1. Nonconventional Modes of Ventilation
VIJAY DESHPANDE, MS, RRT, FAARC
Emeritus Professor Adjunct Professor
Georgia State University Manipal University
Atlanta, Georgia Manipal, Karnataka
USA India
Evolution of Mechanical Ventilation
■ Resuscitation Bags
■ Negative Pressure Ventilation ( Iron Lung etc.)
■ Pressure Cycled Ventilators ( Bird, Bennett etc.)
■ Volume Ventilators (Bennett MA-1, Bear 1,
Emerson Post-op)
■ SIMV Ventilators ( Siemens 900 C etc.)
■ Third Generation Ventilators ( PB 7200,
■ Hamilton Veolar, Bird 6400 etc.)
■ Microprocessor Ventilators ( Siemens 300,
■ Hamilton Galileo, Bird 8400 ST, Bear 1000 etc.)

2. Advancements in Mechanical Ventilation
Control,
Assist,
PEEP,
CPAP
VENTILATOR CLOSED-LOOP
IMV, GRAPHICS VENTILATION
SIMV,
PSV,
PCV,
Combinations of
Volume or Pressure VAPS, Paug
ventilation: Volume Support,
SIMV +PSV,
PRVC, Auto-flow,
SIMV+PSV+CPAP
ASV,APV,
VS, auto mode
PAV,
NAVA
How is Closed Looping Accomplished ?
I have absolutely no idea.

3. Flow Sensor Flow Sensor
Flow Triggering
CHURCH BULLETIN BLOOPERS
A bean supper will be held on Tuesday
evening in the church hall.
Music will follow.

4. Decision Making
After initiating SIMV, within an hour the ABGs
return to normal levels, however the patient
demonstrates use of accessory muscles and
increased work of breathing.
Unsupported Breathing through a Tracheal Tube

5. SIMV + PS
(Pressure-Targeted Ventilation)
Time-Cycled
Time-
Flow-Cycled
Flow
(L/min)
Set PC level
Pressure Set PS level
(cm H2O)
Volume
(ml)
Time (sec)
PS Breath
Acute Lung Injury (ALI)
ALI is described as:
● Acute onset of Hypoxemia with P/F ratio of </= 300 mm Hg
● Bilateral infiltrates on a frontal Chest Radiogram
● Absence of Left Atrial Hypertension (Normal PCWP )
● ALI with most severe hypoxemia with P/F ratio < / = 200 mm
Hg is termed as ARDS

6. ALI and ARDS
● Approximate incidence of 59 (ALI) and 29 (ARDS)
cases per 100,000 persons/year
● Mortality ~ 34-58 %
● Economic burden on Uninsured, inadequately insured
patients, Hospitals, Government and Insurance Companies
Lung Protective Ventilation
NEJM 2000; 342 (18) : 1301-1308
● Small V T and Low Airway Pressures is the only
intervention found to reduce mortality from ALI/ARDS
● May promote progressive lung derecruitment and worsening
of oxygenation

7. Recruitment Maneuver
● Recruitment refers to reopening collapsed lung units using
transient increase in the transpulmonary pressure
● The rationale for recruitment maneuvers is to improve
alveolar recruitment and increase end-expiratory volume
in order to:
a. Improved gas exchange
b. Reduced overdistension of relatively healthy lung units
c. Prevent repetative opening and closing of unstable
alveoli
ARDS
s Acute Respiratory Distress Syndrome
s Pulmonary endothelial Inflammation leading
to Acute Lung Injury
s Further deterioration promotes ARDS

8. ARDS
s Inflammatory response promotes:
increased pulmonary vascular permeability
seepage of proteinaceous fluid into the
pulmonary interstitium and alveoli
reduction in Surfactant production and
inactivation of existing Surfactant
increased surface tension
microatelectasis in the affected areas
The American-European Consensus Conference on ARDS.
Am J Respir Crit Care Med 1994; 149:818-824

9. Dilemma in Ventilatory Management of ARDS
Objective: Reopen collapsed and recruitable alveoli
Strategy: Application of Positive Pressure Ventilation
Commonly used Mode of Ventilation: Volume Targeted
Problem: Alveolar Overdistention

10. Oh! Sh*!
Acute Lung Injury (( ALI )) and ARDS
Acute Lung Injury ALI and ARDS
Damage to the Lung :
G Not distributed homogenously
G Even in severe cases ~ 1/3 lung is open
G Open lung receives the entire tidal volume
resulting in :
' Over-distention
Over-
' Local hyperventilation
' Inhibition of surfactants
Ravenscraft, Sue. Respiratory Care, Vol 41, No 2 : 105-111, Feb
105-
1996

11. ARDS
C o lla p s e d
R e c r u ita b le N orm al
ARDS
Volume Augmented Breath
Collapsed
Recruitable Normal

12. Over-distention
Over-distention
Preset Tidal Volume
With little or
With little or
no change in VT
no change in VT
Normal
Volume (ml) Abnormal
Paw
Paw
Pressure (cm H2O)
Over-distention
G Observed on a Pressure-Volume Loop
Pressure-
G Indicates hyperinflation or excessive application
of pressure
G May promote Barotrauma
G Corrective action includes reduction in the Peak
Inspiratory Pressure or Tidal Volume

13. CRITICAL THINKING
4 Common sense for an
experienced therapist is
critical thinking for a novice.
4 Critical thinking at the bedside
is synonymous with
“Differential diagnosis”.
What should
I do Now?

15. PRESSURE TARGETED VENTILATION
d PIP and Palv are Limited
d Prevents Alveolar Over-
distention
d Provides better Patient-Ventilator
synchrony
d Delivered Tidal Volume depends
on Airway Resistance and Lung
Compliance
d PaCO2 is variable
Assisted Mode
(Pressure-Targeted Ventilation)
(Pressure-Targeted
Patient Triggered, Pressure Limited, Time Cycled Ventilation
Time-Cycled
Flow
(L/min)
Set PC level
Press
(cm H2O)
ure
Volume
(ml)
Time (sec)

16. ARDS
Pressure Augmented Breath
P
P P
Collapsed
Recruitable Normal
ARDS network.
N Eng J Med 2000, 342(18):1301-1308.
Multi-center NIH study demonstrated that
ALI/ARDS patients ventilated with tidal
volumes of 6 ml/Kg were significantly more
likely to survive than those ventilated with
tidal volumes of 12 ml/Kg.

17. ARDSnet Findings
G Lower Tidal Volumes
G Use of rapid rates avoiding auto-PEEP ( 35/min )
G PPLAT 30 cm H2O reduces mortality
G Lower PPLAT showed better outcome
ARDSnet: 6ml/kg reduces mortality vs. 12 ml/kg
Components of Inflation Pressure
PIP
Paw (cm H2O)
} Transairway Pressure (PTA)
Exhalation Valve Opens
Pplateau
Inspiratory Pause
(Palveolar)
Expiration
Time (sec)
Begin Inspiration Begin Expiration

18. Strategies to Ventilate ALI and ARDS patients
G Prevent Alveolar Over-distention
Use of low Tidal Volumes (5-7 ml/Kg)
May promote de-recruitment of alveoli
G Prevent repetitive alveolar opening and closure
Use of Recruitment Maneuver
sustained increase in airway pressure
application of adequate end-expiratory pressure
(PEEP/CPAP)
Possible Approaches to Ventilate ARDS Patients
G APRV
G PCIRV
G BiLevel or BiVent
G PRVC
G HFO
No data to indicate that any mode of ventilation
is BETTER than conventional Pressure-A/C
ventilation

19. CHURCH BULLETIN BLOOPERS
At the evening service tonight,
the sermon topic will be What Is Hell?
Come early and listen to our choir practice
How much PEEP?

20. Amato MB., et al., Effect of a protective-ventilation
strategy on mortality in ARDS.
N Eng J Med 1998;338(6):347-354
Initial recruitment of alveolar units may be
achieved by applying PEEP at a level above
the lower inflection point of the P-V curve.

21. Lung Protective Strategy
Volume (ml)
PEEP 2-3 cm H2O above LIP
Lower Inflexion Point ( Pflex)
The lower inflection point (Pflex)
is obtained by static inflation
maneuver and should not be
measured from the dynamic curve.

22. Initial PEEP Level
2-3 cm H2O above the Lower Inflection Point
CHURCH BULLETIN BLOOPERS
The sermon this morning:
Jesus Walks on the Water.
The sermon tonight:
Searching for Jesus.

23. Rationale for Closed Loop Ventilation
Establish Homeostasis relatively faster
Improve Quality of Care
Improve Safety
Address Resource Limitations
Improve Quality and Safety
Estimated deaths in US due to medical error range from
44,000 to 98,000 per year
Improper use of mechanical ventilation has shown to have
detrimental effects
ICU patients frequently have multiple system illnesses and
require multiple testing and bedside decision makings
Closed-Loop ventilation can prevent improper setting
Marc Wysocki and Josef Brunner ; Closed-Loop Ventilation in Critical Care Clinics
Vol 23, No 2, 223-237, April 2007

24. Address Resource Limitations
Mechanical Ventilation is generally a labor intensive task
On an average daily cost of Mechanical Ventilation is $ 1,500
Labor shortage or excessive work load per clinician is not
uncommon
Closed-Loop can provide care at lower labor cost
Closed–Loop Ventilation can support clinicians with limited
ability to incorporate data into decision making
Marc Wysocki and Josef Brunner ; Closed-Loop Ventilation in Critical Care Clinics
Vol 23, No 2, 223-237, April 2007
Some actions do not correct auto-PEEP

25. Closed-Loop Ventilation
PRVC, VC+, VAPS, PCV-VG ASV PAV, NAVA
Adjust pressure to meet the Advanced Version
set Tidal Volume of PSV
Incorporates several modes
PSV, PCV, P-SIMV to deliver
Appropriate VE
Closed-Loop Ventilation
General Scheme:
PaO2 or
output SpO2
RESPIRATORY
FiO2
SYSTEM

26. Closed-Loop Ventilation
Set P, V or flow
RESPIRATORY
Comparator VENTILATOR
SYSTEM
Measured Pressure,
Volume and Flow
Generic Scheme

27. COMBINED PRESSURE/VOLUME
VENTILATION
G Exploit beneficial effects of both
Pressure and Volume Ventilation
G Improve Patient-ventilator Synchrony
Patient-
G Prevent ventilator induced lung injury

28. CHURCH BULLETIN BLOOPERS
This evening at 7 PM there will be a hymn
sing in the park across from the Church.
Bring a blanket and come prepared to sin
Closed-loop Ventilation
G Volume Support ( VS )
G Pressure Regulated Volume Control ( PRVC )
G Adaptive Support Ventilation ( ASV )
G Proportional Assist Ventilation ( PAV )
G Nuerally Adjusted Ventilator Assistance (NAVA)

29. Volume Support
Patient Trigger
Servo
Trial breath to calculate Compliance i
Pressure limit is set = VT/ C
Breath Delivered
Exhaled Volume
Flow decreases to 5%
measured
of peak flow
PS level is adjusted
until Exhaled VT=Set VT Termination of Inspiration
In case of apnea, the mode switches to PRVC
PRVC
Servo
i
Trigger On
Exhaled VT Set VT
Exhaled VT Set VT
Pressure Support level Pressure Support level
increases stepwise decreases stepwise
until until
Exhaled VT = Set VT Exhaled VT = Set VT
Servo 300 Ventilator, Maquet Inc.

30. Pressure Regulated Volume Control
(PRVC)
Volume Control+ ( VC + )
Autoflow
Adaptive Support Ventilation (ASV)
Pressure Control Ventilation with Volume
Guarantee ( PCV – VG)

31. AUTO- MODE
Control Mode Support Mode
Decrease Work of Breathing Facilitate Weaning
Auto-Mode
Coupling Modes to combine Control and Support
Pressure Control Pressure Support
Volume Control Volume Support
PRVC Volume Support

32. Adaptive Support Ventilation (ASV)
The ASV assures a pre-selected target ventilation
Uses sophisticated calculations based on set tidal
volume, rate, and the patient’s lung mechanics
The clinician sets:
Desired minute ventilation
Maximum Airway Pressure
Prevents rapid shallow breathing and avoids
volutrauma
The patient is protected from apnea and AutoPEEP
Source: Hamilton Medical
Proportional Assist ventilation
(PAV)
!Strictly a patient triggered mode
!The ventilator adjusts pressure in response to
patient effort
!The clinician sets:
IPAP
EPAP
Flow Assist Level PB 840
Volume Assist Level

33. 0%
100 %
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34. NAVA
Neurally Adjusted Ventilatory Assist
Servo
i
Neural Pathway to Cural Diaphragm
Neural pathways to the crural diaphragm.

35. NAVA
Trigger delay from inspiration to the beginning of
flow from ventilator ~ 100 ms
Insuflation during exhalation and the trigger delay
promotes asynchrony in COPD and patients
requiring high PS
Via Electrical activity of the Diaphragm (Edi)
NAVA provides full synchrony with the
respiratory effort made by the patient

36. Clinical Benefits of NAVA
Reduce Work of Breathing
Appropriate ventilation
Variations in the amplitude of Edi prevent
excessively high or low ventilation
Adaptation to changes in metabolic
demands
Avoidance of diaphragmatic atrophy
Reduced weaning time
Shortened hospital stay

37. PATIENT Controlled Ventilation