A Better Bladder for ECMO Controls
Pump Flow as a Function of Inlet Pressure
Yehuda Tamari1,2*, Kerri Lee-sensiba1, and Shane King1
1
North Shore University Hosp., Manhasset, NY
2
Circulatory Technology Inc. Oyster Bay, NY
Supported by NIH NHLBI Grant # R44HL-46057
cirtec.com
The Roller Pump
The most popular pump
used for ECMO is the roller
pump. The RP is a positive Pull
displacement pump that is
insensitive to inlet or outlet
pressure.
The pump can generate:
• Pin –600 mmHg
• Pout > 2,000 mmHg
cirtec.com
Pin
Pout
Push
What does the Bladder do?
Patient
The Bladder protects the patient from the
excess negative pressure the pump can generate
and that can damage
the blood as well as
the cannulated blood
vessel.
cirtec.com
Pump
Silicone
Bladder
How does the Bladder/Bladder Box Work?
When inlet pressure to the pump falls below
ambient pressure, the silicone bladder empties.
A microswitch senses an empty bladder and
switches off the power to the pump.
When the bladder refills
the pump restarts.
Pump
Bladder
Box
Bladder
cirtec.com
Patient
Silicone Bladder/Bladder Box
Limitations
Flow Control
• Gravity Drainage
Dependent = Bladder
on Floor
• On - Off
cirtec.com
Flow Control
PATIENT
Gravity
Drainage
Silicone
Bladder
Additional
tubing length
Silicone Bladder + Bladder Box
Limitations
Long Tubing (Patient to Floor)
• Greater prime volume
• Larger foreign surface
• Blood resides in tubing for a longer time
(greater heat loss and greater
blood/surface interaction)
cirtec.com
Silicone Bladder + Bladder Box
Limitations
Poor Flow
Dynamics
Blood cells
Blood
Cells
Settle
settle
cirtec.com
Limitations of the Silicone Bladder,
Summary
1. Maximum flow is limited to the height of the
patient above the floor
2. On/Off control does not takes advantage of
computer controlled roller pumps
3. Poor flow dynamics - more prone to clotting.
4. Placement on the floor can be hazardous
5. Difficult to use when transporting a patient
cirtec.com
What to do?
cirtec.com
Develop a Better-Bladder System
that provides:
• VAVD for roller pumps that increases flow
• On/Off or Continuous flow control
• Flow pattern less conducive to cell settling
• Shorter tubing
• Need not be placed on the floor
cirtec.com
Control pump speed as a function of inlet pressure
Pressure Monitor
and Controller
Negative pressure
=
Gravity Drainage
cirtec.com
Patient
The Inlet Pressure of a Roller Pump is Pulsatile
Pull
Push
50
W/O -Bladder
(120RPM)
Pin (mmHg)
25
Pulsatile pressure at
pump inlet prevents
smooth pump control
0
-25
-50
-75
-100
0.0
0.4
0.8
Time (s)
cirtec.com
1.2
How the Better-BladderTM is Made
Tube
Form
Tube
cirtec.com
Balloon + Housing = BB
+
=
The Better-Bladder
• Senses Pressure
• Provides Compliance
Pressure
port
Air
Blood
cirtec.com
Functional Tests: Experimental Setup
INLET PRESSURE
INDIRECT
-2 0 0
mmHg
INLET PRESSURE
DIRECT
-2 0 0
mmHg
cirtec.com
Reservoir
DIGITAL
COMPUTER
DATA AQUISATION
DATA ANALYSIS
PUMP SPEED CONTROL
mmHg
Pinlet Pressure (mmHg)
-30
BB Provides a High Fidelity Pressure Signal
BB
-50
-70
Direct
Avg. Pin= -100mmHg
-90
-110
-130
0.20
0.40
0.60
0.80
1.00
Time (sec)
cirtec.com
1.20
1.40
1.60
The Inlet Pressure of a Roller Pump is Pulsatile
Pull
Push
50
W/O -Bladder
(120RPM)
Pin (mmHg)
25
Pulsatile pressure at
pump inlet prevents
smooth pump control
0
-25
-50
-75
-100
0.0
0.4
0.8
Time (s)
cirtec.com
1.2
Roller Pump + BB
Inlet Pulse Pressure is Dampened
50
W/O -Bladder
(120RPM)
0
-25
-50
0
-25
-50
-75
-75
-100
-100
0.0
0.4
0.8
Time (s)
cirtec.com
With Better-Bladder
(120RPM)
25
Pin (mmHg)
25
Pin (mmHg)
50
1.2
0.0
0.4
0.8
Time (s)
1.2
Pump Control with the
Better-Bladder:
Inlet pressure signal
controls pump speed:
• On/Off
or
• Continuos (e.g. CAPS)
cirtec.com
Pressure Monitor
and/or
Pump Controller
Patient
Negative pressure
=
Gravity Drainage Better
Bladder
Better Flow Dynamics
Silicone Bladder
Better-BladderTM
Blood cells
wash through
Blood cells settle
cirtec.com
The BB Allows Increased Flow
Flow = ∆P/Resistance
Pressure Monitor
Patient
The older bladder collapsed
and/or
at ambient pressure. The BB Pump Controller
collapses at the negative
Negative pressure
pressure set by the user.
=
Blood can be actively pulled Gravity Drainage Better
Bladder
from the patient.
No need to raise the bed or
drop the bladder to the
floor.
cirtec.com
High Pressure Tests of Balloon
• Housing side is open to atmosphere
• 1500 mmHg applied to blood side
• Balloon expands to housing
• Housing supports thin section
Water
cirtec.com
20
25
30
15
35
10
40
5
45
psi
0
Ma
de
in
50
U.S
.A.
t#
P ar
G
CC
VPR
Internal Pressure (mmHg)
The BB W ithstands Large Internal Pressures
2000
1600
1200
800
Repressurized
400
0
0
48
96
144
Time (hrs)
cirtec.com
192
240
The BB Requires Shorter Tubing
PATIENT
Gravity
Drainage
Silicone
Bladder
Additional
tubing length
cirtec.com
Pressure Monitor
and/or
Pump Controller
Patient
Negative pressure
=
Gravity Drainage Better
Bladder
The Better-Bladder Provides:
• “Adjustable” gravity
drainage - VAVD
• Flow less conducive to
cell settling
• On/off or continuous
flow control (e.g.
CAPS system)
• Shorter circuit tubing
cirtec.com
Pressure Monitor
and/or
Pump Controller
Patient
Negative pressure
=
Gravity Drainage Better
Bladder
The Better-Bladder Provides
Shorter Tubing
• Lower prime volume
• Reduced foreign surface
• Blood resides in tubing for a shorter time
(lowers heat loss and blood/surface interaction)
cirtec.com
510(k) Number K98-1284
Device Name Better-BladderTM
http://www.accessdata.fda.gov/scripts/cdrh/cfdocs/cfPMN/pmn.cfm
Indications for Use – The Better-BladderTM is a device
that isolates pressure transducers form blood contact when
measurements of blood pressure in extracorporeal circuits
are made during short and long term procedures. The
pressure signal can be used to control pump speed. It is
also used as an inline reservoir to provide compliance in
the circuit during short and long term term procedures.
cirtec.com
To Bladder or not to Bladder?
Yehuda Tamari
Circulatory Technology Inc. Oyster Bay, NY
cirtec.com
Why use a Bladder for ECMO?
O2
Venous
Cannula
cirtec.com
Bladder
Arterial
Cannula
Computerized Roller Pumps
Blood flow is controlled as a function
pump inlet pressure.
Jostra
When inlet pressure drops below a settable
pressure the pump slows down or stops.
When inlet pressure increases above the set
point, pump flow returns to its set value.
Stockert
cirtec.com
Recent comments/questions from the ECLS-Net
•
“Is anyone removing or considering removing the bladder out of
their ECMO circuit that uses roller pumps?”
•
“We have PVC tubing in place of the bladder and it has worked
very well.”
•
“We have a collapsible Silastic bridge.”
No reasons were given for eliminating the bladder.
Cost? Complexity? reliability?
There were no mentions of using a bladder with centrifugal pumps.
cirtec.com
When making changes to a circuit
Practice Caution
•
What follows are results of some tests that we conducted with
and without a bladder under ECMO settings.
•
Serve as an outline for the type of tests that should be
conducted prior to removing or replacing the bladder.
cirtec.com
Pump flow is controlled as a function of inlet pressure
Should we pump
with a bladder
or
without a bladder
Pressure Monitor
and/or
Pump Controller
Patient
Negative pressure
=
Gravity Drainage Better
Bladder
cirtec.com
Pressure Monitor
and Controller
Negative pressure
=
Gravity Drainage
Patient
Pump flow is controlled as a function of inlet pressure
Compliance can be provided by
The Silicone Bladder
The Better Bladder
Pressure Monitor
and Controller
Patient
Pressure Monitor
and/or
Pump Controller
Patient
Negative pressure
=
Gravity Drainage Better
Pump
Bladder
Box
Bladder
cirtec.com
Bladder
Experimental Setup
Pump Controlled by Venous Line Pressure
Pressure
Cannula
Clamp
Sample rate- Data Acquisition
Measure pressure at:
1000/sec
Bladder
Controller set to stop flow
at Pin = -30mmHg
Reduce venous flow below
pump flow and record the
pressures
Cannula tip
Pump inlet
Control Pump flow
cirtec.com
"Patient"
venous
side
"Patient"
Arterial
side
"LV"
ECMO
Roller
Pump
Pump Controlled by the Instantaneous Inlet Pressure:
w/o a Bladder Results in Erratic Pump Flow
600
150
500
100
Pump Flow (ml/min)
Pump inlet (mmHg)
Pavg 0.05sec
[email protected]
125
75
50
25
0
400
300
Pump setting
Patient Flow
Pump flow w/o Bladder
200
-25
100
-50
8
cirtec.com
9
10
Time (s)
11
12
8
10
12
Time (s)
14
16
Pump Controlled by the Instantaneous Inlet Pressure:
Electronic Pressure Averaging
Pump inlet (mmHg)
150
50
-50
[email protected]
[email protected]
-150
Avg 1.5sec, W/O Bladder
-250
10
cirtec.com
11
12
13
14
Time (s)
15
16
Pump Controlled by
Electronically Averaged Inlet Pressure
Pump inlet (mmHg)
150
50
-50
[email protected]
-150
P Lo=-30mmHg
Qpump=500ml/min, Qpt.=400ml/min
W/O Bladder
-250
-350
0
cirtec.com
4
8
12
Time (s)
16
20
24
Pump Controlled by
Electronically Averaged Inlet Pressure
Pump inlet (mmHg)
150
50
-50
[email protected]
[email protected]
P Lo=-30mmHg
-150
Qpump = 500 ml/min,
Qpt. = 400 ml/min
Avg 1.5sec,
W/O Bladder
-250
-350
0
cirtec.com
4
8
12
16
Time (s)
20
24
Pump Controlled by Electronically Averaged Inlet Pressure
Pump inlet (mmHg)
w/o a Bladder
100
50
0
-50
-100
-150
-200
-250
-300
-350
16.4
P inst.
[email protected]
P Lo-30mmHg
16.8
17.2
17.6
18.0
Time (sec)
cirtec.com
18.4
18.8
19.2
19.6
The BB at the
Pump Inlet
Provides
compliance
and reduces
pressure
pulsation.
cirtec.com
Pressure Monitor
and/or
Pump Controller
Patient
Negative pressure
=
Gravity Drainage Better
Bladder
Roller Pump with a Bladder at its Inlet
Pump inlet (mmHg)
150
100
50
0
P inst No BB
P inst.+ BB
[email protected]+BB
-50
-100
-150
10.5
11.0
11.5
Tim e (s)
cirtec.com
12.0
12.5
Bladders Absorb the Pressure Fluctuations of the Roller Pump
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Pump inlet (mmHg)
Pump Controlled by Electronically Averaged Inlet Pressure
With a Bladder
50
-50
W/O Bladder
With Bladder
P Lo -30mmHg
-150
Qpump=500 ml/min
Qpt.=400ml/min
Avg 1.5sec
-250
-350
1.0
2.0
3.0
4.0
5.0
6.0
Time (sec)
cirtec.com
7.0
8.0
9.0
10.0 11.0
High Negative Pump Inlet Pressure is also Seen at the Tip
of the Venous Cannula
Pressure (mmHg)
150
50
-50
-150
Qpump = 750 ml/min
Abrupt Venous Flow Cessation
-250
Avg 0.05sec
-350
NO BB Pin
NO BB Pcan
-450
27
cirtec.com
28
29
30
BB Pin
BB Pcan
31
32
Time (s)
33
34
35
200
160
120
80
40
0
-40
-80
-120
-160
-200
Pump Set = 600ml/min
Patient = 410ml/min
P instantaneous
0
cirtec.com
5
10
15
20
Time (s)
500
450
400
350
300
250
200
150
100
50
0
P w/o BB
Flow w/o BB
25
30
35
Flow (ml/min)
P (mmHg)
Pump Controlled by the Instantaneous Inlet Pressure:
Results in Erratic Pump Flow
200
160
500
450
120
80
40
0
400
350
300
250
-40
-80
-120
200
150
100
Pump Set = 600ml/min
Patient = 410ml/min
P instantaneous
-160
-200
0
cirtec.com
5
10
15
20
Time (s)
P w/o BB
P + BB
Flow w/o BB
Flow +BB
25
30
50
0
35
Flow (ml/min)
P (mmHg)
Pump Controlled by the Instantaneous Inlet Pressure
Minimum Pressure (mmHg)
Maximum Suction due to Abrupt Stoppage of Venous Flow.
Using the Jostra roller pump with and w/o a bladder
cirtec.com
0
200
Pump Flow (ml/min)
300
-100
-200
-300
-400
-500
No BB
+BB
500
Are Bladders Required
When Centrifugal Pump are Used for ECMO?
Effects of a bladder placed at the pump inlet on:
• the maximum negative pressure at pump inlet
due to abrupt stoppage of venous flow.
• the pump outlet pressure due to abrupt stoppage
of venous flow.
• the air handling of a CP.
cirtec.com
"Patient"
arterial
side
Experimental Setup: CP
Tubing
Clamp
"Patient"
venous
side
Data Acquisition
Measure pressure at:
C o n tr o l
P r essu r e
Bladder
Clamp
M icr o P o r o u s
M em b. O xy.
Clamp
Centrifugal
pump
cirtec.com
O x y g e n a to r
P ressu re
M
P
M
O
Inlet Pressure to a CP - Abrupt blockage of Venous Flow
Pressure drops faster and lower w/o a bladder
100
CP
Pvenous w/o BB
Pvenous + BB
0
P (mmHg)
Bladder
V en o u s
L in e
P ressu re
-100
-200
-300
Flow = 2.5 LPM
Pump = 3700RPM
-400
-500
9.4
9.6
9.8
10.0
Time (sec)
cirtec.com
10.2
10.4
Inlet Pressure to a CP - Abrupt Blockage of Venous Flow
Pressure drops faster and lower w/o a bladder
50
CP
Pvenousw w/o BB
Pvenous with BB
-50
P (mmHg)
Bladder
V en o u s
L in e
P ressu re
Flow = 5.5 LPM
Pump = 3000RPM
-150
-250
-350
-450
-550
1.4
cirtec.com
1.6
1.8
2.0
Time (sec)
2.2
2.4
Pressure at Oxygenator can Become NEGATIVE
Bladder
M
P
M
O
CP
P (mmHg)
A rt. L in e
P ressu re
300
250
200
150
100
50
0
-50
-100
-150
Poxy w/o BB
Poxy with BB
Flow = 2.5 LPM
Pump = 3700RPM
9.4
9.6
9.8
10.0
Time (sec)
cirtec.com
10.2
10.4
Abrupt stoppage of Venous Flow can Cause the Pressure
at Oxygenator to go NEGATIVE
Bladder
M
P
M
O
CP
P (mmHg)
A rt. L in e
P ressu re
300
250
200
150
100
50
0
-50
-100
-150
Poxy w/o BB
Poxy with BB
Flow = 5.5 LPM
Pump = 3000RPM
1.4
1.6
1.8
2.0
2.2
Time (sec)
cirtec.com
2.4
2.6
Abrupt stoppage of Venous Flow can Cause the Pressure
at Oxygenator can Become NEGATIVE
When pressure on blood side of a MPMO falls below the
gas pressure then there is a significant possibility that gas
will flow across the porous membrane into the blood side
of the oxygenator and into the arterial line.
Blood Side
Pblood
<
Gas Side
M icro P o r o u s M e m . O x y
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Pgas
Air handling of roller pumps
Heat
Exchanger
A
B
RP
cirtec.com
Bubble Counter
Air handling of roller pumps
Heat
Exchanger
A
B
RP
cirtec.com
Bubble Counter
Air handling of roller pumps
Heat
Exchanger
A
B
RP
cirtec.com
Bubble Counter
Air handling of roller pumps
Heat
Exchanger
A
B
RP
cirtec.com
Bubble Counter
Air handling of roller pumps
Heat
Exchanger
A
B
RP
cirtec.com
Bubble Counter
Air handling of roller pumps
Heat
Exchanger
A
B
RP
cirtec.com
Bubble Counter
Air handling of roller pumps
Heat
Exchanger
A
B
CP
cirtec.com
Bubble Counter
Air handling of roller pumps
Heat
Exchanger
A
B
CP
cirtec.com
Bubble Counter
Air handling of roller pumps
Heat
Exchanger
A
B
CP
cirtec.com
Bubble Counter
Air handling of centrifugal pumps
Heat
Exchanger
A
B
CP
cirtec.com
Bubble Counter
Air handling of centrifugal pumps
Heat
Exchanger
A
B
CP
cirtec.com
Bubble Counter
Air handling of centrifugal pumps
Heat
Exchanger
A
B
CP
cirtec.com
Bubble Counter
Air handling of centrifugal pumps
Heat
Exchanger
A
B
CP
cirtec.com
Bubble Counter
Air handling of centrifugal pumps
Heat
Exchanger
A
B
CP
cirtec.com
Bubble Counter
Air handling of centrifugal pumps
Heat
Exchanger
A
B
CP
cirtec.com
Bubble Counter
Air handling of centrifugal pumps
Heat
Exchanger
A
B
CP
cirtec.com
Bubble Counter
Air handling of centrifugal pumps
Heat
Exchanger
A
B
CP
cirtec.com
Bubble Counter
Air handling of centrifugal pumps
Heat
Exchanger
A
B
CP
cirtec.com
Bubble Counter
Air handling of centrifugal pumps
Heat
Exchanger
A
B
CP
cirtec.com
Bubble Counter
??
Bladders Trap Air
Bladders trap
large bubbles
Large
Bubbles
CP
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Micro
Bubbles
CP
Air handling of centrifugal pumps – Experimental setup
"Patient"
Air in
(1, 5, 8cc)
Outlet
Pressure
Vacuum
-400mmHg
500
MP
ml/min
Flow meter Oxy.Micorporous
memb oxyg
300
Bladder
mmHg
Large
Bubbles
Air
removal
cirtec.com
B
Heat
Exchanger
A
Clamp
Centrifugal
Pump
PRV
Small
Bubbles
Gas port
Closed
000
Bubble
Counter
(15u to 95u)
Bubble counted here
15 u Bubble count
cirtec.com
Centrifugal Pump for ECMO – The Air Study
800
700 CP Flow = 500ml/min
600 Air in = 3cc
500 Water
W/O a bladder
400
With a bladder
300
200
100
0
2000
2500
3000
3500
Pump Speed (RPM)
Centrifugal Pump for ECMO – The Air Study
(Blood Flow = 500 ml/min, 1 cc Air)
15u Bubbles Count
300
250
200
150
100
268
Heat Exchanger Inlet
Heat Exchanger Outlet
Flow = 500mlmin
Poutlet = 300mmHg
Air in inlet = 1cc
*Bubbles >100u were not counted
50
0
0
2
2
0
With BB
w/o BB
Roller Pump
cirtec.com
1
159
0
With BB
w/o BB
Centrifugal Pump
Bladders Add a Safety to Centrifugal Pumps Used for ECMO
• Provide compliance that reduces rate of change in
•
•
•
pressure and allow better pump control as a function of
venous line pressure.
Reduce the maximum negative pressure due to abrupt
stoppage of venous flow.
Eliminate negative pressure at the outlet of the pump
due to abrupt stoppage of venous flow.
Reduce microbubbles generation by the pump.
cirtec.com
To Bladder or not to Bladder? - Costs Considerations
Avg. cost for a neonatal ECMO ~ $100,000/wk.
Peds, post-op cardiac cases, adults, etc. are much higher.
Avg. Cost of ECMO pt. - entire hospital stay …….... $300,000
West Coast hospital
Average hospital cost during ECMO ………………... $195,860
Avg. Cost of ECMO pt. - entire hospital stay ………. $427,027
The bladder cost is about 0.1% of the total cost.
cirtec.com
To Bladder or not to Bladder? - Costs Considerations
Costs of post hospital care are also significant.
52% ECMO infant survivors have abnormal neuro-imaging
(Bulas &Glass Semin Perinat 29:58-65 2005)
12 % have severe mental handicap (FSIQ < 70) and 37%
are at risk for school failure.
(Rais-Bahrami et. al. Clin Pediatr: 39(3):145-52, 2000)
The bladder cost is less then 0.1% of the total cost.
cirtec.com
To Bladder or not to Bladder?
Costs Considerations
Since the bladder’s cost less then 1/1000 of the total cost
of ECMO,
If the bladder prevents a single patient from being
exposed to microbubbles or vessel damage due to excess
negative pressure at the cannula
Then its cost has been justified for hundreds of patients.
cirtec.com
Bladders placed at the pump inlet
• Dramatically reduce the maximum negative
•
•
•
•
pressure at the pump inlet and at the tip of the
venous cannula. Reduced vessel damage?
Reduce pressure pulsations at the pump inlet and at
the tip of the venous cannula. More Physiological?
Provide smoother pump operation. Less clotting?
Cleared by the FDA for that purpose.
Standard of care - reduce liability.
cirtec.com
To change a circuit/procedure the user must answer
to the affirmative the following :
•
•
•
•
•
cirtec.com
Is it as safe or safer then current practice?
Is it standard of care?
Is it supported by publications in a peer reviewed
journal?
Could it introduce other problems?
Do we have the team with the educational background to
properly evaluate the effects of the change?
Blood damage: The Centrifugal Pump
Depends on shear stress (i.e.
RPM) and exposure time.
The greater the shear and the
longer the exposure time the
greater the damage.
cirtec.com
Pinlet
Poutlet
CP’s Flow Characteristics*
745
Revolution
dP (mmHg)
740
735
730
25 mmHg
725
720
715
0.0
*Courtesy
cirtec.com of Cobe Lab.
1.0
2.0
3.0
Flow (LPM)
4.0
5.0
Blood damage: The Centrifugal Pump
Since the line pressure in the adult and neonate
circuits are similar.
And, since the pump speed varies little with flow
but is mostly dependent on line pressure.
Then, we can conclude that the shear stress within
the pump for neonates approximates that for
adults.
Any difference in blood damage between adults
and neonates flow conditions is due to differences
in exposure times to that shear.
cirtec.com
Blood damage by CPs
Pinlet
Poutlet
Patient
Adult
Neonate
Pout Flow Time
mmHg
LPM
sec
250
250
5.0
0.5
0.6
6.0
For a CP with a prime volume of 50 ml, the
residence time at 5.0 LPM is 0.6 sec.
At 0.5 LPM it is 10 times longer or 6.0 sec.
cirtec.com
The finger damage test
=
Exposure to 0.6 sec
cirtec.com
Little or no
damage.
The finger damage test
=
Major damage
Exposure to 6.0 sec
cirtec.com
Serotonin released from sheared platelets
relates to exposure time*
Serotonin Release (%)
70%
60%
50%
40%
Shear Stress = 150 (Dynes/cm2)
30%
20%
10%
0%
0
100
200
300
400
Exposure Time (sec)
cirtec.comet.al. Trans. ASAIO 21:35, ‘75
*Brown
500
600
Blood damage: Comparing RP to CP
Hemolysis:
Shear stress (i.e. RPM)
Exposure time.
Pinlet
Poutlet
RPM = f (pressure)
Exposure time = f (1/Flow)
Shear x Time ≅ Pressure x (1/Flow)
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The effects of pressure and flow on hemolysis caused by BioMedicus centrifugal pumps and roller pumps. Guidelines for
choosing a blood pump.
Tamari Y, Lee-Sensiba K, Leonard EF, Parnell V, Tortolani
AJ. J Thorac Cardiovasc Surg. 1993 Dec;106(6):997-1007.
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IH ratio (RP/CP)
6
5
4
3
2
Guidelines for choosing a
blood pump: RP v. CP
Occlusive RP v CP
Regression line
NonOcclusive RP
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P a lde r, Eng le ha r, Ig o , Kre s s , a nd
1
0
0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8 2.0
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Pressure/Flow (mmHg/(ml/min))
Guidelines for choosing a
blood pump: RP v. CP
Hemolysis for the Biopump is higher than that
of the roller pump when the ratio of the
pressure divided by the flow is less than 0.35
When:
Pressure(mmHg)/Flow(ml/min) > 0.35
use the roller pump.
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Flow (ml/min)
Hemolysis – Choosing between RP and CP
1200
1000
800
600
400
200
0
Use CP
Use RP
0
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50 100 150 200 250 300 350
Pressure (mmHg)
Hemolysis – Choosing between RP and CP
It is important to note that in later studies,
when the RP was set nonocclusively, the
RP was always less hemolytic than the CP*.
*A dynamic method for setting roller pumps nonocclusively
reduces hemolysis and predicts retrograde flow.
Tamari Y, Lee-Sensiba K, Leonard EF, Tortolani AJ. ASAIO
J. 1997 Jan-Feb;43(1):39-52.
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Questions?
[email protected]
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