US 20050143795 A1
A device for restricting the loss of blood during a surgical procedure is disclosed. The device generates localized heating in an organ or volume of tissue and includes an applicator that is positioned against an organ or tissue to be treated, an array of retractable needles that deliver irradiating energy in the vicinity of a selected incision point; a switching mechanism in communication with the needles for energizing and causing movement of the needles and a power unit for supplying irradiating power to the needles when extended into the organ or tissue.
1. A device for restricting the loss of blood during a surgical procedure comprising:
(i) an applicator having a face for positioning against an organ or tissue to be treated;
(ii) an array of retractable needles extending from said face capable of irradiating said organ or tissue to be treated in a vicinity of a selected incision point;
(iii) a switching mechanism in communication with said array of retractable needles for energizing and releasing said array of retractable needles;
(iv) and a power unit in communication with said array of retractable needles for supplying irradiating power to said needles when extended into said organ or tissue in the vicinity of the selected incision point.
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This application is a divisional of U.S. patent application Ser. No. 10/625,232, filed Jul. 22, 2003, which is a continuation of U.S. patent application Ser. No. 09/762,285, filed Apr. 6, 2001, now U.S. Pat. No. 6,628,990, which is a national stage application of International Patent Application No. PCT/GB99/02559, filed Aug. 4, 1999, which claims priority from GB Patent Application No. 9817078.0, filed Aug. 5, 1998.
This invention relates to a device for use in the surgical treatment of human or non-human animals. In particular, it is concerned with a device for use in controlling excessive bleeding from severed tissue during surgical procedures, especially on the patient's liver.
It is well known that raising the temperature of body tissue tends to reduce blood flow within the tissue. If the temperature is raised by 20-30° C. above normal, blood flow within the tissue is greatly diminished.
In surgical procedures performed on deep-seated body tissues and organs, e.g. the liver, blood loss from severed tissue can be a serious problem. There is an obvious need for a device which can assist in limiting such blood loss and, as indicated above, this can be achieved by means of the application of heat. Widespread heating can be achieved relatively easily, but this is not desirable. Very localised heating is required in order to minimise damage to surrounding tissues. In liver surgery, local heating of the liver is ideally required in a tissue volume approximately 5 cm long by 2 cm wide by 4 cm deep; this volume is centred on the planned point of incision. Furthermore, it is important for the local elevation of temperature to be achieved quickly just prior to commencing the surgical procedure.
The present invention aims to provide a device for providing localised heating of a selected region of body tissue prior to surgical incision of that tissue.
According to one aspect of the present invention, there is provided a device for generating localised heating in a selected body tissue, which device comprises an applicator including a source of microwave radiation and an array of retractable needles arranged so as to extend from one face of the applicator and, in operation, to confine the irradiated microwave energy field emanating from the applicator.
The invention also provides the use of the device as defined above for restricting the loss of blood during a surgical procedure on the human or animal body.
According to another aspect of the present invention, there is provided, in the surgical treatment of the human or animal body, a method of controlling excessive bleeding, the method comprising inserting an array of needles into the tissue or organ being treated; and applying microwave energy to the region undergoing treatment for a time sufficient to raise the temperature of said tissue or organ by 20-30 degrees C.
Conveniently, the source of microwave radiation is in the form of a rectangular waveguide whose dimensions correspond to those of the tissue volume which is to be heated. The waveguide is preferably generally rectangular in form, the array of retractable needles being positioned around the periphery of the waveguide.
The device may include a needle advance mechanism including a collar to which the needles are secured; movement of said collar may be actuated by a solenoid mechanism.
In operation of the device, the needles will be advanced from the body of the applicator into the tissue which is to be heated so that the needles function as a extension of the waveguide; in this way, the applicator will direct the required microwave energy into the appropriate tissue volume prior to surgery. When the heating process is completed, the needles are retracted back into the body of the applicator.
Generally, the needles will be disposed mutually parallel; they can conveniently be formed of steel.
Theoretical calculations show that, in order to raise the temperature of body tissues by 30° C., an applicator operating with 100% efficiency would need to deliver about 10 watts of microwave power, assuming that the volume to be heated is 40 cm3. For a typical biological tissue such as muscle, this temperature rise would be achieved in approximately 10 minutes. If the source is increased in energy to 500 watt, and if the applicator is assumed to be about 80% efficient, the time taken to achieve this required temperature increase is approximately 15 seconds.
For a better understanding of the invention, and to show how the same may be carried into effect, reference will now be made, by way of example, to the accompanying drawings, in which:
Referring now to the drawings, a power and control unit (1) supplies up to 500 watts of microwave power via a coaxial cable (2) to a rectangular applicator (3). The head (3) has a handle (4) through which cable (2) passes, and an array (5) of retractable needles which are designed to provide precise irradiation of the tissue in the vicinity of the selected incision point. The unit (1) also contains a switching mechanism and control electronics to energise and release the array of needles.
As shown in
In operation, a surgeon will position the applicator head (3) against the region of tissue (e.g. liver) which is about to be incised. Initially the needle array (5) is retracted within head (3). When the applicator is actuated, solenoid mechanism (10) causes the needles of array (5) to be extended into the patient's tissue. Once they are embedded in the tissue, microwave energy at the desired frequency (e.g. 1 GHz) is supplied to waveguide (6) and passes therefrom into the volume of tissue enclosed by the array (5) of needles. Energy is supplied at a typical power level of 500 watts for a duration of about 15 secs when an applicator of the dimensions 5 cm×2 cm and a needle length of 3 cm is used. At the end of the treatment period, the microwave source is switched off and needle array (5) is retracted. The surgeon may then proceed with the incision and any subsequent procedures as may be necessary.
Blood loss from incision of tissue after heat treatment as described is greatly reduced in comparison to the results obtained in the absence of such heat treatment.