Non-Invasive Ventilation
Arjun Srinivasan, Mahadevan & Pattabhiraman
Pulmonology Associates
KMCH
Agenda
Definition & mechanism of action
Indications
When, who, where, what & how ?
Technical aspects
Weaning off NIV
Complications
NONINVASIVE VENTILATION
Non-invasive ventilation (NIV) refers to a form of
assisted ventilation that involves provision of
ventilatory support without endotracheal
intubation (ETI)
CPAP vs. NIV
CPAP
Pressure greater than atm
applied to proximal
airway throughout resp
cycle
Splints airway
Increases lung volume
Raises intrathoracic
pressures
Does not offload resp
muscles
NIV
Greater pressure applied
during inspiration over
and above the baseline
CPAP
Unloads resp muscles
Can provide complete
resp support
NIV – how it works
Decreasing work of breathing
Off loading of resp muscles & decreasing fatigue
Preventing wide swings in intrathoracic pressure
Decreasing afterload to heart
Preventing complications of IMV
Intubation & MV
Loss of airway defenses
Post extubation issues
NIV
Whom to initiate ?
Acute
COPD
Pulmonary edema
Immunocompromised patients
Weaning from mechanical
Neuromuscular weakness
Bronchial asthma
ARDS
Do not intubate – pts
Other indications
Chronic
When to initiate ?
Appropriate diagnosis with potential reversibility
Establish need for ventilatory assistance
Moderate to severe respiratory distress
Tachypnea
Accessory muscle use or abdominal paradox
Blood gas derangement
pH <7.35
Paco2 >45 mm Hg
Pao2/Fio2 < 200
When not to initiate
Respiratory arrest
Medically unstable
Unable to protect airway
Excessive secretions
Uncooperative or agitated
Unable to fit mask
Recent upper airway or gastrointestinal surgery
Who will initiate ?
Clinicians
Respiratory therapists
Trained nurses
Where to initiate ?
Emergency
ICUs
Step-down units
Wards
Which ventilator to use ?
ICU ventilator
BIPAP
Critical care ventilator Vs NIV
Variables
Inspiratory Pressure
…
Leak Tolerance
…
Different Modes
…
Alarms
…
Monitoring Capability
…
Battery
…
Oxygen Blender
…
Compactness
…
ICU Ventilator
++
+
++
++
++
+
++
+
NIV
++
++
+
+
+
+
++
Mask interface
Pro & cons of interfaces
Ideal interface
dead space
 Low
 Transparent
 Lightweight
to secure
 Easy
 Adequate seal with low facial pressure
 Disposable or easy to clean
(non-allergenic) Inexpensive
 Non-irritating
 Variety of sizes
 Adaptable to variations in facial anatomy
to be removed quickly
 Ability
 Anti-asphyxia mechanism
 Compatible with wide range of ventilators
Vented & Non-vented masks
Tubings
Depends on the type of
ventilator being used
1. BIPAP
2. Intermediate type of
ventilator
3. Critical care ventilators
Modes
CPAP
Bi-level - S (spontaneous)
Bi-level - S/T
PC
Volume preset Vs Pressure preset
Dual modes
How to set pressures ?
IPAP & EPAP
High-low approach
High inspiratory pressures (20-25 cms), rapidly titrated to ensure
adequate tolerance & ventilation in the first hour
Similarly EPAP is adjusted from high (10) to low levels
Rapidly addresses hypoxemia
Low-high approach
Low initial inspiratory pressures (10-12 cms) and rapid upward
titration to ensure adequate ventilation in the first hour
EPAP is titrated upward from 4-5 cms
Better tolerance
Aim for TV ~ 6-7 ml/kg predicted body weight
Trigger
Most portable ventilators have flow triggering
Pressure triggering : associated with increased work of
triggering with auto PEEP (in AE of COPD)
Auto PEEP significantly lower with flow triggering in PSV
mode
Modern ventilators allow manipulation of trigger sensitivity
to allow reduction in work of breathing
ST mode offers a timed back up trigger
FiO2
Most portable BIPAP machines lack O2 blender and are
dependent on oxygen delivery from wall units/cylinder
FiO2 delivered is not constant & is dependent on the flow
rates / inspiratory pressures / site of leak port / air leak
Oxygen delivered through ICU ventilators is regulated &
precise due to blender.
Delivery upto FiO2 of 1 possible
Humidification
Area of intense debate with no clear consensus
High flow rates over long hours tend to dry up secretions
Dried up upper airway adds to discomfort
Probably a good idea in cases of prolonged NIV
Heated humidification is the way to go with lesser intensity
than in intubated patients
HME is strict no as it adds to dead space & interferes with
CO2 wash out
Monitoring during NIV
Subjective and objective parameters
First 2hrs - intense monitoring
Next 8hrs - close monitoring…
There after - routine monitoring
Even if parameters were borderline at start of NIV, early
change / improvement predicts success of NIV
This is the most important aspect of NIV
First few hours predict the outcome of the patient
Monitoring during NIV
…
Look at patient, ventilator, interface, bed side monitor, ABG
…
Patient - Comfort, conscious level
Chest expansion
Accessory muscles
Synchrony
…
Interfaces
…
Trigger,
- leak, tightness
volume delivered, cycling
…
HR, RR, SpO2, BP
…
ABG
- pCO2, pH, pO2
at base line, 1-2hrs after, then based on response
Other settings
Tinsp
Inspiratory time of backup rate in st mode
Rise time
Time taken for IPAP to be reached from EPAP
Shorter in tachypneic patients may ensure better tolerance
Ramp time
Time taken to reach set EPAP/IPAP
Relevant in chronic ventilation
Trouble shooting
Potential issues
Solutions
1.
Leak
1.
Check mask fit/ strap
position/ tubings / ? Chin
strap
2.
Agitation / asynchrony
2.
Talk to patient / adjust
settings / sedation
/analgesia
3.
Hypoxia
3.
Adjust ventilator / FiO2/
intubate
4.
Adjust ventilator / FiO2/
intubate
4.
Hypercarbia
Potential indicators of success in NIV
Younger age
…
Lower acuity of illness
…
Able to cooperate
…
Better neurologic score
…
Less air leak
…
…
PaCO2 45 - 92 mmHg
…
pH 7.10 - 7.35
Synchronous breathing
…
Intact dentition
…
Less secretions
…
Better compliance
…
Improvements in gas
exchange and heart
respiratory rates within
first 2 hours
…
Situations where NIV is likely to
fail
Hypercapnic failure
GCS < 11
RR > 35/min
PH < 7.25
APACHE > 29
Asynchrony
Agitation / intolerance
Edentulous / excessive leak
No initial improvement
Hypoxemic failure
Diagnosis of ARDS /
pneumonia
Age > 40
SBP < 90
Metabolic acidosis PH < 7.25
Low PO2/ FiO2
Simplified APS II > 34
Failure of PO2 / FiO2 to
improve above 175 by 1st hour
Weaning patients from NIV
No specific protocol
Pts of COPD would require at least 24 hours to stabilise
NIV is usually removed as per patient’s request for
feeding/facial hygiene
Re – attached as deemed necessary
Attempt gradual decrease in IPAP / EPAP & discontinue
when patient tolerates
Complications of NIV
Failure is the most serious complication
Most dreaded complication is failure to recognize NIV
failure early leading to delay in intubation
Studies have shown that this can lead to increased mortality
especially when used in situations where NIV is used without
strong evidence
Complications of NIV
Principles of mechanical ventilation. 3e
Summary & conclusions
NIV is an important tool in the hands of RT & intensivist
Provides a level of respiratory support in emergency / wards
unimaginable otherwise
Has changed the way we manage COPD exacerbations
Needs careful monitoring during initial hours
A tool which needs to be used wisely for us to reap the
benefits
Thank you
Questions ?