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Non-invasive Positive Pressure
Ventilation
Dr.jarahzadeh
Intensivist
Introdaction
* Nippv is recent phenomenon, mainly because of
advances in noninvasive interfaces and ventilator
modes
* NIPPV delivered o2 by nasal or oronasal mask
* The efficacy of noninvasive positive-pressure
Ventilation has been demonstrated for acute
pulmonary edema, for respiratory failure in
immunocompromised patients, and to facilitate
extubation in COPD patients.
* Patients who develop respiratory failure or who
refuse intubation are potentially good candidates for
noninvasive positive-pressure ventilation
*Several factors are vital to the success of noninvasive
positive-pressure ventilation: careful patient
selection; properly timed initiation; comfortable,
well-fitting interface; coaching and encouragement;
and careful monitoring.
*Noninvasive ventilation should be used to avert
endotracheal intubation rather than as an alternative to
it.
Definition
The application of positive pressure ventilation
without using an endotracheal tube.
or
As the provision of ventilatory assistance to the
lungs without an invasive artificial airway
History
Until the early 1960s, negative-pressure ventilation in the
form of tank ventilators was the most common type of
mechanical ventilation outside the anesthesia suite
With the introduction of nasal CPAP to treat obstructive sleep
apnea in the early 1980s,
NIPPV rapidly displaced negative-pressure ventilation as the
treatment of choice for chronic respiratory failure in patients with
neuromuscular and chest wall deformitie
The past 12 years, noninvasive ventilation has moved
from the outpatient to the inpatient setting, where it is
used to treat acute respiratory failure.
Non-invasiveVentialtion
1- Positive pressure
2-Negative Pressure
Advantage(NIPPV)
*Decreased direct upper airway trauma & bypass of
the upper airway defense mechanisms
*Allows patients to eat orally, vocalize normally, and
expectorate secretions.
* Noninvasive ventilation reduces infectious hospital
including pneumonia,sinusitis, and sepsis.
* lowers morbidity and mortality
* Shorten hospital length of stay, thus reducing costs.
Goals of NIV
Relieve symptoms
 Reduce work of breathing
 Offset the effect of i PEEP
 Improve gas exchange
 Minimize risk of barotrauma
 Avoid intubation
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Indication
Airway Obstruction
 COPD
 Asthma
 Cystic fibrosis
 Obstructive sleep apnea or obesity hypoventilation
 Upper airway obstruction
 Facilitation of weaning in COPD
 Extubation failure in COPD
Indication
Hypoxemic Respiratory Failure
 ARDS
 Pneumonia
 Trauma or burns
 Acute pulmonary edema (use of CPAP)
 Immuno compromised patients
 Restrictive thoracic disorders
 Post operative patients
 Do-not-intubate patients
 During bronchoscopy
Exclusion Criteria
1.
2.
3.
4.
5.
6.
7.
Respiratory arrest
Medically unstable
Unconscious, unable to protect airways
Excessive secretions
Significant vomiting
Agitated or uncooperative
Facial trauma, burns, surgery or anatomic
abnormalities interfering with mask
application
PATIENT SELECTION
Primary-step
Identify patients in need of ventilatory assistance by using clinical
and blood gas criteria.
Good candidates are those with moderate to severe dyspnea,
tachypnea, and impending respiratory muscle fatigue( use of
accessory muscles of breathing or abdominal paradox).
The level of tachypnea ( COPD when the respiratory rate exceeds
24 breaths per minute & hypoxemic respiratory failure, higher
respiratory rates are used, in the range of 30 to 35 breaths per
minute.
second step
Exclude patients for whom noninvasive ventilation would
be unsafe.
Those with frank or imminent respiratory arrest
Patients who are medically unstable with hypotensive shock,
uncontrolled upper gastrointestinal bleeding, unstable
arrhythmias, or life-threatening ischemia .
who are uncooperative, unable to adequately protect their upper
airway or clear
PREDICTORS OF SUCCESS DURING
ACUTE APPLICATIONS OF NPPV
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Younger age
Lower acuity of illness (APACHE score)
Able to cooperate; better neurologic score
Able to coordinate breathing with ventilator
Less air leaking, intact dentition
Hypercarbia, but not too severe (PaCO2 > 45 mm
Hg, < 92 mm Hg)
Acidemia, but not too severe (pH < 7.35, > 7.10)
Improvements in gas exchange and pulse and
respiratory rates within first 1-2 h
INITIATION OF NONINVASIVE VENTILATION
1-Appropriate candidate selected,
2-Ventilator and interface must be chosen,
3-Ventilator settings must be selected,
4-Location ( Icu or step-down unit that offers adequate
continuous monitoring until stabilized)
Comporison of Noninvasive mechanical ventilators with
standard critical care ventilators
NIMV offers a more portable technology due to the reduced size of the
air compressor.
Because of this reduction in size, these noninvasive ventilators do not
develop pressures as high as their critical care ventilator counterparts.
(>30 cm H20)
Noninvasive ventilators have a single-limb tubing circuit that delivers
oxygen to the patient and allows for exhalation.
lack oxygen blenders or sophisticated alarm or battery backup systems
Modes of Noninvasive Mechanical Ventilation
1-Pressure modes
2-volume modes
* volume ventilation, initial tidal volumes range from
10 to 15 mL.kg.
Pressure-cycled vents are better tolerated than volume-cycled vents
Pressure modes
**Continuous Positive Airway Pressure(CPAP)
Continuous positive airway pressure (CPAP) is a mode for invasive and
noninvasive mechanical ventilation.
It provides positive airway pressure throughout the respiratory cycle.
This static, positive pressure is maintained constantly during inhalation
and exhalation
CPAP is not a stand-alone mode of assisted mechanical ventilation. It is
equivalent to positive end-expiratory pressure (PEEP) and facilitates
inhalation by reducing pressure thresholds to initiate airflow.
This mode should never be used in patients who may have apneic
episodes because of the lack of a backup rate.
Pressure modes
Spontaneous Modes
In spontaneous mode, the airway pressure cycles between an inspiratory
positive airway pressure (IPAP) and an expiratory positive airway
pressure (EPAP).
This is commonly referred to as bilevel or biphasic positive airway
pressure (BL-PAP or BiPAP). The patient's inspiratory effort triggers the
switch from EPAP to IPAP. The limit during inspiration is the set level of
IPAP.
The inspiratory phase cycles off, and the machine switches back to EPAP
when it detects a cessation of patient effort, indicated by a decrease in
inspiratory flow rate, or a maximum inspiratory time is reached, typically
2-3 seconds.
Tidal volume (Vt) varies breath to breath and is determined by degree of
IPAP, patient effort, and lung compliance.
Spontaneous mode depends on patient effort to trigger inhalation. A
patient breathing at a low rate can develop a respiratory acidosis.
Pressure modes
Spontaneous/timed (ST) mode
The trigger in the ST mode can be the patient's effort or an elapsed time
interval, predetermined by a set respiratory backup rate.
If the patient does not initiate a breath in the prescribed interval, then
IPAP is triggered. For machine-generated breaths, the ventilator cycles
back to EPAP based on a set inspiratory time.
For patient-initiated breaths, the ventilator cycles as it would in the
spontaneous mode.
Conceptually:
One can consider BiPAP as PEEP with pressure support (PS).
The pressure during the inspiratory phase is termed IPAP and
is analogous to PS.
The pressure during the expiratory phase is termed EPAP and
is analogous to PEEP.
The IPAP is necessarily set higher than EPAP by a minimum
of 5cm H2O, and the difference between the two settings is
equivalent to the amount of PS provided
Initiating Noninvasive Mechanical Ventilation
Either a face mask or a nasal mask can be used, but a nasal mask is
generally better tolerated.
A respiratory therapist must measure the patient to ensure a good fit and
seal.
Initially supply 3 to 5 cm H2O of CPAP with supplemental oxygen.
sequentially increase the CPAP pressure by 2 to 3 cm H2O increments
every 5 to 10 minutes (ABG-Pulse oximetry)
Recommended initial settings for BiPAP machines in the noninvasive
support of patients in respiratory distress or failure are IPAP of 8 cm H2O
and EPAP of 3 cm H2O, for a pressure support (IPAP minus EPAP) of 5
cm H2O.
The level of supplemental oxygen flowing into the circuit should be
governed by goal pulse oximetry and corroborated by ABG results as
necessary; it is appropriate to initiate therapy with 2 to 5 L/minute, but
this amount should be adjusted with each titration of IPAP or EPAP.
Conceptually:
The intrinsic positive end-expiratory pressure
(PEEPi), or auto-PEEP, cannot be measured by
a noninvasive ventilator; therefore, EPAP
should generally be maintained below 8 to 10
cm H2O to be certain that it does not exceed
PEEPi in patients with obstructive lung disease.
The IPAP must always be set higher than EPAP
Management Strategies
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COPD
– Main goal to decrease work of breathing (decreasing
V/Q mismatch) and provide adequate ventilation
– Relatively low EPAP: 5-8cm H2O (assuming no
obesity or sleep disordered breathing)
– Relatively moderate IPAP+EPAP: 10-14cm H2O
– Goal to have at least a 5cm H2O differential between
EPAP and IPAP+EPAP; may need to go higher
depending on ventilation requirements
» ie BiPAP 14/10 or 8/5
From a Cochrane Review
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A meta-analysis of 14 studies of NIV in COPD
exacerb showed:
  mortality ( RR 0.52 )
  need for intubation ( RR 0.41 )
 pCO2, and resp rate faster
  length of stay by 3.24 days
  complications of treatments
Management Strategies
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CHF
– Goal is to decrease work of breathing, decrease
afterload and decrease overall static pressure
– Relatively moderate EPAP: 6-12 cm H2O
– Relatively low IPAP+EPAP: 12-18cm H2O
– Patient will benefit mostly with EPAP unless
other concurrent disease ( COPD, ObesityHypoventilation)
» Typical starting point: BiPAP 10/6
Management Strategies
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Obesity-Hypoventilation Syndrome
– Goal of therapy is to decrease work of breathing and
increase ventilation
– Combined disease as >90% will also have concurrent
Obstraction sleep Apnea(OSA)
– EPAP: usually on the higher side; enough to overcome
OSA and cardiopulm disease: ~10cmH2O, more for
bigger individuals
– IPAP+EPAP: at least a 4cm H2O differential
– Need to adjust according to ventilation requirements;
may benefit from back up rate
Management Strategies
 Sleep
Disordered Breathing
– Most often post-op with known OSA or as a
complication associated with admit (CHF or
Obesity-Hypoventilation)
– For elective admit with known OSA: usual
CPAP/BiPAP unless physiologic changes with
acute illness, surgery or narcotics.
Management Strategies
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Neuromuscular Disease
– Goal to decrease work of breathing, decrease
fatigue, assist ventilation
– EPAP: usually low; 4-5cm H2O
– IPAP+EPAP: at least 4cmH2O differential
– May benefit from backup rate
Management Strategies
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Other causes of respiratory failure
– Pneumonia/ARDS
– Cancer and respiratory failure
– Post-op management
» Settings depend on disease and other
cardiopulmonary disease
» Most often used as a bridge to mechanical
ventilation or for pts DNR/DNI
» Usually moderate settings: 12/8 or 14/8
Interface
*Definition:
The device that makes physical contact between the patient and the
ventilator is termed the interface.
Interfaces for NPPV come in a variety of shapes and sizes
Include:
Nasal mask,Nasal pillow, Oronasal mask (face mask) or the helmet.
Ideally, interfaces should be comfortable, offer a good seal, minimize
leak, and limit dead space.
Nasal masks are widely used for the administration of
CPAP or noninvasive ventilation, particularly for chronic
applications.
Nasal masks are usually better tolerated than full face masks for
long-term applications, because they cause less claustrophobia
and discomfort and allow eating,conversation, and expectoration.
The standard nasal mask is a triangular or cone-shaped
clear plastic device that fits over the nose and uses a soft cuff
that forms an air seal over the skin.
Full facemasks cover both the nose and the mouth
and are preferable to nasal masks in the acute
setting.
The efficacy of both nasal and oronasal masks in
lowering PaC02 and avoiding intubation is similar in the
acute setting,
but in a recent randomized,
patients tolerated the full facemask better because of reduced
air leakage through the mouth.
Selection of a comfortable mask that fits properly is key
to the success of noninvasive ventilation.
The full facemask
should be tried first in the acute setting, and if possible,
The mask straps are then tightened with the least tension
necessary to avoid excessive air leakage.
NIPPV masks
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Nasal mask
NIPPV masks
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Full face mask
NIPPV masks
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Full face mask
Most of our patients!!
NIPPV machines
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BiPAP
NIPPV machines
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CPAP machine
Head straps
Head straps hold the mask in place and are important for
patient comfort.
Straps attach at two to five points, depending
on the type of mask. More points of attachment add to
stability.
OXYGENATION AND HUMIDIFICATION
Oxygen is titrated to achieve a desired oxygen saturation,
usually greater than 90% to 92%
Either by using oxygen
blenders on critical care and some bilevel ventilators or
By adjusting liter flow (up to 15 L/min) delivered via oxygen tubing connected
directly to the mask or ventilator circuit.
Bilevel ventilators
have limited oxygenation capabilities (maximal inspired oxygen fraction( %45 to
50)
so ventilators with oxygen blenders should be used for patients with hypoxemic
respiratory failure.
A heated humidifier should be used to prevent drying of the nasal passage and
oropharynx when the duration of application is anticipated to be more than a
few hours.
MONITORING
Once noninvasive ventilation is initiated, patients should be
closely monitored in a critical care unit or a step-down unit
until they are sufficiently stable to be moved to a regular
medical floor.
The aim of monitoring is
Relief of symptoms, reduced work of breathing, improved or stable
gas exchange, good patient-ventilator synchrony, and patient comfort
A drop in the respiratory rate with improved oxygen saturation or
improving pH with a lower PaCO2, reduce heart rate, within the first
1 to 2 hours portends a successful outcome.
The absence of these propitious signs indicates a poor response to
noninvasive ventilation
MONITORING OF PATIENTS RECEIVING
NON-INVASIVE VENTILATION IN ACUTE CARE SETTINGS
Location
Critical care or step-down unit
Medical or surgical ward if able to breathe unassisted for >20-30 min
"Eyeball“ test
Dyspnea
Comfort (mask, air pressure)
Anxiety
Asynchrony
Leaks
Vital signs
Respiratory and heart rates
Blood pressure
Continuous electrocardiography
Gas exchange
Continuous oximetry
Arterial blood gases (baseline after 2 h ,and as clinically indicated)
ADVERSE EFFECTS AND COMPLICATIONS in
NIV
The mask,
Discomfort and erythema or skin ulcers.
Airflow or pressure,
Conjunctival irritation. Ear pain. nasal or oral dryness .
Nasal congestion and discharge. Gastric insufflation.
Patient-ventilator asynchrony
Caused by high airflow is usually indicative of air leaking
through the mouth.