các dạng sóng trong thở máy
DESCRIPTION
Các dạng sóng trong thông khí nhân tạoTRANSCRIPT
The ABC’s of Smarter Breath
DeliveryP
ressu
re
A
C (PCV Only)
D (PS Only)B
Current “Standard” Breath Delivery Capabilities
� State-of-the-art gas delivery systems� proportional solenoids
� revolutionary new exhalation valve technologies
� Flexible breath delivery� flow triggering, volume ventilation, PCV and PS
� Advantages� current breath types are accepted and well
understood
� less education needed
New “Standard” Breath Delivery Strategies
� Improved flexibility of accepted breath types� broadened performance with pediatric and/or infant
capabilities
� new pressure support and PCV capabilities allowing titration and improved vent / patient synchrony
Pre
ssu
re
A
C (PCV Only)
D (PS Only)B
A
Work to Trigger
� Great strides have been made in recent years to decrease work to initiate breaths with flow triggering� new data comparing ventilator trigger performance
� Leaks can cause triggering problems� possible in infants, broncho - pleural fistulas, mask ventilation,
and cuff problems
� these leaks result in loss of PEEP and Autocycling
� Flow triggering and increasing flow sensitivity to a level above the leak will maintain PEEP, eliminate Autocycling, and maintain sensitivity
Effects Of Leaks With PEEP
� PEEP = 10 cmH20
� No leak - no Auto-cycling
40PCIRCcmH2O
INSP
L
min
EXP
PLOT SETUP
30
20
10
0
10
-20
80
60
40
20
0
20
-80
40
60
V.
0 4 8 12s2 6 10
UNFREEZE
40PCIRCcmH2O
INSP
L
min
EXP
PLOT SETUP
30
20
10
0
10
-20
80
60
40
20
0
20
-80
40
60
V.
0 4 8 12s2 6 10
UNFREEZE
Effects Of Leaks With PEEP
� Leak develops – Auto-cycling occurs
� Excessive ventilation and asynchrony results
Effects Of Leaks With PEEP
� If pressure sensitivity is lowered - loss of PEEP develops
40PCIRCcmH2O
INSP
L
min
EXP
PLOT SETUP
30
20
10
0
10
-20
80
60
40
20
0
20
-80
40
60
V.
0 4 8 12s2 6 10
UNFREEZE
Loss of PEEP
Flow Triggering With Leaks
� Triggering will not occur until leak flow rate + patient Inspiratory flow exceeds flow sensitivity setting
� Auto-cycling is eliminated, PEEP is maintained, and patient sensitivity is enhanced
40PCIRCcmH2O
INSP
L
min
EXP
PLOT SETUP
30
20
10
0
10
-20
80
60
40
20
0
20
-80
40
60
V.
0 4 8 12s2 6 10
UNFREEZE
Flow Triggering turned on here
740 and 840 Response Time Testing
� ALA / ATS conference in San Diego, April 1999 - Bob Kacmarek abstract presented publishing first comprehensive study comparing ventilator performance
� reported response time tests for 740, 840, Evita, Galileo, Bear 1000, and T-Bird
� looked at response time and negative pressure drop during CPAP, PS, and PCV
PTP (imposed)
Pressure
Time
Response Time or DTOT
PT
What is PT and DTOT in Kacmarek Study?
*
PTP(Imposed)
Pressure
Time
Response Time or DTOT
PT
Greater negative pressure or longer response time = Imposed WOB
*
Pressure Support and Pressure Control in New
Generation Mechanical VentilatorsFuinoY, Goddon S, Kratohvil J, Ritz R, Hess D, Kacmarek, RM, Anesthesia andRespiratory Care, Harvard Medical School, Massachusetts General Hospital, Boston
Am Rev Resp Crit Care Med, April 1999
Flow triggering was set as sensitive as possible without causing autocycling
Pressure Control 300 840 740 Evita 4 Galileo T-Bird
Pt (cm H20) 1.9 1.5 -- 4.4 5.8 4.1
DTOT 80 80 -- 110 160 130
Pressure Support 300 840 740 Evita 4 Galileo T-Bird
Pt (cm H20) 1.8 1.5 4.4 4.5 5.3 4.1
DTOT 80 80 90 110 150 150
Flow and Pressure Triggering During CPAP in New
Generation Mechanical VentilatorsFuinoY, Goddon S, Kratohvil J, Ritz R, Hess D, Kacmarek, RM, Anesthesia andRespiratory Care, Harvard Medical School, Massachusetts General Hospital, BostonAm Rev Resp Crit Care Med, April 1999
Flow or pressure triggering set as sensitive as possible without causing autocycling
Flow Triggering 300 840 Galileo Bear 1000
Pt (cm H20) 2.29 2.28 5.78 4.61
DTOT 240 127 212 253
Pressure Triggering 300 840 Galileo Bear 1000
Pt (cm H20) 3.44 3.07 5.91 5.50
DTOT 238 130 217 184
Without Adjustment of Pressure Rise
� Many ventilators are sensitive to changes in impedance� increasing resistance causes pressure to rise more quickly
� can result in discomfort, or premature termination of PS
40PCIRCcmH2O
INSP
L
min
EXP
PLOT SETUP
30
20
10
0
10
-20
80
60
40
20
0
20
-80
40
60
V.
0 4 8 12s2 6 10
UNFREEZE
RES = 5 RES = 20 RES = 50cmH20/L/SEC cmH20/L/SEC cmH20/L/SEC
Rise to Pressure Adjustment
� Applicable in all pressure breaths
� Tailors inspiratory rise in pressure ventilation to match patient demand or reach MAP goals
� Should allow rise to be tailored from slow to fast
40PCIRCcmH2O
INSP
L
min
EXP
PLOT SETUP
30
20
10
0
10
-20
80
60
40
20
0
20
-80
40
60
V.
0 4 8 12s2 6 10
UNFREEZE
Slow rise Moderate rise Fast rise
Optimal Rise to Pressure Adjustments
� Spontaneous breathing patients - easily set
with regard to patient comfort and synchrony
� titrate while watching patient at bedside
� Generally set by watching patient breathing
patterns
� if spontaneous flow demands are explosive - faster rise
� if spontaneous flow demands are relaxed - slower rise
Breathing During PCV
� Patient efforts during the inspiratory phase of PCV can result in fighting and pressure spikes
40PCIRCcmH2O
INSP
L
min
EXP
30
20
10
0
10
-20
80
60
40
20
0
20
-80
40
60
V.
0 4 8 12s2 6 10
Spontaneous Efforts Spontaneous Efforts
PCV W/O Active Valve PCV with Active Valve
Active Exhalation Valve
� During inspiration, the valve is closed with the force of the insp pressure setting
� Allows coughing or spontaneous breathing at upper pressure level by venting excess pressure and flow (PCV or Bi-Level)
40PCIRCcmH2O
INSP
L
min
EXP
30
20
10
0
10
-20
80
60
40
20
0
20
-80
40
60
V.
0 4 8 12s2 6 10
Spontaneous Efforts Spontaneous Efforts
PCV W/O Active Valve PCV with Active Valve
Expiratory Sensitivity
� Pressure support breaths terminate when patient flow decelerates to a selectable percentage of peak flow
40PCIRCcmH2O
INSP
L
min
EXP
30
20
10
0
10
-20
80
60
40
20
0
20
-80
40
60
V.
0 4 8 12s2 6 10
PS Termination Criteria (25%)
Expiratory Sensitivity
� Leaks can cause inability to terminate pressure support breaths, causing profound asynchrony
� I-times too long or too short can also cause asynchronous breathing
40PCIRCcmH2O
INSP
L
min
EXP
30
20
10
0
10
-20
80
60
4020
020
-80
40
60
V.
0 4 8 12s2 6 10
PS Termination Criteria (25%)
Leak rate = 35%
Expiratory Sensitivity
� ESENS allows adjustment of the termination criteria for pressure supported breaths� sets the percent of peak flow that cycles the pressure support breath into
exhalation� especially helpful to match the patient’s desired inspiratory time (with or
w/o leaks)� can improve synchrony between patient and ventilator
25% (Set)40% (Set)
35% (Leak Rate)
Flow
Setting Esens
ESENS 25%
1 2 3 4 5 6
SEC
120
120
V.
LPM
ESENS 35%
100%
50%
25%35%
Back-up timer stops the breath
automatically
Rise to Pressure and Esens
Adjustments
� Easily set with regard to patient comfort and synchrony� titrate while watching patient at bedside
� Set rate of rise first� this helps with comfort early in the breath and
determines peak flow
� Set Esens if longer or shorter inspiratory times are desired during PS
Disconnect Sensitivity
� Adjusts how the machine handles alarms associated with large leaks
� Neonatal patients with uncuffed Endotracheal tubes and some adult tracheostomy patients may have very large leaks.
� Dsens allows you to adjust the minimum amount of Tidal Volume that must return to the machine before it declares a circuit disconnect.
� Available under the more settings tab on the Vent.
Dsens
� When set to 20% - means 80% of volume must return to the machine � More sensitive to leaks
� When set to 95% - means only 5% of volume must return to machine� Less sensitive for leaks
� Can be turned off in NIV mode� Machine can still declare a disconnect, as machine
looks at� Volume� Flow� Pressure