Note: Descriptions are shown in the official language in which they were submitted.
CA 02361604 2001-08-10
'' . K 62 P 1 WO
Mobile heart-lung machine
The invention relates to a mobile heart-lung machine
for maintaining circulation according to the preamble
of claim 1.
' For maintaining a person's circulation, anoxemic venous
blood is removed from the person by means of a heart-
lung machine with a cannula and fed by a blood pump to
io an oxygenator to avoid or eliminate a circulatory
arrest or lack of perfusion during an operation as the
result of an accident or some other organ failure. In
the oxygenator, which performs the function of an
artificial lung, the blood is enriched with oxygen and
COZ is removed. Subsequently, the oxygen-rich, arterial
blood is fed back to the patient's circulation through
a cannula after cleaning in an arterial filter. Heart-
lung machines of this type are used for stationary
applications in hospitals. Such a stationary heart-
lung machine is described for example in WO 99/59654
(CARDIOVENTION). It comprises an integrated oxygenator
and pump unit, arranged in the sterile area around the
patient, and a control console outside the sterile area
and connected to said unit via a connecting cable. The
control console has control devices and drives for the
pump and oxygenator.
DE 43 43 334 A1 discloses a heart-lung machine for
mobile use. It has a supporting structure, provided
3o with carrying handles at the front and back, with
standing feet protruding downward. For fixing the
component parts of the heart-lung machine,
corresponding fastening means are provided. In the
case of this machine, the functionally important
elements are arranged such that they are freely
accessible and are consequently not protected against
damage, which may impair serviceability during use. In
addition, the machine must always be carried by two
people.
CA 02361604 2001-08-10
K 62 P 1 WO
- 2 -
A mobile heart-lung machine is also disclosed by DE 197
02 098 Al. This comprises a loop for feeding blood to
an artery, a second loop for removing blood from a
- 5 vein, a venous reservoir, an oxygenator, a blood pump
y designed as a roller pump, and an oxygen di$penser in
~ the form of an oxygen concentrator connected on the
a drive side to the pump. The machine has a controller
for the oxygen concentrator and the delivery rate of
1o the pump and also connections for a decentralized
energy supply and/or for an electrical energy Store.
Although this heart-lung machine is also intended for
mobile use, it cannot normally be handled by one person
on account of its size and weight. Owing .to the
15 confined space in an ambulance, it is virtually
impossible to take this machine along on an emergency
call-out in a ready-to-operate state. The haste
required in emergency call-outs makes the long set-up
and preparation times disadvantageous. In addition,
2o after each time they are used, the aforementioned
heart-lung machines have to be newly set up and cleaned
in a complicated procedure before they are used again.
As a result, immediate re-use is not possible.
25 WO 97/16213 (BAXTER) already discloses a mobile heart-
lung machine in which the blood-circulating elements,
including the blood pump, heat exchanger and
oxygenator, are accommodated in an arrangement intended
for once-only use and the pump motor is accommodated in
3o a reusable drive unit. The arrangement intended for
once-only use is connected to the drive unit by a force
closure by means of a connecting part protruding high
up from said drive unit. Further connections exist
with the separate drive and automatic control units.
35 The connections for the respective tubes to the
arrangement are exposed and can be easily damaged or
interrupted, in particular during mobile use.
CA 02361604 2001-08-10
K s2 p 1 wo
- 3 -
It is therefore the object of the present invention to
provide a mobile heart-lung machine of the type stated
at the beginning which can be universally used and can
be handled reliably and easily.
s
This object is achieved by the subject-matter, of claim
1. The division into a module with elements which
circulate the blood, receive the biochemical and
physiological signals and implement the control signals
to ("disposable module") and a module with drive and
automatic control elements ("reusable module") permits
a rapid exchange of the module intended for once-only
use, containing the blood-circulating elements, after
use, so that the heart-lung machine can quickly be used
15 again. On account of the modularity, it is
additionally possible to produce the respective modules
in an already serviceable and compact form. This
ensures particularly high functional reliability in
use, since no complicated operating and setting-up
2o measures have to be carried out under the time pressure
existing during use. Furthermore, the grouping
together of the blood-circulating elements in a compact
module allows the tubular blood-circulating system
between the individual elements to be of a particularly
25 short length, as a result of which the filling volume
can be reduced, which is advantageous for the patient.
Moreover, the routing and nature of the blood channels
in this module can be precisely defined and designed to
provide favorable flow conditions, in order to reduce
3o the blood trauma as much as possible . In this respect
it is possible, for example, for commercially available
components such as the oxygenator, centrifugal pump
head, filter etc. to be connected by fixed blood
channels. The individual components of the disposable
3s module, designed as a cartridge, can be easily
exchanged and replaced by others if need be.
CA 02361604 2001-08-10
' - K 62 P 1 WO
- 4 -
The subclaims are directed at advantageous embodiments
of the invention.
According to the invention, the two modules can be
joined together in a simple way to form one unit, in
that they can be fitted one on top of the other and can
' be connected mechanically and electrically to each
_ other. The heart-lung machine is therefore easy to
handle in mobile applications and can be carried by one
1o person. This is also made possible by the blood pump
being a centrifugal pump. Roller pumps are usually
used as blood pumps . On account of their massive pump
element, they are heavy and require considerable energy
during operation. Centrifugal pumps, on the other
hand, are particularly economical in terms of energy.
In addition, they are distinguished by a suction action
on the basis of the negative pressure produced. As a
result, the blood is sucked in to the extent required
for supplying the patient, and according to the pumping
2o rate, if an adequate supply by the passive return flow
of blood alone cannot be ensured. This is important in
particular when they are used in an emergency, if the
cannulation of the patient has not been performed
optimally or the tubes cannot be optimally arranged on
account of outside circumstances.
According to the invention, the pump head through which
the blood flows and the pump drive of the blood pump
are respectively arranged in the corresponding modules.
3o With the modules joined together, the pump head and the
pump drive are connected to each other via a coupling.
Since the elements coming into contact with blood are
arranged in a single disposable module, designed as a
sterile-packed unit, the production costs of the module
intended for once-only use, and consequently the
operating costs of the mobile heart-lung machine, can
be kept low.
CA 02361604 2001-08-10
. K 62 P 1 WO
- 5 -
According to a preferred embodiment of the invention,
the connections between the individual blood-
circulating elements comprise flexible and/or rigid
tubes to optimize and standardize the hemodynamics and
to increase the internal rigidity. The blood-
circulating components of the extracorporeal circuit
and the tubes connecting them are fastened in the
module housing by means of retaining or fastening
devices. Such a system is more reliable than
1o straightforward plug-in tube connections and
contributes to the rigidity and better retention 4f the
individual elements in a disposable module.
It has proven to be expedient for at least some of the
blood-circulating elements to be formed in one piece
with the module, for example as an injection molding.
If the blood-circulating system or, for example, the
housings of other blood-circulating elements in the
module are an integral part of the disposable module,
2o the latter can be further reduced in size and produced
in an integrated form. It is also conceivable to make
the housing of the module with the blood-circulating
elements and the blood-circulating system in the form
of a cartridge into which commercially available blood-
circulating elements, such as the oxygenator, blood
pump, pump head of a centrifugal pump, arterial filter
or the like, can be fitted with the aid of fastening
devices. Oxygenators, pumps, filters or similar blood-
circulating elements with their own blood channels,
3o gas-supply lines or the like, specially designed for
use in the heart-lung machine according to the
invention, can also be fitted into the cartridge,
designed for example as an injection molding. This
allows even greater integration and compactness of the
disposable module to be achieved.
CA 02361604 2001-08-10
' . K 62 P 1 WO
- 6 -
To provide an optical check on the blood flow at any
time during the operation of the heart-lung machine,
the disposable module has a transparent housing.
It has proven to be advantageous for the elements
receiving the biochemical and physiological signals to
be sensors which sense, inter alia, blood pH, blood
pC02, blood p02, blood temperature, blood flow rate,
Fi02, gas temperature, gas flow rate, gas p02, gas pC02,
1o water temperature, rotational speed of the pump or the
current flow to the pump drive.
According to the invention, the sensors for sensing the
parameters, for indicating purposes and for being used
for acoustic, optical or acoustooptical warnings and
for processing the values for control purposes are
connected to the drive and automatic control system.
They automatically control, inter alia, the pump drive
of the blood pump and, in the event of deviations from
2o the setpoint value of the blood flow, give acoustic,
optical or acoustooptical warnings. In this way, any
possible malfunctions and/or changes in the state of
the patient are quickly and reliably indicated and
appropriate action can be taken. For monitoring the
blood flow, a flow sensor which quantitatively monitors
the blood flow without coming into contact with the
blood may also be arranged on the arterial tube. The
pumping rate of the blood pump expediently lies between
2 1/min and 10 1/min and can be controlled infinitely
3o variably or in discrete increments by means of the
automatic control system.
According to a further embodiment of the invention,
closable filling and venting openings which can be
operated from the outside are provided on a reservoir
arranged upstream of the blood pump for receiving
venous blood, on the arterial filter and/or on the
oxygenator, to allow the reservoir to be filled and
CA 02361604 2001-08-10
' ~ K 62 P 1 WO
vented completely and simply when the heart-lung
machine is put into operation. They serve in
particular for the feeding in of priming solution or
medicaments, such as for example heparin for reducing
coagulation. The reservoir may in this case be
designed as a bag. Such a reservoir serves as a
buffer, to compensate for a varying inflow and outflow
of the blood. The use of a bag allows the reservoir to
be adapted in a simple way to the amount of blood
1o respectively to be received. -
According to the invention, a temperature-control
device may be provided on the oxygenator, for example
in the form of a heat exchanger which can be operated
with water and through which blood flows, in order to
control the temperature of the blood as desired before
it is fed back to the patient.
A pre-filled priming solution has the effect that the
2o heart-lung machine is completely vented and kept on
immediate standby before it is connected to the patient
in circulatory operation. For this purpose, the blood-
circulating system has a pre-bypass filter, which is
connected as a bypass between the arterial tube and the
venous tube and through which the priming solution
circulates before it is operated for the patient.
Furthermore, the blood circulation can be maintained
through a bypass which can be operated from the outside
in the possible event of clogging of the arterial
3o filter.
In a development of the idea of the invention, the
automatic control system has an input unit and an
output unit for conducting a dialog with the user, in
particular buttons/controls and/or a display, and also
a program for initialization and functional control
during the operation of the heart-lung machine, in
order to ensure simple operator control.
CA 02361604 2001-08-10
' ~ K 62 P 1 WO
_ g _
The self-sufficient voltage supply provided may be
designed according to the invention as a storage
battery and have an indicator for its charging state.
Imminent discharging of the storage battery can
therefore be detected in good time, in order if need be
' to take measures for providing an external power
supply. In the meantime, the pump could be operated by
a mechanical hand crank.
io
The heart-lung machine advantageously also has a
connection for an external voltage supply, to allow the
storage battery to be charged for example in the
ambulance or to permit operation with an external power
supply when the storage battery has been depleted.
The invention is explained in more detail below on the
basis of an exemplary embodiment represented in the
drawing, in which:
figure 1 shows a view obliquely from above of a mobile
heart-lung machine according to the
invention, with modules separated from each
other,
figure 2 shows a view of the heart-lung machine
represented in figure 1, with the modules
joined together,
3o figure 3 shows a schematic representation of the
blood-circulating elements of the heart-lung
machine according to figure 1,
figure 4 shows a front view of the heart-lung machine
according to figure 1,
figure 5 shows a view from above of the heart-lung
machine represented in figure 1 and
CA 02361604 2001-08-10
K 62 P 1 WO
- 9 -
figure 6 shows a side view of the heart-lung machine
according to figure 1.
' S The mobile heart-lung machine 1 shown in figure 1
comprises two separate modules 2 and 3. AcOommodated
' in the first module 2 ("disposable module"), intended
_ for once-only use, are the elements which circulate the
blood,receive the biochemical and physiological
1o signals and carry out the control commands, and
accommodated in the second, reusable module 3 ars the
drive and control elements. The two modules 2 and 3 can
be joined together to form one functional unit, be
fitted one on top of the other and connected
15 mechanically and at the same time electrically to each
other by means of retaining elements (not represented)
(cf. figure 2). In the joined-together state, the
heart-lung machine 1 is ready for use after it has been
filled with a priming solution, and can be connected by
2o means of the arterial and venous tubes 4 and 5 to the
blood circulation of the patient to be supplied.
The construction and mode of operation of the
disposable module 2 is explained on the basis of the
25 schematic representation in figure 3. Anoxemic blood
of the patient is passed through a venous tube 5 to the
module 2 of the heart-lung machine 1 containing the
blood-circulating elements. The venous tube 5 may in
this case be connected to a closed reservoir 6 for
so receiving venous blood. Through a blood-circulating
system 7, the reservoir 6 is connected via a blood pump
8 to an oxygenator 9 for enriching the blood with
oxygen and for eliminating carbon dioxide. A gas
connection 10 opens into the oxygenator 9 through a
35 filter 11 and serves for the connecting of an external
gas supply. It is consequently possible to fall back
on mobile oxygen and carbon dioxide cylinders or a
hospital's oxygen supply system~for the gas exchange in
CA 02361604 2001-08-10
K 62 P 1 WO
- 10 -
the oxygenator 9. Also arranged on the oxygenator 9 is
a temperature-control device 12, which is flowed
through by a temperature-control medium, through a
circuit 13. For controlling the temperature of the
' S blood, the blood-circulating system 7 has a portion 14
_ protruding into the temperature-control dwice 12.
' Arranged downstream of the oxygenator 9 in the blood
- circulating system 7 is an arterial filter 15 for
cleaning the blood. Provided around the arterial
1o filter 15 is a bypass 16, which can be operated from
outside by a valve 17, to allow the blood circu7,ation
to be maintained even in the possible event of clogging
of the arterial filter 15. Connected to the outlet of
the arterial filter 15 is the arterial tube 4 for
15 returning the blood to the patient. For contactless
monitoring of the blood flow, a flow sensor 18 which
detects the blood flow and reports it to an automatic
control system 24 is provided on the arterial tube 4.
2o Figure 4 shows the front view of the heart-lung machine
1 with the disposable module 2, having the blood-
circulating elements, and the reusable module 3 with
the drive and control elements. Standing on the base
of the disposable module 2 is the oxygenator 9 with the
25 temperature-control device 12. The reservoir 6,
designed as a bag, for receiving the venous blood is~
arranged above the oxygenator 9 on a sloping mount 19.
Along with the oxygenator 9, the blood pump 8 is
located on the base of the module 2. This blood pump
3o is designed as a centrifugal pump and has a pump head
21, which is connected via a coupling 22 to a pump
drive 23 arranged in the reusable module 3. The
coupling 22 is a magnetic coupling. Arranged above the
blood pump 8 is the arterial filter 15, which is
35 connected to the arterial tube 4 and on which the
bypass 16 with the valve 17 is located. Arranged just
before the point where the arterial tube 4 leaves the
module 2 is the contactless flow sensor 18. The blood-
CA 02361604 2001-08-10
K 62 P 1 WO
- 11 -
circulating elements are connected to one another via
tubes of the blood-circulating system 7.
Arranged in the reusable module 3 is an automatic
control system 24 with buttons 25 and a display 26.
The buttons 25 and the display 26 may also be designed
in the form of a touch screen. In addition to the
_ automatic control system 24, on the module 3 there is
an indicator 27 for indicating the charging state of
1o the storage battery, a controller 28 and a -rotational
speed indicator 29 for manually controlling the pumping
rate of the centrifugal pump 8 and also a connection 30
for the connecting of an external voltage supply. Also
provided are a central on/off switch 31 and a pilot
z5 lamp 32. In addition, the module 3 has a storage
battery (not represented) for a self-sufficient voltage
supply.
The disposable module 2 has a transparent module
2o housing 33, while the reusable module 3 with the drive
and control elements has an opaque module housing 34.
Attached to the upper top surface of the transparent
module housing 33 of the disposable module 2 is a
carrying handle 35.
Figure 5 shows the blood-circulating elements arranged
in the disposable module 2 in plan view. The venous
tube 5 is connected to the reservoir 6. By means of
the blood-circulating system 7, the reservoir 6 is in
3o connection through the blood pump 8 with the (hidden)
oxygenator 9, the outlet of which opens via the
arterial filter 15 into the arterial tube 4.
In figure 6, the heart-lung machine 1 is represented
from the side, with the connections for the arterial
and venous tubes 4 and 5. The outlets of the circuit
13 of the temperature-control device 12 and also the
gas connection 10 with the filter 11 can also be seen.
CA 02361604 2001-08-10
K 62 P 1 WO
- 12 -
Not represented is the connecting tube 36,
schematically shown in figure 3, with the pre-bypass
filter 37 between the venous tube 5 and the arterial
tube 4. By opening closures which are not represented
. and can be operated from the outside, and by
simultaneously clamping off the tubes 4 and 5, an
_ internal circuit of the blood-circulating elements can
be completed. In such circulating operation before
1o connection of the heart-lung machine 1 to the patient,
the blood-circulating elements can be completely vented
by means of venting valves 38 and 40 on the reservoir
6. For this purpose, venting tubes 39 are also
connected to the arterial filter 15 and the oxygenator
9 .
The mode of operation of the mobile heart-lung machine
1 described above is as follows:
2o During the operation of the mobile heart-lung machine
1, anoxemic blood flows through the venous tube 5 into
the reservoir 6. The feeding in of priming solution,
medicaments or the like is possible through venting
valves 38, 40 on the venous tube 5 and/or on the
reservoir 6. From the reservoir 6, the blood is pumped
by the centrifugal pump 8 into the oxygenator 9, in~
which it is enriched with oxygen. During the gas
exchange in the oxygenator 9, the blood flows through
the temperature-control device 12, in which the
3o temperature of the blood can be controlled. For this
purpose, a temperature-controlled medium, preferably
water, can be fed into the temperature-control device
12 from the outside through the circuit 13. Oxygen or
an oxygen mixture is introduced into the oxygenator 9
via a gas connection 10. Once it has been enriched
with oxygen, the blood is passed for cleaning through
the arterial filter 15, which is equipped with a bypass
16. Should the arterial filter l5 become clogged
CA 02361604 2001-08-10
K 62 P 1 WO
- 13 -
during operation, the bypass 16 can be manually opened
in order to maintain the patient's blood circulation.
The blood is subsequently fed back to the patient
through the arterial tube 4, past the flow sensor 18.
' S
. The flow sensor 18 measures the flow of the blood in
' the arterial tube 4 and is connected to the automatic
_ control system 24 of the mobile heart-lung machine 1
via an electrical plug-in contact 20 (cf. figure 1).
1o According to the flow measured, the automatic control
system 24 controls the pump drive 23. When critical
values are reached, the automatic control system 24
produces corresponding acoustic, optical or
acoustooptical warnings.
Additionally provided in the disposable module 2 are
further sensors (not represented) for receiving
biochemical or physiological signals, which serve for
checking the function of the heart-lung machine 1. The
2o sensor 'signals are transmitted through contacts
comparable to the plug-in contact 20 to the automatic
control system 24, it being possible for all the
contacts also to be grouped together in a multiple
plug. This makes it easier for the two modules 2 and 3
to be joined together. Elements implementing the
control signals, such as for example electrically
activatable valves, may also be arranged in the
disposable module 2 and be triggered by the automatic
control system 24 via electrical contacts.
To disaccustom the patient from the heart-lung machine
1, the pumping rate of the blood pump 8 is continously
reduced by means of the automatic control system 24
while checking and adapting the filling state of the
heart. Only then can the heart-lung machine 1 be
switched off, provided that the patient is again in a
stable state. After switching off, the disposable
module 2 with the blood-circulating elements can be
CA 02361604 2001-08-10
K 62 P 1 WO
- 14 -
separated in a simple way from the reusable module 3
with the drive and control elements by releasing the
retaining elements and can be replaced by a new sterile
disposable module 2. After closing the retaining
elements and filling with priming solution, the heart-
lung machine 1 is immediately ready for use again.
This provides a mobile heart-lung machine 1 which, on
account 'of its modular construction, comprising a
1o disposable module 2 and a reusable module -3, can be
quickly put to use and, on account of the compactness
of the two modules 2 and 3, can be handled by one
person and, consequently, is particularly suitable for
emergency call-outs.
1s
By adding a suction-device/cardioplegia management
system for venting, suction and stabilizing of the
heart, the mobile heart-lung machine 1 is also suitable
for stationary use in hospitals, for example for heart
2o surgery.
CA 02361604 2001-08-10
K 62 P 1 WO
- 15 -
List of designations
1 Mobile heart-lung machine
2 Module with blood-circulating elements
3 Module with drive and control elements
4 Arterial tube
Venous tube
6 Reservoir
7 Blood-circulating system
8 Blood pump _
9 Oxygenator
Gas connection
11 Filter
12 Temperature-control device
13 Circuit
14 Portion
Arterial filter
16 Bypass
17 Valve
18 Flow sensor
19 Mount
Plug-in contact
21 Pump head
22 Coupling
23 Pump drive
24 Automatic control system
Buttons
26 Display
27 Indicator
28 Controller
29 Rotational speed indicator
Connection
31 On/off switch
32 Pilot lamp
33 Transparent module housing
34 Module housing
Carrying handle
36 Connecting tube
37 Pre-bypass filter
CA 02361604 2001-08-10
K 62 P 1 WO
- 16 -
38 Venting opening or valve
39 Venting tubes
40 Venting opening or valve
