial mask or nasal prongs > nasal mask
Navalesi P et al. Crit Care Med 2000;28:2139-2140
The respiratory System
Lungs Respiratory Pump
Pulmonary
Failure
• PaO2
• PaCO2 N/
Ventilatory Failure
• PaO2
• PaCO2
Hypoxic Respiratory Failure
Hypercapnic Respiratory Failure
Lungs Respiratory
Pump
Pulmonary Failure
• PaO2
• PaCO2 N/
Ventilatory Failure
• PaO2
• PaCO2
Hypoxic Respiratory Failure
Hypercapnic Respiratory Failure
The respiratory System
CNS breathing center 1. motor neuron
PNS 2. motor neuron
Motor endplate neuromuscular junction
Inspiratory respiratory muscles
Rib cage
Pleural pressure
Alveolar pressure
INSPIRATION
Respiratory
pump
CNS breathing center 1. motor neuron
PNS 2. motor neuron
Motor endplate neuromuscular junction
Inspiratory respiratory muscles
Rib cage
Pleural pressure
Alveolar pressure
INSPIRATION
Respiratory drive disturbances
Neuromuscular disorders ALS, Myasthenia gravis,
Duchenne Muscular Dystrophy, myopathy
Mechanical disturbances hyperinflation,
rib cage deformities
Thoracic instability
Reduced compliance
Increased airway resistance
Jolley CJ and Moxham J. Eur Respir Rev 2009; 18:112,1-14
• Diaphragm flattening
• Diaphragm
prestretching
• Systemic involvement
• Inflammation
• Steroids
• VIDD
• Co-morbidities
• Heart failure
• Pulmonary
hypertension
• Diabetes
• Shortening of
inspiration
• Airway obstruction
• Dynamic hyperinflation
• Intrinsic PEEP
• Thoracic prestretching
• Increased ventilatory
demand
• pulmonary failure
• anemia
• heart failure
COPD
Jolley CJ and Moxham J. Eur Respir Rev 2009; 18:112,1-14
Evans TW. Intensive Care Med 2001; 27:166-178
Mechanical ventilation
Noninvasive
“NIV”
invasive
NIV
success within
1-2 hours ?
Improveme
nt for several
days ?
Weaning
from NIV
Spontaneou
s breathing NIV Start
NIV in acute hypercapnic failure
- successful intervention
Rationale for
Non-invasive Ventilation (NIV)
to improve respiratory function and symptoms
• blood gases
• dyspnea
• respiratory rate
to avoid intubation and related complications
• ventilator-associated pneumonia (VAP)
- i.e. tube associated pneumonia
• local complications related to tube (early & late)
• complications related to catheterization
• tracheostomy and weaning failure
to improve outcome
• to reduce length of ICU and hospital stay
• mortality
NIV: Further advantages
Intermittent application
Improved clearance of secretion
Communication
Swallowing
No or mild sedation
NIV = MECHANICAL VENTILATION !
RATIONALE :
NIV improves oxygenation
Antonelli et al. NEJM 1998; 339:429-35
NIV increases VT and unloads diaphragm
Brochard et al. Am Rev Respir Dis 1989; 139:513-21
NIV decreases nosocomial infections
Girou E, Schortgen F, Delclaux C, et al. JAMA 2000, 284, 2361-7
Level Pathophysiology
High
(several RCT)
COPD Exacerbation
Acute cardiogenic failure
Weaning & Postextubation faulire in COPD
Medium Asthma bronchiale
Cystic fibrosis
Avoiding extubation failure
Do-not-intubate order
Low
ARDS (Acute respiratory distress syndrome)
NIV in acute hypercapnic failure
Level of evidence
NIV IN ACUTE HYPERCAPNIC FAILURE
CAUSED BY COPD
MORTALITY OF PATIENTS WITH COPD
REQUIRING INVASIVE MECHANICAL
VENTILATION FOR ACUTE RESPIRATORY
FAILURE
study year In-hospital Mortality, %
Knaus 1989 42
Stauffer et al 1993 33
Rieves et al 1993 43
Seneff et al 1995 32
Brochard et al 1995 29
Corrado et al 1998 27
Hill et al 1998 49
NIV bei AE-COPD
Behandlung von 8 Patienten,
um 1 Leben zu retten
BMJ 2003, 25; 326: 185
Lightowler JV. et al. BMJ 2003; 326:185-189
• NIV prevents intubation (NNT = 5) • NIV reduces mortality (NNT = 8)
NNT = number needed to treat
META-ANALYSIS (N=8)
• NIV resulted in
– decreased mortality (RR 0.41; 95% CI 0.26,
0.64),
– decreased need for ETI (RR 0.42; 95%CI
0.31, 0.59)
• Greater improvements within 1 hour in
– pH (WMD 0.03; 95%CI 0.02, 0.04),
– PaCO2 (WMD -0.40 kPa; 95%CI -0.78, -
0.03),
– RR (WMD –3.08 bpm; 95%CI –4.26, -1.89).
• Complications associated with treatment (RR
0.32; 95%CI 0.18, 0.56) and length of hospital
stay were also reduced with NPPV (WMD –
3.24 days; 95%CI –4.42, -2.06)
Lightowler, Elliott, Wedzicha & Ram BMJ 2003; 326:185
Lightowler JV. et al. BMJ 2003; 326:185-189
Conclusions NIV should be the first line intervention in addition to usual medical care to manage respiratory failure secondary to an acute exacerbation of chronic obstructive pulmonary disease in all suitable patients. NIV should be tried early in the course of respiratory failure and before severe acidosis, to reduce mortality, avoid endotracheal intubation, and decrease treatment failure.
first line
pH: 7.20–7,35
Improves outcome
NIV:
Confalonieri, et al. AJRCCM 1999; 160: 1585-1591
• 56 Pats with Pneumonia
• 23 COPD - 33 non-COPD
• Prospektive RCT:
- PSV + Standard-treatment
- O2 + Standard-treatment
Am J Respir Crit Care Med 1999;160:1585-1591
*
PaCO2 [mmHg]
Intubation [%]
ICU – length of stay [d]
2-Mo-moratliy [%]
NIV Standard
73
0
<1
11
68
55
8
63
32
38
3
43
34
47
5
33
NIV Standard
*p < 0.05 COPD (n = 23) Non-COPD (n = 33)
* *
*
* *
NIV in weaning: Early extubation
NIV in the weaning of patients with respiratory
failure due to COPD
NIV in weaning: Early extubation
24-36 hrs of PSV
50 patients
2 hr T-piece trial
failed
Randomized
NIV to 25 br/min, ABGs
6 by 2-4 cmH20/day
SBT 2 x/day
IPSV to 25 br/min, ABGs
“gradually” 6
CPAP or T piece, 2 x/day
Nava et al. Ann Intern Med 1998;128:721-8
NIV in the weaning of patients with respiratory failure due to
COPD
Invasive MV
NIV
Weaning success with NIV
NIV in the weaning of patients with ARF due to COPD Nava et al. Ann Intern Med. 1998;128:721-8
NIV in weaning: Early extubation
NIV to wean from respirator in stable COPD Nava et al. Ann Intern Med 1998;128:721-8
Invasive Non-invasive
MV days 17 10*
ICU days 24 15*
60d wean success 68% 88% *
60 d survival 72% 92% *
Pneumonia 25% 0% *
wean failure: death from MV and reintubation in 72h
NIV
success within
1-2 hours ?
Improveme
nt for several
days ?
Weaning
from NIV
Spontaneou
s breathing NIV Start
NIV IN ACUTE HYPERCAPNIA
Early Failure
Early NIV-failure
Intubation
Ineffective ventilation
Failing synchrony
NIV-failure
NIV IN ACUTE HYPERCAPNIA
Failure
Moretti M. et al. Thorax 2000;55:819-825
N= 137
Patients with
NIV success*
*NIV > 24 Std.
N= 31 Patients with late NIV-failure after primary NIV-success*
23%
Acute exacerbation of COPD
after 48 hours
Mortality IMV 53%, continuing NIV 92%
(NIV group pH 7.1 IMV 7.29)
Late failure predicted by low ADL scores,
pH and co-morbidity at admission
Moretti M. et al. Thorax 2000;55:819-825
Late NIV failure:
• lower pH at admission
• higher complication rates
• ICU-Mortality • 92% when NIV was continued
• 53% when intubation was performed
Invasive MV instead of NIV
- in terms of clinical issues
Invasive MV
Lavage
bei Hypersecretion
Unloading
respir. muscles
Improvement of
neurophysiologic
situation
Aim: Extubation after 2-3 day
- with/without consecutive NIV
Massive hypersecretion Massive Load
on respir. muscles Neurophysiologic
disaster
NIV im Koma
Thoraco-Restriction & Neuromuscular
disease
Obesity
Palliation
Special indication for NIV in acute hypercapnia
in Non-COPD patients
Flandreau G et al. Management and long-term outcome of patients with chronic
neuromuscular disease admitted to the intensive care unit for acute respiratory failure:
a single-center retrospective study. Respir Care 2011; 56: 953 – 960
Special indication for NIV in acute hypercapnia
Neuromuscular disease
Intermittent NIV
to recondition
respiratory
muscles
Bronchoscopy
Physiotherapy
NIV & aggressive secretion management
DNI: Do not intubate
• Aims
– Reduced Dyspnea
– Improved quality of
life („Comfort“)
– Buy time
INDICATION: NIV IN PALLIATION
DYSPNEA INDEX
0
1
2
3
4
5
6
7
8
9
10
ADMISSION NIV 1 hr
*
THE RATIONALE
LV failure
Pulmonary
edema
Pulmonary
compliance
Airway
resistance
Negative
Intrathoracic
Pressure
Swing
Work of
breathing
CO
PaO2 Respiratory
muscle
fatigue
DaO2
+
PaCO2
LV failure
Pulmonary
edema
Pulmonary
compliance
Airway
resistance
Negative
Intrathoracic
Pressure
Swing
LV
transmural
pressure
O2
Cost of
breathing
LV afterload
+
Rasen et al: Chest 1985; 87: 158-162
Negative intrathoracic pressure swings during CPE
Pes (cmH20)
0
-20
IntraThoracicPressure
and
LV function
AO
LV
ITP effort = ITP = Ptm
LV afterload
100
-20
Ptm = 100-(-20) = 120
CPAP IN CPE
Rasen et al: Chest 1985; 87: 158-162
Pes
(cmH20)
0
-20
Spontaneous breathing CPAP 15 cmH20
IntraThoracicPressure
and
LV function
AO
LV
ITP effort = ITP = Ptm
LV afterload
100
-5
Ptm = 100-(-5) = 105
Rationale of positive pressure ventilation in CPE
Positive Pressure
ITP FRC
Pre-load Venous return
LVafterload PTM
PaO2 WOB
Cardiac performance pulmonary congestion
Targets of ventilation in
cardiogenic pulmonary oedema
• improvement of oxygenation
• improvement of respiratory acidosis
• reduction of work of breathing
• improvement of cardiac performance
• reduction of patient’s distress
NIV and obesity: in the acute
setting
OHS: Definition
- Obesity (BMI 30 kg/m2)
- Hypercapnia (PaCO2 45 mmHg)
- Sleep-disordered breathing
Thomas Nast, The Pickwick Papers
OHS: Clinical Presentation
Middle-aged
2:1 male-to-female
Extremely obese
Significant sleep-disordered breathing
(fatigue, hypersomnolence, snoring, AM
headache)
Needs confirmation
Conclusions
Multiple organ failure and pneumonia were the main factors associated with
NIV failure and death in morbidly obese patients in hypoxic ARF. On the
opposite, NIV was constantly successful and could be safely pushed further in
case of severe hypercapnic acute respiratory decompensation of OHS.
Potential goals of noninvasive ventilation (NIV) in severe acute asthma.
Dean R Hess Respir Care 2013;58:950-972
(c) 2012 by Daedalus Enterprises, Inc.
Bronchoscope inserted through the swivel adaptor of a face mask for noninvasive ventilation.
Dean R Hess Respir Care 2013;58:950-972
(c) 2012 by Daedalus Enterprises, Inc.
Monitoring of NIV in the acute setting
AIMS
Goals of monitoring
Types of monitoring
Setting for monitoring
Goals of monitoring
Types of monitoring
Setting for monitoring
Why we need Monitoring during MV?
To Assess the effectiveness of MV in -Unloading respiratory muscles
-Correcting gas exchange abnormalities
-Improving alveolar ventilation
To Identify complications during MV
-correlated with MV
-correlated with ARF
To predict patient’s outcome in terms of
-Survival
-Dependence on MV
-Autonomy in performing ADLs
Is Monitoring less important during NIV? Airways not protected
Presence of leaks
Lack of sedation
Use outside ICU
Which goals of Monitoring during NIV?
To Assess the effectiveness of NIV in -Unloading respiratory muscles
-Correcting gas exchange abnormalities
-Improving alveolar ventilation
-Patient-ventilatory synchrony
To Identify complications during NIV
-correlated with NIV
-correlated with ARF
To predict patient’s outcome in terms of
- NIV failure (i.e. Need of ETI)
-Survival
-Dependence on MV
-Autonomy in performing ADLs
To Assess the effectiveness of NIV in -Unloading respiratory muscles
-Correcting gas exchange abnormalities
-Improving alveolar ventilation
-Patient-ventilatory synchrony
To Identify complications during NIV
-correlated with NIV
-correlated with ARF
To predict patient’s outcome in terms of
- NIV failure (i.e. Need of ETI)
-Survival
-Dependence on MV
-Autonomy in performing ADLs
AIMS
Goals of monitoring
Types of monitoring
Setting for monitoring
Availability of
ETI • in case of NIV
failure
Ventilatory
Monitoring • Respiratory pattern
• Pt-vent interaction
TYPES OF
MONITORING
CLINICAL
MONITORING
PHYSIOLOGI
C
MONITORING
LABORATORY
MONITORING NIV
MONITORING
TYPES OF
MONITORING
CLINICAL
MONITORING PHYSIOLOGIC
MONITORING
LABORATORY
MONITORING NIV
MONITORING
HOOVER
SIGN
ACCESSORY RESPIRATORY
MUSCLES PARADOXYCAL BREATHING
How is the patient
breathing?
Bott J. et al. Lancet 1993; 341:1555-7
Monitoring Dyspnea
NIV
SMT
VAS
Carlucci A. et al Am J Respir Crit Care Med
2001;163:874-80
Patient’s Cooperation and Sensorium
NIV
OUTCOME
Hypercapnic
Encephalopathy
Scala R.
Levels of Hypercapnic
Encephalopathy and NIV failure
KELLY=1 KELLY=2 KELLY=3 KELLY>3
Scala R. et al, Chest. 2005;128(3):1657-66
Agitation and sedation
Roche-Campo F et al., Crit Care Med 2010
Delirium
TYPES OF
MONITORING
CLINICAL
MONITORING
PHYSIOLOGIC
MONITORING
LABORATOR
Y
MONITORING
NIV
MONITORING
TECHNICAL LIMITATIONS
• Poor peripheral perfusion
• Movements artifacts
• Haemoglobinopathies
• Nail polish
• Hyperbilirubinemia (> 15 mg/dL)
Pulse-oximetry CONTINUOUS MONITORING OF OXYGENATION
DURING NIV
AND SPONTANEOUS BRETAHING
PHYSIOLOGICAL LIMITATIONS
• Variable PaO2/SpO2 correlation
• Lack of information on PaCO2
PLATEAU
REGION
STEEP
REGIO
N
ETCO2
Expiratory Capnography
LIMITED APPLICATION in
NIV -Leaks
-Additional dead space (Interface)
-Variable Circuit
-Variable Expiratory system (single-
limb)
46 pts with ARF under NIV (Range PaCO2: 33-91 mmHg) -TCM4: trunk
PtCO2 sensor
Under-estimation of PaCO2 in pts
with greater hypercapnia (PaCO>60
mmHg)
TREND OF TC-PCO2
Kocher S et al, J Clin Monitor Comput 2004
Domingo Ch et al, Arch Bronchoneumol 2006
Arterial blood gas-analysis
Gold standard
Oxygenation status (PaO2/FiO2
ratio)
Ventilatory status (PaCO2)
Metabolic status (pH/HCO3)
Co-oximetry (COHb)
Weak points: -Invasive
procedure
-Spot data
Prognostic
value -Baseline
-After 1-2 hrs
-Late failure
Antonelli M. et al. Crit Care Med 2007;35(1):18-25
PaO2/FiO2 during NIV in
ARDS
pH at baseline in COPD exacerbations
Nava S. et al., Intensive Care Med 2006; 32(3):361-70.
Respiratory Rate and NIV
failure
Confalonieri M et al.
How to assess RR on spont
breathing? Clinical
evaluation
Impedenzometry
Capnography
Pnemotacograph
Schettino G. et al., Crit Care Med 2008;36(2):441-7
Reasons for NIV failure
Cardiovascular
monitoring (ECG, NIBP, PR)
Helpful in
Understanding the causes of nocturnal desaturations
Re-Setting the ventilator
Janssens JP et al. Thorax 2011;66(5):438-45
Sleep monitoring
TYPES OF
MONITORING
CLINICAL
MONITORING
PHYSIOLOGIC
MONITORING
LABORATORY
MONITORING
NIV
MONITORING
X RAY
BIOCHEMISTRY Pro-BNP
CRP
Procalcitonin
Miocardial markers
Electrolites
………
TYPES OF
MONITORING
CLINICAL
MONITORING
PHYSIOLOGI
C
MONITORING
LABORATOR
Y
MONITORING
NIV
MONITORING
Am J Respir Crit Care Med. 2001
Feb;163(2):540-77
Almost all the side effects of NIV are due to
problems with interfaces
Types of Leaks
Intentional leaks
Monitor the tightness of the
mask
LOOK FOR A BALANCE
BETWEEN
LEAKS AND COMFORT
Ventilator monitoring:
numeric data and curves
Berg KM et al., Respir Care 2012;57:1548-54
Respiratory pattern and NIV
Failure
INTUBATION
aRSBI= RR/exp- TV during NIV
Exp TV = pt TV
HOW COULD WE MONITOR exp-TV and RR DURING NIV?
Monitoring: ready access to ETI and
CPR
Non-invasive ventilation failure in the acute patient
What is the NIV failure?
Need for tracheal intubation and death
When does it happen?
Immediate: < 1 hr
Early : 1- 48 hrs
Late: > 48hrs
NIV FAILURE (%)
Immediate Early Late
17
68
15
How to Reduce Air Leaks During NIV
Proper interface type and size
Proper securing system
Mask-support ring
Comfort flaps
Tube adapter
Hydrogel or foam seals
Chin strap
Lips seal or mouth taping
Nava S et al. Respiratory Care 2009; 54: 71-82
Mask occlusion pressure = Pmask-fit – Paw
How to Reduce the Risk of Skin Damage During NIV
Proper harness and tightening
Skin and mask hygiene
Nava S et al. Respiratory Care 2009;54:71-82
Nasal-forehead spacer
• To reduce the pressure on the bridge of the nose
Forehead and skin pads
• To obtain the most comfortable position
Cushioning system between mask prong and forehead
Remove patient’s dentures when making impression for moulded mask
In home care, replace the mask according to the patient’s daily use
Skin ulcers
Risk for skin lesion
A possible solution: the total face mask
Another solution: the “Helmet”
Courtesy of Dr. Stefano Nava (Bologna, Italy)
• Not always appear where expected!!!
Pressure ulcer
Predictors of failure: NIV for hypercapnic respiratory failure
Advanced age
Higher acuity of illness (APACHE score)
Uncooperative
Poor neurological score
Unable to coordinate breathing with ventilator
Large air leaks
Edentulous
Tachypnoea (>35/min)
Acidaemia (pH <7.18)
Failure to improve pH, heart and respiratory rates or Glasgow Coma Score within the first 2 hours
Soo Hoo et al. Crit Care Med 1994; 22: 1253–61 Ambrosino et al. Thorax 1995; 50: 755–7
Confalonieri et al. Eur Respir J 2005; 25: 348–55
Non-COPD conditions: Pneumonia (n=37) Neuromusculoskeletal disorders (n=11) Pulmonary oedema (n=9) Bronchiectasis (n=5) Sepsis (n=3) Asthma (n=3)
Outcomes of NIV in non-COPD patients by specific diagnosis
At admission
• 1,033 consecutive patients •Success rate: 797 (77%)
After 2 h of NIV
• Eight ICUs • n=354:
• Success: 246 • Failure: 108
Other predictors of failure:
Higher SAPS
Lower PaO2/FIO2 and failure to improve
Low pH
Older age
Septic shock, MOF
Common reasons for NIV failure Environmental/caregiver team
factors
• Lack of skilled, experienced caregiver team
• Poor patient selection
• Lack of adequate monitoring Selection guidelines for NIV in the acute setting Appropriate diagnosis with potential reversibility (COPD,
congestive heart failure, …..)
Establish need for ventilatory assistance:
• Moderate to severe respiratory distress
and
• Tachypnoea (>24/min for COPD, >30/min for CHF)
• Accessory muscle use or abdominal paradox motion
• Blood gas derangement: pH <7.35, PaCO2 >45, or PaO2/FiO2 <300
Contraindications of NIV Respiratory or cardiac arrest
Too unstable patient: • Shock
• Myocardial infarction requiring intervention
• Uncontrolled ischemia or arrhythmias
• Uncontrolled upper GI bleed
• Non-evacuated pneumothorax
Unable to protect airway* • Excessive secretions
• Poor cough
• Impaired swallowing
*Relative contraindications?
Aspiration risk*
• Distended bowel; obstruction or ileus
• Frequent vomiting
Uncooperative or agitated*
Unable to fit mask
Recent upper airway or oesophageal surgery
Multiple organ system failure (>2)
Common reasons for NIV failure
Patient-related factors
• Intolerance
• Mask problems:
• Discomfort
• Poor fit
• Skin ulceration
• Claustrophobia
• Agitation
• Excessive secretions, inability to protect airway
• Progression of underlying disease
Approach to the agitated/intolerant patient using NIV
Common reasons for NIV failure
Technical factors
• Inadequate equipment
• Failure to ventilate
• Failure to oxygenate
• Patient–ventilator asynchrony
• Air leaks
Successful NIV: Important factors
More likely with a good team
• A skilled, experienced staff helps to optimize outcomes
The underlying disease is an important determinant
• Selecting appropriate patients and monitoring them closely
Severity at presentation
Change in physiology after a short period of NIV
• If failure to ventilate or oxygenate, rapidly assess for reversible contributing factors
• Be prepared to intubate without undue delay if rapid reversal cannot be achieved (particularly in hypoxemic patients)
A systematic approach to troubleshooting can help assure the best possible NIV outcomes
