Transcript Slide 1
Chapter 45
Noninvasive Ventilation
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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.
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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.
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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
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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
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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
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Pneumobelt
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Types of Noninvasive Ventilation
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 positivepressure ventilation
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Noninvasive Ventilators
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Types of Noninvasive Ventilation
(cont.)
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All of the following are goals for noninvasive
ventilation, except?
A.
B.
C.
D.
Avoid Intubation
Improve mortality
Maximize patient comfort
Airway protection
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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
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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
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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
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Acute Care:
Other Indications for NIV
DNI patients (do not intubate)
Postoperative use shows promise
Only use if it makes patient more comfortable or to
manage a reversible disorder
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
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Noninvasive ventilation may be used for a
patient with a DNI (do not intubate) order, in all
of the following situations, except:
A.
B.
C.
D.
Make patient more comfortable
Patient refuses artificial ventilation
Managing a reversible disorder
Manage obstructive sleep apnea
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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
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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
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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
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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
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All of the following are selection criteria for NIV
patients in respiratory failure, except:
A.
B.
C.
D.
Excessive use of accessory muscles
Respiratory rate <25 breaths/min
Paradoxical breathing
Dyspnea
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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
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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
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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
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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
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Patient Interfaces: Full-Face Masks
(cont.)
Disadvantages compared to nasal mask:
Increased deadspace, claustrophobia, risk of
aspiration
Harder to talk and expectorate
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Full Face Mask
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Noninvasive Ventilators
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
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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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Noninvasive Ventilators
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All of the following are types of NIV modes, except:
A.
B.
C.
D.
CPAP
PSV
PRVC
P-A/C
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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
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Critical Care Ventilators
CPAP, PSV, and P-A/C have all have been
used.
VC modes used but not recommended
Various NIV packages now available on ICU
ventilators; some will
Leaks can lead to hypoventilation
Compensate for leaks
Allow audio alarm deactivation
Set maximum inspiratory time (great option)
No proven advantage of any mode
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Critical Care Ventilators
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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
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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
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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
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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
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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
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All of the following are types problems which may
occur with NIV, except:
A.
B.
C.
D.
Mask-related problems
Flow-related problems
Large air leaks
Improvement in gas exchange
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Time and Costs of NIV
Success of NPPV is closely tied to timeintensive 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
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