Transcript /pslocum/Waveforms.ppt

BASICS OF WAVEFORM
INTERPRETATION
RET 2284
Principles of Mechanical Ventilation
Objectives
• Identify graphic display options
provided by mechanical ventilators.
• Describe how to use graphics to
more appropriately adjust the patient
ventilator interface.
Introduction
Monitoring and analysis of graphic display
of curves and loops during mechanical
ventilation has become a useful way to
determine not only how patient are being
ventilated but also a way to assess
problems occurring during ventilation.
Uses of Flow, Volume, and
Pressure Graphic Display
• Confirm mode functions
•
•
•
•
•
•
•
•
Detect auto-PEEP
Determine patient-ventilator synchrony
Assess and adjust trigger levels
Measure the work of breathing
Adjust tidal volume and minimize overdistension
Assess the effect of bronchodilator administration
Detect equipment malfunctions
Determine appropriate PEEP level
Uses of Flow, Volume, and
Pressure Graphic Display
• Evaluate adequacy of inspiratory time in pressure
control ventilation
• Detect the presence and rate of continuous leaks
• Assess inspiratory termination criteria during
Pressure Support Ventilation
• Determine appropriate Rise Time
Measured Parameters
Flow
Pressure
Volume
Time
Most Commonly Used
Waveforms (Scalars)
• Pressure vs. Time
• Flow vs. Time
• Volume vs. Time
Pressure vs. Time Curve
30
A
B
C
PIP
Baseline
P
aw
cmH O
Mean Airway Pressure
Sec
2
1
-10
2
3
4
5
6
Pressure-Time Curve
20
Volume Ventilation
Pressure Ventilation
Paw
cmH2O
Sec
1
2
3
4
5
6
Patient Triggering
30
Paw
cmH2O
Sec
1
-10
2
3
4
5
6
Adequate Flow During
Volume-Control Ventilation
30
Adequate flow
Paw
cmH2O
1
-10
2
3
Time (s)
Inadequate Flow During
Volume-Control Ventilation
30
Adequate flow
Paw
Flow set too low
cmH2O
1
-10
2
3
Time (s)
Patient/Ventilator Synchrony
Volume Ventilator Delivering a Preset Flow and Volume
Adequate Flow
Paw
Sec
cmH2O
1
-20
2
3
4
5
6
Patient/Ventilator Synchrony
The Patient Outbreathing the Set Flow
Air Starvation
Paw
Sec
cmH2O
1
-20
2
3
4
5
6
Plateau Time
30
Inadequate plateau time
SEC
Paw
cmH2O
-20
1
2
3
4
5
6
Plateau Time
30
Adequate Plateau Time
SEC
Paw
cmH2O
-20
1
2
3
4
5
6
Flow vs.Time Curve
120
INSP
Inspiration
.
V
LPM
120
SEC
1
2
3
4
5
6
EXH
Flow vs.Time Curve
120
INSP
Inspiration
.
V
LPM
SEC
1
2
3
4
5
6
Expiration
120
EXH
Flow vs.Time Curve
120
Constant Flow
Descending Ramp
INSP
Inspiration
.
V
LPM
120
SEC
1
2
3
4
5
6
EXH
Flow-Time Curve
120
INSP
.
Insp. Pause
V
LPM
SEC
1
2
3
4
5
6
Expiration
120
EXH
Inspiratory Time
Short
Normal Long
Expiratory Flow Rate and Changes
in Expiratory Resistance
120
.
SEC
V
LPM
-120
1
2
3
4
5
6
A Higher Expiratory Flow Rate and a
Decreased Expiratory Time Denote a Lower
Expiratory Resistance
120
.
SEC
V
LPM
120
1
2
3
4
5
6
Obstructed Lung
Delayed flow return
Pressure-Time and Flow-Time Curves
20
Volume Ventilation
Expiration
Paw
cmH2O
Sec
1
.
V
2
3
4
5
6
Pressure-Time and Flow-Time Curves
Different Inspiratory Flow Patterns
20
Volume Ventilation
Expiration
Paw
Inspiration
cmH2O
Sec
1
.
V
2
3
4
5
6
Pressure-Time and Flow-Time Curves
20
Pressure Ventilation
Volume Ventilation
Inspiratory Time
Paw
cmH2O
Sec
1
.
V
2
3
4
5
6
Rise Time
How quickly set pressure is reached
Flow Acceleration Percent
Rise Time
Minimal Pressure Overshoot
P
Slow rise
Moderate rise
Fast rise
.
V
Pressure Relief
Time
Patient / Ventilator Synchrony
Volume Ventilation Delivering a Preset Flow and Volume
30
Adequate Flow
Paw
Sec
cmH2O
1
-20
2
3
4
5
6
Patient -Ventilator Synchrony
The Patient Is Outbreathing the Set Flow
30
Air Starvation
Paw
Sec
cmH2O
1
-20
2
3
4
5
6
If Peak Flow Remains the Same, I-Time
Increases: Could Cause Asynchrony
120
.
V
SEC
LPM
1
-120
2
3
4
5
6
Changing Flow Waveform in Volume
Ventilation: Effect on Inspiratory Time
120
.
V
SEC
LPM
1
-120
2
3
4
5
6
Increased Peak Flow: Decreased
Inspiratory Time
120
.
V
SEC
LPM
1
-120
2
3
4
5
6
Detecting Auto-PEEP
120
.
V
SEC
LPM
1
2
3
4
5
Zero flow at end exhalation indicates
equilibration of lung and circuit pressure
-120
Note: There can still be pressure in the lung behind
airways that are completely obstructed
6
Detecting Auto-PEEP
120
.
V
SEC
LPM
1
120
2
3
4
5
6
The transition from expiratory to inspiratory
occurs without the expiratory flow returning
to zero
Volume vs.Time Curve
800 ml
Inspiration
VT
SEC
1
2
3
4
5
6
Volume vs.Time Curve
800 ml
Expiration
VT
SEC
1
2
3
4
5
6
Typical Volume Curve
I-Time
E-Time
1.2
A
B
VT
Liters
SEC
1
2
-0.4
A = inspiratory volume
B = expiratory volume
3
4
5
6
Leaks
1.2
A
VT
Liters
SEC
1
2
3
-0.4
A = exhalation that does not return to zero
4
5
6
Setting Appropriate I-Time
600 cc
450 cc
VT
SEC
0
1
2
3
4
5
6
120
.
V
LPM
SEC
1
120
2
3
4
5
6
Setting Appropriate I-Time
600 cc
450 cc
500 cc
VT
SEC
0
1
2
3
4
5
6
120
Lost VT
.
V
LPM
SEC
1
120
2
3
4
5
6
Loops
• Pressure-Volume Loops
• Flow-Volume Loops
Pressure-Volume Loop
VT
LITERS
0.6
0.4
0.2
Paw
cmH2O -60
40
20
0
20
40
60
Mandatory Breath
VT
LITERS
0.6
0.4
Inspiration
0.2
Paw
cmH2O -60
40
20
0
20
40
60
Mandatory Breath
VT
Counterclockwise
LITERS
0.6
Expiration
0.4
Inspiration
0.2
Paw
cmH2O -60
40
20
0
20
40
60
Spontaneous Breath
VT
Clockwise
LITERS
0.6
0.4
Inspiration
0.2
Paw
cmH2O -60
40
20
0
20
40
60
Spontaneous Breath
VT
Clockwise
LITERS
0.6
0.4
Inspiration
Expiration
0.2
Paw
cmH2O -60
40
20
0
20
40
60
Work of Breathing
VT
LITERS
0.6
0.4
0.2
Paw
cmH2O
-60
-40
-20
0
20
40
60
Assisted Breath
VT
LITERS
0.6
0.4
Assisted Breath
0.2
Paw
cmH2O -60
40
20
0
20
40
60
Assisted Breath
VT
LITERS
0.6
0.4
Assisted Breath
0.2
Inspiration
Paw
cmH2O -60
40
20
0
20
40
60
Assisted Breath
VT
Clockwise to Counterclockwise
LITERS
0.6
Expiration
0.4
Assisted Breath
0.2
Inspiration
Paw
cmH2O -60
40
20
0
20
40
60
Pressure-Volume Loop Changes
VT
LITERS
0.6
0.4
0.2
Paw
cmH2O
-60
-40
-20
0
20
40
60
Changes in Compliances
VT
LITERS
Indicates a drop in compliance
(higher pressure for the same
volume)
0.6
0.4
0.2
Paw
cmH2O
-60
40
20
0
20
40
60
Overdistension
VT
A = inspiratory pressure
LITERS
B = upper inflection point
0.6
C = lower inflection point
A
0.4
B
0.2
Paw
cmH2O
C
-60
-40
-20
0
20
40
60
Lung Overdistension
Normal Flow-Volume Loops
Flow -Volume Loops
Volume Control
Tidal Volume
Inspiration
Volume
Expiration
Flow -Volume Loops
Volume Control
Tidal Volume
Peak Inspiratory Flow
Peak Expiratory Flow
Inspiration
Volume
Expiration
ETT or Circuit Leaks
Obstructive Pattern
Bronchodilator Response
BEFORE
3
2
1
.
V
LPS
1
2
3
.
V
LPS
Bronchodilator Response
BEFORE
AFTER
Worse
3
3
2
2
1
1
V
LPS
V
LPS
1
1
2
2
3
3
.
.
Bronchodilator Response
BEFORE
AFTER
Better
Worse
3
3
3
INSP
2
2
2
1
1
1
V
LPS
V
LPS
V
LPS
1
1
1
2
2
2
3
3
3
.
.
.
VT
EXH
Remember!
Waveforms and loops are graphical representation of the
data generated by the ventilator.
Typical Tracings
Pressure-time,
Flow-time,
Volume -time
Loops
Pressure-Volume
Flow-Volume
Assessment of pressure, flow and volume
waveforms is a critical tool in the management
of the mechanically ventilated patient.