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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 a...
Introduction
Monitoring and analysis of graphic display of
curves and loops during mechanical
ventilation has become a use...
Uses of Flow, Volume, and Pressure
Graphic Display
• Confirm mode functions
• Detect auto-PEEP
• Determine patient-ventila...
Uses of Flow, Volume, and Pressure
Graphic Display
• Evaluate adequacy of inspiratory time in pressure
control ventilation...
Measured Parameters
Flow
Pressure
Volume
Time
Most Commonly Used Waveforms
(Scalars)
• Pressure vs. Time
• Flow vs. Time
• Volume vs. Time
Pressure vs. Time Curve
1 2 3 4 5 6
30
Sec
Paw
cmH2O
A B
C
PIP
Baseline
Mean Airway Pressure
-10
Pressure-Time Curve
1 2 3 4 5 6
20
Sec
Paw
cmH2O
Pressure VentilationVolume Ventilation
Patient Triggering
1 2 3 4 5 6
30
Sec
Paw
cmH2O
-10
Adequate Flow During
Volume-Control Ventilation
30
Time (s)
-10
1 2
awP
cmH2O
Adequate flow
3
Inadequate Flow During
Volume-Control Ventilation
30
Time (s)
-10
1 2
awP
cmH2O
Adequate flow
Flow set too low
3
Patient/Ventilator Synchrony
Volume Ventilator Delivering a Preset Flow and Volume
Adequate Flow
1 2 3 4 5 6
-20
SecPaw
cm...
Patient/Ventilator Synchrony
The Patient Outbreathing the Set Flow
Air Starvation
1 2 3 4 5 6
-20
SecPaw
cmH2O
Plateau Time
Inadequate plateau time
-20
1 2 3 4 5 6
30
SEC
Paw
cmH2O
Adequate Plateau Time
-20
1 2 3 4 5 6
30
SEC
Paw
cmH2O
Plateau Time
Flow vs.Time Curve
1 2 3 4 5 6
SEC
120
120
EXH
INSP
V
.
LPM
Inspiration
Flow vs.Time Curve
1 2 3 4 5 6
SEC
120
120
EXH
INSP
V
.
LPM
Inspiration
Expiration
Flow vs.Time Curve
1 2 3 4 5 6
SEC
120
120
EXH
INSP
Inspiration
V
.
LPM
Constant Flow Descending Ramp
Flow-Time Curve
1 2 3 4 5 6
SEC
120
120
EXH
INSP
Insp. Pause
Expiration
V
.
LPM
Inspiratory Time
Short Normal Long
1 2 3 4 5 6
SEC
120
-120
V
.
LPM
Expiratory Flow Rate and Changes
in Expiratory Resistance
A Higher Expiratory Flow Rate and a
Decreased Expiratory Time Denote a Lower
Expiratory Resistance
1 2 3 4 5 6
SEC
120
120...
Obstructed Lung
Delayed flow return
Pressure-Time and Flow-Time Curves
1 2 3 4 5 6
20
Sec
Paw
cmH2O
Expiration
V
.
Volume Ventilation
Pressure-Time and Flow-Time Curves
Different Inspiratory Flow Patterns
1 2 3 4 5 6
20
Sec
Paw
cmH2O
Expiration
V
.
Volume ...
20
Pressure-Time and Flow-Time Curves
1 2 3 4 5 6
Sec
Paw
cmH2O
V
.
Pressure Ventilation
Inspiratory Time
Volume Ventilati...
Rise Time
How quickly set pressure is reached
Time
Minimal Pressure Overshoot
Pressure Relief
Slow rise Moderate rise Fast rise
P
V
.
Flow Acceleration Percent
Rise Time
Patient / Ventilator Synchrony
Volume Ventilation Delivering a Preset Flow and Volume
Adequate Flow
1 2 3 4 5 6
30
-20
Sec...
Air Starvation
1 2 3 4 5 6
30
-20
SecPaw
cmH2O
Patient -Ventilator Synchrony
The Patient Is Outbreathing the Set Flow
If Peak Flow Remains the Same, I-Time
Increases: Could Cause Asynchrony
LPM
1 2 3 4 5 6
SEC
120
-120
V
.
Changing Flow Waveform in Volume
Ventilation: Effect on Inspiratory Time
1 2 3 4 5 6
SEC
120
-120
V
.
LPM
Increased Peak Flow: Decreased
Inspiratory Time
1 2 3 4 5 6
SEC
120
-120
V
.
LPM
Note: There can still be pressure in the lung behind
airways that are completely obstructed
Detecting Auto-PEEP
LPM
Zero f...
Detecting Auto-PEEP
The transition from expiratory to inspiratory
occurs without the expiratory flow returning
to zero
1 2...
Volume vs.Time Curve
Inspiration
SEC
800 ml
2 3 4 5 61
VT
Volume vs.Time Curve
Expiration
SEC
800 ml
2 3 4 5 61
VT
Typical Volume Curve
1 2 3 4 5 6
SEC
1.2
-0.4
VT
Liters
I-Time
E-Time
A B
A = inspiratory volume
B = expiratory volume
Leaks
1 2 3 4 5 6
SEC
1.2
-0.4
VT
Liters
A
A = exhalation that does not return to zero
1 2 3 4 5 6
SEC
1 2 3 4 5 6
VT
600 cc
120
120
SEC
.
V
LPM
0
450 cc
Setting Appropriate I-Time
Setting Appropriate I-Time
500 cc450 cc
Lost VT
1 2 3 4 5 6
SEC
1 2 3 4 5 6
VT
600 cc
120
120
SEC
.
V
LPM
0
Loops
• Pressure-Volume Loops
• Flow-Volume Loops
Pressure-Volume Loop
0 20 40 602040-60
0.2
LITERS
0.4
0.6
Paw
cmH2O
VT
Mandatory Breath
Inspiration
0 20 40 602040-60
0.2
LITERS
0.4
0.6
Paw
cmH2O
VT
Mandatory Breath
Expiration
0 20 40 602040-60
0.2
LITERS
0.4
0.6
Paw
cmH2O
Inspiration
VT Counterclockwise
Spontaneous Breath
Inspiration
0 20 40 602040-60
0.2
LITERS
0.4
0.6
Paw
cmH2O
VT
Clockwise
Spontaneous Breath
Inspiration
Expiration
0 20 40 602040-60
0.2
LITERS
0.4
0.6
Paw
cmH2O
VT
Clockwise
Work of Breathing
0 20 40 60-20-40-60
0.2
0.4
0.6
LITERS
Paw
cmH2O
VT
Assisted Breath
0 20 40 602040-60
0.2
LITERS
0.4
0.6
Paw
cmH2O
Assisted Breath
VT
Assisted Breath
Inspiration
0 20 40 602040-60
0.2
LITERS
0.4
0.6
Paw
cmH2O
Assisted Breath
VT
Assisted Breath
Inspiration
Expiration
0 20 40 602040-60
0.2
LITERS
0.4
0.6
Paw
cmH2O
Assisted Breath
VT Clockwise to Coun...
Pressure-Volume Loop Changes
0 20 40 60-20-40-60
0.2
0.4
0.6
LITERS
Paw
cmH2O
VT
Changes in Compliances
Indicates a drop in compliance
(higher pressure for the same
volume)
0 20 40 602040-60
0.2
0.4
0.6
...
Overdistension
B
A
0 20 40 60-20-40-60
0.2
0.4
0.6
LITERS
Paw
cmH2O
C
A = inspiratory pressure
B = upper inflection point
...
Lung Overdistension
Normal Flow-Volume Loops
Flow -Volume Loops
Volume Control
Volume
Tidal Volume
Inspiration
Expiration
Flow -Volume Loops
Volume Control
Volume
Peak Expiratory Flow
Peak Inspiratory Flow
Tidal Volume
Inspiration
Expiration
ETT or Circuit Leaks
Obstructive Pattern
Bronchodilator Response
2
1
1
2
3
3
V
LPS
.
BEFORE
V
LPS
.
Bronchodilator Response
2
1
1
2
3
3
V
LPS
.
BEFORE AFTER
Worse
2
1
1
2
3
3
V
LPS
.
Bronchodilator Response
2
1
1
2
3
3
V
LPS
.
VT
INSP
EXH
BEFORE AFTER
Worse Better
2
1
1
2
3
3
V
LPS
.
2
1
1
2
3
3
V
LPS
.
Remember!
Waveforms and loops are graphical representation of the data
generated by the ventilator.
Typical Tracings
Press...
Waveforms, lecture about mechanical ventilation, by Prof Ahmed Tarek, Prof of Pediatrics, Abu El rich hospital, Cairo univ...
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Waveforms, lecture about mechanical ventilation, by Prof Ahmed Tarek, Prof of Pediatrics, Abu El rich hospital, Cairo university

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Waveforms, lecture about mechanical ventilation, by Prof Ahmed Tarek, Prof of Pediatrics, Abu El rich hospital, Cairo university

  1. 1. BASICS OF WAVEFORM INTERPRETATION RET 2284 Principles of Mechanical Ventilation
  2. 2. Objectives • Identify graphic display options provided by mechanical ventilators. • Describe how to use graphics to more appropriately adjust the patient ventilator interface.
  3. 3. 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.
  4. 4. 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
  5. 5. 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
  6. 6. Measured Parameters Flow Pressure Volume Time
  7. 7. Most Commonly Used Waveforms (Scalars) • Pressure vs. Time • Flow vs. Time • Volume vs. Time
  8. 8. Pressure vs. Time Curve 1 2 3 4 5 6 30 Sec Paw cmH2O A B C PIP Baseline Mean Airway Pressure -10
  9. 9. Pressure-Time Curve 1 2 3 4 5 6 20 Sec Paw cmH2O Pressure VentilationVolume Ventilation
  10. 10. Patient Triggering 1 2 3 4 5 6 30 Sec Paw cmH2O -10
  11. 11. Adequate Flow During Volume-Control Ventilation 30 Time (s) -10 1 2 awP cmH2O Adequate flow 3
  12. 12. Inadequate Flow During Volume-Control Ventilation 30 Time (s) -10 1 2 awP cmH2O Adequate flow Flow set too low 3
  13. 13. Patient/Ventilator Synchrony Volume Ventilator Delivering a Preset Flow and Volume Adequate Flow 1 2 3 4 5 6 -20 SecPaw cmH2O
  14. 14. Patient/Ventilator Synchrony The Patient Outbreathing the Set Flow Air Starvation 1 2 3 4 5 6 -20 SecPaw cmH2O
  15. 15. Plateau Time Inadequate plateau time -20 1 2 3 4 5 6 30 SEC Paw cmH2O
  16. 16. Adequate Plateau Time -20 1 2 3 4 5 6 30 SEC Paw cmH2O Plateau Time
  17. 17. Flow vs.Time Curve 1 2 3 4 5 6 SEC 120 120 EXH INSP V . LPM Inspiration
  18. 18. Flow vs.Time Curve 1 2 3 4 5 6 SEC 120 120 EXH INSP V . LPM Inspiration Expiration
  19. 19. Flow vs.Time Curve 1 2 3 4 5 6 SEC 120 120 EXH INSP Inspiration V . LPM Constant Flow Descending Ramp
  20. 20. Flow-Time Curve 1 2 3 4 5 6 SEC 120 120 EXH INSP Insp. Pause Expiration V . LPM
  21. 21. Inspiratory Time Short Normal Long
  22. 22. 1 2 3 4 5 6 SEC 120 -120 V . LPM Expiratory Flow Rate and Changes in Expiratory Resistance
  23. 23. A Higher Expiratory Flow Rate and a Decreased Expiratory Time Denote a Lower Expiratory Resistance 1 2 3 4 5 6 SEC 120 120 V . LPM
  24. 24. Obstructed Lung Delayed flow return
  25. 25. Pressure-Time and Flow-Time Curves 1 2 3 4 5 6 20 Sec Paw cmH2O Expiration V . Volume Ventilation
  26. 26. Pressure-Time and Flow-Time Curves Different Inspiratory Flow Patterns 1 2 3 4 5 6 20 Sec Paw cmH2O Expiration V . Volume Ventilation Inspiration
  27. 27. 20 Pressure-Time and Flow-Time Curves 1 2 3 4 5 6 Sec Paw cmH2O V . Pressure Ventilation Inspiratory Time Volume Ventilation
  28. 28. Rise Time How quickly set pressure is reached
  29. 29. Time Minimal Pressure Overshoot Pressure Relief Slow rise Moderate rise Fast rise P V . Flow Acceleration Percent Rise Time
  30. 30. Patient / Ventilator Synchrony Volume Ventilation Delivering a Preset Flow and Volume Adequate Flow 1 2 3 4 5 6 30 -20 SecPaw cmH2O
  31. 31. Air Starvation 1 2 3 4 5 6 30 -20 SecPaw cmH2O Patient -Ventilator Synchrony The Patient Is Outbreathing the Set Flow
  32. 32. If Peak Flow Remains the Same, I-Time Increases: Could Cause Asynchrony LPM 1 2 3 4 5 6 SEC 120 -120 V .
  33. 33. Changing Flow Waveform in Volume Ventilation: Effect on Inspiratory Time 1 2 3 4 5 6 SEC 120 -120 V . LPM
  34. 34. Increased Peak Flow: Decreased Inspiratory Time 1 2 3 4 5 6 SEC 120 -120 V . LPM
  35. 35. Note: There can still be pressure in the lung behind airways that are completely obstructed Detecting Auto-PEEP LPM Zero flow at end exhalation indicates equilibration of lung and circuit pressure 1 2 3 4 5 6 SEC 120 -120 V .
  36. 36. Detecting Auto-PEEP The transition from expiratory to inspiratory occurs without the expiratory flow returning to zero 1 2 3 4 5 6 SEC 120 120 V . LPM
  37. 37. Volume vs.Time Curve Inspiration SEC 800 ml 2 3 4 5 61 VT
  38. 38. Volume vs.Time Curve Expiration SEC 800 ml 2 3 4 5 61 VT
  39. 39. Typical Volume Curve 1 2 3 4 5 6 SEC 1.2 -0.4 VT Liters I-Time E-Time A B A = inspiratory volume B = expiratory volume
  40. 40. Leaks 1 2 3 4 5 6 SEC 1.2 -0.4 VT Liters A A = exhalation that does not return to zero
  41. 41. 1 2 3 4 5 6 SEC 1 2 3 4 5 6 VT 600 cc 120 120 SEC . V LPM 0 450 cc Setting Appropriate I-Time
  42. 42. Setting Appropriate I-Time 500 cc450 cc Lost VT 1 2 3 4 5 6 SEC 1 2 3 4 5 6 VT 600 cc 120 120 SEC . V LPM 0
  43. 43. Loops • Pressure-Volume Loops • Flow-Volume Loops
  44. 44. Pressure-Volume Loop 0 20 40 602040-60 0.2 LITERS 0.4 0.6 Paw cmH2O VT
  45. 45. Mandatory Breath Inspiration 0 20 40 602040-60 0.2 LITERS 0.4 0.6 Paw cmH2O VT
  46. 46. Mandatory Breath Expiration 0 20 40 602040-60 0.2 LITERS 0.4 0.6 Paw cmH2O Inspiration VT Counterclockwise
  47. 47. Spontaneous Breath Inspiration 0 20 40 602040-60 0.2 LITERS 0.4 0.6 Paw cmH2O VT Clockwise
  48. 48. Spontaneous Breath Inspiration Expiration 0 20 40 602040-60 0.2 LITERS 0.4 0.6 Paw cmH2O VT Clockwise
  49. 49. Work of Breathing 0 20 40 60-20-40-60 0.2 0.4 0.6 LITERS Paw cmH2O VT
  50. 50. Assisted Breath 0 20 40 602040-60 0.2 LITERS 0.4 0.6 Paw cmH2O Assisted Breath VT
  51. 51. Assisted Breath Inspiration 0 20 40 602040-60 0.2 LITERS 0.4 0.6 Paw cmH2O Assisted Breath VT
  52. 52. Assisted Breath Inspiration Expiration 0 20 40 602040-60 0.2 LITERS 0.4 0.6 Paw cmH2O Assisted Breath VT Clockwise to Counterclockwise
  53. 53. Pressure-Volume Loop Changes 0 20 40 60-20-40-60 0.2 0.4 0.6 LITERS Paw cmH2O VT
  54. 54. Changes in Compliances Indicates a drop in compliance (higher pressure for the same volume) 0 20 40 602040-60 0.2 0.4 0.6 LITERS Paw cmH2O VT
  55. 55. Overdistension B A 0 20 40 60-20-40-60 0.2 0.4 0.6 LITERS Paw cmH2O C A = inspiratory pressure B = upper inflection point C = lower inflection point VT
  56. 56. Lung Overdistension
  57. 57. Normal Flow-Volume Loops
  58. 58. Flow -Volume Loops Volume Control Volume Tidal Volume Inspiration Expiration
  59. 59. Flow -Volume Loops Volume Control Volume Peak Expiratory Flow Peak Inspiratory Flow Tidal Volume Inspiration Expiration
  60. 60. ETT or Circuit Leaks
  61. 61. Obstructive Pattern
  62. 62. Bronchodilator Response 2 1 1 2 3 3 V LPS . BEFORE V LPS .
  63. 63. Bronchodilator Response 2 1 1 2 3 3 V LPS . BEFORE AFTER Worse 2 1 1 2 3 3 V LPS .
  64. 64. Bronchodilator Response 2 1 1 2 3 3 V LPS . VT INSP EXH BEFORE AFTER Worse Better 2 1 1 2 3 3 V LPS . 2 1 1 2 3 3 V LPS .
  65. 65. 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.

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