mechanical ventilator waveform analysis · mechanical ventilator waveform analysis! a review !...

©2014 MFMER | slide-1

Mechanical Ventilator Waveform Analysis − A Review −

Christopher L. Bosley BS, AAS, RRT-NPS, RCP Neonatal-Pediatric Transport Clinical Specialist Department of Anesthesia – Respiratory Care Mayo Clinic-Eugenia Litta Children’s Hospital


Conflict of Interest

•  None


 Steven Holets RRT, CCRA

Study Coordinator/Clinical Specialist

Assistant Professor of Anesthesiology

Department of Anesthesia – Respiratory Care

Mayo Clinic - Rochester, MN

 Robert J. Kahoud, M.D.

Assistant Professor of Neurology

Assistant Professor of Pediatrics

Department of Pediatrics

Mayo Clinic - Rochester, MN

Acknowledgement


Objectives

•  Identify common graphic options available on mechanical ventilators

•  Learn to how to utilize waveforms as a means to troubleshoot & optimize ventilator settings

•  Learn to how use waveform graphics as a way identify patient response to therapies


Neonatal-Pediatric ICU Ventilators


Ventilator Waveform Display

• Scalars •  Pressure

•  Flow

•  Volume

• Loops •  Pressure vs Volume

•  Flow vs Volume


Scalar Graphics

• Pressure vs. Time

• Flow vs. Time

• Volume vs. Time


Phase Variable

A.  Trigger: “Start of Breath”

•  Patient (Assisted)

•  Flow

•  Pressure

•  Machine (Controlled)

B.  Target: (Limit)

•  Volume

•  Pressure

C.  Cycle: Terminates the Breath •  Time

•  Flow

“Ventilator Waveform Analysis” Dr. M. V. Nagarjuna Slide

Time


Control Variables

Volume Ventilation Pressure Ventilation

Pressure

Flow time

Pressure

Flow time


Pressure Waveform

Pressure Support Ventilation

Ventilator settings:

• PEEP

• Trigger sensitivity

• Rise time

• PSV level •  Insp press above PEEP

•  Inspiratory to expiratory cycle criteria

•  E-sens/E-trigger

PEEP

Trig Sens

Rise time

PS level

Cycle criteria E-sens/trig


Flow Waveform Auto-PEEP

  Evaluate if expiratory flow returns back to baseline

  No?

•  Mechanical causes?

•  Ventilator settings

•  ETT size (Small)

•  Airway disease?

•  Asthma

•  COPD


Air Trapping with Inappropriate Inspiratory Time

Inspiratory Time 0.5 s

Inspiratory Time 0.3 s


Pressure Waveform (Volume Control)

Curves and Loops in Mechanical Ventilation. Frank Rittner, Martin Döring. Dräger. 2001.


“Ventilator Waveform Analysis” Dr. M. V. Nagarjuna Slide

Let’s take a closer look at a Flow & Pressure

Tracing…. Asthmatic Case

Mode: SIMV-VC FiO2: 50%

Vt: 420 cc

PEEP 5cmH20

Ppeak: 31cmH20

Pplat: 20 cmH20 Pmean: 10cmH20

Ti: 0.63 seconds

I:E 2.5

52Kg (~8cc/Kg)


Assessing Trigger Sensitivity Flow Trigger

Spontaneous breaths not detected


Note the jagged flow waveform

indicating a wet flow sensor

Assessing Trigger Sensitivity Wet Flow Sensor


Loops

• Pressure-Volume Loops

• Flow-Volume Loops


Loops

Flow-Volume Loop Pressure-Volume Loop


Evaluating Pressure - Volume Loops Evaluating Compliance Changes

0 20 40 60 20 40 -60

0.4

LITERS

0.8

1.2

Paw

cmH2O

VT Slope

Compliance

Compliance Example:

Compliance: Emphysema,

Surfactant Therapy

Compliance:

ARDS, CHF, Atelectasis Dynamic

Compliance

(Cdyn) Cdyn =Δvolume

Δpressure


Evaluating Pressure - Volume Loops Identifying Lung Over distention

Charles S. Williams RRT, AE-C

Evaluate:

  Correct Tidal Volume

  Correct ETT Depth

  Surfactant

Administration

β2 Bronchodialator

Suction ETT

Sedation

Surfactant Replacement Therapy

Red: Pre Surfactant Black: Post Surfactant


Evaluating Pressure - Volume Loops Indentifying Airway Resistance

Charles S. Williams RRT, AE-C

Increased expiratory resistance: Secretions, bronchospasms, etc.

Increased inspiratory resistance: Too small ETT, kinked ET tube,

patient biting tube.


Kacmarek RM, Hess D, Stoller JK. Monitoring in Respiratory Care, St. Louis, 1993, Mosby.

Evaluating Pressure - Volume Loops Identifying Work of Breathing


Evaluating Flow - Volume Loops Bronchodilator Response

VT

INSP

BEFORE AFTER

2

1

1

2

3

3

V

LPS

.

2

1

1

2

3

3

V

LPS

.

EXH

  Scalping = Airway Obstruction

 PEFR


Evaluating Flow - Volume Loops Identifying Leaks


Evaluating Flow - Volume Loops Airway Obstruction- Secretions

Before Suctioning


Evaluating Flow - Volume Loops Airway Obstruction- Secretions

After Suctioning


In Conclusion

• Waveforms are graphical representation of the

data generated by the mechanical ventilator

• Assessment of scalar & loop waveforms can provide insight into patient synchrony as well as an adjunct tool used to troubleshoot & optimize ventilator settings.


Questions & Discussion

mechanical ventilator waveform analysis · mechanical ventilator waveform analysis! a review !...

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