Transcript Bi-level and Volume Ventilators.

“Bi-Level and Non-invasive
Intermittent Postive Pressure
Ventilation”.
M.A . King
Respiratory Support & Sleep Centre,
Papworth Hospital, Cambridge,
CB3 8RE, UK
Bi-level and NIPPV
Volumetric mechanical ventilation is
usually reserved for the unconscious
patient and is delivered by an
endotracheal tube.
 Non-invasive Intermittent Positive
Pressure Ventilation is delivered by a
mask.
Bi-level and NIPPV
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Plan
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Avoid mentioning CPAP and Bi-Level in OSA !
Focus in non-invasive ventilatory support.
What is ventilatory failure?
Who needs this treatment?
What do the machines do?
What are the outcomes?
Discusion
: Do Sleep Technologists need to be involved in
these treatments?
Technological developments since the invention of
CPAP
OSA
CPAP
Ventilatory
insufficiency
OSA with lung
problems
Bi-Level
Ventilatory
Failure
Bi-Level
Bi-Level
Pressure
support
ventilators
1987
1990
1995
<1987
Pressure
support
ventilators
2000
<1987
Ventilatory Failure.
Lung Function = Ventilation and gas exchange
Minute Ventilation is a function of respiratory rate
and tidal volume
Ventilatory Failure causes a rise in CO2 and drop in
O2
Gas Exchange (respiratory) failure causes hypoxia
alone
“Pump” Failure.
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Respiratory control centres.
Neurological system ( Nerves and synapses)
Muscle
Mechanics ( Thoracic cage).
RESTRICTIVE VENTILATORY DEFECT
Restrictive defect.
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Small lungs in a rigid
chest cage.
Normal lungs which
can not be expanded.
Lung mechanics are
altered and
efficiencey lost.
Ventilatory Pump.
Cerebral cortex
Brainstem
WAKE
Sleep-wake
Respiratory muscles
Airflow resistance
Restrictive lung defect.
Chemoreceptors
Mechanoreceptors
Ventilation
Minute ventilation = MV
Respiratory Muscle Weakness
Begin AJRCCM 1997 156 133-139
pump
Control
TV
MV reduced
work
RR
Muscle
fatigue
Prolonged hypoventilation +
or – events (AHI), Desats,
Arousals, WASO, poor sleep
architecture.
Hypoxia
Hypercapnoea
(hypersomnia)
Progressive and
insidious
Acidosis
Ventilatory Failure
TV
Control
MV reduced
work
RR
Neuro-Muscle
insult
CVA
Trauma
Neuro’
disease
Prolonged hypoventilation +
or – events (AHI), Desats,
Arousals, WASO, poor sleep
architecture.
Hypoxia
Hypercapnoea
Infection
Acidosis
Acute
Ventilatory Failure
Obesity epidemic hits Europe (not France).
Nocturnal ventilatory insufficiency
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Reduced tidal volume and reduced
frequency.
Reduced minute volume = hypercapnoea
and hypoxia.
Indications for NIPPV.
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Ventilatory pump failure.
Chronic or acute.
Reduced MV, hypoxia with hypercapnoea.
( potential for normal gas exchange – single
system failure).
Assessment.
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Arterial blood gases (ABGs).
Overnight oximetry and CO2
Lung Function.( volumes and muscle
strength)
Medical exam ( cardio-vascular)
AHI and sleep stages have little diagnostic
or prognostic value.
Simple overnight oximetry.
What do the machines do?
Non-invasive ventilation- objectives
1.
2.
3.
Improve alveolar ventilation &
oxygenation.
Reduction of work of breathing.
Airway support.
Objective:Improve alveolar ventilation
& oxygenation.
The physiological mechanism is complex &
dependent upon the pathology/disease
mechanism.
1.
2.
paO2=[(Pb-SWVP)xFiO2]-PaCO2/RQ
Increased Tidal volume and rate =
minute Ventilation.
Work of breathing
Work increases when
FRC reduced or when
TV = VC
Work of breathing
When FRC and lung compliance are reduced more work is required to
inflate the lung. By applying PEEP, the lung volume at the end of
exhalation is increased. The already partially inflated lung requires
less pressure and energy than before for full inflation
TV
FiO2 & improved MV ( TV & RR)
Te
FiO2
TV
rco
RR
Ti
Mechanical Ventilatory Support
Invasive – endo-tracheal tube.
Non- invasive ventilation (NIV).
 Negative Pressure NIV
 Positive Pressure NIV *
Negative Pressure NIV precedes positive
pressure ventilation by 100 years.
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- Patient lays inside a rigid cylinder with neck and head
outside cylinder.
A vacuum pump creates a negative pressure within the
chamber (outside of chest)
- this causes expansion of the patient's chest. This
change in chest geometry reduces intrapulmonary
pressure and ambient air flows into the lungs.
When the vacuum ends, the negative pressure applied to
the chest drops to zero, and the elastic recoil of the
chest and lungs results in passive exhalation.
Pump – Adjustable rate and adjustable negative
pressure.
Iron lung.
Limitations of Negative Pressure
NIV
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Unsupported upper airway- obstruction
induced with high transluminal pressure
gradients.
Can reduce cardiac OP and peripheral
oedema.
CONTROLLED ventilation.
Limited technologies.
Positive Pressure NIV
1. Delivery of positive pressure to lungs
without intubation.
2. Delivery of air is patient controlled (with
machine back up delivery).
3. Air is delivered via a nasal mask or oronaso mask ( full face mask).
NIPPV
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Nomenclature of Positive pressure systems
CPAP
Bi-level
NIPPV
IPAP
EPAP
PEEP
Ventilating – peak pressure (pressure support)
Triggers - Cycling
Ti. Te, I/E ratio
Mode S, ST, T
Rise Time
Ramps
FiO2, tidal volume & rate.
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FiO2 – room air 20.8%, facility to add
oxygen. O2 % not measured.
TV – Patient controlled breath enhanced
by delivery of air to a target pressure
level. Missed breaths recognised.
RR- apnoea recognised. Back up rate.
delivered. Tachypnea reduced by control
of inspiratory time and expiratory time.
Improved alveolar ventilation &
oxygenation.
The physiological mechanism is dependent
upon the pathology/disease mechanism.
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paO2=[(Pb-SWVP)xFiO2]-PaCO2/RQ
Increased Tidal volume and rate = minute
Ventilation.
Basic summary
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Trigger level= spontaneous patient effort to
trigger a machine “breath”.
IPAP = expands the lungs more.
EPAP = supports small airways and allows for
PEEP.
PEEP= increases the volume held in the lungs
after passive recoil. Holds open alveoli &
improves gas exchange.Reduces work.
T or back up rate- ensures machine breaths if
the patient does not trigger.
Status/progress measured with CO2 & O2
measurements
FiO2 & improved MV ( TV & RR)
Te
FiO2
TV
rco
RR
Ti
Bi-level
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Technology has developed from CPAP over
several years.
Splints upper airway.
Supplements Spontaneous breathing,
synchronisation, improves comfort.
Reduces work of breathing.
Time. Missed breaths delivered.
Range of features and settings added in recent
times. Alarms – essentially a ventilator.NIPPV
Unrecognised ventilatory
insufficiency leads to big problems
Problems with Home nocturnal NIV
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Cost of ventilator.
Choice of ventilator- locked settings.
Mask problems.
Compliance ( nights and hrs used)
Need to monitor efficacy and share
medical care with local doctor.
Rare diseases, physical disability, mental
disability, agitation, poor sleep.
Clinical Outcomes & observational
studies.
Physiology – ABGs, TcCO2, SpO2.
Lung Function.
Psg – AHI little value. WASO and better
sleep.
Quality of Life – Activities of Living.
Health care utility (cost)
Survival
Post NIV
Mean overnight oximetry before and after NIV
Sleep Study
Baseline
Mean O2
100.0
95.0
Discharge
Mean O2
90.0
85.0
80.0
75.0
70.0
elective
Mode of Referral
Post exacerbation
NIV : Wake ABGs in Myotonic Dystrophy
Nugent Chest 2002 121
459-464
Numerous publications: NIV in Restrictive
lung and neuromuscular disease
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No prospective randomised controlled
trials
Multiple case series and 2 withdrawal
trials all showing similar treatment effects
Should NIV be used in COPD?
600,000 patients diagnosed with COPD in the UK
UK: 30,000 COPD deaths each year
· By 2020 COPD is predicted to be the third biggest killer in
the world and will be responsible for the deaths of over six
million people
· COPD is a major cause of medical admissions, particular in
winter. 308,355 emergency hospital admissions per year.
· Of those that are admitted to hospital for COPD, 1 in 10 will
die in hospital, one in three will die within six months, and 43%
will die within twelve months of their admission to hospital
Cochrane Systematic Review
Nocturnal NIPPV for at least 3 months in
hypercapnic patients with stable COPD had no
consistent clinically or statistically significant
effect on lung function, gas exchange, respiratory
muscle strength, sleep efficiency or exercise
tolerance.
The small sample sizes of these studies
precludes a definite conclusion regarding the
effects of NIPPV in COPD.
More evidence is required.
Summary
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Bi Level is needed for some OSA patients.
Bi-Level machines have some features of
pressure support ventilators but may not be
appropriate for all patients.
Ventilatory Failure is common in some diseases.
Long term NIV is more effective for some patient
groups than others.
Potential for dramatic increase of Obesity
Hypopnoea Syndrome across Europe.
Should Psg technologists be
involved in NIV services?
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Nocturnal (sleep related) Ventilatory
insufficiency.
Diagnostics. (type of abnormality)
Ventilatory Failure is not determined by
events (AHI)
Treatment – medical speciality.
Outcomes. (efficacy of NIV)
Is our speciality led by technologies ?
Bi-level
machines
CPAP
(OSA is one of 87
sleep disorders)
Ventilatory
Failure
?
Equipment by disorder ( few patients with OSA
develop Ventilatory failure) Papworth,Cambridge,Sept 2006
Bi-level machines
used for OSA and
in 78 COPD
CPAP=3503
(OSA is one of 87
sleep disorders)
Ventilatory
Failure = 385