Non-invasive Positive Pressure Non-invasive Positive Pressure VentilationVentilation

Dr.jarahzadehDr.jarahzadehIntensivistIntensivist

IntrodactionIntrodaction

* * Nippv is recent phenomenon, mainly because of Nippv is recent phenomenon, mainly because of advances in noninvasive interfaces and ventilator advances in noninvasive interfaces and ventilator modes modes

* * NIPPV delivered o2 by nasal or oronasal mask NIPPV delivered o2 by nasal or oronasal mask

* * The efficacy of noninvasive positive-pressureThe efficacy of noninvasive positive-pressure

Ventilation has been demonstrated for acute Ventilation has been demonstrated for acute pulmonary edema, for respiratory failure in pulmonary edema, for respiratory failure in immunocompromised patients, and to facilitate immunocompromised patients, and to facilitate extubation in COPD patients.extubation in COPD patients.

* * Patients who develop respiratory failure or who Patients who develop respiratory failure or who refuse intubation are potentially good refuse intubation are potentially good candidates for noninvasive positive-pressure candidates for noninvasive positive-pressure ventilatventilationion

**Several factors are vital to the success of noninvasiveSeveral factors are vital to the success of noninvasive

positive-pressure ventilation: careful patientpositive-pressure ventilation: careful patient

selection; properly timed initiation; comfortable,selection; properly timed initiation; comfortable,

well-fitting interface; coaching and encouragement;well-fitting interface; coaching and encouragement;

and careful monitoringand careful monitoring..

*Noninvasive ventilation should be used to avertendotracheal intubation rather than as an alternative to it.

DefinitionDefinition

The application of positive pressure ventilation The application of positive pressure ventilation

without using an without using an endotracheal tubeendotracheal tube..

or or

As the provision of ventilatory assistance to the lungs without an invasive artificial airway

HistoryHistory Until the early 1960s, negative-pressure ventilation in the Until the early 1960s, negative-pressure ventilation in the

form of tank ventilators was the most common type of form of tank ventilators was the most common type of mechanical ventilation outside the anesthesia suitemechanical ventilation outside the anesthesia suite

With the introduction of nasal CPAP to treat obstructive sleep With the introduction of nasal CPAP to treat obstructive sleep apnea in the early 1980s, apnea in the early 1980s, NIPPV rapidly displaced negative-pressure ventilation as the NIPPV rapidly displaced negative-pressure ventilation as the treatment of choice for chronic respiratory failure in patients with treatment of choice for chronic respiratory failure in patients with neuromuscular and chest wall deformitieneuromuscular 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- 1- Positive pressurePositive pressure

22--NeNegative Pressuregative Pressure

AdvantageAdvantage(NIPPV)(NIPPV)

**Decreased direct upper airway trauma & bypass of Decreased direct upper airway trauma & bypass of the upper airway defense mechanismsthe upper airway defense mechanisms

**Allows patients to eat orally, vocalize normally, and Allows patients to eat orally, vocalize normally, and expectorate secretions.expectorate secretions.

** Noninvasive ventilation reduces infectious hospital Noninvasive ventilation reduces infectious hospital including pneumonia,sinusitis, and sepsis.including pneumonia,sinusitis, and sepsis.

* * lowers morbidity and mortalitylowers morbidity and mortality* * Shorten hospital length of stay, thus reducing costsShorten hospital length of stay, thus reducing costs ..

Goals of NIVGoals of NIV

Relieve symptomsRelieve symptoms Reduce work of breathingReduce work of breathing Offset the effect of Offset the effect of i i PEEPPEEP Improve gas exchangeImprove gas exchange Minimize risk of barotraumaMinimize risk of barotrauma Avoid intubationAvoid intubation

IndicationIndicationAirway ObstructionAirway Obstruction COPDCOPD Asthma Asthma Cystic fibrosis Cystic fibrosis Obstructive sleep apnea or obesity hypoventilation Obstructive sleep apnea or obesity hypoventilation Upper airway obstruction Upper airway obstruction Facilitation of weaning in COPDFacilitation of weaning in COPD Extubation failure in COPDExtubation failure in COPD

IndicationIndicationHypoxemicHypoxemic Respiratory FailureRespiratory Failure ARDSARDS Pneumonia Pneumonia Trauma or burns Trauma or burns Acute pulmonary edema (use of CPAP)Acute pulmonary edema (use of CPAP) Immuno compromised patients Immuno compromised patients Restrictive thoracic disorders Restrictive thoracic disorders Post operative patients Post operative patients Do-not-intubate patients Do-not-intubate patients During bronchoscopy During bronchoscopy

Exclusion CriteriaExclusion Criteria

1.1. Respiratory arrestRespiratory arrest

2.2. Medically unstableMedically unstable

3.3. Unconscious, unable to protect airwaysUnconscious, unable to protect airways

4.4. Excessive secretionsExcessive secretions

5.5. Significant vomitingSignificant vomiting

6.6. Agitated or uncooperativeAgitated or uncooperative

7.7. Facial trauma, burns, surgery or anatomic Facial trauma, burns, surgery or anatomic abnormalities interfering with mask applicationabnormalities interfering with mask application

PATIENT SELECTIONPATIENT 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 wouldbe unsafe.

Those with frank or imminent respiratory arrest

Patients who are medically unstable with hypotensive shock,uncontrolled upper gastrointestinal bleeding, unstablearrhythmias, or life-threatening ischemia .

who are uncooperative, unable to adequately protect their upper airway or clear

PREDICTORS OF SUCCESS DURING PREDICTORS OF SUCCESS DURING ACUTE APPLICATIONS OF NPPV ACUTE APPLICATIONS OF NPPV

Younger ageYounger age Lower acuity of illness (APACHE score)Lower acuity of illness (APACHE score) Able to cooperate; better neurologic scoreAble to cooperate; better neurologic score Able to coordinate breathing with ventilatorAble to coordinate breathing with ventilator Less air leaking, intact dentitionLess air leaking, intact dentition Hypercarbia, but not too severe (PaHypercarbia, but not too severe (Pa

CO2CO2 > 45  > 45 mm mm HgHg, < 92 , < 92 mm Hgmm Hg) )

Acidemia, but not too severe (pH < 7.35, > 7.10) Acidemia, but not too severe (pH < 7.35, > 7.10) Improvements in gas exchange and pulse and Improvements in gas exchange and pulse and

respiratory rates within first 1-2 hrespiratory 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

* volume ventilation, initial tidal volumes range from 10 to 15 mL.kg.

1-Pressure modes

2-volume modes

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 ModesIn 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.

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.

Pressure modes

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 VentilationEither 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.

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

Conceptually:

Management StrategiesManagement Strategies

COPDCOPD– Main goal to decrease work of breathing (decreasing Main goal to decrease work of breathing (decreasing

V/Q mismatch) and provide adequate ventilationV/Q mismatch) and provide adequate ventilation

– Relatively low EPAP: 5-8cm H2O (assuming no Relatively low EPAP: 5-8cm H2O (assuming no obesity or sleep disordered breathing)obesity or sleep disordered breathing)

– Relatively moderate IPAP+EPAP: 10-14cm H2ORelatively moderate IPAP+EPAP: 10-14cm H2O

– Goal to have at least a 5cm H2O differential between Goal to have at least a 5cm H2O differential between EPAP and IPAP+EPAP; may need to go higher EPAP and IPAP+EPAP; may need to go higher depending on ventilation requirementsdepending on ventilation requirements

» ie BiPAP 14/10 or 8/5ie BiPAP 14/10 or 8/5

From a Cochrane ReviewFrom a Cochrane Review

A meta-analysis of 14 studies of NIV in COPD A meta-analysis of 14 studies of NIV in COPD

exacerb showedexacerb showed:: mortality ( RR 0.52 )mortality ( RR 0.52 ) need for intubation ( RR 0.41 )need for intubation ( RR 0.41 ) pCOpCO22, and resp rate faster, and resp rate faster

length of stay by 3.24 dayslength of stay by 3.24 days complications of treatmentscomplications of treatments

Management StrategiesManagement Strategies

CHFCHF– Goal is to decrease work of breathing, decrease Goal is to decrease work of breathing, decrease

afterload and decrease overall static pressureafterload and decrease overall static pressure– Relatively moderate EPAP: 6-12 cm H2ORelatively moderate EPAP: 6-12 cm H2O– Relatively low IPAP+EPAP: 12-18cm H2ORelatively low IPAP+EPAP: 12-18cm H2O– Patient will benefit mostly with EPAP unless Patient will benefit mostly with EPAP unless

other concurrent disease ( COPD, Obesity-other concurrent disease ( COPD, Obesity-Hypoventilation)Hypoventilation)

» Typical starting point: BiPAP 10/6Typical starting point: BiPAP 10/6

Management StrategiesManagement Strategies Obesity-Hypoventilation SyndromeObesity-Hypoventilation Syndrome

– Goal of therapy is to decrease work of breathing and Goal of therapy is to decrease work of breathing and increase ventilationincrease ventilation

– Combined disease as >90% will also have concurrent Combined disease as >90% will also have concurrent Obstraction sleep Apnea(OSA)Obstraction sleep Apnea(OSA)

– EPAP: usually on the higher side; enough to overcome EPAP: usually on the higher side; enough to overcome OSA and cardiopulm disease: ~10cmH2O, more for OSA and cardiopulm disease: ~10cmH2O, more for bigger individualsbigger individuals

– IPAP+EPAP: at least a 4cm H2O differentialIPAP+EPAP: at least a 4cm H2O differential

– Need to adjust according to ventilation requirements; Need to adjust according to ventilation requirements; may benefit from may benefit from back up rateback up rate

Management StrategiesManagement Strategies

Sleep Disordered BreathingSleep Disordered Breathing– Most often post-op with known OSA or as a Most often post-op with known OSA or as a

complication associated with admit (CHF or complication associated with admit (CHF or Obesity-Hypoventilation)Obesity-Hypoventilation)

– For elective admit with known OSA: usual For elective admit with known OSA: usual CPAP/BiPAP unless physiologic changes with CPAP/BiPAP unless physiologic changes with acute illness, surgery or narcotics.acute illness, surgery or narcotics.

Management StrategiesManagement Strategies

Neuromuscular DiseaseNeuromuscular Disease– Goal to decrease work of breathing, decrease Goal to decrease work of breathing, decrease

fatigue, assist ventilationfatigue, assist ventilation– EPAP: usually low; 4-5cm H2OEPAP: usually low; 4-5cm H2O– IPAP+EPAP: at least 4cmH2O differentialIPAP+EPAP: at least 4cmH2O differential– May benefit from backup rateMay benefit from backup rate

Management StrategiesManagement Strategies

Other causes of respiratory failureOther causes of respiratory failure– Pneumonia/ARDSPneumonia/ARDS– Cancer and respiratory failureCancer and respiratory failure– Post-op managementPost-op management

» Settings depend on disease and other Settings depend on disease and other cardiopulmonary diseasecardiopulmonary disease

» Most often used as a bridge to mechanical Most often used as a bridge to mechanical ventilation or for pts DNR/DNIventilation or for pts DNR/DNI

» Usually moderate settings: 12/8 or 14/8Usually moderate settings: 12/8 or 14/8

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.

Interface*Definition:

Nasal masks are widely used for the administration ofNasal masks are widely used for the administration ofCPAP or noninvasive ventilation, particularly for chronicCPAP or noninvasive ventilation, particularly for chronicapplications. 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 inlowering PaC02 and avoiding intubation is similar in theacute setting,

but in a recent randomized, patients tolerated the full facemask better because of reducedair leakage through the mouth.

Selection of a comfortable mask that fits properly is keyto the success of noninvasive ventilation.

The full facemaskshould be tried first in the acute setting, and if possible,

The mask straps are then tightened with the least tensionnecessary to avoid excessive air leakage.

NIPPV masksNIPPV masks

Nasal maskNasal mask

NIPPV masksNIPPV masks

Full face maskFull face mask

NIPPV masksNIPPV masks

Full face maskFull face mask

Most of our patients!!Most of our patients!!

NIPPV machinesNIPPV machines

BiPAP BiPAP

NIPPV machinesNIPPV machines

CPAP machineCPAP machine

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.

Head straps

OXYGENATION AND HUMIDIFICATION

Oxygen is titrated to achieve a desired oxygen saturation,usually greater than 90% to 92% Either by using oxygenblenders on critical care and some bilevel ventilators or By adjusting liter flow (up to 15 L/min) delivered via oxygen tubing connecteddirectly to the mask or ventilator circuit.

Bilevel ventilatorshave limited oxygenation capabilities (maximal inspired oxygen fraction( %45 to 50)so ventilators with oxygen blenders should be used for patients with hypoxemicrespiratory 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 afew hours.

MONITORING

Once noninvasive ventilation is initiated, patients should beclosely monitored in a critical care unit or a step-down unituntil they are sufficiently stable to be moved to a regularmedical floor.

The aim of monitoring is

Relief of symptoms, reduced work of breathing, improved or stablegas 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 RECEIVINGMONITORING OF PATIENTS RECEIVINGNON-INVASIVE VENTILATION IN ACUTE CARE SETTINGSNON-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.