HERE IS A SEMINAR BASED ON ALL THE NEWER MODES OF MECHANICAL VENTILATION . MY SINCERE APOLOGIES , BECAUSE I HAD TO TAKE INFORMATION FROM OTHERS SLIDES TOO , SINCE THERE IS VERY LESS INFORMATION AVAILABLE ABOUT THIS TOPIC

1. NEWER MODES OF VENTILATION
PRESENTER : DR RAJESH M
MODERATOR : DR KIRAN B R
HOD : DR ARUNKUMAR A
SSIMS & RC
DEPARTMENT OF ANESTHESIA
DAVANGERE , KARNATAKA

2. Understanding basics
• The ability of ventilator to initiate, maintain, and terminate
an assisted/artificial breath derives its basis from “
Equation of motion.
• The equation of motion postulates that the pressure
necessary to deliver a breath has two components; the
pressure to overcome elastic recoil of the lungs and chest
wall and the pressure to cause flow through the airways
P = Presistive + Pelastance

3. • Alveolar diagram showing various pressures involved
in inspiration/expiration. The same are either provided
or overcome by the ventilator

4. Ventilatory graphics in classical
volume control mode

5. Variable
• Control variable : Constant throughout inspiration,
regardless of changes in respiratory impedance
• Trigger variable: For initiating a breath.
• Limit variable: Constant throughout inspiration but does
not result in the termination of inspiratory time
• Cycle variable: Causes inspiration to end
• Conditional variable: results in a change in output

6. VOLUME CONTROL MODE

7. PRESSURE CONTROL MODE

8. WHY NEW MODES ?
• Conventional modes are uncomfortable
• Need for heavy sedation & paralysis
• Patients should be awake and interacting with the
ventilator
• To enable patients to allow spontaneous breath
on inverse ratio ventilation
• Lung protective ventilation : VILI
Satisfies our craving for adventure -(engineers and clinicians)
We like better numbers - (Obsessed with pulse oximetry)

9. PROBLEMS WITH CONVENTIONAL MODES OF
VENTILATION
• These ventilators only deliver the set parameters and take no
feedback from patient variables.
• Thus, all the classical volume/pressure control modes are “Open
Loop” (the feedbackloop is absent).
• The newer modes target to make alterations with the changing lung
and take feedback from patient parameters, thus completing the
feedback loop and are “Closed loop” type
• The control, cycle, or the limit variables undergo self-adjustment and
these variables are no longer limited to single parameter determinant
but if the threshold of one component is reached they shift to the
other alternate set parameter. This has lead to name “Dual control”
ventilation

11. CLASSIFICATION :

12. Dual control modes
Modern ventilators now incorporate complex computer based
algorithms, and are capable of simultaneously controlling two
variables.
1.Intrabreath control (dual control WITHIN a single
breath, DCWB):
During a part of an essentially pressure-targeted breath, flow
is also controlled
2.Interbreath control (dual control from breath to breath,
DCBB):
The configuration of a pressure-targeted breath is
manipulated in SUBSEQUENT breaths to deliver a targeted
tidal volume

13. Dual Control within a Breath
Volume-assured pressure support (VAPS)
• This is modification of pressure control mode
• This mode allows a feedback loop based on the volume
• It makes ventilator to switch from pressure control to
volume control if a minimum set TV is not achieved.

14. • operator adjustable parameters are same as in
conventional PC mode
• – pressure limit, peak flow rate, ventilator rate, and PEEP
• Additionally “minimum TV” is also defined
• This combination provides an optimal inspiratory flow
during assisted/controlled cycles, reducing the patient’s
work of breathing
• Unlike typical PSV, VAPS assures stable tidal volume
along with pressure support in patients with irregular
breathing patterns

17. BENEFIT OF VAPS
• Lower peak airway pressure
• Reduced patient work of breathing
• Improved gas distribution
• Less need for sedation
• Improved patient comfort

18. DISADVANTAGES/ LIMITATIONS OF
VAPS
• Set pressure limit should not be too high to cause
unwanted trauma to lung and generate higher volume
than minimal
• Set flow rates must not be very low as in situations where
minimal volume is not met , it would cause a delayed
switch from pressure control to volume control and would
lead to unwanted prolongation of inspiratory time
• Patients with airflow obstruction should be monitored
closely in order to prevent air trapping

19. Applications of VAPS
• A patient who requires a substantial level of ventilatory
support and has a vigorous ventilatory drive to improve
gas distribution and synchrony
• A patient being weaned from the ventilator and having an
unstable ventilatory drive who may require backup tidal
volume as a safety net in case the patients effort or/and
lung mechanics change

20. Dual control breath-to-breath
Volume Support
• Entirely a spontaneous mode
• Ventilator assesses initial breaths and steps up pressure
support in subsequent breaths if TV is low.
• Tidal volume is used as feedback control to adjust the
pressure support level
• Intended to provide a control tidal volume and increased
patient comfort

21. • Delivers a patient triggered (pressure or flow),
pressure targeted, flow cycled breath
• Can also be timed cycled (if TI is extended for some
reason) or pressure cycled (if pressure rises too high).
• It adjusts pressure (up or down) to achieve the set volume
(the maximum pressure change is < 3 cm H2O and
ranges from 0cm H2O to 5 cm H2O below the high
pressure alarm setting.

22. • The ventilator delivers a single spontaneous pressure
support type of breath and uses variable pressure support
levels to provide the target tidal volume
• During weaning or awakening from anesthesia, the
patient assumes a higher spontaneous tidal volume and
the ventilator decreases the pressure support level
accordingly

23. • When the spontaneous tidal volume decreases, the
ventilator increases the pressure support level
automatically to maintain the target tidal volume.
• During VS, the ventilator frequency and minute ventilation
are determined by the triggering effort of the patient.
• The inspiratory time is determined by the patient
respiratory demand.
• This mode achieves the advantages of pressure support
assuring an adequate tidal volume despite changes in
lung compliance.

24. • If the set tidal volume is too large, the ventilator will raise
the pressure support to achieve it and lead to problems
like barotrauma, hemodynamic compromise, and intrinsic
PEEP.
• If the set volume is too low, it may lead to inadequate
pressure support and thus increased respiratory rate
leading to increased work of breathing.

25. INDICATIONS
• Spontaneous breathing patient who require minimum
ventilatory effort
• Patients who have inspiratory effort needing adaptive
Support
• Patients who are asynchronous with the ventilator
• Used for patients ready to be “weaned” from the ventilator
• Used for patients who cannot do all the WOB but who are
breathing spontaneously

26. Ventilatory graphics in volume support
mode

27. Pressure regulated volume control
• Ventilation that provides volume controlled breaths with
the lowest pressure possible by altering the flow and
inspiratory time
• Delivers patient or timed triggered, pressure-targeted
(controlled) and time-cycled breaths
• Ventilator measures VT delivered with VT set on the
controls.
If delivered VT is less or more, ventilator increases or
decreases pressure delivered until set VT and delivered VT
are equal

28. • PRVC provides volume support while keeping the PIP at a
lowest level possible by altering the peak flow and
inspiratory time in response to changing airway or
compliance characteristics.
Control Trigger Limit Target cycle
Volume Patient or
time
Pressure
PC
Lowest
pressure for
set volume
Time

29. • 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 patient’s needs

31. • To compensate for a lower inspiratory flow, PRVC
prolongs the inspiratory time to deliver the target
volume
• (VT - Increased Constant Flow * decreased Inspiratory
Time)
• The ventilator will not allow delivered pressure to rise
higher than 5 cm H2O below set upper pressure limit
• Example: If upper pressure limit is set to 35 cm H2O and
the ventilator requires more than 30 cm H2O to deliver a
targeted VT of 500 mL, an alarm will sound alerting the
clinician that too much pressure is being required to
deliver set volume

32. Indications
• Patient who require the lowest possible pressure and a
guaranteed consistent VT
• ALI/ARDS
• Patients requiring high and/or variable ventilatory effort
• Patient with the possibility of changes in compliance of
lung/ Resistance of airway

33. Advantages
• Maintains a minimum PIP
• Guaranteed VT
• Patient has very little WOB requirement
• Allows patient control of respiratory rate
• Decelerating flow waveform for improved gas Distribution
• Breath by breath analysis

34. Disadvantages
• Varying mean airway pressure
• May cause or worsen auto-PEEP
• When patient demand is increased, pressure level may
diminish when support is needed
• May be tolerated poorly in awake non-sedated patients
• A sudden increase in respiratory rate and demand may
result in a decrease in ventilator support

36. Adaptive support ventilation
• This is a unique mode that sets minimal work of breathing
as its end point to achieve desired minute ventilation. The
control variable is “pressure” and is capable of delivering
both pressure control or pressure support breaths
• The operating principle is based on pressure controlled
synchronized intermittent mandatory ventilation with
automatic adjustments to set pressure level and
respiratory rate on the basis of measured lung
mechanics in the previous breaths
• The set parameters are the ideal body weight, minimum
minute ventilation, PEEP, and trigger sensitivity

37. • The ventilator calculates the optimum respiratory rate
(ORR) by using otis equation. Tidal volume is derived by
dividing the minute ventilation by ORR
• If the patient has no breaths ,the mode works as
adaptive pressure control
• If the patient has less spontaneous breaths, it works as
simv
• If the patient has more spontaneous breaths than target, it
works as adaptive pressure support
•

38. Advantages
• Guaranteed VT
• Minimal patient Work Of Breathing
• Ventilator adapts to the patient
• Weaning is done automatically and continuously
• Variable to meet patient demand
• Decelerating flow waveform for improved gas distribution
• Breath by breath analysis

39. Disadvantages
• Inability to recognize and adjust to changes in alveolar VD
• Possible respiratory muscle atrophy
• Varying mean airway pressure
• In patients with COPD, a longer TE may be
Required
• A sudden increase in respiratory rate and demand may
result in a decrease in ventilator support

40. PROPOTIONALASSIST VENTILATION
• Advantage of improving ventilator patient synchrony
• Amplifies patient’s ventilatory effort giving patient freedom to
adopt his own breathing pattern
• Unloads respiratory muscles without imposing a fixed
breathing pattern thus allows synchrony
• Percentage of assistance to be delivered is set and other
parameters are adjusted automatically according to the
patients“air hunger”
• I:E ratio also decided by patient allowing more synchrony

42. Advantages
• Better synchrony
• More comfort in NIV with PAV compared to PSV
• Low airway pressures
• Optimal weaning
• Decreased work of breathing
• Early/late ALI/ARDS
• Hypercapnic ventilatory failure

43. Disadvantages
• If patient worsens or improves ,the proportion of
assistance needs to be readjusted according to
patient’s clinical condition
• This disadvantage has been adjusted in newer
modification “PAV + “ mode … capable of sensing patient
respiratory mechanics and adjusting accordingly

44. PAV +(Proportional Assist Ventilation)
• Provides pressure, flow assist, and volume assist in
proportion to the patient’s spontaneous effort, the greater
the patient’s effort, the higher the flow, volume, and
pressure .
• The operator sets the ventilator’s volume and flow assist
at approximately 80% of patient’s elastance and
resistance. The ventilator then generates proportional flow
and volume assist to augment the patient’s own effort

47. PAV+ is NOT recommended for…
• 1. Low Respiratory drive
• 2.Abnormal breathing pattern
• 3.Extreme air trapping
• 4. Large mechanical leaks.

48. Mandatory minute ventilation
• The operator selects a minimum minute ventilation
setting that is lower than the patient’s spontaneous
minute ventilation.
• The ventilator monitors the patient’s spontaneous
minute ventilation, and if it falls below the
operator’s set value, the ventilator increases its
output to meet the minimum set minute ventilation.

49. • MMV forms a reliable weaning mode, as the set value can be
gradually decreased loading the respiratory muscles.
• In patients with apneic episodes or central drive pathologies,
MMV sets safety by providing a set value ventilation as
mandatory ventilation
• The ventilatory setting of MMV need extreme caution, if the set
value is significantly lower than current minute ventilation, this
may lead to increased work of breathing by the patient and in
reverse situation this can lead to complete unloading of
respiratory muscles causing possibility of muscle atrophy.

50. BI-LEVEL VENTILATION MODES
• Is a spontaneous breathing mode in which two levels of
pressure i.e. high /low are set.
• Substantial improvements for SPONTANEOUS
BREATHING
• Better synchronization,
• More options for supporting spontaneous breathing
• Potential for improved monitoring

51. • These modes deliver
• pressure-controlled breaths
• time-triggered
• time-cycled breaths
• using a set-point targeting scheme

52. Airway pressure release ventilation
(APRV)
• It provides two levels of continuous positive airway pressure
(CPAP) with an inverse I:E ratio of 2:1 or more.
• The rationale of using prolonged high-pressure phase is to
prevent alveolar collapse and maintain recruitment.
• The release phase (expiratory phase) brings down mean
airway pressure and plays significant role in maintaining
normocarbia.
• The mode has dual functionality; in presence of spontaneous
breathing the patient can breathe in any phase of respiratory
cycle with supported breaths thus bringing down needs of
sedation.

53. • In absence of spontaneous breathing activity, the bi-level
pressure acts as time-cycled inverse ratio ventilation.
• The tidal volume generated mainly depends upon respiratory
compliance and difference between the two CPAP levels.
• APRV should be avoided in patients with obstructive lung
diseases as it can cause air trapping or rupture of bullae in
COPD.
• APRV has been shown to improve oxygenation in patients with
ARDS simultaneously decreasing need of sedation or paralysis

54. Ventilatory graphics in airway pressure release
ventilation

57. Neurally adjusted ventilatory assist
(NAVA)
• The NAVA system was first
described by Sinderby’s group in
1999, as a way to detect
diaphragmatic electrical activity via
an adapted nasogastric (NG) tube
(the NAVA catheter) and use it to
drive a ventilator.
• The commercial NAVA system is
now available on the Servo-I
(Maquet) ventilator platform.

58. • NAVA is a closed loop
mode that delivers
breath proportional to
patient’s inspiratory
effort
• NAVA uses
diaphragmatic
electromyogram to
detect inspiratory
effort of patient

59. • An esophageal catheter with electrodes placed at the
level of diaphragm is used to record time of initiation and
strength of contraction
• This mode over scores all other modes in synchronization
of patients efforts to ventilator by having least possible
delay among the two
• Nava is completely unaffected by leaks in the system

60. • There are two major differences between NAVA and
conventional modes of ventilation.
• The first is that rather than using pneumatic/flow
triggering (where the ventilator detects a pressure/flow
change in the circuit from patient effort), NAVA uses the
neural signal of diaphragmatic electrical activity (EAdi) to
initiate the mechanical offloading of respiratory muscles,
referred to as neural triggering.

61. • The second difference is that, once initiated, a breath is
assisted with pressure support in proportion to the
amplitude of the EAdi signal.
• The EAdi signal is sampled every 16 ms; such rapid
sampling enables the ventilator to titrate support
throughout the course of every breath as well as between
breaths.
• NAVA works as if its connected to one’s own respiratory
centre.

63. • In other modes auto-PEEP increases work of ventilator
initiation in COPD and asthma, this does not effect
ventilatory cycle in NAVA and thus overall work of
breathing decreases in these patients.
• Setting up a NAVA ventilator is straightforward and gain
over diaphragmatic electrographic potential is the only
single input required.
• A practical limitation with NAVA is placement of
esophageal catheter with electrodes and its validity of
longer duration of ventilation

64. Components

65. CATHETERS

66. • EAdi signal is measured trans-oesophageally by means
of EAdi catheter, which is double the length of ryle’s
tube, has 10 bipolar electrodes mounted at its tip, &
positioned near the crural diaphragm.
• Nose-Ear-Xiphoid or
‘NEX’ measurement provides an
estimated catheter insertion length.
• Although NAVA has been used for extended periods, it is
important to emphasise the manufacturer’s
recommendation of a maximum use period of seven
days per catheter.

68. Screenshot from a Servo-I ventilator showing NAVApreview mode.
The white pressure curve is the hypothetical pressure trace that would be
achieved if NAVAmode were used at the specified level, superimposed over the
current pressure trace.

69. Benefits of NAVA
• Synchrony with least possible delay
• Safer and improved ventilation
• Leaks do not cause false initiation of breaths (unaffected by
circuit)
• Eliminates man sleep disturbances
• Adapts to altered metabolic demand with consistent unloading
• Prevents disuse atrophy
• Improves NIV

71. NEOGANESH(SMARTCARE)
• Closed loop type modification of PSV WITH INREGRATED
ARTIFICIAL INTELLIGENCE
• Adjusts ventilator assistance depending on patient,s
respiratory pattern and literature based weaning protocols
• Based on 3 fundamental principles:
• – Adapt PS to patient’s present clinical situation
• – In case of stability wean off PS
• – Initiate spontaneous breathing trials as per
prerecorded clinical guidelines

72. • Ventilator takes feedback from monitored RR, VT, etCO2
• Trials have shown that it reduces weaning failure and also
hastens weaning duration.

73. CLOSED LOOP : AT A GLANCE

74. Automatic Tube Compensation(virtual
extubation)
• Compensates for the resistance of the endotracheal tube
• increasing PS levels as endotracheal tube diameter
decreases and inspiratory flow increases
• Under static conditions PS can effectively eliminate
endotracheal-tube resistance.
• ATC attempts to compensate for ET resistance via closed-
loop control of calculated tracheal pressure

76. • Dual modes most popular but no great evidence
• NAVA-emerging evidence even in children and NIV
• ASV- physiological mode –accumulating evidence
(ARDS/COPD)
• PAV+-better than PAV, physiological mode – accumulating
evidence, NIV good evidence
• Smartcare-unique mode can say ventilator has intensivist’s
brain-good evidence for weaning

79. TO CONCLUDE …………
• Dual modes of ventilation are more patient friendly than
conventional modes even in difficult ventilation or at time of
weaning
• These modes have become sensitive to patient ventilation
requirements and demands.
• Newer modes reduced the need of ventilation and decreased
ventilator induced lung injury
•
• However, long-term studies are needed to prove their efficacy.
• Classical modes are used in most intensive care setups; however,
understanding these newer modes may help to chart out patient-
based ventilatory strategies and improve outcomes.

80. References
• Singh PM, Borle A, Trikha A. Newer nonconventional
modes of mechanical ventilation. Journal of emergencies,
trauma, and shock. 2014 Jul;7(3):222.
• REVIEW ARTICLE : Advances in ventilation — neurally
adjusted ventilatory assist (NAVA) 317 1A03 1B04 2C04
3C00 A Skorko, D Hadfield, A Shah, P Hopkin- JOURNAL
OF INTENSIVE CARE SOCIETY 2013
• Clinical application of mechanical ventilation . DAVID W
CHANG , 4TH EDITION.

81. AUTOMATED MECHANICAL
VENTILATION IS THE FUTURE !!!!
Thank you !!!