Cannulae - Perfusion.com

Chapter 22 Cannulae
Cannulae
The various cannulae used in surgery are important to the perfusionist.
These cannulae link the perfusion circuit with the patient. The cannulae of the
perfusion circuit include the arterial, venous, antegrade cardioplegia and
retrograde cardioplegia. In addition, there are left ventricular vents, pulmonary
artery vents and aortic root vents. Features of the cannulae are discussed in
this section. These features should be considered when cannulae are chosen.
The arterial and venous cannulae often create controversy. The
perfusionist wants the largest possible cannula while the surgeon prefers to
place the smallest possible cannula. The perfusionist requires a certain size
cannula to achieve certain flows without exceeding pressure gradients. The
surgeon must limit the size of the cannula if surgical considerations make it
imperative.
Arterial Cannulae
The arterial cannula used is determined by evaluating the flow and
pressure drop charts. The pressure drop (the difference between the pressure
entering the cannula and that leaving) shows resistance. The greater the
pressure drop, the greater is the resistance. This is usually inversely related to
the size of the cannula. With higher pressure across the cannula, there is an
increase in jetting at the tip that can cause intimal damage to the aorta and
hemolysis. The accepted limit of pressure drop is 100 mmHg. This should not
ordinarily be exceeded. By examining the charts the manufacturer provides
with the cannula, determination of maximum flow can be made. The charts
found later in this chapter will list some of the common arterial cannulae used
and their maximum flows.
Venous Cannulae
Venous cannulae flows are by gravity drainage. The higher the
pressure drop, the greater is the resistance to flow. Therefore, the lower the
pressure drop, the better the flow is. The pressure drop is inversely related to
size. Generally, the larger the venous cannula, the lower the pressure drop, and
the better the flow is. The most common venous cannula used is the two stage
cannula. It has an open tip that is placed in the inferior vena cava (IVC), and
more proximal openings that will be located in the right atrium. This produces
only partial bypass and may require venting of the heart to prevent distention.
There are large single stage cannulae that may be placed in the right atrium.
These do not always drain as well as a two stage, but are sometimes used when
a two stage cannula will not go into the IVC. The other method of venous
cannulation is with two single stage cannulae. One is placed in the superior
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Chapter 22 The Manual of Clinical Perfusion
vena cava (SVC) and the other in the IVC. These are connected to a common
venous line with a Y-connector. This type of cannulation also causes the
effect of partial bypass as the two stage cannula does. That is some blood
manages to go around the cannulae, through the heart and to the lungs. When
the cannulae in the SVC and IVC have either a clamp or umbilical tape pulled
around them, all blood coming to the heart is diverted to the cannulae. This is
termed total bypass. This manner of venous cannulation is most often used in
valvular or congenital surgery. A venous cannulae chart will be listed later in
this chapter. This chart suggests the cannulae used with certain weight
categories.
Cardioplegia Cannulae
The other cannulae used during bypass are specific to certain
procedures. Retrograde cardioplegia is a popular technique of giving
cardioplegia. The cannula is placed into the coronary sinus through the right
atrium. The cannula has a balloon near its tip that when inflated prevents the
flow of the cardioplegia back into the right atrium. The flow is, instead, forced
backwards through the coronary veins, capillaries and arteries. The cannulae
are of two basic types: either automatic or manual balloon inflation. Selection
is surgeon preference.
Antegrade cardioplegia is given through a cannula in the aortic root
or directly into the coronary os. (When given directly into the os a coronary
perfusion cannula is used.) These cannulae come in various sizes and in different
configurations. Basically, they have short needle tips that are placed into the
aorta. Cardioplegia is then given into the root. The aortic valve and the aortic
cross clamp prevent flow in either direction and thus force the cardioplegia
into the coronary arteries. Some have an extra arm coming off the side to allow
a vent tubing to be connected and thus provide both functions in turn. The
sizes of these cannulae affect the pressure drop and thus the maximum flow.
Selection is surgeon preference.
Coronary perfusion cannulae come in different sizes and shapes. A
common design is the small hand held cannula with a soft tip that is placed
over the coronary os. Others have tips that engage the coronary os. These
cannulae are used when the aortic root is opened for a valve replacement.
Since the development of the retrograde cannula these cannulae are not often
used. Retrograde delivery is easier and may be done while the surgeon continues
to work.
Vents
The LV vents, PA vents and aortic root vents are the last of the cannulae
types to be discussed. These vents are available in many sizes and shapes.
The type of vent depends on the cannulation site. There are short metal tipped
needles that fit in the aortic root. There are long thin cannulae placed through
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Chapter 22 Cannulae
the right superior pulmonary vein, through the mitral valve and into the left
ventricle. There are short right angled cannulae that may be placed into the
apex of the left ventricle. There are cannulae placed in the main pulmonary
artery distal to the pulmonary valve. The selection of these cannulae depends
on the vent placement the surgeon prefers and the type cannula he prefers.
NOTE: Always use a one-way valve in pump tubing connected to a
vent to prevent accidental introduction of air into either the aorta or the left
ventricle.
The following is a chart of arterial cannulae, their pressure drops and
maximum flows. These values come from flow charts provided with the products.
The venous cannulae chart is one that lists the standard recommendations at
certain weights. The charts are general recommendations and more specific
information can be obtained from the manufacturers.
NOTE: On the arterial charts many cannulae reached the maximum
flow on the chart before reaching the 100mmHg pressure drop. In these
cases the maximum flow listed is actually less than its maximum flow that
could be achieved at the 100mmHg pressure drop.
ARTERIAL CANNULAE
model size(OD) flow ( L/min ) pressure drop
mmHg
Bard
Opti-Clear Aortic Arch 18 FR 4.75 100
Opti-Clear Aortic Arch 20 FR 6.25 100
Opti-Clear Aortic Arch 22 FR 7 70
Opti-Clear Aortic Arch 24 FR 7 50
Bio Medicus - Femoral
96530-015 15 FR 3 100
96530-017 17 FR 4 100
96530-019 19 FR 5.5 100
96530-021 21 FR 6.5 100
DLP - curved tip arterial
model 83020 20 FR 6.5 100
model 83022 22 FR 8 81
model 83024 24 FR 9 68
DLP - descending arch cannula
71321 21 FR 5 100
71324 24 FR 6 100
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Chapter 22 The Manual of Clinical Perfusion
ARTERIAL CANNULAE
model size(OD) flow ( L/min ) pressure drop
mmHg
Gish-Curved tip, wire reinforced, with vent plug
RA-1116 18FR 5.2 100
RA-1117 21FR 6 56
RA-1118 24FR 6 31
Gish-Straight tip with vented connector
NA-2116 18FR 5.2 100
NA-2117 21FR 6 56
NA-2118 24FR 6 31
Research Medical
ARL-2011-90-TA 20 FR 5.9 100
ARL-2211-90-TA 22 FR 6 60
ARL-2411-90-TA 24 FR 6 35
Research Medical - Femoral arterial cannulae
TF-A-020-25 20FR 3.3 100
TF-A-022-25 22FR 5.25 100
TF-A-024-25 24FR 6.2 100
TF-A-024-25-H 24FR 7 87
Sarns
High Flow Aortic Arch 3.8 mm 1.5 100
High Flow Aortic Arch 5.2 mm 3.5 100
High Flow Aortic Arch 6.5 mm 5.25 100
High Flow Aortic Arch 8.0 mm 8 60
Sorin
A211-30 3.0 mm 1.2 100
A211-38 3.8 mm 1.8 100
A211-45 4.5 mm 2.9 100
A211-52 5.2 mm 4.1 100
A211-65 6.5 mm 6.3 90
A211-80 8.0 mm 6.5 40
A211-95 9.5 mm 6.5 20
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Chapter 22 Cannulae
model size(OD) flow ( L/min ) pressure drop
mmHg
William Harvey - Bard Arterial
Type 1858 18 FR 4 100
Type 1858 20 FR 5.5 100
Type 1858 22 FR 6 85
Type 1858 24 FR 6 70
William Harvey - Bard Arterial
Type 1860 18 FR 4 100
Type 1860 20 FR 5 100
Type 1860 22 FR 6 85
Type 1860 24 FR 6 50
VENOUS CANNULAE
weight in kgs SVC/IVC Cannulae RA Cannula
in French size in French size
0-3 12 / 12 18
3-6 12 / 14 18
6-8 14 / 14 20
8-10 14 / 16 22
10-12 16 / 16 24
12-15 16 / 20 24
15-20 20 / 20 26
20-25 20 / 24 28
25-30 24 / 24 28
30-35 26 / 26 30
35-40 28 / 28 32
40-50 30 / 30 36
50-60 30 / 32 36
60-70 32 / 32 51
70-80 34 / 34 51
80-90 34 / 36 51
90-100 36 / 36 51
100-110 36 / 38 51
110-120 38 / 38 51
120-130 38 / 40 51
130-140 40 / 40 51
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Chapter 22 The Manual of Clinical Perfusion
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