Page 1
©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
Page 2
©2014 MFMER | slide-2
Conflict of Interest
• None
Page 3
©2014 MFMER | slide-3
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
Page 4
©2014 MFMER | slide-4
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
Page 5
©2014 MFMER | slide-5
Neonatal-Pediatric ICU Ventilators
Page 6
©2014 MFMER | slide-6
Ventilator Waveform Display
• Scalars • Pressure
• Flow
• Volume
• Loops • Pressure vs Volume
• Flow vs Volume
Page 7
©2014 MFMER | slide-7
Scalar Graphics
• Pressure vs. Time
• Flow vs. Time
• Volume vs. Time
Page 8
©2014 MFMER | slide-8
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
Page 9
©2014 MFMER | slide-9
Control Variables
Volume Ventilation Pressure Ventilation
Pressure
Flow time
Pressure
Flow time
Page 10
©2014 MFMER | slide-10
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
Page 11
©2014 MFMER | slide-11
Flow Waveform Auto-PEEP
Evaluate if expiratory flow returns back to baseline
No?
• Mechanical causes?
• Ventilator settings
• ETT size (Small)
• Airway disease?
• Asthma
• COPD
Page 12
©2014 MFMER | slide-12
Air Trapping with Inappropriate Inspiratory Time
Inspiratory Time 0.5 s
Inspiratory Time 0.3 s
Page 13
©2014 MFMER | slide-13
Pressure Waveform (Volume Control)
Curves and Loops in Mechanical Ventilation. Frank Rittner, Martin Döring. Dräger. 2001.
Page 14
©2014 MFMER | slide-14
“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)
Page 15
©2014 MFMER | slide-15
Assessing Trigger Sensitivity Flow Trigger
Spontaneous breaths not detected
Page 16
©2014 MFMER | slide-16
Note the jagged flow waveform
indicating a wet flow sensor
Assessing Trigger Sensitivity Wet Flow Sensor
Page 17
©2014 MFMER | slide-17
Loops
• Pressure-Volume Loops
• Flow-Volume Loops
Page 18
©2014 MFMER | slide-18
Loops
Flow-Volume Loop Pressure-Volume Loop
Page 19
©2014 MFMER | slide-19
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
Page 20
©2014 MFMER | slide-20
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
Page 21
©2014 MFMER | slide-21
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.
Page 22
©2014 MFMER | slide-22
Kacmarek RM, Hess D, Stoller JK. Monitoring in Respiratory Care, St. Louis, 1993, Mosby.
Evaluating Pressure - Volume Loops Identifying Work of Breathing
Page 23
©2014 MFMER | slide-23
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
Page 24
©2014 MFMER | slide-24
Evaluating Flow - Volume Loops Identifying Leaks
Page 25
©2014 MFMER | slide-25
Evaluating Flow - Volume Loops Airway Obstruction- Secretions
Before Suctioning
Page 26
©2014 MFMER | slide-26
Evaluating Flow - Volume Loops Airway Obstruction- Secretions
After Suctioning
Page 27
©2014 MFMER | slide-27
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.
Page 28
©2014 MFMER | slide-28
Questions & Discussion