Surgery – Blood drawn and replaced or treated and returned to body – Constituent removed from blood and remainder returned to body
Reexamination Certificate
2001-07-23
2003-09-30
Sykes, Angela D. (Department: 3762)
Surgery
Blood drawn and replaced or treated and returned to body
Constituent removed from blood and remainder returned to body
C604S004010, C604S005010, C604S006090, C604S006110, C422S044000
Reexamination Certificate
active
06626857
ABSTRACT:
TECHNICAL FIELD
The present invention relates to an extracorporeal circulation apparatus used for various treatments in the medical field related to a mammal and especially a human, and particularly to a novel extracorporeal circulation apparatus which is usable for a case in which a selected part of a body is to be kept at a predetermined (or preset) temperature by the “selective temperature controlling (or adjusting) method” such as the “selective cooling method” or the “selective warming method.” The apparatus of the present invention will be explained hereinafter with an example in a case of a human, but it is understood that the present invention is applicable to any mammal.
BACKGROUND ART
Since Woodhall introduced in 1960 a systemic profound hypothermia under a cardiac arrest for the purpose of protecting a brain against a hemorrhage or an ischemia upon a craniotomy, the systemic profound hypothermia has been employed in many types of operations. However, a pump-oxygenator employed in this method makes the procedure complicated and the blood perfusion to various organs insufficient and the method requires a large amount of heparin as an anticoagulant, resulting in problems such as a secondary cerebral hemorrhage.
One of the inventors has made an effort to overcome the problems mentioned above and has developed a method for cooling a brain selectively (which is substantially the same in its meanings as the abovmentioned “selective cooling method”) while using a pump-oxygenator, and applied the method to a craniotomy (see J. Neurosurg; Vol 24, pages 993 to 1001, 1996). This selective cooling method did provide a cerebral hypotension of the brain safely, but still involved the problems with regard to the intra- and post-operative hemorrhages due to the use of a large amount of heparin still associated therewith.
In order to overcome these problems, one of the inventors discovered a method for injecting a cooled lactated Ringer's solution as a fluid replacement (or a replenisher liquid) into a cerebral artery so as to cool only a brain exclusively and to dilute a blood simultaneously while cooling the blood, resulting in a substantially reduced heparin level, whereby reducing the risk of the hemorrhage (see Neurosurgery; Vol 31, pages 0149 to 1054, 1992). This method allows a reversible extreme hypotension to be established without undergoing an oxygen deficit and enables an extreme reduction in the amount of heparin to be used as a result of introduction of the cooled fluid replacement, whereby allowing the amount of heparin to be close to that used in an ordinary angiography. In addition, the introduction of the diluted blood into a lesion leads to various safety-improving effects such as reduction in blood loss.
As described above, since the brain temperature is lowered by injecting the cooled lactated Ringer's solution. However, an amount of the lactated Ringer's solution to be injected is generally large, the injection of the lactated Ringer's solution dilutes the blood excessively and an amount of circulating blood is increased which results in the excessive body fluid condition, so that keeping the low temperature condition for a long time becomes difficult. Therefore, there is a problem in that a satisfactory low blood pressure condition (or cerebral hypotension) of the brain is not ensured. In addition to this, other problems may be occur: for example a large amount of low temperature diluted blood fills the body and a body temperature is lowered, a blood activity is lowered, balancing electrolytes in the blood becomes required, and an excessive overhydration condition may occur which cannot be attended at all with a diuretic drug.
Thus, one of the inventors studied the above problems extensively and proposed an extracorporeal circulation apparatus, which comprises (1) a fluid replacement supply unit which cools a fluid replacement (or a diluent or a replenisher liquid) and quantitatively injects the fluid replacement into a blood vessel (and thus into a body), (2) a blood concentration unit which quantitatively withdraws blood diluted by the fluid replacement from a blood vessel (and thus from the body) and concentrates the withdrawn diluted blood, and (3) a blood supply unit which quantitatively injects the concentrated blood into a blood vessel. Details of this apparatus is disclosed in Japanese Patent Kokai Publication No.9-290021. It is noted that the disclosure of the Publication is incorporated herein by the reference thereto. Using such extracorporeal circulation apparatus allows the selective cooling method to be carried out effectively.
DISCLOSURE OF INVENTION
In order to carry out the selective cooling method more smoothly, the present inventors have further studied the extracorporeal circulation apparatus which has been already proposed as described above, and have found that it is necessary for the more effective selective cooling method to more precisely control a temperature of an object which is a part of a body and to which the selective cooling method is applied (or a region of the body such as an organ, for example a brain, which is also referred to as merely “object”), and that it is important for such precise temperature control to measure a temperature of the diluted blood which is withdrawn from the interior of the body and control a temperature of the fluid replacement which is to be supplied into the interior of the body based on the measured temperature of the diluted blood when the extracorporeal circulation apparatus as described above is used, whereby the inventors have completed the present invention. That is, it has been found that the temperature of the object to which the selective cooling method is applied is more precisely controlled by measuring the temperature of the diluted blood which is withdrawn from the inside of the body and controlling the temperature of the fluid replacement which is to be supplied into the inside of the body based on the measured temperature of the diluted blood, whereby the selective cooling method is carried out more effectively.
In addition, there is a case in which it is desirable to warm an object to a predetermined temperature depending on a treatment for the object (i.e. a case of a selective warming method), and it has been found that when the object is, not cooled as described above, but warmed, the object to which the selective warming method is applied is more precisely controlled by controlling the temperature of the fluid replacement which is to be supplied into the inside of the body based on the measured temperature of the diluted blood, whereby the selective warming method is carried out more effectively.
That is, it has been found that when an selective temperature controlling method is applied in which a temperature of an object which is a part of a body is controlled to a predetermined temperature depending on a treatment for the object, the temperature of the object to which the selective temperature controlling method is applied is more precisely controlled by measuring the temperature of the diluted blood which is withdrawn from the interior of the body and controlling (or adjusting) the temperature of the fluid replacement which is to be supplied into the interior of the body based on the measured temperature of the diluted blood, whereby the selective temperature controlling method is carried out more effectively. The application of the present invention to the selective temperature controlling method will be explained hereinafter with reference mainly to the selective cooling method as an example. Since the selective warming method can be generally carried out substantially similarly to the selective cooling method except that the object is warmed in the selective warming method, those skilled in the art would readily apply the apparatus according to the present invention to the selective warming method based on the example of the selective cooling method.
It should be noted that in the extracorporeal circulation apparatus of the prior art which can be applie
Kinoshita Yoshihiko
Miyatake Tetsuya
Murakami Tomoya
Ohta Tomio
Darby & Darby
Deak Leslie R
Ohta Tomio
Sykes Angela D.
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