ventilator graphics in picu part 1
TRANSCRIPT
vENTILATORGRAPHICS
IN PICU….. Optimizing
Ventilation
Dr Vishram BucheCentral India’s CHILD hospital & Research institute, NAGPUR
Part 1……..
OBJECTIVES……OBJECTIVES……
How to identify different WAVES and LOOPS ? and thereby mode of vent ?
How it helps to monitor Ventilator parameters ?
How it helps to adjust vent settings/ parameters ?
How it helps to manage disease pattern ?
How it helps to identify / quantify the problem?
GOAL …….
1. Reduce WOB, Optimize ventilation & Improve patient comfort 2. Maximize therapeutic effect 3. Minimize ventilator associated lung injury
Measured
FlowPressureTime
Calculated
VolumeComplianceResistanceWOBAuto-Peep
PARAMETERS…………
How it is measured….?
Pressure differential Pneumotachometer
Hot wire Anemometer
Where it is measured….?
At ETT
Inside ventilator
MEASUREMENT OF FLOW…….
MEASUREMENT OF PRESSURE ……….MEASUREMENT OF PRESSURE ……….
At ETT
In esophagus
Inside Ventilator
Where it is measured…. ?
Inside the Pt’s airway ……..???
A. Trigger …….What causes the breath to begin?
B. Limit ……….What regulates gas flow during the breath?
C. Cycle ……… What causes the breath to end?
D. Baseline…… End exp Pressure (FRC level)
Basic phase variables…………..
A
B C
DD
Pressure-time
Flow-time
Volume-time
Pressure- flow
Flow- volume Flow- pressure…???
Scalars……
Loops……...
The Pulmonary graphics display in two formats………
Basic shapes….. Square, Sine and Exponential rise or decay
Spontaneous Breaths…. Mechanical Breaths….
Time
volume
Pressure
FLOW
Volume ModesPressure Modes
Pre
ssur
eF
low
Vol
ume
Time
Volume ModesPressure Modes
Pre
ssur
eF
low
Vol
ume
Time
Breath type Triggering I:E ratio PIP/Plateau pressure MAP PEEP
Active exhalation Auto-PEEP Airway obstruction Bronchodilator response Compliance/Raw Asynchrony
Pressure waveform used to access…… Pressure waveform used to access……
Pressure mode volume mode
I:E ratio Breath type Inspiratory flow rate
(set/PIF) Rise time
Auto-PEEP Airway obstruction I-Time adjustment Active exhalation Bronchodilator response Asynchrony
Flow waveform used to access………
F
time
Time
Pressure mode Volume mode
Volume waveform used to access………
I:E Tidal volume Auto-PEEP Active exhalation Air-leak Airway resistance Asynchrony
Loops…….Loops…….
Pressure-Volume Loops
Flow-Volume Loops
Flow-pressure loops ???
inspiration
expiration
15 305
Volu
me
Pressure
PIPVolume
Inspiration
Expiration
Flow
PIFR
PEFR
FRC
VT
P-V loop F-V loop
Breath typeTidal volumePIPI & E flow rate
ResistanceComplianceAsynchrony
Air leakssecretions
Graphic analysis to optimize ventilation…..
Tidal volumes too low Inspiratory flow too slow Inspiratory time too long Trigger sensitivity too negative Increased resistance of ETT AutoPEEP Pain, discomfort and agitation
Common causes of Pt-vent asynchrony……………..
PIP
P plat
PIP
P plat
Pressure wave…………Effect of ed air way resistance/compliance
Effect of Auto-PEEP....
While performing an expiratory hold maneuver, trapped air will cause the waveform to rise above the baseline.
Air-trapping…..Auto-PEEP
Pressure wave…………
Tachypnoea ....earliest sign Appearance of s/o resp distress With present vent setting like Accessory muscles usage, intercostal retractions etc Rising PaCO2 is a late sign
Clinical signs of AUTOPEEP…………
I Rise time……. How do I adjust it?I Rise time……. How do I adjust it?
P
F
time
time
0
0
Too fast time
Bart simpson spike
Rise time “overshoots”Desired pressure
I Rise time…….fastI Rise time…….fast
“SPIKE ” on graphics IRT is set at 0.05 seconds
I Rise time…….fastI Rise time…….fast
Increase IRT…………….. …..waveform will return to normal
I Rise time…….fastI Rise time…….fast
P
0
I Rise time…….slowI Rise time…….slow
Inspiratory rise time is directly Proportional to inspiratory flow to get proportional Vt is deliverd
PRESSURE waveform………
Time
PIP
PEEP
Ti
Pre
ssur
e
TE
To Increase Mean Airway Pressure….
1. Increase flow
2. Increase peak pressure
3. Lengthen inspiratory time
4. Increase PEEP
5. Increase Rate
MAP…..
PEF
PIF
TV
In severe insp airway obstruction, the wave form can become a plateau. This can become a problem in flow-cycled modes, such as Pressure Support. (asynchrony, W.O.B.)
Flow waveform……Effects of airway resistance/ obstruction
Effects of ed expiratory resistanceFlow waveform……
Air Trapping……… AUTO PEEPAir Trapping……… AUTO PEEP
Inspiration
Expiration
NormalPatient
Time
Flo
w (
L/m
in)
Air-trappingAUTO PEEP
Flow waveform……
Response to Bronchodilator….Response to Bronchodilator….Before
Time
Flo
w
PEFR
After
Long TE
Improved PEFR
Normal TE
To assess response to bronchodilator therapy,…. 1. An increase in peak expiratory flow rate. 2. The expiratory curve should return to baseline sooner.
Flow waveform……
Bronchodilator Response….. F-V loopBronchodilator Response….. F-V loop
2
1
1
2
3
3
VLPS
.VT
Normal
AFTER
Bronchospasm Relief
2
1
1
2
3
3
V.
2
1
1
2
3
3
V.
Assessing Bronchodilator Therapy……
Optimizing Auto –PEEP……
1 2 3
Inspiratory flow pattern…… I –time synchrony
1 : short2 : Normal 3 : Prolonged
Asynchrony leads to……. Low tidal volume delivery Auto-PEEP
Flow waveform……
1 2 3 4 5 60
18 cc
Setting Appropriate I-Time ……….……to get desired V T = 25
PCV…. PIP= 20, Vt (achieved) = 18
Short I – time ……low Vt
volu
me
Time
1 2 3 4 5 6
Flo
w
Time
Setting Appropriate I-Time ……….
25 cc18 cc
Lost VT
1 2 3 4 5 6
1 2 3 4 5 60
Appropriate I – time ……good Vt
volu
me
Time
Flo
w
Inspiratory Cycle off %............................flow cycling
100%
75%
50%
30%25%
Adjusting I-time………
60%
time time
Inspiratory Cycle off %............................flow cycling
10%
time time
Exhalation “spike”
Inspiratory Cycle off %............................flow cycling
Secretions Or water in circuit
F
Flow time wave…….
Time
Exhaled vol taking longer time to reach baseline
VOLUME waveform………………..
Exhaled volume takes longer time to return to baseline……… damp or blocked expiratory filter/valve
Increased Airway resistance
Vol
ume
(ml)
Time (sec)
Air Leak
Air trapping / Air Leak…………Air trapping / Air Leak…………
Exhalation side of the waveform doesn’t return to baseline, it could be 1---- air-trapping (improperly set I-time, emphysema),2---- air leak (ET tube, vent circuit, chest tube, etc.) And can lead to auto-triggering
VOLUME waveform………………..
Air Leak……Air Leak……
VT
ml
30
-10
V
P
F
V
P-V loop
F-V loop
Volume waveform….
VOLUME waveform………………..
Air-trapping….. Resolved…..
NOT all Air-trapping ……… is Pathological……..
Air Trapping….. P-V loop and F-V loopAir Trapping….. P-V loop and F-V loop
•The expiratory portion of the loop doesn’t return to baseline. •This indicates a air trapping/or air leak.
Insp
Exp
Pressure
volu
me
Insp
Exp
Flow PIFR
PEFR
VT
Air trapping on Loops……
At 1st session of vent graphics class…… At 1st session of vent graphics class……
A DUCKY!
AHORSIE
NoA
DOGGIE
MYMOM-IN-LAW
BENDING OVER!
PCV… SIMV
A….Ineffective tidal volume in spontaneous breaths; B….Improved tidal volume during spontaneous breaths.
Volume waveform … trending..guides for weaning
Loops…….Loops…….
Pressure-Volume Loops
Flow-Volume Loops
Pressure-Volume Loops
Flow-Volume Loops
P-V loops……P-V loops……
Lung OverdistentionAirway ObstructionBronchodilator ResponseRespiratory Mechanics WOBFlow StarvationLeaksTriggering Effort
Spontaneous Breath………
Inspiration Expiration
0 20 40 602040-60
0.2
0.4
0.6
Pressure
cmH2O
VT
Clockwise
CPAP
Controlled Breath…….
Expiration
0 20 40 602040-60
0.2
LITERS
0.4
0.6
Paw
cmH2O
Inspiration
VT
Anticlockwise
PEEP
P-V loop and PEEP…..
Assisted Breath…………
Inspiration
Expiration
0 20 40 602040-60
0.2
LITERS
0.4
0.6
Paw
cmH2O
Assisted Breath
VT Clockwise to Counterclockwise
PEEP
Trigger deflection………WOB, T sensitivity
P-V Loops….in Airway ResistanceP-V Loops….in Airway Resistance
“hys
teresis
”exp.
resis
tance
insp.
resis
tance
Insp resistance 1. ETT size too small, 2. tube kinked, 3. patient biting tube, etc.
exp resistance: 1. secretions, 2. bronchospasm, etc.
Compliance……….Compliance……….
Volu
me
Pressure
↓compliance… Loops moves down (angle becomes < 40)…….RDS (HMD), Pleural effusion, consolidation ….moves up (>45) …….. ↑ compliance……. Surfactant therapy
Lung Compliance Changing in P-V Loop (pressure mode)………….Lung Compliance Changing in P-V Loop (pressure mode)………….
Volume
Preset PIP
VT
leve
ls
Pressure
RDS…lung
1.With surfactant2. Emphysematous L
Constant PIP……… variable VT
Lung Compliance Changes and the P-V Loop…. (Volume mode)
Lung Compliance Changes and the P-V Loop…. (Volume mode)
Volume
PIP levels
Preset VT
Pressure
↑C C ↓C
Constant VT………. Variable Pressure
Overdistension……….Overdistension……….
Vol
ume
Pressure
NormalAbnormal
With little or no change in VT
Pressure rises
C20
C dyne
If C20/Cdyne ………..< 1……… Overdistension
PEEP
volu
me
PIP4 6 17 19
P =13
P=13
TV = 12.3 mlCL = 0.95 ml/cm H20
TV = 8.7 mlCL = 0.67 ml/cm H20
Optimizing PEEP…………….
Lowerinflectionpoint
Upperinflectionpoint
Air Trapping….. P-V loop and F-V loopAir Trapping….. P-V loop and F-V loop
•The expiratory portion of the loop doesn’t return to baseline. •This indicates a air trapping/or air leak.
Insp
Exp
Pressure
volu
me
Insp
Exp
Flow PIFR
PEFR
VT
Air Leak…………Air Leak…………
VT
ml
30
-10
V
P
F
V
P-V loop
F-V loop
Volume waveform….
Flow –Volume Loops……
Flow volume loop can be used to assess……Flow volume loop can be used to assess……
Air trapping Airway Obstruction Airway Resistance Bronchodilator Response Insp/Exp Flow Leaks Water or Secretion accumulation Flow Starvation Asynchrony
Flow-Volume Loop……….Flow-Volume Loop……….
Volume (ml)
Inspiration
Expiration
Flow
(L /
min
)
PIFR
PEFR
FRC
VT
Pressure Mode
F-V loops…. variationsF-V loops…. variations
Volume (ml)
Inspiration
Expiration
Flow
(L /
min
)
PIFR
FRC
VT
↓PEFR
“Scooped out” pattern
Increased Airway Resistance……Increased Airway Resistance……
Air Leak…………Air Leak…………
VT
ml
30
-10
V
P
F
V
P-V loop
F-V loop
Volume waveform….
Volume (ml)
Inspiration
Expiration
Flow
(L /
min
)
PIFR
PEFR
FRC
VT
Airway Secretions ……….Water in the CircuitAirway Secretions ……….Water in the Circuit
Looking Trend Data……Looking Trend Data……
Accurate measurement requires a proximal flow sensor.
Compare waves and loops to previous ones after making adjustments, rather than interpreting them in isolation.
Clinical assessment at the bedside very important in the mechanically ventilated child.
Real time pulmonary graphics provide useful information about ventilator performance and interaction with child.
The future: closed loop control of ventilation, including FiO2and PEEP (autopilot of aeroplane)
Summary………………………..
Ref……. 1. Neonatal and Pediatric Pulmonary Graphics: Principles and Clinical Applications, with Bedside Guide
…….Steven M. Donn 2. Rapid Interpretation of Ventilator Waveforms (2ndEdition)….. by Jonathan B. Waugh, Vijay M. Deshpande, Melissa K. Brown and Robert Harwood.3. Ventilator Graphics.. by Scott Richey4. Ventilator Graphics..simplified approach
(2011, 1st edition) Dr Vishram Buche & associates
VENTILATOR GRAPHICS IS ANART OF VENTILATION IN TO SCIENCE OF VENTILATION
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