chapter 45 noninvasive ventilation

Copyright © 2013, 2009, 2003, 1999, 1995, 1990, 1982, 1977, 1973, 1969 by Mosby, an imprint of Elsevier Inc.

Chapter 45

Noninvasive Ventilation

Copyright © 2013, 2009, 2003, 1999, 1995, 1990, 1982, 1977, 1973, 1969 by Mosby, an imprint of Elsevier Inc. 2

Learning Objectives

Discuss the concept of noninvasive ventilation (NIV).

List the goals of and indications for NIV. Select patients who should be managed with

NIV. List those factors that are predictive of

success during NIV.


Learning Objectives (cont.)

Discuss patient interfaces, types of ventilators, and modes of ventilation used during NIV.

Discuss the initiation and management of NIV in the acute care setting.

List and discuss complications associated with NIV and their possible solutions.

Discuss the appropriate approach to the initial application of NIV.


Introduction to Noninvasive Ventilation

Abbreviated NPPV, NIPPV, or NIV Supports ventilation without artificial airway

bag-mask provides the earliest example Encompasses both ventilation and CPAP Typically provided by nasal or oral mask


Introduction to Noninvasive Ventilation (cont.)

Use has increased due to: Improved patient interfaces Improved quality of NIV ventilators NIV software available for critical care ventilators Reports of success in literature


Types of Noninvasive Ventilation

Can be provided by a number of mechanisms Pneumobelt

Rubber bladder strapped to abdomen Bladder filling compresses abdominal contents

pushing up diaphragm causing exhalation Bladder deflation causes diaphragm to fall and

inhalation occurs Some patients prefer this while in wheelchair


Pneumobelt

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Negative-pressure ventilators (NPV) Negative pressure around thorax causes pressure

gradient across chest wall – inspiration occurs• Iron lung: widely for polio epidemic (1920-1960s)

Surrounds entire body Porta lung is a simplified, cheaper version

• Chest cuirass: seals around the chest

NPV fell from use with development of positive-pressure ventilation

Types of Noninvasive Ventilation


Noninvasive Ventilators

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Types of Noninvasive Ventilation (cont.)


All of the following are goals for noninvasive ventilation, except?

A.Avoid Intubation

B.Improve mortality

C.Maximize patient comfort

D.Airway protection


Acute Care: COPD

Hypercapnic respiratory failure due to COPD is primary indication for NIV Strong evidence of efficacy in reducing

• Need for intubation

• Hospital mortality and length of stay

• Complications

Standard of care for managing an acute exacerbation of COPD

• First-line therapy


Acute Care: Asthma & Cardiogenic Pulmonary Edema

Asthma and NIV Some evidence of positive results

• Improved P/F ratio, PaCO2, and pH• Reduction intubation rates

Use remains controversial Acute cardiogenic pulmonary edema:

Numerous studies show power of CPAP• CPAP first-line therapy

NIV reserved for those with ventilatory failure


Acute Care: CAP & Hypoxemic Respiratory Failure

CAP and NIV Only improves outcomes with COPD patients who

develop pneumonia Hypoxemic respiratory failure (P/F < 300)

First-line therapy for immunocompromised, awaiting transplant, and post lung resection

NIV very controversial for all other groups• If used, note marked improvement in 1 to 2 hours or accept

failure and intubate. 60% mortality noted if intubation is further delayed


Acute Care: Other Indications for NIV

DNI patients (do not intubate) Only use if it makes patient more comfortable or to

manage a reversible disorder Postoperative use shows promise

Some evidence CPAP post abdominal surgery improves outcomes

NIV to facilitate weaning Reserve for COPD and CHF patients For other patient groups, NIV instead of reintubation

worsened outcomes


Noninvasive ventilation may be used for a patient with a DNI (do not intubate) order, in all of the following situations, except:

A.Make patient more comfortable

B.Patient refuses artificial ventilation

C.Managing a reversible disorder

D.Manage obstructive sleep apnea


Chronic Care:Restrictive Thoracic Diseases

Indicated for patients: post polio, NMD, chest wall deformities, spinal injuries, and severe kyphoscoliosis If evidence of nocturnal hypoventilation

• Hypersomnolence, morning headache, fatigue, dyspnea, cognitive dysfunction

• If present, use NIV to prevent chronic hypercapnia and associated hypoxemia

Helps by resting muscles, lowering CO2, and improved compliance, FRC, and deadspace


Chronic Care of COPD Patients

Use is controversial Consensus conference recommendation

Use for severe COPD with symptoms of nocturnal hypoventilation and one of the following

• PaCO2 > 55 mm Hg

• PaCO2 50 to 54 mm Hg with nocturnal

desaturation

• Two hospital admissions for ventilatory failure


Hypoventilation

Associated with a number of diseases including central and obstructive sleep apnea and lung parenchymal diseases

Nasal CPAP is first-line therapy NIV is recommended when other first-line

therapies failed to alleviate hypoventilation


Patient Selection & Exclusion & Predictors of Success: NIV

Selection is generally established by signs and symptoms of respiratory distress (see Box 45-3).

Exclusion occurs once the need for ventilatory assistance has been established (see Box 45-4).

Predictors of success Summarized in Box 45-5 but generally patients are

not as sick and/or respond rapidly to NIV


All of the following are selection criteria for NIV patients in respiratory failure, except:

A.Excessive use of accessory muscles

B.Respiratory rate <25 breaths/min

C.Paradoxical breathing

D.Dyspnea


NIV Equipment: Patient Interfaces

Most common types Nasal mask Full-face mask (nasal-oral) Mouthpiece

Less common Total face mask (covers whole face) Nasal pillows helmet


Face Masks

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Nasal Pillows

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Patient Interfaces: Nasal Masks

Triangular in shape, only covers the nose Made of hard, clear plastic with a cushion below

for contact with face A strap assembly holds mask on face.

Do not overtighten as may cause tissue necrosis


Nasal Masks

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Patient Interfaces: Nasal Masks (cont.)

Proper sizing Reduces incidence of pressure sores and tissue

necrosis Reduces leaks Increases patient comfort Improves likelihood of long-term patient tolerance


Nasal Masks

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Patient Interfaces: Full-Face Masks

Interface of choice for patients with acute respiratory failure >90% of this group should start with full-face mask

Designed for either Noninvasive ventilators: entrainment valve that

prevents asphyxia if ventilator fails ICU ventilators: entrainment valve absent


Patient Interfaces: Full-Face Masks (cont.)

Disadvantages compared to nasal mask: Increased deadspace, claustrophobia, risk of

aspiration Harder to talk and expectorate


Full Face Mask

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Most are electrically powered, blower driven, microprocessor controlled

Designed to work with small leak and compensate for that leak Advantage: Patient ability to trigger and cycle

properly in face of small to moderate leaks Internal oxygen blender is desirable but often

absent hard to obtain >0.5 FIO2



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Noninvasive Ventilators (cont.)

Typical modes CPAP Pressure support (PSV) Pressure assist/control (P-A/C)

With PSV and P-A/C, machine is patient or time triggered, pressure limited, and flow or time cycled

Generate lower rates, pressures, and flows than ICU ventilators



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All of the following are types of NIV modes, except:

A.CPAP

B.PSV

C.PRVC

D.P-A/C


Critical Care Ventilators

Much more sophisticated, allow for precise oxygen control, high flows, pressures, etc

Inability to compensate for leaks is common Often results in triggering and cycling issues

• PSV breaths end at set percent peak flow; if flow does not fall to set percent, may lock in inspiration

• Modern vents can adjust cycle off percent• Time-cycling solves problem and improves patient comfort

Often causes lots of nuisance alarms Use full-face mask to minimize leaks



CPAP, PSV, and P-A/C have all have been used.

VC modes used but not recommended Leaks can lead to hypoventilation

Various NIV packages now available on ICU ventilators; some will Compensate for leaks Allow audio alarm deactivation Set maximum inspiratory time (great option)

No proven advantage of any mode



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Humidification

Patients with symptoms of sneezing, nasal draining, nasal and oral dryness, and/or nasal obstruction benefit from humidity therapy

Heated humidity relieves many of above symptoms, thus improving patient compliance Heat to about 30º C (patient comfort level).

As length of use is unpredictable, recommend use of humidification for all patients receiving NIV


Identifying Success or Failure of NIV

Success easy to identify Improved ABGs: PaCO2 decreases, pH increases,

PaO2 increases

Clinical improvement: decreased RR, VT increased, diminished accessory muscle use

Failure If in 1 to 2 hours the above are not noted; move to

intubation Waiting too long can result in cardiac arrest


Adjusting NIV

Adjustments determined by patient presentation and ABGs High PaCO2: Increase pressure (VT) or rate

Low PaCO2: Decrease pressure (VT) or rate

• Often rate is for backup only; if set in A/C may have above effects, but patient inspiratory efforts override ventilator setting

High PaO2: Decrease oxygen or PEEP

Low PaO2: Increase oxygen or PEEP

• When PEEP is adjusted, may alter pressure gradient and thus VT


Monitoring NIV

Must assess for Leaks Accessory muscle use Ventilator synchrony and patient comfort Improved vital signs and ABGs

If patient worsens on optimal setting, think immediate intubation

Particular attention must be paid to those with respiratory failure


Adverse Effects & Complications of NIV

Causes of NPPV failure include: Mask-related problems Flow-related problems Large air leaks Patientventilator asynchrony Lack of improvement in gas exchange See Table 45-2.

Major complications: aspiration, hypotension, and pneumothorax


All of the following are types problems which may occur with NIV, except:

A.Mask-related problems

B.Flow-related problems

C.Large air leaks

D.Improvement in gas exchange


Time and Costs of NIV

Success of NPPV is closely tied to time-intensive involvement of RT staff for Mask fitting Application Adjustment of NIV settings Patient education

Following initiation, time required (costs, also) should fall to reflect those required for invasive ventilation

chapter 45 noninvasive ventilation

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