1) Ventilator graphics display waveforms that facilitate assessment of a patient's condition on mechanical ventilation. The most commonly used graphics are scalars (flow vs time, pressure vs time, volume vs time) and loops (pressure-volume, flow-volume). 2) Scalar graphics show the relationship between flow, volume, or pressure over time. Loops show the relationship between pressure and volume or flow and volume. These graphics provide information about ventilator settings, lung mechanics, and the identification of common issues like airway obstruction or air trapping. 3) Proper analysis of ventilator graphics is essential for optimizing ventilator settings and recognizing abnormalities that may require intervention to improve a patient's ventilation

1. Ventilator
Graphics
Prithviraj S J

2. Concepts
• Is an Essential tool in managing patients on Mechanical
ventilators.
• All Latest Mechanical Ventilators are equipped with graphics that
display selected ventilator waveforms facilitating assessment of
the patient’s condition.
• Graphics displayed are two types
1. Scalars
2. Loops

3. • Most commonly used ventilator graphics are
1. Scalars
• Flow vs Time
• Pressure vs Time
• Volume vs Time
2. Loops
• Pressure – Volume Loop
• Flow – Volume Loop

4. Scalar Graphics
• 3 components that make up
the ventilator graphics flow,
Volume and Pressure are
plotted against Time
• X axis is Time
• Y axis is pressure, volume and
flow.
• Typically its Flow vs Time,
Pressure vs Time and Volume
vs Time ,

5. Analysis of Scalar
Graphics
• Basics of Flow vs Time Curve
1. Spontaneous Breath
2. Mechanical Breath

6. Flow Patterns
• Insp Flow Pattern Square, indicating
constant flow delivery – Selected by
operator
• Below Baseline – Expiratory Flow
which is dependent on the patient’s
lung characteristics and effort
• Only flow vs Time curve demonstrates
tracing below baseline.
• Except Pressure vs Time Curve where
a small deflation occurs below the
baseline when the patient initiates
inspiration.

7. Components of
Inspiratory Flow
• Initiation of Flow at the
beginning of inspiration
• Peak Inspiratory Flow
• End of Insp flow delivery and
beginning of expiration
• Inspiratory time
• Expiratory Time
• Total Cycle Time

8. Components of
Expiratory Flow
Expiration is a passive process
whether its mechanical or
spontaneous .
• Initiation of expiration
• Peak Expiratory Flow Rate
• Duration of expiratory flow
• Expiratory Time

9. Recognition of
common
abnormalities
• Airway Obstruction vs Active Exhalation
• Response of Bronchodilators.

10. Air Trapping or Auto
Peep
• Presence of Air Trapping may result
from
1. Inadequate Expiratory Time
2. Too high Respiratory Rate
3. Long Inspiratory Time
4. Prolonged Exhalation due to
bronchoconstriction
Higher Inspiratory flow rate (In Volume
Cycled) or Shorted Ti ( In Time Cycled
Ventilators ) allow for Longer TE and
may eliminate auto PEEP

11. Basics of Volume vs Time
• Information obtained from Volume
vs Time Scalar graph includes
• Inspiratory Tidal Volume
• Inspiratory Phase
• Expiratory Phase
• Inspiratory Time

12. Recognition of Common
Abnormalities
• Air Leaking – Leak in the circuit or around
tracheal tube. The expiratory tracing smoothly
and doesn’t reach baseline. Volume of leak can
be easily estimated by measuring the distance
from the plateau to end of expiratory tracing.
• Active Exhalation – Forces Exhalation is seen as
tracing extends below zero line. It can occur if the
flow transducer is out of calibration.

13. Basics of
Pressure Vs
Time Curve
Spontaneous Breath -
Inspiration below the baseline
and expiration above .

14. Mechanical Breath
Most useful waveform and Visual
Representations of
• PIP – Maximum Pressure achieved
during a breath.
Increased airway resistance Paw or
decreased lung compliance results in
increased PIP.
• PEEP - its confirmed only on Pressure
Time and Pressure volume loop, PEEP is
present when baseline pressure is above
Zero.

15. Assisted Vs Controlled Breath
• Pressure vs Time scalar
verifies the triggering
mechanism of the breath.
• If breaths are initiated at
baseline at fixed intervals , the
mode is time triggered or
control mode ,
• In Assist mode , patient
initiates the breath by
generating the negative
pressure, sensor recognizes
the patient’s effort and
delivers the mechanical
breath

16. Components of
Inflation Pressure
• Plateau Pressure /
Alveolar Pressure-
• Transairway pressure
PTA = PIP – P Plat

17. Recognition of
common
Abnormalities
• Normal curve
• High Raw – Increase in the PTA
is associated with airway
resistance .
• High Flow – Insp Time is
shorter than normal indicating a
higher Insp gas flow rate.
• Decreased Lung compliance –
Increase in plateau pressure and
corresponding increase in PIP is
consistent with decreased lung
compliance.

18. Inadequate Flow
• Pressure Vs Time can also
detect inadequate flow that is
indicated when the pressure
rises slowly or sometimes is
indicated when there is a
depression in inspiratory limb
of the pressure control.

19. Loops Graphics
• Pressure Volume Loop
• Flow Volume Loop

20. Pressure -Volume Loops
- Type of Breath

21. Components of Pressure Volume loops
• Beginning point on p-V loop is the FRC
level. When PEEP added , FRC
increases.
• Pressure Volume loop traces changes in
pressure and corresponding volumes in
changes in volume.
• Insp begins from the FRC Level and
terminates when preset parameter (
Volume and Pressure) is achieved.
• Tracing continues during expiration and
returns FRC at the end of exhalation.
• PIP and delivered tidal volume can be
obtained from PV Loop

22. PEEP

23. Inflection Points
• It’s a point of change in the slope of
line. It represents the sudden change
in alveolar opening and closing.
• Lower Inflection points – Opening
pressure
• Higher Inflection points – recoiling
characteristics.
• Higher the opening pressure , the
stiffer the lung.
• Setting PEEP levels at the level of the
lower inflection points is
recommended to optimize alveolar
recruitment and prevent repeated
opening and closing of alveoli.

24. Work of Breathing
• Advantage of PV loop is that it
provides a quick assessment
of elastic as well as resistive
work of breathing.
• WOB = Pressure * Volume

25. Recognition of common
abnormalities
• Decreased lung compliance
Right shift is Decreased and left shift is
Increased
• Volume targeted ventilation
PIP is Variable and Vt is Preset

26. • Pressure Targeted Ventilation
PIP is constant and Vt is changing variable
• Increased airway resistance/ Hysteresis
Increased airway resistance is associated with the
abnormal widening of the inspiratory tracing
Eg- Obstructive disorder patients

27. • Alveolar Overdistension
It common in ARDS patient in Volume Targeted
Mode.
Classic Sign Known as Beak effect / Duckbill
shows increase in airway pressure w/o any
appreciable increase in volume.
Switch to Pressure Targeted at appropriate
pressure or reduction in volume are indicated.
• Increased WOB
Inadequate sensitivity setting promotes
increased WOB.

28. Inadequate
Inspiratory Flow
• Inappropriate Inspiratory flow
rates are recognized from a
scooped-out pattern.
• In some situations, the patient
makes inspiratory effort in the
middle of the mechanical
breath exhibiting “notch” on the
inspiratory curve.

29. Air Leak
Expiratory Curve doesn’t reach
to zero , an air leak is present

30. Flow –
Volume Loop

31. Recognition of common
abnormalities
• Air Leak
• Auto Peep / Air trapping

32. • Increased Airway Resistance
• Airway Secretions / Accumulation of
condensate

33. Questions ?