VENTILATOR WAVEFORM · PDF fileVENTILATOR WAVEFORM ANALYSIS By Dr M V Nagarjuna 1 Dr. M. V....
Transcript of VENTILATOR WAVEFORM · PDF fileVENTILATOR WAVEFORM ANALYSIS By Dr M V Nagarjuna 1 Dr. M. V....
![Page 1: VENTILATOR WAVEFORM · PDF fileVENTILATOR WAVEFORM ANALYSIS By Dr M V Nagarjuna 1 Dr. M. V. Nagarjuna. Seminar Overview 1. Basic Terminology ( Types of](https://reader034.fdocuments.net/reader034/viewer/2022051721/5a7b38d97f8b9a49588bbb9a/html5/thumbnails/1.jpg)
VENTILATOR WAVEFORM ANALYSISANALYSIS
ByDr M V Nagarjuna
1
Dr. M. V. Nagarjuna
![Page 2: VENTILATOR WAVEFORM · PDF fileVENTILATOR WAVEFORM ANALYSIS By Dr M V Nagarjuna 1 Dr. M. V. Nagarjuna. Seminar Overview 1. Basic Terminology ( Types of](https://reader034.fdocuments.net/reader034/viewer/2022051721/5a7b38d97f8b9a49588bbb9a/html5/thumbnails/2.jpg)
Seminar Overview
1. Basic Terminology ( Types of variables, Breaths, modes of , ,ventilation)
2. Ideal ventilator waveforms (Scalars)( )
3. Diagnosing altered physiological states
4. Ventilator Patient Asynchrony and its management.
5. Loops (Pressure volume and Flow volume)
2
![Page 3: VENTILATOR WAVEFORM · PDF fileVENTILATOR WAVEFORM ANALYSIS By Dr M V Nagarjuna 1 Dr. M. V. Nagarjuna. Seminar Overview 1. Basic Terminology ( Types of](https://reader034.fdocuments.net/reader034/viewer/2022051721/5a7b38d97f8b9a49588bbb9a/html5/thumbnails/3.jpg)
Basics phase variablesBasics phase variables…………..
A. Trigger …….What causes the breath to begin?
B C
B. Limit ……What regulates gas flow during the breath?
C CycleA
C. Cycle …….What causes the breath to end?
![Page 4: VENTILATOR WAVEFORM · PDF fileVENTILATOR WAVEFORM ANALYSIS By Dr M V Nagarjuna 1 Dr. M. V. Nagarjuna. Seminar Overview 1. Basic Terminology ( Types of](https://reader034.fdocuments.net/reader034/viewer/2022051721/5a7b38d97f8b9a49588bbb9a/html5/thumbnails/4.jpg)
VARIABLESVARIABLES1 TRIGGER VARIABLE : Initiates the breath1. TRIGGER VARIABLE : Initiates the breath
Flow (Assist breath) Pressure (Assist Breath) Pressure (Assist Breath) Time (Control Breath) Newer variables (Volume Shape signal neural)Newer variables (Volume, Shape signal, neural)
Flow trigger better than Pressure trigger. ow t gge ette t a essu e t gge . With the newer ventilators, difference in work of triggering is of
minimal clinical significance. g
British Journal of Anaesthesia, 2003
4
![Page 5: VENTILATOR WAVEFORM · PDF fileVENTILATOR WAVEFORM ANALYSIS By Dr M V Nagarjuna 1 Dr. M. V. Nagarjuna. Seminar Overview 1. Basic Terminology ( Types of](https://reader034.fdocuments.net/reader034/viewer/2022051721/5a7b38d97f8b9a49588bbb9a/html5/thumbnails/5.jpg)
2. TARGET VARIABLE : Controls the gas delivery during the breath Flow ( Volume Control modes) Pressure ( Pressure Control modes)
3. CYCLE VARIABLE : Cycled from inspiration into i iexpiration
Volume ( Volume control)Ti (P l) Time (Pressure control)
Flow (pressure Support) P (S f t li i bl ) Pressure (Safety cycling variable)
5
![Page 6: VENTILATOR WAVEFORM · PDF fileVENTILATOR WAVEFORM ANALYSIS By Dr M V Nagarjuna 1 Dr. M. V. Nagarjuna. Seminar Overview 1. Basic Terminology ( Types of](https://reader034.fdocuments.net/reader034/viewer/2022051721/5a7b38d97f8b9a49588bbb9a/html5/thumbnails/6.jpg)
Modes of Ventilation
Mode of ventilation Breath types available
Volume Assist Control Volume Control, Volume Assist
Pressure Assist Control Pressure Control, Pressure Assist,
Volume SIMV Volume Control, Volume Assist, Pressure Support
Pressure SIMV Pressure Control, Pressure Assist, Pressure Support
Pressure Support Pressure support
6
![Page 7: VENTILATOR WAVEFORM · PDF fileVENTILATOR WAVEFORM ANALYSIS By Dr M V Nagarjuna 1 Dr. M. V. Nagarjuna. Seminar Overview 1. Basic Terminology ( Types of](https://reader034.fdocuments.net/reader034/viewer/2022051721/5a7b38d97f8b9a49588bbb9a/html5/thumbnails/7.jpg)
SCALARS
7
![Page 8: VENTILATOR WAVEFORM · PDF fileVENTILATOR WAVEFORM ANALYSIS By Dr M V Nagarjuna 1 Dr. M. V. Nagarjuna. Seminar Overview 1. Basic Terminology ( Types of](https://reader034.fdocuments.net/reader034/viewer/2022051721/5a7b38d97f8b9a49588bbb9a/html5/thumbnails/8.jpg)
FLOW vs TIME
8
![Page 9: VENTILATOR WAVEFORM · PDF fileVENTILATOR WAVEFORM ANALYSIS By Dr M V Nagarjuna 1 Dr. M. V. Nagarjuna. Seminar Overview 1. Basic Terminology ( Types of](https://reader034.fdocuments.net/reader034/viewer/2022051721/5a7b38d97f8b9a49588bbb9a/html5/thumbnails/9.jpg)
Flow versus time
Never forget to look at the expiratory limb of the flow waveformThe expiratory flow is determined by the elastic recoil of the
respiratory system and resistance of intubated airwaysrespiratory system and resistance of intubated airways
9
![Page 10: VENTILATOR WAVEFORM · PDF fileVENTILATOR WAVEFORM ANALYSIS By Dr M V Nagarjuna 1 Dr. M. V. Nagarjuna. Seminar Overview 1. Basic Terminology ( Types of](https://reader034.fdocuments.net/reader034/viewer/2022051721/5a7b38d97f8b9a49588bbb9a/html5/thumbnails/10.jpg)
Types of Inspiratory flow waveforms
a Square wave flowa. Square wave flowb. Ascending ramp flowc Descending ramp flowc. Descending ramp flowd. Sinusoidal flowe Decay flowe. Decay flow
10
![Page 11: VENTILATOR WAVEFORM · PDF fileVENTILATOR WAVEFORM ANALYSIS By Dr M V Nagarjuna 1 Dr. M. V. Nagarjuna. Seminar Overview 1. Basic Terminology ( Types of](https://reader034.fdocuments.net/reader034/viewer/2022051721/5a7b38d97f8b9a49588bbb9a/html5/thumbnails/11.jpg)
Which form to use??
P t l d Al D l ti d fl Pressure control mode : Always Decelerating or decay flow. Cannot be changed.
Volume control mode : Flow waveform can be changed d di h il idepending on the ventilator options.
11
![Page 12: VENTILATOR WAVEFORM · PDF fileVENTILATOR WAVEFORM ANALYSIS By Dr M V Nagarjuna 1 Dr. M. V. Nagarjuna. Seminar Overview 1. Basic Terminology ( Types of](https://reader034.fdocuments.net/reader034/viewer/2022051721/5a7b38d97f8b9a49588bbb9a/html5/thumbnails/12.jpg)
SQUARE FLOW WAVEFORM :• Inspiratory time is shortest for Inspiratory time is shortest for Square wave flow form.• Highest Peak Inspiratory pressures•Low Mean Inspiratory pressure •Low Mean Inspiratory pressure,, thus better venous return and cardiac output
DESCENDING RAMP FLOW :• Increases inspiratory time (if not fixed) or peak inspiratory flow rate (if inspiratory time is fixed)p y•Least Peak inspiratory pressures (19% decrease).•High mean airway pressure, helps g y p , p lung inflation and oxygenation.
12
![Page 13: VENTILATOR WAVEFORM · PDF fileVENTILATOR WAVEFORM ANALYSIS By Dr M V Nagarjuna 1 Dr. M. V. Nagarjuna. Seminar Overview 1. Basic Terminology ( Types of](https://reader034.fdocuments.net/reader034/viewer/2022051721/5a7b38d97f8b9a49588bbb9a/html5/thumbnails/13.jpg)
Sinusoidal and ascending ramp flow :Sinusoidal and ascending ramp flow :
Initial flow rates are slow and hence cause dyssynchrony –FLOW STARVATIONFLOW STARVATION.
Should not be used in assist modes.
Descending ramp and Square wave flow :
Usually preferred as the initial flow rate meets the flow demand of the patient. Decreases air hunger.
13
![Page 14: VENTILATOR WAVEFORM · PDF fileVENTILATOR WAVEFORM ANALYSIS By Dr M V Nagarjuna 1 Dr. M. V. Nagarjuna. Seminar Overview 1. Basic Terminology ( Types of](https://reader034.fdocuments.net/reader034/viewer/2022051721/5a7b38d97f8b9a49588bbb9a/html5/thumbnails/14.jpg)
SQUARE WAVE FLOW DECSENDING RAMP
14
SQUARE WAVE FLOWFLOW
![Page 15: VENTILATOR WAVEFORM · PDF fileVENTILATOR WAVEFORM ANALYSIS By Dr M V Nagarjuna 1 Dr. M. V. Nagarjuna. Seminar Overview 1. Basic Terminology ( Types of](https://reader034.fdocuments.net/reader034/viewer/2022051721/5a7b38d97f8b9a49588bbb9a/html5/thumbnails/15.jpg)
Decelerating flow waveform
Advantages : Decreases Peak inspiratory pressures Increases oxygenation, decreases A-aDo2 Improves patient ventilator synchrony (more physiological)
Disadvantages : Decreases expiratory time , potential for auto PEEP Increases mean airway pressure, decreases cardiac output Increased intracranial pressures
Egan's Fundamentals of Respiratory Care. 8th ed. 2003:1064.
Mechanical Ventilation; Physiological and Clinical Applications 4thed 2006:113 Mechanical Ventilation; Physiological and Clinical Applications.4thed.2006:113. Intensive Care Med. 1985;11:68-75.
15
![Page 16: VENTILATOR WAVEFORM · PDF fileVENTILATOR WAVEFORM ANALYSIS By Dr M V Nagarjuna 1 Dr. M. V. Nagarjuna. Seminar Overview 1. Basic Terminology ( Types of](https://reader034.fdocuments.net/reader034/viewer/2022051721/5a7b38d97f8b9a49588bbb9a/html5/thumbnails/16.jpg)
Expiratory flow waveform
Passive and determined by compliance of the lung and resistance of the airwaysresistance of the airways.
F i b b d Four points to be observed :1. Peak Expiratory Flow2 Sl f h i li b2. Slope of the expiratory limb3. Expiratory time4 D th f h th b li ?4. Does the waveform reach the baseline?
16
![Page 17: VENTILATOR WAVEFORM · PDF fileVENTILATOR WAVEFORM ANALYSIS By Dr M V Nagarjuna 1 Dr. M. V. Nagarjuna. Seminar Overview 1. Basic Terminology ( Types of](https://reader034.fdocuments.net/reader034/viewer/2022051721/5a7b38d97f8b9a49588bbb9a/html5/thumbnails/17.jpg)
PRESSURE vs TIME
17
![Page 18: VENTILATOR WAVEFORM · PDF fileVENTILATOR WAVEFORM ANALYSIS By Dr M V Nagarjuna 1 Dr. M. V. Nagarjuna. Seminar Overview 1. Basic Terminology ( Types of](https://reader034.fdocuments.net/reader034/viewer/2022051721/5a7b38d97f8b9a49588bbb9a/html5/thumbnails/18.jpg)
Pressure vs Time Scalar
18
![Page 19: VENTILATOR WAVEFORM · PDF fileVENTILATOR WAVEFORM ANALYSIS By Dr M V Nagarjuna 1 Dr. M. V. Nagarjuna. Seminar Overview 1. Basic Terminology ( Types of](https://reader034.fdocuments.net/reader034/viewer/2022051721/5a7b38d97f8b9a49588bbb9a/html5/thumbnails/19.jpg)
PIPNo active breathingT t l i l it PIP
resistance
Treats lung as single unit
Pplat
flow
Pplatend-inspiratoryalveolar pressureDriving
compliancetidal volume
Pressure (PIP-PEEP)
tidal volume
PEEP
PIP- PEEP= (Flow x Resistance) + (Vt/Compliance RS)
![Page 20: VENTILATOR WAVEFORM · PDF fileVENTILATOR WAVEFORM ANALYSIS By Dr M V Nagarjuna 1 Dr. M. V. Nagarjuna. Seminar Overview 1. Basic Terminology ( Types of](https://reader034.fdocuments.net/reader034/viewer/2022051721/5a7b38d97f8b9a49588bbb9a/html5/thumbnails/20.jpg)
tidal volume
Respiratory System Compliance
C =Pplat - PEEP
tidal volume
Pulmonary Disorder: Extra Pulmonary Disorder:Decreased with:
y mainstem intubation congestive heart failure
ARDS
Extra Pulmonary Disorder:
abdominal distension
chest wall edema/Obesity ARDS Atelectasis, consolidation fibrosis
chest wall edema/Obesity
thoracic deformity
Hyperinflation Tension pneumothorax
l l ff Normal : 100 mL/cm H2O pleural effusion
![Page 21: VENTILATOR WAVEFORM · PDF fileVENTILATOR WAVEFORM ANALYSIS By Dr M V Nagarjuna 1 Dr. M. V. Nagarjuna. Seminar Overview 1. Basic Terminology ( Types of](https://reader034.fdocuments.net/reader034/viewer/2022051721/5a7b38d97f8b9a49588bbb9a/html5/thumbnails/21.jpg)
P l t PEEP = Vt/ C liPplat – PEEP = Vt/ Compliance
P plateau increased by a) Decreasing compliance of lung : Pulm edema, ARDS, g p g
Atelectasis, Pneumonia.b) Decreasing compliance of the chest wall : Morbid obesity,
ascites, stiff chest wall.c) Increasing Tidal volumed) Patient ventilator dyssynchrony
21
![Page 22: VENTILATOR WAVEFORM · PDF fileVENTILATOR WAVEFORM ANALYSIS By Dr M V Nagarjuna 1 Dr. M. V. Nagarjuna. Seminar Overview 1. Basic Terminology ( Types of](https://reader034.fdocuments.net/reader034/viewer/2022051721/5a7b38d97f8b9a49588bbb9a/html5/thumbnails/22.jpg)
PIP Pplat
Inspiratory Resistance
Ri = PIP - Pplat
flow
Increased with: Airways : Secretions, Mucus plugging,
Bronchospasmp ET tube : Small size, ET block Ventilator Circuit: Kinking Clogged HME Ventilator Circuit: Kinking, Clogged HME
Normal: 5 - 10 cm H2O/L/s for intubated ventilated adults2 / /measured with 60 L/min (1 L/s) constant flow
![Page 23: VENTILATOR WAVEFORM · PDF fileVENTILATOR WAVEFORM ANALYSIS By Dr M V Nagarjuna 1 Dr. M. V. Nagarjuna. Seminar Overview 1. Basic Terminology ( Types of](https://reader034.fdocuments.net/reader034/viewer/2022051721/5a7b38d97f8b9a49588bbb9a/html5/thumbnails/23.jpg)
P k P l t = Fl R i tP peak – P plat = Flow x Resistance
Increased by a) Increasing resistance : Bronchospasm, Mucus g p
plugging/secretions, ET block , Biting the ET tube, Tube kinking, Clogged HME.
b) Increasing flow : Increasing Vt, Increasing Insp.pause, Increasing I:E ratio
23
![Page 24: VENTILATOR WAVEFORM · PDF fileVENTILATOR WAVEFORM ANALYSIS By Dr M V Nagarjuna 1 Dr. M. V. Nagarjuna. Seminar Overview 1. Basic Terminology ( Types of](https://reader034.fdocuments.net/reader034/viewer/2022051721/5a7b38d97f8b9a49588bbb9a/html5/thumbnails/24.jpg)
PIPCrs =
P l t PEEP
tidal volume
Ppl
Pplat - PEEP
Ctidal volumePpl
(Peso)Ccw =
Peso
Palv (Pplat)
CL =(Pplat – PEEP) - Peso
tidal volume
(Pplat) ( p )
Ri =PIP - Pplat
Ri flow
![Page 25: VENTILATOR WAVEFORM · PDF fileVENTILATOR WAVEFORM ANALYSIS By Dr M V Nagarjuna 1 Dr. M. V. Nagarjuna. Seminar Overview 1. Basic Terminology ( Types of](https://reader034.fdocuments.net/reader034/viewer/2022051721/5a7b38d97f8b9a49588bbb9a/html5/thumbnails/25.jpg)
STRESS INDEX (ARDS)
Increase PEEP Ideal PEEP Decrease PEEP(Recruitment) (Overdistension)
25
![Page 26: VENTILATOR WAVEFORM · PDF fileVENTILATOR WAVEFORM ANALYSIS By Dr M V Nagarjuna 1 Dr. M. V. Nagarjuna. Seminar Overview 1. Basic Terminology ( Types of](https://reader034.fdocuments.net/reader034/viewer/2022051721/5a7b38d97f8b9a49588bbb9a/html5/thumbnails/26.jpg)
SQUARE WAVE FLOW DECSENDING RAMP
26
SQUARE WAVE FLOWFLOW
![Page 27: VENTILATOR WAVEFORM · PDF fileVENTILATOR WAVEFORM ANALYSIS By Dr M V Nagarjuna 1 Dr. M. V. Nagarjuna. Seminar Overview 1. Basic Terminology ( Types of](https://reader034.fdocuments.net/reader034/viewer/2022051721/5a7b38d97f8b9a49588bbb9a/html5/thumbnails/27.jpg)
VOLUME vs TIME
27
![Page 28: VENTILATOR WAVEFORM · PDF fileVENTILATOR WAVEFORM ANALYSIS By Dr M V Nagarjuna 1 Dr. M. V. Nagarjuna. Seminar Overview 1. Basic Terminology ( Types of](https://reader034.fdocuments.net/reader034/viewer/2022051721/5a7b38d97f8b9a49588bbb9a/html5/thumbnails/28.jpg)
Information derived from VolumeTime ScalarInformation derived from VolumeTime Scalar
Tidal Volume Volume on y axis
Air leak Expiratory limb fails to return to x axis
Active Expiration Tracing continues beyond the baseline
A l b f l h h b lAuto PEEP Expiratory limb fails to reach the baseline
28
![Page 29: VENTILATOR WAVEFORM · PDF fileVENTILATOR WAVEFORM ANALYSIS By Dr M V Nagarjuna 1 Dr. M. V. Nagarjuna. Seminar Overview 1. Basic Terminology ( Types of](https://reader034.fdocuments.net/reader034/viewer/2022051721/5a7b38d97f8b9a49588bbb9a/html5/thumbnails/29.jpg)
HOW TO USE THE HOW TO USE THE GRAPHS FOR GRAPHS FOR
DIAGNOSIS OF DISEASE DIAGNOSIS OF DISEASE STATES ?STATES ?
29
![Page 30: VENTILATOR WAVEFORM · PDF fileVENTILATOR WAVEFORM ANALYSIS By Dr M V Nagarjuna 1 Dr. M. V. Nagarjuna. Seminar Overview 1. Basic Terminology ( Types of](https://reader034.fdocuments.net/reader034/viewer/2022051721/5a7b38d97f8b9a49588bbb9a/html5/thumbnails/30.jpg)
Which waveforms to monitor ?
Mode of ventilation
Independent variables
Dependent variables
Waveforms that will be useful
Waveforms that normally remain unchanged
Volume Control/ Assist-Control
Tidal volume, RR, Flow rate, PEEP, I/E ratio
PawPressure-time:
Changes in Pip, Pplat
Flow-time (expiratory): Ch i li
Volume-time
Flow time (inspiratory)
Changes in compliance
Pressure-volume loop: Overdistension, optimal PEEP
l i d flPressure Control
Paw, Inspiratory time (RR), PEEP and I/E ratio
Vt, flowVolume-time and flow-time: Changes in Vt and compliance
Pressure-volume loop:
Pressure-time
Overdistension, optimal PEEP
Pressure PS and PEEP Vt and RR, Volume- timesupport/
CPAP
Vt,and RR, flow, I/E Ratio
Flow- time
(for Vt and VE)
30
![Page 31: VENTILATOR WAVEFORM · PDF fileVENTILATOR WAVEFORM ANALYSIS By Dr M V Nagarjuna 1 Dr. M. V. Nagarjuna. Seminar Overview 1. Basic Terminology ( Types of](https://reader034.fdocuments.net/reader034/viewer/2022051721/5a7b38d97f8b9a49588bbb9a/html5/thumbnails/31.jpg)
Increased airway resistance (ACMV- VC)
Pressure Time Waveform : Increased difference between Ppeak and Pplat Normal P plat
Expiratory flow waveform :d Decreased PEFR
Increased expiratory time Scooped out appearance of expiratory limbScooped out appearance of expiratory limb Potential for auto PEEP Loss of peak (emphysema)
Volume Time Waveform : Expiratory limb long
31
![Page 32: VENTILATOR WAVEFORM · PDF fileVENTILATOR WAVEFORM ANALYSIS By Dr M V Nagarjuna 1 Dr. M. V. Nagarjuna. Seminar Overview 1. Basic Terminology ( Types of](https://reader034.fdocuments.net/reader034/viewer/2022051721/5a7b38d97f8b9a49588bbb9a/html5/thumbnails/32.jpg)
A patient with Endotracheal Tube block (When received from Dialysis room)
32
![Page 33: VENTILATOR WAVEFORM · PDF fileVENTILATOR WAVEFORM ANALYSIS By Dr M V Nagarjuna 1 Dr. M. V. Nagarjuna. Seminar Overview 1. Basic Terminology ( Types of](https://reader034.fdocuments.net/reader034/viewer/2022051721/5a7b38d97f8b9a49588bbb9a/html5/thumbnails/33.jpg)
A patient with acute severe asthma on ventilator
33
![Page 34: VENTILATOR WAVEFORM · PDF fileVENTILATOR WAVEFORM ANALYSIS By Dr M V Nagarjuna 1 Dr. M. V. Nagarjuna. Seminar Overview 1. Basic Terminology ( Types of](https://reader034.fdocuments.net/reader034/viewer/2022051721/5a7b38d97f8b9a49588bbb9a/html5/thumbnails/34.jpg)
Decreased Compliance of Respiratory System
Pressure Time Waveform : Increased P plat and Ppeak Increased P plat and Ppeak. Normal P peak – Pplat
Flow Time Waveform : Increased PEFR Increased PEFR Shortened expiratory time
34
![Page 35: VENTILATOR WAVEFORM · PDF fileVENTILATOR WAVEFORM ANALYSIS By Dr M V Nagarjuna 1 Dr. M. V. Nagarjuna. Seminar Overview 1. Basic Terminology ( Types of](https://reader034.fdocuments.net/reader034/viewer/2022051721/5a7b38d97f8b9a49588bbb9a/html5/thumbnails/35.jpg)
Auto PEEP/Intrinsic PEEPAuto PEEP/Intrinsic PEEP
Notice how the expiratory flow failsNotice how the expiratory flow failsto return to the baseline indicating
air trapping (Auto PEEP)
Also notice how air trapping causes an increase in airway pressurey p
due to increasing end expiratorypressure and end inspiratory
lung volume.
35
![Page 36: VENTILATOR WAVEFORM · PDF fileVENTILATOR WAVEFORM ANALYSIS By Dr M V Nagarjuna 1 Dr. M. V. Nagarjuna. Seminar Overview 1. Basic Terminology ( Types of](https://reader034.fdocuments.net/reader034/viewer/2022051721/5a7b38d97f8b9a49588bbb9a/html5/thumbnails/36.jpg)
A patient of acute severe asthma. Note failure of expiratory limb to return to baseline
36
![Page 37: VENTILATOR WAVEFORM · PDF fileVENTILATOR WAVEFORM ANALYSIS By Dr M V Nagarjuna 1 Dr. M. V. Nagarjuna. Seminar Overview 1. Basic Terminology ( Types of](https://reader034.fdocuments.net/reader034/viewer/2022051721/5a7b38d97f8b9a49588bbb9a/html5/thumbnails/37.jpg)
37
![Page 38: VENTILATOR WAVEFORM · PDF fileVENTILATOR WAVEFORM ANALYSIS By Dr M V Nagarjuna 1 Dr. M. V. Nagarjuna. Seminar Overview 1. Basic Terminology ( Types of](https://reader034.fdocuments.net/reader034/viewer/2022051721/5a7b38d97f8b9a49588bbb9a/html5/thumbnails/38.jpg)
AUTO- PEEP : Consequencesq Increases the work of Triggering Ineffective triggering Worsens Oxygenationyg Lung Hyperinflation- barotrauma Hemodynamic Compromise
AUTO PEEP : Recognition Analysis of ventilator graphics:
Delay between start of Inspiratory effort and Pressure drop No increase in P peak with increase in Applied PEEP
38
![Page 39: VENTILATOR WAVEFORM · PDF fileVENTILATOR WAVEFORM ANALYSIS By Dr M V Nagarjuna 1 Dr. M. V. Nagarjuna. Seminar Overview 1. Basic Terminology ( Types of](https://reader034.fdocuments.net/reader034/viewer/2022051721/5a7b38d97f8b9a49588bbb9a/html5/thumbnails/39.jpg)
39
![Page 40: VENTILATOR WAVEFORM · PDF fileVENTILATOR WAVEFORM ANALYSIS By Dr M V Nagarjuna 1 Dr. M. V. Nagarjuna. Seminar Overview 1. Basic Terminology ( Types of](https://reader034.fdocuments.net/reader034/viewer/2022051721/5a7b38d97f8b9a49588bbb9a/html5/thumbnails/40.jpg)
VENTILATOR PATIENT VENTILATOR PATIENT SYNCHRONY SYNCHRONY
VSVS
DYS-SYNCHRONYS S C O
40
![Page 41: VENTILATOR WAVEFORM · PDF fileVENTILATOR WAVEFORM ANALYSIS By Dr M V Nagarjuna 1 Dr. M. V. Nagarjuna. Seminar Overview 1. Basic Terminology ( Types of](https://reader034.fdocuments.net/reader034/viewer/2022051721/5a7b38d97f8b9a49588bbb9a/html5/thumbnails/41.jpg)
Wh t i V til t P ti t S h ?What is Ventilator Patient Synchrony?The ventilator should start inspiration at p
the time of onset of patients inspiration.Th fl id d b th til t h ld The flow provided by the ventilator should
meet the flow demand of the patient.pThe Ventilator Inspiratory time should
t h ith th ti t i i t timatch with the patients inspiratory time.
41
![Page 42: VENTILATOR WAVEFORM · PDF fileVENTILATOR WAVEFORM ANALYSIS By Dr M V Nagarjuna 1 Dr. M. V. Nagarjuna. Seminar Overview 1. Basic Terminology ( Types of](https://reader034.fdocuments.net/reader034/viewer/2022051721/5a7b38d97f8b9a49588bbb9a/html5/thumbnails/42.jpg)
Ventilator Patient Dys-synchrony
FLOW CYCLE TRIGGER ASYNCHRONY ASYNCHRONYASYNCHRONY
1. Ineffective Triggering
2. Auto Triggering
1. Delayed Cycling
2 Premature 3. Double Triggering
4. Delayed i i
2. Premature Cycling
triggering
42
![Page 43: VENTILATOR WAVEFORM · PDF fileVENTILATOR WAVEFORM ANALYSIS By Dr M V Nagarjuna 1 Dr. M. V. Nagarjuna. Seminar Overview 1. Basic Terminology ( Types of](https://reader034.fdocuments.net/reader034/viewer/2022051721/5a7b38d97f8b9a49588bbb9a/html5/thumbnails/43.jpg)
INEFFECTIVE TRIGGGERING One of the most common asynchronies One of the most common asynchronies
Failure of the patients inspiratory effort to initiate a ventilator breathventilator breath.
Identified by Vi l i ti f ti t di th i l b t Visual inspection of patients expanding thoracic volume but
without delivery of ventilator breath. Ventilator graphics which show a decrease in airway pressure Ventilator graphics which show a decrease in airway pressure
with an increase in flow but no initiation of breath.
43
![Page 44: VENTILATOR WAVEFORM · PDF fileVENTILATOR WAVEFORM ANALYSIS By Dr M V Nagarjuna 1 Dr. M. V. Nagarjuna. Seminar Overview 1. Basic Terminology ( Types of](https://reader034.fdocuments.net/reader034/viewer/2022051721/5a7b38d97f8b9a49588bbb9a/html5/thumbnails/44.jpg)
Ineffective triggering What causes this? What causes this? Improper sensitivity of trigger threshold Respiratory muscle weakness (disease related critical illness Respiratory muscle weakness (disease related, critical illness
neuromyopathy, electrolyte imbalances) Intrinsic PEEP in COPD patientsp Decreased respiratory drive ( Excessive sedatives) Alkaline pHp External nebulizers High Tidal volumes/High Pressure support decrease respiratory g g pp p y
drive.
44
![Page 45: VENTILATOR WAVEFORM · PDF fileVENTILATOR WAVEFORM ANALYSIS By Dr M V Nagarjuna 1 Dr. M. V. Nagarjuna. Seminar Overview 1. Basic Terminology ( Types of](https://reader034.fdocuments.net/reader034/viewer/2022051721/5a7b38d97f8b9a49588bbb9a/html5/thumbnails/45.jpg)
AUTO TRIGGERINGDefinition : Ventilator delivers an assisted breath Definition : Ventilator delivers an assisted breath
that was not initiated by the patient
Causes :
1 Ci i l k (ET ff ICTD i h BPF )1. Circuit leaks (ET cuff, ICTD with BPF etc)
2. Fluid in the circuit
3. Cardiac oscillations (High cardiac output states)
4. Very low trigger threshold
.
45
![Page 46: VENTILATOR WAVEFORM · PDF fileVENTILATOR WAVEFORM ANALYSIS By Dr M V Nagarjuna 1 Dr. M. V. Nagarjuna. Seminar Overview 1. Basic Terminology ( Types of](https://reader034.fdocuments.net/reader034/viewer/2022051721/5a7b38d97f8b9a49588bbb9a/html5/thumbnails/46.jpg)
DOUBLE TRIGGERING Patients inspiration continues after the ventilator inspiration Patients inspiration continues after the ventilator inspiration
and triggers another breath immediately after the inspiration.
Also called Breath Stacking Also called Breath Stacking
Causes :
1 Hi h V il d d f h i (ARDS)1. High Ventilatory demand of the patient (ARDS)
2. Inappropriate settings ( Low tidal volume, Short i i i Hi h l h h ld)inspiratory time, High cycle threshold)
46
![Page 47: VENTILATOR WAVEFORM · PDF fileVENTILATOR WAVEFORM ANALYSIS By Dr M V Nagarjuna 1 Dr. M. V. Nagarjuna. Seminar Overview 1. Basic Terminology ( Types of](https://reader034.fdocuments.net/reader034/viewer/2022051721/5a7b38d97f8b9a49588bbb9a/html5/thumbnails/47.jpg)
A case of Morbid Obesity with Obesity hypoventilation syndrome. y y yp yNote the low tidal volumes generated on PSV mode
47
![Page 48: VENTILATOR WAVEFORM · PDF fileVENTILATOR WAVEFORM ANALYSIS By Dr M V Nagarjuna 1 Dr. M. V. Nagarjuna. Seminar Overview 1. Basic Terminology ( Types of](https://reader034.fdocuments.net/reader034/viewer/2022051721/5a7b38d97f8b9a49588bbb9a/html5/thumbnails/48.jpg)
DELAYED TRIGGERINGComponents of Triggering :Components of Triggering :
Trigger threshold : The pressure/flow that must be attained b the patients breath to trigger the entilatorattained by the patients breath to trigger the ventilator.
Inspiratory Trigger Time (ITT) : Time from the initiation f ff h T h h ld of effort to the Trigger threshold .
Rise Time to Baseline Pressure (RTBP)
Inspiratory Delay Time (IDT) = ITT + RTBP p y y ( )
48
![Page 49: VENTILATOR WAVEFORM · PDF fileVENTILATOR WAVEFORM ANALYSIS By Dr M V Nagarjuna 1 Dr. M. V. Nagarjuna. Seminar Overview 1. Basic Terminology ( Types of](https://reader034.fdocuments.net/reader034/viewer/2022051721/5a7b38d97f8b9a49588bbb9a/html5/thumbnails/49.jpg)
DELAYED TRIGGERING
A I h t bl ith ll th ti l d f An Inherent problem with all the conventional modes of ventilation
Can be overcome by Newer modes of ventilation ( NAVA) Newer methods of triggering ( Shape signal triggering)
49
![Page 50: VENTILATOR WAVEFORM · PDF fileVENTILATOR WAVEFORM ANALYSIS By Dr M V Nagarjuna 1 Dr. M. V. Nagarjuna. Seminar Overview 1. Basic Terminology ( Types of](https://reader034.fdocuments.net/reader034/viewer/2022051721/5a7b38d97f8b9a49588bbb9a/html5/thumbnails/50.jpg)
Neurally Adjusted Ventilatory Assist (NAVA)
Diaphragmatic Electrical activity is sensed by an electrode placed in the esophagus and is used to trigger the breath and cycle into expiration.
50
![Page 51: VENTILATOR WAVEFORM · PDF fileVENTILATOR WAVEFORM ANALYSIS By Dr M V Nagarjuna 1 Dr. M. V. Nagarjuna. Seminar Overview 1. Basic Terminology ( Types of](https://reader034.fdocuments.net/reader034/viewer/2022051721/5a7b38d97f8b9a49588bbb9a/html5/thumbnails/51.jpg)
Sinderby Nature Med 1999;5:1433NEJM 2001;344 : 1986-1996
![Page 52: VENTILATOR WAVEFORM · PDF fileVENTILATOR WAVEFORM ANALYSIS By Dr M V Nagarjuna 1 Dr. M. V. Nagarjuna. Seminar Overview 1. Basic Terminology ( Types of](https://reader034.fdocuments.net/reader034/viewer/2022051721/5a7b38d97f8b9a49588bbb9a/html5/thumbnails/52.jpg)
FLOW ASYNCHRONYCauses :Causes : High Ventilatory demand (ALI/ARDS) Low ventilatory settings ( Flow rate Tidal volume Pramp)Low ventilatory settings ( Flow rate, Tidal volume, Pramp)What to do : Treat reversible causes of air hunger (fever acidosis) Treat reversible causes of air hunger (fever, acidosis) Increase the tidal volume ( if feasible) Increase the flow rate ( directly or by decreasing inspiratory Increase the flow rate ( directly, or by decreasing inspiratory
time, increasing pause) Change to pressure control mode with variable flow g p Sedate /Paralyze the patient (last resort)
52
![Page 53: VENTILATOR WAVEFORM · PDF fileVENTILATOR WAVEFORM ANALYSIS By Dr M V Nagarjuna 1 Dr. M. V. Nagarjuna. Seminar Overview 1. Basic Terminology ( Types of](https://reader034.fdocuments.net/reader034/viewer/2022051721/5a7b38d97f8b9a49588bbb9a/html5/thumbnails/53.jpg)
Patient of ARDS being ventilated using ARDS Network strategy (Tidal volume = 6 ml/kg, Body weight = 66 kg)
53
![Page 54: VENTILATOR WAVEFORM · PDF fileVENTILATOR WAVEFORM ANALYSIS By Dr M V Nagarjuna 1 Dr. M. V. Nagarjuna. Seminar Overview 1. Basic Terminology ( Types of](https://reader034.fdocuments.net/reader034/viewer/2022051721/5a7b38d97f8b9a49588bbb9a/html5/thumbnails/54.jpg)
Tidal volume increased to 440 ml from 400 ml to improve the flow synchrony
54
![Page 55: VENTILATOR WAVEFORM · PDF fileVENTILATOR WAVEFORM ANALYSIS By Dr M V Nagarjuna 1 Dr. M. V. Nagarjuna. Seminar Overview 1. Basic Terminology ( Types of](https://reader034.fdocuments.net/reader034/viewer/2022051721/5a7b38d97f8b9a49588bbb9a/html5/thumbnails/55.jpg)
Same patient during a spike of fever 39.2 C showing severe flow dyssynchrony
55
![Page 56: VENTILATOR WAVEFORM · PDF fileVENTILATOR WAVEFORM ANALYSIS By Dr M V Nagarjuna 1 Dr. M. V. Nagarjuna. Seminar Overview 1. Basic Terminology ( Types of](https://reader034.fdocuments.net/reader034/viewer/2022051721/5a7b38d97f8b9a49588bbb9a/html5/thumbnails/56.jpg)
CYCLING ASYNCHRONY
Delayed Cycling : Ventilator Ti > Patient Ti
V til t ti I i ti h t ll i ti h Ventilator continues Inspiration when actually expiration has started.
Premature Cycling : Ventilator Ti < Patient Ti
Patients inspiratory effort continue into the expiratory phase of ventilator breath.
56
![Page 57: VENTILATOR WAVEFORM · PDF fileVENTILATOR WAVEFORM ANALYSIS By Dr M V Nagarjuna 1 Dr. M. V. Nagarjuna. Seminar Overview 1. Basic Terminology ( Types of](https://reader034.fdocuments.net/reader034/viewer/2022051721/5a7b38d97f8b9a49588bbb9a/html5/thumbnails/57.jpg)
DELAYED CYCLING
Patient while weaning . Expiratory trigger sensitivity of 25 %
57
![Page 58: VENTILATOR WAVEFORM · PDF fileVENTILATOR WAVEFORM ANALYSIS By Dr M V Nagarjuna 1 Dr. M. V. Nagarjuna. Seminar Overview 1. Basic Terminology ( Types of](https://reader034.fdocuments.net/reader034/viewer/2022051721/5a7b38d97f8b9a49588bbb9a/html5/thumbnails/58.jpg)
How to Manage : How to Manage :
D I i t ti Decrease Inspiratory time
Decrease Tidal volume ( SCMV mode)
Increase Expiratory Trigger Sensitivity ( PSV mode)
58
![Page 59: VENTILATOR WAVEFORM · PDF fileVENTILATOR WAVEFORM ANALYSIS By Dr M V Nagarjuna 1 Dr. M. V. Nagarjuna. Seminar Overview 1. Basic Terminology ( Types of](https://reader034.fdocuments.net/reader034/viewer/2022051721/5a7b38d97f8b9a49588bbb9a/html5/thumbnails/59.jpg)
Expiratory trigger sensitivity increased to 60 % to improve cycling synchrony.
59
![Page 60: VENTILATOR WAVEFORM · PDF fileVENTILATOR WAVEFORM ANALYSIS By Dr M V Nagarjuna 1 Dr. M. V. Nagarjuna. Seminar Overview 1. Basic Terminology ( Types of](https://reader034.fdocuments.net/reader034/viewer/2022051721/5a7b38d97f8b9a49588bbb9a/html5/thumbnails/60.jpg)
A case of Acute severe asthma on SCMV mode. I : E ratio kept at 1: 3.3 to avoid auto PEEP.
Ventilator shows double triggering60
![Page 61: VENTILATOR WAVEFORM · PDF fileVENTILATOR WAVEFORM ANALYSIS By Dr M V Nagarjuna 1 Dr. M. V. Nagarjuna. Seminar Overview 1. Basic Terminology ( Types of](https://reader034.fdocuments.net/reader034/viewer/2022051721/5a7b38d97f8b9a49588bbb9a/html5/thumbnails/61.jpg)
I : E ratio decreased to 1 : 2.5 along with control of bronchospasm.None of the other parameters changed. No further double triggering.
Illustrates double triggering due to short inspiratory time and premature cycling
61
![Page 62: VENTILATOR WAVEFORM · PDF fileVENTILATOR WAVEFORM ANALYSIS By Dr M V Nagarjuna 1 Dr. M. V. Nagarjuna. Seminar Overview 1. Basic Terminology ( Types of](https://reader034.fdocuments.net/reader034/viewer/2022051721/5a7b38d97f8b9a49588bbb9a/html5/thumbnails/62.jpg)
PATIENT VENTILATOR DYS-SYNCHRONY CLINICAL SIGNIFICANCE ??
Increases Work Of BreathingIncreases Work Of Breathing Causes Ultra structural damage to the respiratory muscles. Worsens Respiratory mechanics ( Auto PEEP)Worsens Respiratory mechanics ( Auto PEEP) Alters gas exchange ( Auto, double triggering – lower CO2) Increased need for sedation Increased need for sedation Longer duration of mechanical ventilation Difficulty in weaning Difficulty in weaning Confounds lung protective ventilation ( Double breaths) Sleep Fragmentation Sleep Fragmentation Inability to tolerate NIV
62
![Page 63: VENTILATOR WAVEFORM · PDF fileVENTILATOR WAVEFORM ANALYSIS By Dr M V Nagarjuna 1 Dr. M. V. Nagarjuna. Seminar Overview 1. Basic Terminology ( Types of](https://reader034.fdocuments.net/reader034/viewer/2022051721/5a7b38d97f8b9a49588bbb9a/html5/thumbnails/63.jpg)
Loops
Pressure-Volume Loops
Flow-Volume Loopsp
![Page 64: VENTILATOR WAVEFORM · PDF fileVENTILATOR WAVEFORM ANALYSIS By Dr M V Nagarjuna 1 Dr. M. V. Nagarjuna. Seminar Overview 1. Basic Terminology ( Types of](https://reader034.fdocuments.net/reader034/viewer/2022051721/5a7b38d97f8b9a49588bbb9a/html5/thumbnails/64.jpg)
Pressure-Volume LoopVLITERS
0.6
VT
0.4
0.6
0.2
0.4
Paw
0 20 40 602040-60cmH2O
![Page 65: VENTILATOR WAVEFORM · PDF fileVENTILATOR WAVEFORM ANALYSIS By Dr M V Nagarjuna 1 Dr. M. V. Nagarjuna. Seminar Overview 1. Basic Terminology ( Types of](https://reader034.fdocuments.net/reader034/viewer/2022051721/5a7b38d97f8b9a49588bbb9a/html5/thumbnails/65.jpg)
Spontaneous BreathSpontaneous Breath
V
0.6
VTClockwise
CPAP
I i ti 0.4
0.6 CPAP
Inspiration Expiration
0.2
0.4
Pressure
0 20 40 602040-60cmH2O
![Page 66: VENTILATOR WAVEFORM · PDF fileVENTILATOR WAVEFORM ANALYSIS By Dr M V Nagarjuna 1 Dr. M. V. Nagarjuna. Seminar Overview 1. Basic Terminology ( Types of](https://reader034.fdocuments.net/reader034/viewer/2022051721/5a7b38d97f8b9a49588bbb9a/html5/thumbnails/66.jpg)
Controlled BreathControlled Breath
VAnticlockwise
LITERS
0.6
VT
Expiration0.4
0.6
0.2
0.4
Inspiration
Paw
0 20 40 602040-60cmH2O
PEEP
P-V loop and PEEP…..
![Page 67: VENTILATOR WAVEFORM · PDF fileVENTILATOR WAVEFORM ANALYSIS By Dr M V Nagarjuna 1 Dr. M. V. Nagarjuna. Seminar Overview 1. Basic Terminology ( Types of](https://reader034.fdocuments.net/reader034/viewer/2022051721/5a7b38d97f8b9a49588bbb9a/html5/thumbnails/67.jpg)
Assisted BreathAssisted Breath
VLITERS
0.6
VT Clockwise to Counterclockwise
Expiration0.4
0.6
Inspiration0.2
0.4
Assisted Breath Inspiration
Paw
Assisted Breath
0 20 40 602040-60cmH2O
PEEP
![Page 68: VENTILATOR WAVEFORM · PDF fileVENTILATOR WAVEFORM ANALYSIS By Dr M V Nagarjuna 1 Dr. M. V. Nagarjuna. Seminar Overview 1. Basic Terminology ( Types of](https://reader034.fdocuments.net/reader034/viewer/2022051721/5a7b38d97f8b9a49588bbb9a/html5/thumbnails/68.jpg)
Lung Compliance Changes and the P-V Loop…. (Volume mode)
Lung Compliance Changes and the P-V Loop…. (Volume mode)p ( )p ( )
Preset VT
↑C C ↓CT
Volume
PIP levelsPressurePressure
Constant VT………. Variable Pressure
![Page 69: VENTILATOR WAVEFORM · PDF fileVENTILATOR WAVEFORM ANALYSIS By Dr M V Nagarjuna 1 Dr. M. V. Nagarjuna. Seminar Overview 1. Basic Terminology ( Types of](https://reader034.fdocuments.net/reader034/viewer/2022051721/5a7b38d97f8b9a49588bbb9a/html5/thumbnails/69.jpg)
Lung Compliance Changing in P-V Loop (pressure Lung Compliance Changing in P-V Loop (pressure g p g g pmode)………….
g p g g pmode)………….
els
1.With surfactant2. Emphysematous L
VT
leve
RDS lRDS…lung
Volume
Preset PIPPressure
Constant PIP……… variable VT
![Page 70: VENTILATOR WAVEFORM · PDF fileVENTILATOR WAVEFORM ANALYSIS By Dr M V Nagarjuna 1 Dr. M. V. Nagarjuna. Seminar Overview 1. Basic Terminology ( Types of](https://reader034.fdocuments.net/reader034/viewer/2022051721/5a7b38d97f8b9a49588bbb9a/html5/thumbnails/70.jpg)
OverdistensionOverdistension
0 6
LITERSA = inspiratory pressure
B = upper inflection point
VT
A
0 4
0.6pp p
C = lower inflection point
B0 2
0.4
B0.2
Paw C0 20 40 60-20-40-60
Paw
cmH2O
![Page 71: VENTILATOR WAVEFORM · PDF fileVENTILATOR WAVEFORM ANALYSIS By Dr M V Nagarjuna 1 Dr. M. V. Nagarjuna. Seminar Overview 1. Basic Terminology ( Types of](https://reader034.fdocuments.net/reader034/viewer/2022051721/5a7b38d97f8b9a49588bbb9a/html5/thumbnails/71.jpg)
Insufficient flow
NormalVo
lum
e Insufficient FlowV
Cusping
Pressure
![Page 72: VENTILATOR WAVEFORM · PDF fileVENTILATOR WAVEFORM ANALYSIS By Dr M V Nagarjuna 1 Dr. M. V. Nagarjuna. Seminar Overview 1. Basic Terminology ( Types of](https://reader034.fdocuments.net/reader034/viewer/2022051721/5a7b38d97f8b9a49588bbb9a/html5/thumbnails/72.jpg)
![Page 73: VENTILATOR WAVEFORM · PDF fileVENTILATOR WAVEFORM ANALYSIS By Dr M V Nagarjuna 1 Dr. M. V. Nagarjuna. Seminar Overview 1. Basic Terminology ( Types of](https://reader034.fdocuments.net/reader034/viewer/2022051721/5a7b38d97f8b9a49588bbb9a/html5/thumbnails/73.jpg)
Flow-Volume LoopFlow-Volume Loop
InspirationInspirationPIFR
Volume (ml)
VT
FRC
VT
E i ti PEFRExpiration
![Page 74: VENTILATOR WAVEFORM · PDF fileVENTILATOR WAVEFORM ANALYSIS By Dr M V Nagarjuna 1 Dr. M. V. Nagarjuna. Seminar Overview 1. Basic Terminology ( Types of](https://reader034.fdocuments.net/reader034/viewer/2022051721/5a7b38d97f8b9a49588bbb9a/html5/thumbnails/74.jpg)
Air TrappingAir TrappingAir TrappingAir Trapping
InspirationInspirationPIFR
Volume (ml)
VTDoes not returnDoes not return VTDoes not returnDoes not returnto baselineto baseline
E i ti PEFRExpiration
![Page 75: VENTILATOR WAVEFORM · PDF fileVENTILATOR WAVEFORM ANALYSIS By Dr M V Nagarjuna 1 Dr. M. V. Nagarjuna. Seminar Overview 1. Basic Terminology ( Types of](https://reader034.fdocuments.net/reader034/viewer/2022051721/5a7b38d97f8b9a49588bbb9a/html5/thumbnails/75.jpg)
Bronchodilator Response….. F-V loop
AFTER
3Normal Bronchospasm Relief
3 3
2
1
2
1
2
11
VLPS
.VT
1
V.
1
V.
1
2
1
2
1
22
3
2
3
2
3
![Page 76: VENTILATOR WAVEFORM · PDF fileVENTILATOR WAVEFORM ANALYSIS By Dr M V Nagarjuna 1 Dr. M. V. Nagarjuna. Seminar Overview 1. Basic Terminology ( Types of](https://reader034.fdocuments.net/reader034/viewer/2022051721/5a7b38d97f8b9a49588bbb9a/html5/thumbnails/76.jpg)
SUMMARY
Identify the correct waveforms to monitor
S d ti t th b d id Spend more time at the bedside
Never Ignore any ventilator alarm
Monitor P peak, P plat and expiratory limb of flow volume loop to diagnose changes in lung resistance or compliance.
Identify Dys synchrony early and correct the cause.
76