This document provides an overview of mechanical ventilation including definitions, modes, settings, and management. It discusses non-invasive ventilation techniques like CPAP and BiPAP as well as various modes of invasive ventilation such as CMV, SIMV, and pressure support. Key variables, advantages, and disadvantages of different modes are explained. Graphs are presented to illustrate concepts like PEEP, auto-PEEP, and the relationship between pressure and volume ventilation. Management considerations for various disease states are also covered.

1. Dr. Mohammed
Indoor Medical officer
ICU & Anaesthesiology Department
Chittagong Medical College Hospital

2. 1) Definition
2) Classification of different modes of ventilation
3) Patient Ventilator asynchrony by interpretation of
different graphs.
4) Troubleshooting of ventilator machine.
5)Ventilator Management in different disease entities.

3. A) Non Invasive ventilation
1) CPAP (Continuous positive airway pressure)
2) BiPAP( Bi-level positive airway pressure)
B) Invasive Ventilation:
1)Continuous Mandatory breath(CMV)
a)Volume (V-CMV)
b)Pressure (P-CMV)
2)Synchronized Intermittent Mandatory Breath
a)Volume (V-SIMV)
b)Pressure (P-SIMV)
3) Continuous Spontaneous Ventilation(CSV)
or Pressure support.

4. -MMV (Mandatory minute ventilation)
-HFOV(High frequency Oscillatory Ventilation)
-NAVA(Neurally adjusted ventilatory Assist)
-APRV( Airway pressure release ventilation)
-ATC( Automatic tube compensation).
-VAPS(volume assured pressure support).
-PRVC(pressure regulated volume control)
-IRV(inverse ratio ventilation)

5. 1) Breathing pattern:
a)Primary breath control variable.
1)Volume
2) Pressure.
3) Dual
b)Breath squence
1)CMV
2)SIMV
2)CSV or PS
2) Control Type: a)Setpoint
b) Servo
c)Adaptive
d) Optimal

6. 3) Control Strategy:
a)Phase variable (trigger, limit, cycle)
b) Operational logic (conditional variables,
output variables, performance function)
Respir Care 2001;46(6):604-621

7. Allows the patients to
maintain normal functions
•Speech
•Eating
Helps avoid the risks and
complications related to:
•Intubation
•Sedation
 Less ventilator-associated
pneumonia
Less airway pressure is
tolerated
Does not protect against
aspiration
No access to airway for
suctioning
Advantages of NIPPV Disadvantages of NIPPV

8. Decompensated COPD (Hypercapnic Respiratory Failure)
Cardiogenic pulmonary edema
Hypoxic respiratory failure
Other possible indications
•Weaning (post-extubation)
•Obesity hypoventilation syndrome
•Patients deemed not to be intubated
•Post-surgery
•Asthma

9. Cardiac or respiratory arrest
Non-respiratory organ failure
Severe encephalopathy (e.g., GCS < 10)
Severe upper gastrointestinal bleeding
Hemodynamic instability or unstable cardiac arrhythmia
Facial surgery, trauma, or deformity
Upper airway obstruction
Inability to cooperate/protect the airway
Inability to clear respiratory secretions
High risk for aspiration

10. Continuous Mandatory Breath(CMV):
- all breaths are mandatory, and machine triggered.
Continuous spontaneous ventilation(csv) or PS:
-all breaths are spontaneous, triggered by the
patient .
SIMV:
-when mandatory breath are patient triggered they are
called SIMV. breaths can be either mandatory or spontaneous Breaths
can occur separately or breaths can be superimposed on each
other. Spontaneous breaths can be superimposed on mandatory
breaths, as in Airway Pressure Release Ventilation (APRV).
Alternatively, mandatory breaths can be superimposed on
spontaneous breaths, as in high frequency oscillatory
ventilation(HFOV)

11. How the work of breathing partitions between the patient and the ventilator
depends on:
• Mode of ventilation (e.g., in assist control most of the work is usually done by the ventilator)
• Patient effort and synchrony with the mode of ventilation
• Specific settings of a given mode (e.g., level of pressure in PS and set rate in SIMV)

12. Basic definitions
-Airway pressure
-Peak inspiratory pressure(PIP)
-plateau pressure
-Positive end expiratory pressure(PEEP)
-Continuous Positive airway pressure(CPAP)
-Mean airway pressure.
-Inspiratory time, I:E ratio
- Tidal Volume: amount of gas delivered with each
breath.
-FiO2(fraction of inspired O2)

13. PIP(Peak inspiratory pressure)
-The PIP is the maximum pressure obtainable
during active gas delivery. It is thus important to adjust PIP
as per lung compliance & thus ventilate with optimal tidal
volume.
Plateau pressure
-The PP is defined as the end inspiratory pressure
during a period of no gas flow. The PP reflects lung & chest
wall compliance. It should be limited to 35 cm H₂O.
Mean airway pressure:
- Is an average of the system pressure over the entire
ventilator period.

14. Plauteau pressure

16. Calculating PEEP

17. -High intra thoracic pressure can cause decreased venous
return & decrease cardiac output.
-May produce pulmonary barotrauma.
-May worsen air- trapping in Obstructive Pulmonary
disease.
-Increase intracranial pressure
-Alteration of renal function & water metabolism.
PEEP should be kept 0 (zero) is pneumothorax.
PEEP should be kept high in ARDS
Normal PEEP in 5 mm of Hg

18. Suspecting and Measuring AutoPEEP
Time
Pressure
PEEPe
PEEPi
Total PEEP
Suspect AutoPEEP if flow at the
end of expiration does not return
to the zero baseline.
AutoPEEP is commonly measured by performing a pause at the end of expiration. In
a passive patient, flow interruption is associated with pressure equilibration through
the entire system. In such conditions, proximal airway pressure tracks the mean
alveolar pressure caused by dynamic hyperinflation.
End expiratory pause

19. PEEP, Regional Lung Volume, and Shunting
PEEP
CPAP
Lung regions with shunt tend to distribute preferentially in the dependent
regions. Tidal ventilation helps open collapsed regions, and PEEP helps to
maintain those regions open throughout expiration and to reduce shunt.
Note that level of PEEP required to achieve such varies along the
gravitational axis.

22. A)Trigger (time, pressure ,flow)
-What causes the breath to begin.
B)Limit what regulates gas flow during breath
C)Cycle: What causes the breath to end

23. A)Set point: Means that the output of the ventilator
automatically matches a constant, unvarying, operator
preset input value(production of a constant inspiratory
pressure or flow from breath to breath)
B) Servo: The output automatically follows dynamic
varying , operator specified input.
C)Adaptive dual control : Means that ventilator
automatically adjust the pressure set point over several
breaths to maintain an operator selected volume set point
(target volume) as the mechanics of respiratory system
change)
Eg: PRVC in servo 300 & Autoflow Drager evita 4, E-vent,

24. Optimal control:( Most advance control strategy)
The Ventilator automatically adjust both the pressure
& volume set points to optimize other performance
variable as respiratory mechanics change.

25. CPAP( Continuous positive airway pressure):
Refers to the addition of a fixed amount of positive airway pressure to
spontaneous respirations.
-Patient must initiate all the breath.
-Functionally similar to PEEP
Indication: Obstructive sleep apnea
Cardiogenic pulmonary edema
Maintain a continuous level of positive airway pressure in a
spontaneous breathing pattern.
It is functionally similar to PEEP except that PEEP is
applied pressure against exhalation & CPAP is pressure
applied by a constant pressure.

26. BiPAP

27. Pressure and volume targeted ventilation obey the same principles set
by the equation of motion. Pressure and volume targeted ventilation
obey the same principles set by the equation of motion.
In pressure-targeted ventilation: an airway pressure target and
inspiratory time are set, while flow and tidal volume become the
dependent variables.
In volume targeted ventilation (flow-controlled, volume cycled), a
target volume and flow (or inspiratory time in certain ventilator) are
preset and pressure and inspiratory time (or flow in the ventilator where
inspiratory time is preset) become the dependent variables.
The tidal volume is the integral of the flow during inspiration = area
under the curve of the flow time curve during inspiration .

28. Pressure V/S volume ventilation
Pressure ventilation Volume ventilation
Parameters set by the
operator
PIP, PEEP, Rate, FiO2,Ti Vт, PEEP, rate, Ti
Parameters determined
by the ventilator
Vт, Te PIP, Te
Advantage Higher MAP with the
same PIP
-Lung protective for non
compliant lung
Guaranteed minute
ventilation
Disadvantage -Does not accommodate
for rapid changes in
pulmonary compliance
PIP may reach to
dangerous level if
compliance is worsening
-Minute ventilation not
guaranteed

29. Set variables
•-Volume, flow rate, respiratory rate, PEEP and FIO2.
Mandatory breaths
•-Ventilator delivers preset volume and preset flow.
•-Ventilator delivers mandatory breath.
•-time cycle (machine triggered).

32. Set variables
•Volume, TI , flow rate, frequency, PEEP and FIO2
Mandatory breaths
•Ventilator delivers preset volume and preset flow rate at a set back-up rate
Spontaneous breaths
•Additional cycles can be triggered by the patient but otherwise are identical to the
mandatory breath.

33. Assist control :a) Volume AC
Flow targeted , volume cycle breath
b) Pressure AC
Pressure targeted, time cycle breath
-Guarantees set number of positive pressure ventilation
-If respiratory rate exceeds this breath are patient triggered
breath.
If respiratory rate is below guarantee ventilator delivers
Mandatory breath.
(In ICU E-vent & pneumovent no AC mode Only in 2 China machine Name as APNEA mode)

35. Key set variables
•Targeted volume (or pressure target), flow rate (or inspiratory time, Ti), mandated frequency
•PEEP, FIO2, pressure support
Mandatory breaths
•Ventilator delivers a fixed number of cycles with a preset volume at preset flow rate.
•Alternatively, a preset pressure is applied for a specified Ti
Spontaneous breaths
•Unrestricted number, aided by the selected level of pressure support

36. -Set ventilator breath:
Set minimum minute ventilation with respiratory
rate+ Vт( V-SIMV) or Inspiratory Pressure(P-SIMV).
-Ventilator breaths are synchronized with patients
inspiratory breath.
-Patient increases MV by adding spontaneous breath which
can be unassisted or spontaneous.

37. e

40. Pressure Control ventilation
Key set variables:
•Pressure, TI, and frequency
•PEEP and FIO2
Mandatory breaths
•Ventilator generates a predetermined pressure for a preset time
Spontaneous breaths
•PCV-AC mode: same as mandatory breaths
•PCV-SIMV mode: unsupported or PS
Important caveat
•It is important to understand that in pressure-controlled ventilation the relation
between the set rate and minute ventilation is complex. Above a certain frequency
(e.g., when intrinsic PEEP is created due to a reduced expiratory time), the driving
pressure (set PC pressure – PEEPtotal) starts to drop--and so does the delivered tidal
volume.
•A pneumothorax or other adverse change in the mechanics of the respiratory system
will not trigger a high alarm pressure but a low tidal volume alarm instead.

41. Pressure = set variable.
Mandatory breaths: none.
Spontaneous breaths
•Ventilator provides a preset pressure assist, which terminates when flow drops to a
specified fraction (typically 25%) of its maximum.
•Patient effort determines size of breath and flow rate.

43. -Strategy to inverse ratio ventilation I:E ration I>E to
potentially improve oxygenation.
-When pt is severely hypoxemic despite optimal PEEP and
FiO₂.
Can be used Volume or pressure limited MV
- In pressure:- Increase I:E ration
-In volume:- Ramp wave is reduced Peak inspiratory
flow rate Until I>E.
-In volume square wave add increase end inspiratory
pause until I>E

44. Graph

45. 1)Dual control within a breath modes:
-Volume assured PS(VAPS):Bird 8400 STi, Tbird,
- Pressure Augmentation: Bear 1000
2)Dual control breath to breath modes:
- Pressure limited , Flow cycled
-Volume support(VSV): servo 300
-Variable PS: Ventrui
-Pressure limited, time cycled:
-PRVC(pressure regulated volume
control):servo 300, E-vent,
-Auto flow: Drager Evita 4
-VC +(volume control plus): Puritan Bennett
840 Nelcore
-Adaptive pressure support: Hamilton gallileo
3) Combination mode:
-Adaptive support ventilation: Hamilton gallileo

46. -causes:
-ET tube problem(pts biting, kinked, obstruction)
-Bronchospasm
-High flow rate
-Secretion
-Water in HME filter
All can be identified by the graph.

47. Leak in the circuit

49. 29 year old patient weight 70 kg height 150cm
Dx case of ARDS with Pneumonia
Ventilator settings: AC with Vт 500 ml Respiratory rate 12
PEEP 7 cm of H2O , FiO2 80%.
Measured variables : Rate 25, Ve: 12.5L/min , Ppeak 40 cm
H2O Pplat 35 cm of H2O.
ABG: pH 7.40, PaO2 75 mm of Hg PaCO2 38 mm of Hg
SpO2 92 %.
Are we happy with this ventilator setup & ABG.

51. Ventilator Management in ARDS

59. Trouble Shooting the Ventilator
 High peak pressure differential:
High Peak Pressures
Low Plateau Pressures
High Peak Pressures
High Plateau Pressures
Mucus Plug ARDS
Bronchospasm Pulmonary Edema
ET tube blockage Pneumothorax
Biting ET tube migration to a single
bronchus
Effusion

60. Ventilator showing high O2 pressure despite FiO₂ is
40% or 0.4
-There is no air in the central Medical Air.