US 3295297 A
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Description (OCR text may contain errors)
Jan. 3, 1967 R. M. COLLINS FILTER AND BUBBLE TRAP Filed Oct. 19, 1965 AGENT United States Patent Office 3 ,295,297 Patented Jan. 3, 1967 3,295,297 FILTER AND BUBBLE TRAP Robert M. Collins, La Canada, Calif, assignor to Cobe Laboratories Inc, Los Angeles, Calif., a corporation of California Filed Oct. 19, 1965, Ser. No. 497,965 2 Claims. (Cl. 55178) The present invention pertains to equipment for separating foreign material from liquids and more particular to equipment for separating entrained solid and gas embolisrns from human blood during cardiovascular surgery.
During cardiovascular surgery the blood of a patient is shunted around the heart or lungs thereby permitting an operation to be performed on these organs without the presence of excessive blood. Also during an operation of this type the patients blood must necessarily be continuously circulated through his veins and arteries, this operation is normally effected with pump-oxygenator or simular equipment. Further, in duplicating the function of the patients heart by artificial means, it is essential that the patients blood be maintained free of solid and gas embolisms. This is essentialin fact imperative-as small amounts of foreign material (air or solid embolisms) returned to the patients arterial system may be fatal for obvious reasons, this is especially true of air embolisms.
The quantity of blood contained in the arterial system of an average person ranges from between six (6) to eight (8) quarts all of which must be regularly and continuously recirculated. It, therefore, becomes apparent that equipment purging foreign material from recirculated blood must necessarily be capable of processing relative large quantity of blood.
An object of the present invention is to disclose a device functioning to separate foreign material from a liquid flow passing through the device and which does not appreciably restrict or retard the flow of liquid during the actual separation operation.
Another object is to provide a device functioning to separate foreign material from liquids flowing therethrough and the actual separation components of the device having a relative large capacity at least equal -in the sense of liquids passedto other components of the device.
Another object is to disclose a device functioning to separate foreign material from liquids flowing therethrough which provides a smooth continuous flow path void of abrupt changes in the direction of flow.
Another object is to provide a device for separating foreign material from liquids flowing therethrough which is simple and rugged in construction, economical to manufacture and which may be easily adapted to a plurality of purposes.
Although the characteristic features of the present invention are particularly pointed out in the appended claims, the invention itself, also the manner in which it may be carried out, will be better understood by referring to the following description taken in connection with the accompanying drawings forming a part of this application and in which:
FIGURES 1 and 2 are plan and elevational views, respectively, of the device disclosed herein for separating foreign material from liquids.
FIGURE 3 is an enlarged exploded view of the device of FIGURES 1 and 2.
Referring to the drawing, FIGURES 1 and 2 show a device 11 as disclosed herein for separating foreign material entrained in liquids flowing therethrough. The device 11 is discussed herein in connection with cardiovascular surgery for separating embolisms (solid and gas) entrained in blood circulated by artificial means. During cardiovascular surgery the entire quantity of a patients blood must be recirculated, accordingly it becomes apparent that the device 11 must remove foreign embolisms (solid and gas) from relatively large quanties of blood.
The device 11 comprises a pair of circular dish-like members 12 and 14 and a screen member 16, all of which are of equal diameter. The members 12 and 14 include rim and convex portions 17 and 18, respectively, as best seen in FIGURE 3.
The members 12 and 14 also include passageways 19 and 21 adjacent the peripheries of the members providing ingress and egress of blood to and from the device 11.
In the assembled relation of the components 12, 14 and 16, the rim portions of the members 12 and 14 are secured together with the screen member 16 positioned therethrough in fluid tight relation to define a chamber 22. As assembled, the relation of the members 12 and 14 are further characterized in that structure defining the passageways 19 and 21 have a diametrically opposed relation as best seen in FIGURE 1. In other words with the device 11 positioned with the screen member 16 in a vertical attitude and with the passageway 19 at substantially the upper most portion of the device, the passageway 21 is located substantially at the lowermost portion of the device.
The convex portions of the members 12 and 14, except for wall portions defining the passageways 19 and 21, have a very shallow configuration, accordingly in the assembled relation thereof their convex wall portions have a close relationship with respect to the screen member 16. Internal construction of the members 12 and 14 is such that, except for blood entering the device 11 through the passageway 19 and immediately passing through the screen member 16, they provide a smooth continuous flow path for the blood as best seen in FIGURE 3. In this respect, the inner surface of the member 12 and the portion of member 14- defining the passageway 21 cooperate to provide the above mentioned smooth continuous flow path through the device 11.
A plurality of crescent shaped embossments 23 are provided on the inner wall portion of the member 14. The crest (center line) of these embossments coincide with a reference plane passing through or containing the axes of the passageways 19 and 21. The embossments 2 3 have a symmetrical relation with respect to the aforementioned reference plane and increase in length progressively from the uppermost to the lowermost one. Constructed in this manner, that portion of blood entering through passageway 19 and flowing through the screen member 16 contacts the uppermost one of the embossment 26 and cascades from the end portions thereof on to the embossment located directly below and adjacent thereto, similar operations are repeated and the blood finally elgresses through the passageway 21. Apertures 24 are provided in the uppermost wall portions of the members 12 and 1 4, that is the wall portions adjacent the inlet passageway 19 as the members 12 and 14 are assembled. The apertures 24 provide egress for gaseous embolisms which may be separated from blood flowing either through the screen member 16 or by action provided by the embossments 23.
The screen member 16 is constructed of an inert material the mesh of which varies according to the viscosity of the particular liquid flowing through the device 11. In the present case (recirculated blood) the mesh of the material constituting the member 16 is necessarily small, for this reason, and in view of the quantity of blood which must be recirculated, known devices of this type have a tendency to retard or restrict the flow of blood therethrough. For this reason, the device 11 is constructed in a manner in which the area of the member 16 far exceeds the cross-sectional area of either the inlet or the outlet passageways 19 or 21, respectively. In view of the fact that blood enters the device at the uppermost portion thereof providing a storage space (chamber 22) in which excess blood accumulates, also the area of the screen member 16 exceeds the cross-sectional area of the inlet or outlet passageway 19 or 21, for these reasons the present device provides a continuous and uninterrupted flow of large quantity. In order that the device 11 functions at a steady and continuous rate (when blood is recirculated therethrouigh) the area of the screen member 16 should exceed the cross-sectional area of the inlet 19 or of the outlet passageway 21 by at least a ratio of fifteen (15) to one (1).
In operation recirculated blood enters the device 11 through the passageway 19 usually under slight pressure corresponding to pressure applied thereto by the human heart. Regardless of the precautions and care taken, and due to the inherent nature of human blood, air and solid embolisms-to some degreewill be entrained in the blood stream. These embolisms must be removed from the recirculated blood and at the same time normal fiow maintained. The recirculated blood contacts the screen member 16 and a certain amount passes therethrough immediately. The remaining portion collects in the lower portion of chamber 22 upstream of the member 16 until such time as the dilferential in pressure is sufficient to cause passage thereof through the member 16. Blood passing through the screen member r16 causes separation of major air embolisms from the blood, they rise to the surface of the blood and escape through the apertures 24.
The portion of the blood which passes through the screen member 16 immediately constitutes the foam portion and necessarily the major air embolisms. This portion contacts the em bossments 23 and air embolisms are further separated (freed) as the blood contacts the embossments and gently cascades off the ends thereof and on to the next lower embossment. Accordingly, the air embolisms rise to the surface of the blood and escape through the apertures 24. Solid embolisms entrained in the blood are separated (filtered out) by the screen member 16 and settle in the lower portion of the chamber 22.
While in order to comply with the statute, the invention has been described in language more or less specific as to structural features, it is to be understood that the invention is not limited to the specific features shown, but that the means and construction herein disclosed comprise a preferred form of putting the invention into effect, and the invention is therefore claimed in any of its forms or modifications within the legitimate and valid scope of the appended claims.
1. A device for separating solid and gas embolisms entrained in a liquid comprising:
(a) a pair of circular dish-lilge shell members of the 4 same diameter each including rim and concave portions;
(b) a screen member;
(c) the rim portions of said shell members being secured together in liquid tight relation defining a chamber and having said screen member secured therebetween;
(d) first and second passage means of circular crosssection provided in each of said pair of shell members adjacent their respective rim portions;
(e) in the assembled relation of said pair of shell-like members said first and second passage means having a diametrical opposite relation and normally providing ingress and egress, respectively, for liquid flowing through said chamber;
(f) the area of said screen member secured between said rim portions being at least fifteen times the area of one of said first and second passage means;
(g) first and second apertures provided in each of said pair of shell-like members adjacent the rim portions thereof and said first passage means in the assembled relation of said pair of shell-like members and through which gas embolisms separated from liquid flowing through said chamber may escape;
(h) and a plurality of crescent shaped embossments on the inside surface of the one of said pair of shelllike members having said second passage means therein with the crest of each embossment coinciding with the plane containing the axes of said first and second passage means and the concave portion of the other of said pair of shell members sloping generally upwardly toward, and the concave surfaces of said embossments facing, said second passage means, said embossments being spaced from said screen member.
2. A device for separating entrained solid and gas embolisms from a liquid as set forth in claim 1:
(a) in which each of said embossments extend equal distances from the inner surface of the other of said pair of shell members and the normal distance between said screen member and the outer most portion of said embossments progressively increase as the latter are located nearer to said second passage means.
References Cited by the Examiner UNITED STATES PATENTS 2,776,055 1/1957 Adler 210-445 X 2,818,178 12/1957 Hodsdon 210445 3,175,555 3/1965 Ling 128214 REUBEN FRIEDMAN, Primary Examiner, R- W- BURKS, Assistant Examiner.