Device for forming and delivering a mixture

Details Device for forming and delivering a mixture Device for forming and delivering a mixture

2000-08-29

2003-08-12

Mendez, Manuel (Department: 3754)

Surgery

Means for introducing or removing material from body for...

Treating material introduced into or removed from body...

C604S518000, C604S082000, C604S083000, C604S186000, C424S045000

Reexamination Certificate

active

06605066

ABSTRACT:

Device for the formation and delivery of a mixture, notably for the surgical application of this mixture.
The present invention concerns a device for the formation and application of a mixture of two constituents, notably, the delivery of a mixture for surgical application, such as, in particular, a collagen preparation.
Collagen preparations, designed for application in fluid form, as a liquid or paste, for example, have already been proposed for surgical application, notably in the form of surgical adhesive.
Application WO 97/29715 concerned the proposal of adhesives made from a mixture of gelatine and a polyaldehyde type of crosslinking agent, to produce a fluid mixture for application at a relatively high temperature, above 50° C. Such temperatures are much too high for some tissues, notably in central nervous system surgery, fine innervated, vascularized tissues such as vascular and digestive walls, particularly the blood vessels, heart, intestines and uterus. It should be emphasized that official standards require a temperature lower than 41° C. for the product applied.
Collagen preparations are also known in the form of adhesive described in application WO 98/15299, applied in the form of a mixture of a collagenic substance and a polyaldehyde agent, for example, starch. This mixture can be applied in fluid form at a temperature of around 37° C., which is optimal. This type of mixture is characterized particularly by a substance of collagenic origin as defined in the afore-mentioned application, for example, a collagen which has lost at least part of its spiral, non hydrolyzed structure, consisting mainly of alpha chains.
For these preparations, to make an extemporaneous mixture easily, i.e. prepared at the time the surgeon is ready to apply the preparation consisting of a collagenic substance and a crosslinking agent, it is favourable to raise the collagenic preparation to a temperature higher than the application temperature, for example to a temperature of around 42° C. to 50° C., necessary to achieve adequate fluidity. The problem is then to administer the mixture to the receiving tissue at a temperature close to body temperature at 37° C., or in any case, lower than 41° C.
It has already been proposed to make these mixtures at the last moment, having previously raised the temperature of the preparation of collagenic substance in a drying oven or a water bath. This method of preparation has a number of disadvantages, however, for use under hospital conditions, notably because the heated product begins to cool as soon as it leaves the thermostatically controlled atmosphere, so that the temperature of the product applied is not constant and is difficult to control.
The invention therefore proposes to provide a device which can be used to prepare an extemporaneous mixture, at the time of application by the surgeon, of a collagenic substance and a crosslinking agent, for delivery of a mixture at a temperature close to body temperature.
It should be noted that this objective is made particularly difficult in that collagen or gelatine solutions are extremely viscous, whereas solutions of crosslinking agents display very low viscosity and it is difficult to mix fluids of very different viscosities.
Another of the invention's objectives is to provide such a device which displays a high level of safety with respect to delivery at the required temperature.
Another of the invention's objectives is to provide such a device which can be used to provide several deliveries separated by time intervals likely to cause considerable polymerization of the mixture.
Another of the invention's objectives is to provide such a device which is extremely practical to use.
Another objective is to provide such a device which can be used to deliver the mixture in the form of a foam.
The invention's objective is to provide a device for the formation and delivery of a mixture, notably for the surgical application of this mixture, characterized in that it includes:
a receptacle suitably shaped for handling by the surgeon and including means of holding two syringe barrels, these being a syringe containing the first constituent of the mixture, for example, a collagenic solution, and a syringe containing the second constituent of the mixture, for example, a solution of crosslinking agent;
means for simultaneously expelling the contents of the two syringes;
the means of maintaining the contents of the syringe holding the first constituent, for example, the collagenic solution, at a fixed temperature in excess of body temperature, for example, about 45° C. to 50° C.
and a mixer receiving the contents of both syringes simultaneously during application, which mixing device also secures cooling.
The means of heating the contents of the syringe favourably includes an electrical resistance or thermistor. This resistance can be fitted to the receptacle itself.
It is preferable, however, that this electrical resistance should be permanently fastened to the barrel of the syringe, for example, in the form of a resistance embedded in a film glued around the body of the syringe. The electrical power supply for this film can be provided, for example, by conductors connected to the film and terminating in a means of connection to a source of electrical power, either directly from an appropriate battery, or by using a complementary means of connection which is then connected to the source of electrical power. In this last case, when the device is in use, the user must also connect the conductors leading from the barrel of the syringe to the complementary means of connection.
A thermostat can be used favourably, preferably also fixed to the barrel of the syringe, to control the power supply to the thermistor and detect when the required temperature is reached. This thermostat then preferably emits a signal, informing the surgeon that the syringe has reached the desired temperature. Setting and fitting such a thermostat are routine operations for technicians.
Preferably, an extra safety thermostat is provided in the circuit, this thermostat being designed to cut the thermistor's power supply when a temperature safety threshold is reached or exceeded, this thermostat, in addition, only restoring the power supply once the temperature has fallen back to a level which is substantially below the predetermined temperature setting, so that the first thermostat cannot emit a signal before a new correct heating cycle has been completed.
The mixer will preferably include a removable connector used to receive the contents of the two syringes and carry them to the inlet of an end-piece or mixer body extension containing a device fitted with baffles providing obstacles which gradually produce a homogeneous mixture.
This mixer body will preferably include extended particles and it is particularly preferred that these particles be formed of small sections of plastic tubing or other cut in two across the diameter. It was observed that this type of structure ensures intermingling of the particles leading to obtention of the mixture required, over a short distance of a few centimetres, while ensuring that the temperature falls during its passage through the mixer, which constitutes one of the invention's characteristics.
The connector and mixer end-piece can preferably be removed separately and are replaceable, which means that the contents of the syringes can be used in several successive applications, separated by long periods in spite of the start of polymerization of the mixture in the end-piece or body of the mixer which will simply be replaced.
In the preferred application of the invention, using a collagen constituent or gelatine, as defined, for example in WO 98/15299, the volume of the expellable contents of the syringe containing the first constituent, i.e. the collagenic constituent, is about three to ten times as much, for example four times as much as that of the contents of the second syringe, i.e. the solution of crosslinking agent, such as a solution of oxidized starch.
When the collagenic c

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