Newer modes of ventilation

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Newer modes of ventilation

• Dr P K Dash
• Trivandrum

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Transition
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Older ventilators
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Newer ventilators
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History of ventilation
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Introduction of modes
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Goals of ventilation
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Best mode selection
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Why new modes

• More safely assist patient
• Less likelihood of ventilator associated lung
  injury.
• Less hemodynamic compromise
• More effectively ventilate/oxygenate
• Improve patient - ventilator synchrony
• More rapid weaning

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Evolution

• Volume control
• Pressure control
• Pressure support
• Dual control
• Algorithm based
• Knowledge based

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Basic modes
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Settings
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Newer modes

• Dual control modes
• Proportional Assist Ventilation (PAV)
• Closed loop PSV
• Automatic tube compensation
• Adaptive Support Ventilation (ASV)

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Dual control modes
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First generation dual modesVAPS and PA
Bear 1000
Bird 8400Sti
Tbird

• Combines volume ventilation pressure support
• Uses TV, peak flow, and pressure support
• Targets PS level with at least set peak flow
• Continues until flow decreases to set peak flow,
  then
• If TV not delivered, peak flow maintained until
  vol. limit
• If TV or more delivered, breath ends

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First generation dual modesPRVC and Volume
support
Servo 300
Maquet Servo-i

• Combines volume ventilation pressure control
• Set TV is targeted
• Ventilator estimates vol./press. relationship
  each breath
• Ventilator adjusts level of pressure control
  breath by breath

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PRVC

1. Test breath (5 cm H2O)
2. Pressure is increased to deliver set volume
3. Maximum available pressure
4. Breath delivered at preset E, at preset f,
   and during preset TI

(5)When VT corresponds to set value, pressure
remains constant (6) If preset volume
increases, pressure decreases the ventilator
continually monitors and adapts to the patients
needs
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Volume support
(1) VS test breath (5 cm H2O) (2) Pressure is
increased slowly until target volume is achieved
(3) Maximum available pressure is 5 cm H2O below
upper pressure limit
(4) VT higher than set VT delivered results in
lower pressure (5) Patient can trigger breath
(6) If apnea alarm is detected, ventilator
switches to PRVC
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Summary
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Ventilator settings

• Minimum respiratory rate
• Target tidal volume
• Upper pressure limit
• FIO2
• Inspiratory time or IE ratio
• Rise time
• PEEP

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Advantages and disadvantages

• Decelerating inspiratory flow pattern
• Pressure automatically adjusted for changes in
  compliance and resistance within a set range
• Tidal volume guaranteed
• Limits volutrauma
• Prevents hypoventilation

• Pressure delivered is dependent on tidal volume
  achieved on last breath
• Intermittent patient effort ? variable VT
• Less suitable for patients with asthma or COPD

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Second generation of dual modes
Auto flow
Evita 4,
Adaptive support ventilation
Hamilton Galileo
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Autoflow

• First breath uses set TV I-time
• Pplateau measured
• Pplateau then used
• V/P measured each breath
• Press. changed if needed (/- 3)
• Then similar to PRVC
• Adds high TV alarm limit
• Can be used in CMV, SIMV and MMV

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Adaptive support ventilation
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Adaptive support ventilation
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Bi-level ventilation methodsAllow spontaneous
breaths at two airway pressures

• Reduction of shunt due to the alveolar
  recruitment
• Better venous return
• Reduced Risk of Pulmonary Muscle Atrophy
• Weaning is enhanced

Advantages of spontaneous ventilation

• BiPAP (Drager E-4 E-2 dura)
• BiLevel (NPB 840)
• APRV (NPB 840, Drager E-4 E-2 dura)

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BiPAP (Drager E-4 E-2 dura)

• Reduction of the invasivness of Ventilation
• Reduction of Sedation
• One Ventilation Mode from Intubation to Weaning
• More comfortable for the Patient
• Fewer Alarms (easier handling)

Spontaneous Breathing
BIPAP
PCV
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Other newer modes

• Proportional assist ventilation
• Smart care
• Automatic tube compensation
• Neural adjusted ventilator assist

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Proportional assist ventilation

• Supports according to the patient's effort, based
  on the respiratory flow signal and by adjusting
  inspiratory airway pressure in proportion to the
  patient's effort
• PAV requires accurate, instantaneous measurement
  of compliance and resistance
• Only provides assisted ventilation
• Improves patient ventilator synchrony
• Does not improve ventilation/oxygenation no
  control of ventilatory pattern!
• May prevent lung injury, Not shown to improve
  weaning!

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Automatic tube compensation

• Designed to Maintain Tracheal Pressure at
  Baseline
• Does not require ongoing assessment of
  resistance!
• Pressure Applied Based Upon Resistive Properties
  of the Airway and Patients Inspiratory Flow
• Positive Pressure During Inspiration
• Negative Pressure During Exhalation
• Effectively unloads resistive effort imposed by
  ETT
• Improves patient ventilator synchrony
• Reduces risk of lung injury
• Does not improve ventilation/oxygenation
• No control over ventilatory pattern
• No demonstrated improvement in weaning!

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Indications of ATC
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Smart care

• It is a knowledge based automated weaning
  system.
• It contains an automated clinical weaning
  guideline
• Based on recognised medical expertise and
  research.

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Smart care working principles

• Step 1 Stabilizing within a respiratory comfort
  zone
• Step 2 Reducing invasiveness
• Step 3 Testing readiness for extubation

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Respiratory Comfort Zone
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Contraindications to smart care
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Neural adjusted ventilator assistNAVA
Ideal Technology
Central Nervous System ? Phrenic
Nerve ? Diaphragm Excitation ? Diaphragm
Contraction ? Chest Wall and Lung
Expansion ? Airway Pressure, Flow and Volume
New Technology
Ventilator Unit
Neuro-Ventilatory Coupling
Current Technology
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Conventional triggering

• Conventional ventilator technology uses a
  pressure drop or flow reversal to provide
  assistance to the patient.
• This is the last step of the signal chain
  leading to inhalation.
• This last step is subject to disturbances such
  as intrinsic PEEP, hyperinflation and leakage.

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NAVA triggering

• The earliest signal that can be registered with a
  low degree of invasivity is the excitation of the
  diaphragm.
• The excitation of the diaphragm is independent of
  pneumatic influence and insensitive to the
  problems with pneumatic triggering technologies.
• By following diaphragm excitation and adjusting
  the support level in synchrony with the rise and
  fall of the electrical discharge, the ventilator
  and the diaphragm will work with the same signal
  input.
• In effect, this allows the ventilator to function
  as an extra muscle, unloading extra respiratory
  work induced by the disease process.

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Availability
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Components
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Diaphragm need to work or else
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Catheters
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Signal capture

• All muscles (including the diaphragm and other
  respiratory muscles) generate electrical activity
  to excite muscle contraction.
• The electrical activity of the diaphragm is
  captured by an esophageal catheter with an
  attached electrode array. The signal is filtered
  in several steps and provide the input for
  control of the respiratory assist delivered by
  the ventilator.

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Catheter verification
P and QRS waves are present on the top leads and
the P-waves disappear on the lower leads and with
a decrease of the QRS-amplitude on the lower
leads. When an Edi waveform is present, observe
which leads are highlighted in blue. If the leads
highlighted in blue are in the center (i.e.
second and third leads), secure the Edi Catheter
in this position. To finally verify correct
positioning of the Edi Catheter press the Exp.
Hold and keep the button depressed until a
breathing effort is registered. A negative
deflection in the pressure curve with a
simultaneous positive inflection in the Edi curve
verifies correct position of the Edi Catheter.
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Setting the NAVA level
NAVA preview is a help tool to set the NAVA level
to reach an estimated NAVA On the uppermost
waveform (the pressure curve), there are two
curves presented simultaneously. The gray curve
shows the estimated pressure, Pest, based on
the Edi signal and the set NAVA level. NAVA
preview is available in all invasive modes of
ventilation except NAVA.
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Setting of the ventilator
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Setting the ventilator
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Post extubation monitoring
Monitoring of the ventilatory pattern of the
patient is superior with NAVA as the control
signal of the respiratory center is known. This
can of course be done in any mode of ventilation
and is an invaluable tool in determining
adaptation to the ventilator strategy. However,
patients breathing spontaneously can also be
monitored, which is a very helpful tool if
patients are developing wheezing after extubation
or during a T-piece trial.
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Benefits of NAVA
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Closed loop ventilation
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New horizon
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Thank you