Abstract:
A perfusion pump comprising an assembly of inner and outer tubes interconnected by a field of perforations, a chamber configured to closely contain the tube assembly, valving apparatus for substantially closing the ends of the inner tube by compression against the chamber, and sources of positive and negative pressure gas selectively applicable against the wall of the outer tube.

Description:
FIELD OF THE INVENTION 
     This invention relates to the field of surgery, and more specially to apparatus for use in providing a flow of a patient&#39;s own blood when needed for perfusion and other surgical practices. 
     BACKGROUND OF THE INVENTION 
     There are surgical procedures in which it is desirable to have available a flow of the patient&#39;s own blood for perfusion. An example is coronary transluminal angioplasty with coronary perfusion. For such purposes, it is customary to draw blood from the patient&#39;s femoral artery for use in the perfusion. 
     SUMMARY OF THE INVENTION 
     The present invention comprises a pump having an input which may be connected to a catheter inserted in the patient&#39;s femoral artery or other convenient location, and an output which may be connected to a CTA/CP (coronary transluminal angioplasty/coronary perfusion) catheter to supply perfusion blood reliably and safely as long as is needed, without causing mechanical damage to the blood. A CTA/CP catheter suitable for this use is taught in the co-pending patent application of Gilmore T. Schjeldahl et al., Ser. No. 185,273, filed Sept. 8, 1980, and assigned to the assignee of the present application. 
     Various advantages and features of novelty which characterize my invention and are pointed out with particularity in the claims annexed hereto and forming a part hereof. However, for a better understanding of the invention, its advantages, and objects attained by its use, reference should be had to the drawings which form a further part hereof, and to the accompanying descriptive matter, in which there is illustrated and described a preferred embodiment of the invention. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     In the drawings, in which like reference numerals indicate corresponding parts throughout the several views, 
     FIG. 1 is a plan view of the invention, with parts broken away for clarity of illustration; 
     FIG. 2 is an end view of the invention seen from the left of FIG. 1; and 
     FIG. 3 is a schematic diagram showing the operation of the invention. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     A pump according to the invention is shown in the drawings to comprise an inner flexible, resilient tube 20 having an inlet end 21 and an outlet end 22. The wall 23 of tube 20 is provided, at a medial site between ends 21 and 22, with a field 24 of perforations 25. Inlet end 21 is to be connected to a catheter in a patient&#39;s femoral artery or other advantageous source of patient&#39;s blood, and outlet end 22 is to be connected to a CTA/CP catheter or other perfusion apparatus. 
     An outer flexible resilient tube 26, of a length somewhat greater than that of the field of perforations in tube 20, surrounds the inner tube in the region of the field. At its ends 27 and 28, tube 26 is secured in fluid tight relation around tube 20. The dimensions of the tube assembly 30 are such that a space 31 between the tubes has a desired volume of, for example, 2 milliliters. 
     The tube assembly is contained in a chamber 32 made up of two portions 33 and 34 interconnected by a hinge 35 and provided with supporting feet 36. A cavity is formed jointly in portions 33 and 34 along their abutting surfaces, and has a central portion 40 configured to closely enclose tube 26, and end portions 41 and 42 configured to closely enclose tube 20 where it extends beyond tube 26. Portion 33 is further provided with a bore 43 opening inwardly to central portion 40 of the cavity, and outwardly to a threaded connection 44 for receiving metal tubing. 
     Portion 33 is configured with a horizontal ledge 45 at one end and a vertical wall 46 at the other end. A solenoid 47 is mounted on ledge 45 by a clevis 50 and a vertical pivot 51. Portion 34 is configured with a horizontal ledge 52 at one end and a vertical wall 53 at the other end. A solenoid 54 is mounted on ledge 52 by a clevis 55 and a vertical pin 56. 
     A first bell crank 60 is pivoted on a vertical pin 61 extending upward from ledge 45. The long arm 62 of the bell crank is pivotally connected by a vertical pin 63 and a clevis 64 to the movable armature 65 of solenoid 47, and carries a stop screw 66 and lock nut 67 for limiting the inward stroke of the armature by engagement with portion 33 at an abutment 70. The short arm 71 of crank 60 carries a roller 72 on a vertical pivot pin 73. 
     A second bell crank 74 is pivoted on a vertical pin 75 extending upward from ledge 52. The long arm 76 of the bell crank is pivotally connected by a vertical pin 77 and a clevis 80 to the armature 81 of solenoid 54, and carries a stop screw 82 and lock nut 83 for limiting the inward stroke of the armature by engagement with portion 34 at an abutment 84. The short arm 85 of crank 74 carries a roller 86 on a vertical pivot pin 87. 
     The function of solenoids 47 and 54 is to open and close the ends of tube 20 as desired. In FIG. 1, solenoid 47 is shown with its armature retracted, so that stop screw 66 engages abutment 70. In this situation, roller 73 compresses tube 21 against wall 53 so as to practically close the tube, leaving only a very small gap. Solenoid 54 is shown with its armature extended. In this situation, roller 86 disengages tube 20 to enable it to expand to its full diameter. 
     As shown in FIG. 1, bore 43 is connected at 44 by a tube 90, a tee 91, and a pair of tubes 92 and 93, to a pair of valves 94 and 95 which are connected respectively to a source 96 of gas under pressure and a source of vacuum 97. Helium is the preferred gas, and the usual regulators are to be provided for the negative and positive pressure sources. Valves 94 and 95, as well as solenoids 47 and 54, are controlled by a supervisory apparatus or sequencing switch 100 in a manner shown schematically in FIG. 3. 
     The sequence of operation is such as to draw blood into tube 20 at end 21 and through apertures 25 into space 31, then to impel the blood out of space 31 and out of tube 20 at end 22. To do this, sequencer 100 first retracts armature 81 and opens valve 95, admitting negative pressure to bore 43 to expand outer tube 26 fully and maximize space 31, thus drawing blood in at tube end 21 and through apertures 26 into space 31. Valve 95 is then closed, armature 81 is extended, armature 65 is retracted, and valve 94 is opened, admitting helium gas under pressure to bore 43 to compress outer tube 26 and impel the blood out of space 31 through apertures 25 and tube end 22. The fact that rollers 72 and 86 do not completely close tube 20 does not materially degrade the efficiency of the pump, but does avoid mechanical damage to the blood by crushing any of its cellular components. 
     While sequencer 100 may operate in an arbitrary time sequence, it is desirable that its operation be synchronized or coordinated with the patient&#39;s own heartbeat, and to that end a signal from a suitable sensor may be supplied to sequencer 100 as suggested at 101. 
     From the foregoing it will be evident that I have invented a safe, reliable pump for supplying, for use in coronary perfusion for example, blood from a patient&#39;s artery. The pump operates in a manner which results in minimum mechanical damage to the blood. It meets all the requirements for use in an operative environment, and is adapted to have its operation coordinated with the patient&#39;s own heartbeat. 
     Numerous characteristics and advantages of the invention have been set forth in the foregoing description, together with details of the structure and function of the invention, and the novel features thereof are pointed out in the appended claims. The disclosure, however, is illustrative only, and changes may be made in detail, especially in matters of shape, size, and arrangement of parts, within the principle of the invention, to the full extent indicated by the broad general meaning of the terms in which the appended claims are expressed.