Ventilator Graphics

Vijay Deshpande, MS, RRT, FAARC

Emeritus ProfessorGeorgia State UniversityAtlanta, Georgia, USA

Adjunct Visiting Professor,Manipal UniversityCollege of Allied Health SciencesManipal, Karnataka, INDIA

Mechanical Ventilation

GraphicsSCALARS LOOPS

Inspiratory Flow Pattern Inspiratory Flow Pattern

Inspiration

Expiration

Time (sec)

Flo

w (

L/m

in)

Beginning of inspirationexhalation valve closes

Peak inspiratory flow ratePIFR

Beginning of expirationexhalation valve opens

Total cycle timeTCT

Insp. timeTI

Expiratory Time TE

Expiratory Flow PatternExpiratory Flow Pattern

Inspiration

Expiration

Time (sec)

Flo

w (

L/m

in)

Beginning of expirationexhalation valve opens

Peak Expiratory Flow RatePEFR

Duration of expiratory flow

Expiratory time

TE

Auto-PEEPAuto-PEEP

Inspiration

Expiration

NormalPatient

Time (sec)

Flo

w (

L/m

in)

Air TrappingAuto-PEEP

}

Inadequate Inspiratory FlowInadequate Inspiratory Flow

Flow (L/min)

Time (sec)

NormalAbnormal

Active Inspiration or Asynchrony

Patient’s effort

Inspiration

Expiration

Time (sec)

Vo

lum

e (m

l)

Inspiratory Tidal Volume

TI

Volume Ventilation breaths are Volume Cycled

Volume Cycling

Air LeakAir LeakV

olu

me

(ml)

Time (sec)

Air Leak

Components of Inflation PressureComponents of

Inflation Pressure

Begin Expiration

P aw (

cm H

2O)

Time (sec)

Begin Inspiration

PIP

Pplateau

(Palveolar)

Transairway Pressure (PTA)}Exhalation Valve Opens

Expiration

Inspiratory Pause

Inadequate Inspiratory Flow

Adequate Flow

Time (sec)

Inadequate Flow

Pa

w

(cm

H2O

)

Assisted Mode(Volume-Targeted Ventilation)

Assisted Mode(Volume-Targeted Ventilation)

Time (sec)

FlowL/m

Pressurecm H2O

VolumemL

Preset VTVolume Cycling

Patient triggered, Flow limited, Volume cycled Ventilation

From: Essentials of Ventilator Graphics- An interactive CD. Vijay Deshpande, MS, RRT and Ruben Restrepo, MD, RRT. Available at www.respiratorybooks.com

SIMV(Volume-Targeted Ventilation)

SIMV(Volume-Targeted Ventilation)

Spontaneous Breaths

FlowL/m

Pressurecm H2O

VolumemL

Pressure

Flow

Volume

(L/min)

(cm H2O)

(ml)

SIMV + PS (Pressure-Targeted Ventilation)

SIMV + PS (Pressure-Targeted Ventilation)

PS Breath

Set PS levelSet PC level

Time (sec)

Time-Cycled Flow-Cycled

Fig 7.21

PSVPSV

Time (sec)

Flow CyclingFlow Cycling

Set PS level

Set PS level

FlowL/m

Pressurecm H2O

VolumemL

PSV Flow-Cycle CriteriaF

low

T

Peak Inspiratory Flow

5%20%

40%

CPAP + PSV ( BiPAP ) CPAP + PSV ( BiPAP )

Set PS level

CPAP level

Time (sec)

FlowL/m

Pressurecm H2O

VolumemL

Flow Cycling

Fig 7.31

Components of Pressure-Volume LoopComponents of Pressure-Volume Loop

Volume (mL)

Insp

irat

ion

Expirat

ion

PIP

VT

Paw (cm H2O)

Air LeakAir Leak

Volume (ml)

Pressure (cm H2O)

Air Leak

Inadequate Inspiratory FlowInadequate Inspiratory Flow

Paw (cm H2O)

Volume (ml)

NormalAbnormal

Active Inspiration

Inappropriate Flow

Increased RawIncreased Raw

Pressure (cm H2O)

Higher PTA

Norm

al S

lope

Vol (mL)

Lower S

lope

Lung Compliance Changes and the P-V LoopLung Compliance Changes and the P-V Loop

Volume (mL)

PIP levels

Preset VT

Paw (cm H2O)

COMPLIANCEIncreasedNormalDecreased

COMPLIANCEIncreasedNormalDecreased

Volume Targeted Ventilation

Over-distentionOver-distention

Volu

me (

ml)

Pressure (cm H2O)

With little or no change in VT

With little or no change in VT

Paw rises

Paw rises

NormalAbnormal

Preset Tidal Volume

Lung Compliance Changes and the P-V Loop

Lung Compliance Changes and the P-V Loop

Volume (mL)

PIP levels

Preset VT

Paw (cm H2O)

COMPLIANCEIncreasedNormalDecreased

COMPLIANCEIncreasedNormalDecreased

Volume Targeted Ventilation

Flow-Volume LoopFlow-Volume Loop

Volume (ml)

PEFR

FRC

Inspiration

Expiration

Flo

w (

L/m

in) PIFR

VT

Air LeakAir Leak

Inspiration

Expiration

Volume (ml)

Flow (L/min)

Air Leak in mL

NormalAbnormal

Air TrappingAir TrappingInspiration

Expiration

Volume (ml)

Flow (L/min)

Does not returnto baseline

NormalAbnormal

Assisted Mode (Pressure-Targeted Ventilation)Assisted Mode (Pressure-Targeted Ventilation)

Pressure

Flow

Volume

(L/min)

(cm H2O)

(ml)

Set PC level

Time (sec)

Time-Cycled

Patient Triggered, Pressure Limited, Time Cycled Ventilation

Assisted Mode(Volume-Targeted Ventilation)

Assisted Mode(Volume-Targeted Ventilation)

Time (sec)Time (sec)

FlowL/m

Pressurecm H2O

VolumemL

Preset VT

Volume Cycling

Patient triggered, Flow limited, Volume cycled Ventilation

Assisted Mode (Pressure-Targeted Ventilation)

Assisted Mode (Pressure-Targeted Ventilation)

Pressure

Flow

Volume

(L/min)

(cm H2O)

(ml)

Set PC level

Time (sec)Time (sec)

Time-Cycled

Patient Triggered, Pressure Limited, Time Cycled Ventilation

Scalars in Assisted Mode

FIGURE 1

Pressure Control VentilationFlow – Time Scalar

Flow

Time

TIMECYCLING

TI

Fig 8.16

PCV with long T I or Decreased Lung Compliance

Exhalation ValveOpens

Inspiratory flowDecreases to zero

No FlowPeriod

Flow

Time Set TI

Fig 8.17

Flow

Time

TI

Pressure Control Ventilation with inadequate TI

TIME CYCLINGExhalation valve opens

Fig 8.18

Pressure Control Ventilation - Effect of Changes in Lung Compliance on Flow-time scalar

Flow

TIMECYCLING

A

B

C

TI

A : Decreased ComplianceB : Normal complianceC : Increased Compliance

Fig 8.19

Thank You !

Apnea Alarm

Patient becomes Apneic Disconnection inSedated Patient

Oversedation inPatients on Low rate SIMV or PCV

“Ventilator inoperative”

Alarm

Absent Electrical Source(Unplugged)

Power Failure

Internal Batteryhas very low charge

High Minute Volume or High

Respiratory Frequency

Pain Anxiety

Hypoxemia

Low PEEP Alarm

Active Inspiration Inappropriate Alarm setting

A leak in the circuit

Other Useful Alarms

● High Minute Volume

Check Sensitivity setting for trigger level If using external nebulizer, reset the alarm until the treatment is completed, and then reset it to the initial setting. Check physiological causes of increased minute ventilation

● Low FiO2

Check Gas Source pressures Check Oxygen sensor for proper function (using oxygen analyzer)

High Pressure Alarm

Asynchrony(patient fighting)

Increased Resistance

Decreased Lung Compliance

Coughing

Secretions Bronchospasm

Kinking or displacement of

the tube

Pneumothorax Pulmonary

Edema, Pleural

Effusion

Inadequate Flow

Auto PEEP, Improper

Sensitivity

Low Pressure Alarm

Leak In the System,Tracheal Tube Cuff Leak, Chest tube leakage

Proximal PressureLine Disconnected

PatientDisconnection

Associated withlow minute ventilationor low tidal volume

Low Tidal volume or

Low Minute Volume

Leak In the System

Partial Disconnection

Increase in f or decreasein Tidal Volume( In Volume Ventilation)

Increased Resistanceand/or Decreased Lungcompliance

(Leak in the system does NOTTrigger low volume alarm)

IN VOLUME VENTILATION IN PRESSURE VENTILATION

42

Double triggering

Volume-targeted ventilation. Notice the circled double volume breath and the pressure-time Waveform to drop below baseline triggering another breath immediately following the first breath. Hallmark of double triggering-peak pressure of the second breath rises as the second breath is stacked on the first breath.

From Nilsestuen J, Hargett K. Using Ventilator Graphics to Identify Patient-Ventilator Asynchrony. Resp Care 2005;50(2):202-234

43

Double triggering

44

Causes Commonly occurs with VC continuous mandatory

ventilation Also with PSV with high termination flow criterion High respiratory drive Insufficient respiratory support such as minute ventilation

or tidal volume too low with a high respiratory rate. Patient’s Itime (neural) is different (longer) than the

ventilator set Itime Small Vt and short inspiratory time

Missed trigger with pressure control ventilation using the expiratory flow waveform.

The arrow points to the positive flow deflection that is the hallmark sign of a missed trigger.

Missed triggers

45From: Branson R, Blakeman T, Robinson B. Respiratory Care, 2013

Ineffective inspiratory efforts corrected by flow and expiratory time

COPD receiving assist-control ventilation with a constant Vt of 0.55 L. Arrows indicate ineffective ventilation with flow rate at 30 L/min in A.

Black arrows indicate ineffective inspiratory efforts.

Inspiratory flow rate was increased to 90 L/min which decreased inspiratory time and prolonged expiratory time.

This reduced dynamic hyperinflation and the number of ineffective ventilations was reduced.

Increasing flow rate can help reduce ineffective triggeringin COPD patients with dynamic hyperinflation.

During pressure control ventilation reducing inspiratory time will prolong expiratory time to help reduce dynamichyperinflation.

From:Kondili E, Prinianakis G, Georgopoulos D. Patient-Ventilator interaction. Br J Anaesth 2003;91(1):106-119 46

Inspiratory Rise Time

Inspiratory Time