U.S. patent number 3,886,930 [Application Number 05/419,659] was granted by the patent office on 1975-06-03 for blood collecting assembly.
This patent grant is currently assigned to Abbott Laboratories, Inc.. Invention is credited to George R. Ryan.
United States Patent |
3,886,930 |
Ryan |
June 3, 1975 |
Blood collecting assembly
Abstract
A blood collecting assembly having a cannula, a holder for the
cannula, and a valve which is useful in indicating when the
venipuncture has been made by means of a blood telltale, which is
easily compressed when the cannula is pierced through a resealable
closure of a blood collecting container, which returns to the
extended position when the cannula is withdrawn from the closure,
and which prevents the flow of blood through the cannula when it
has returned to its extended position.
Inventors: |
Ryan; George R. (Waukegan,
IL) |
Assignee: |
Abbott Laboratories, Inc.
(North Chicago, IL)
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Family
ID: |
46650987 |
Appl.
No.: |
05/419,659 |
Filed: |
November 28, 1973 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
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138990 |
Apr 30, 1971 |
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715 |
Jan 5, 1970 |
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Current U.S.
Class: |
600/577; 604/236;
600/579; 600/584 |
Current CPC
Class: |
A61B
5/150389 (20130101); A61B 5/15003 (20130101); A61B
5/150213 (20130101); A61B 5/150496 (20130101); A61B
5/1545 (20130101); A61B 5/150259 (20130101); A61B
5/150732 (20130101); A61M 5/31 (20130101); A61B
5/150221 (20130101); A61B 5/150351 (20130101) |
Current International
Class: |
A61B
5/15 (20060101); A61b 005/14 () |
Field of
Search: |
;128/2F,2R,DIG.5,221,276,218NV |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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880,516 |
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Nov 1970 |
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IT |
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950,588 |
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Mar 1949 |
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FR |
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935,122 |
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Jan 1948 |
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FR |
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1,019,500 |
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Feb 1966 |
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GB |
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Other References
The Bulletin, Dow Corning Corp. Publication, Vol. 4, No. 2, Apr.
1962, pp. 5-8..
|
Primary Examiner: Howell; Kyle L.
Attorney, Agent or Firm: Grass; Joseph J.
Parent Case Text
CROSS REFERENCE TO RELATED APPLICATION
This application is a continuation of application Ser. No. 138,990
filed Apr. 30, 1971, now abandoned, which is a continuation-in-part
of application Ser. No. 715 filed Jan. 5, 1970, now abandoned.
Claims
1. A holder, cannula and valve assembly for collecting blood,
comprising: a holder having a generally tubular longitudinally
extending passageway open at one end and having an end portion
opposite the open end, a cannula extending longitudinally and
connected to the end portion of said holder, said cannula having an
interior marginal end terminating in the passageway at a piercing
end and having an exterior marginal end extending exteriorly of
said holder and terminating at a vein-piercing end, said interior
marginal end having an opening through which blood can pass, valve
means received about said interior marginal end of said cannula and
connected to said holder, said valve means including air vent means
providing communication from said cannula opening, through said air
vent means, into said passageway, and to the atmosphere, and
mounting means for said valve means connected to the end portion of
said holder and enabling lengthwise shifting movement of the valve
means relative to the cannula from a first position in which said
cannula opening communicates with the atmosphere to provide a blood
telltale at said cannula opening when said vein-piercing end has
pierced the vein of a patient to a second position at which said
cannula opening is closed off from the atmosphere by said valve
means to prevent additional blood from passing out of said cannula
opening until blood is to be collected, said valve means being
composed of a material which is cannula pierceable, resealable and
sufficiently transparent to enable visual observation of the blood
telltale through the valve means.
2. An assembly as defined in claim 1, wherein the air vent means
includes a groove which can provide communication with the
atmosphere.
3. An assembly as defined in claim 1, said air vent means including
an aperture in said valve means.
4. An assembly as defined in claim 1, said mounting means
comprising a hub connected to said holder, said valve means being
engaged with said hub, said air vent means including a groove in
said hub.
5. An assembly as defined in claim 1, said mounting means
comprising a hub connected to said holder, said valve means being
engaged with said hub, said air vent means including a groove in
said valve means where said valve means engages said hub.
6. An assembly as defined in claim 1, wherein said valve means
includes a generally tubular body having a closed end and an
integral sealing ring spaced apart from said closed end, said
interior marginal end being out of sealing engagement with said
sealing ring when said valve means is in its first position, said
sealing ring being in sealing engagement with the outer surface of
said interior marginal end when said valve means is in its second
position.
7. An assembly as defined in claim 1, said passageway being capable
of receiving an evacuated container having a pierceable closure,
said valve means including at least two separate spaced apart
columns which can buckle as said container is moved relative to
said cannula until said cannula has pierced through said closure to
provide passage of blood through said cannula into said container.
Description
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to the art of collecting blood.
2. Brief Description of the Prior Art
In the art of collecting blood it is common practice to use an
evacuated container having a pierceable and resealable closure
closing off one end. When the venipuncture has been made, a pointed
end of a cannula is pierced through the closure and blood flows
into the unvented container. It is also common practice to use a
syringe having a barrel with an attached needle and a plunger
within the barrel. When the venipuncture has been made blood flows
into the syringe barrel as the plunger is withdrawn. The art is
replete with disclosures of various types of valves for use with a
cannula in a blood collecting assembly.
SUMMARY OF THE INVENTION
The blood collecting assembly of the invention includes a cannula,
a holder for the cannula, and an improved valve for the cannula.
The valve is movable between a position in which the valve provides
air venting through a restricted passage to provide a blood
telltale and another position in which the valve prevents either
air or blood from passing through the passage. The valve has means
for facilitating its compression, and in particular its eccentric
buckling relative to the cannula. This reduces the force which
would otherwise be required to cause effective shortening of the
length of the valve. The valve has a pierceable resealable wall or
diaphragm through which the piercing end of the cannula can extend
during the collection of blood and which can reseal when the valve
returns to its extended position following the collection of blood.
The valve preferably has a small internal diameter section and a
large internal diameter section. The small internal diameter
section is disposed at the open end of the cannula and the larger
internal diameter section surrounds a substantial portion of the
length of the interior marginal end of the cannula in one form of
the invention. The small internal diameter section has an internal
valve ring or seal around which air can pass in one position of the
valve and which prevents the passage of both air and blood in the
other position. The air vent can be provided in a number of ways
such as by one or more holes in the valve body, by a groove in the
hub which receives the valve, by a projection formed on the hub
which receives the valve, or by a groove in the valve body at the
hub.
The holder has a tubular body and a section, which has an internal
conical surface, joining the tubular body. The tubular body
provides a passageway into which an evacuated container having a
pierceable closure is adapted to be inserted. The holder also has a
visual indicator for indicating when the closure-piercing end has
penetrated into the closure. The conical surface provides a stop
for the container when the closure-piercing end has pierced through
the closure.
In one embodiment of the invention the valve includes a pair of
columns which can buckle to facilitate of the valve as the cannula
is inserted through the pierceable closure of the blood collecting
container and which can effect extention of valve immediately
following removal of the cannula from the pierceable closure.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a side elevational view, partly broken away and partly in
section, of a blood collecting assembly in accordance with one
embodiment of the invention;
FIG. 2 is a side elevational view of an evacuated container with a
closure closing off its one end, for use with the blood collecting
assembly of the invention;
FIG. 3 is an enlarged sectional view of the embodiment shown in
FIG. 1, with the container inserted into the passageway of the
cannula holder and with its closure just touching the valve;
FIG. 4 is a sectional view taken along line 4--4 of FIG. 3;
FIG. 5 is a fragmentary view similar to FIG. 3, but showing the
valve in a position in which its air vent is closed off;
FIG. 6 is a sectional view similar to FIG. 5, but showing the valve
eccentrically buckled and showing the cannula as penetrating the
closure of the evacuated container;
FIG. 7 is a sectional view similar to FIG. 6, but showing the valve
completely eccentrically buckled and showing the cannula as having
penetrated through the closure;
FIG. 8 is a fragmentary sectional view of another embodiment of the
invention.
FIG. 9 is an enlarged sectional view taken along line 9--9 of FIG.
8;
FIG. 10 is a fragmentary sectional view of yet another embodiment
of the invention;
FIG. 11 is an enlarged sectional view taken along line 11--11 of
FIG. 10;
FIG. 12 is a fragmentary sectional view of still another embodiment
of the invention, showing the valve in its initial position;
FIG. 13 is a fragmentary sectional view of the embodiment shown in
FIG. 12, but showing the valve in a position in which its air vent
means is closed off;
FIG. 14 is an enlarged sectional view taken along line 14--14 of
FIG. 12;
FIG. 15 is a fragmentary sectional view of another embodiment of
the invention, with the evacuated container inserted into the
passageway of the cannula holder and with its closure just touching
the valve;
FIG. 16 is a fragmentary view similar to FIG. 15, but showing the
valve in a position in which its air vent valve is closed off;
FIG. 17 is a sectional view similar to FIG. 16, but showing the
valve buckled outwardly and showing the cannula penetrating the
closure of the container;
FIG. 18 is a sectional view similar to FIG. 17, but showing the
valve completely buckled and showing the cannula as having
penetrated through the closure;
FIG. 19 is a perspective view of the valve shown in section in
FIGS. 15 through 18;
FIG. 20 is a sectional view taken along line 20--20 of FIG. 19;
and
FIG. 21 is a sectional view taken along line 21--21 of FIG. 20.
DESCRIPTION OF THE EMBODIMENTS OF THE INVENTION
Referring to FIGS. 1 and 3, there is shown a blood collecting
assembly generally indicated at 20. The assembly 20 includes a
cannula 21 mounted in a one-piece holder 22. The holder 22 has a
generally tubular body 23 with an end wall or end portion 24 at one
end and terminating at an opening 25 at its other end. A hub
portion or hub 27 formed integrally with the end wall 24 and having
the same axis as the generally tubular body 23 extends into the
interior of the passageway 23' provided by the body 23. A hub
portion or hub 26 formed integrally with the end wall 24 and having
the same axis as the hub 27 and the body 23 extends exteriorly of
the passageway 23'.
A sheath 28 removably received by the hub 26 preserves the
sterility of the exterior marginal end 29 of the cannula 21 until
the venipuncture is ready to be made. A valve 30 is disposed about
the interior marginal end 31 of the cannula 21 and is shown to
receive the hub 27. A removable cap 33 is shown in FIG. 1 to close
off and preserve the sterility of the passageway 23', the valve 30,
and the interior marginal end 31 of the cannula 21 until the
assembly is ready to be used. The holder body 23 has a plurality of
external annular rings 34 extending about its periphery. The rings
34 not only assist in gripping the holder 22, but they also
strengthen the holder body 23.
The exterior marginal end 29 of the cannula 21 terminates at an
open vein-piercing end 35. A bevel indicator 36 is formed on the
periphery of the holder body in alignment with the bevel at the
vein-piercing end 35. The interior marginal end 31 terminates at a
closure-piercing end 37. It is preferred that the opening in the
interior marginal end 31 be directly at the closure-piercing end 37
rather than in the side of the interior marginal end 31, although
the invention does not require it to be located at the piercing end
37.
With reference to FIG. 2, there is shown a rigid evacuated
container 38 in the form of a transparent glass tube. The container
38 has a pierceable, resealable elastomeric closure 39 closing off
one end and maintaining the vacuum in the container 38.
With reference to FIGS. 3 and 4, the valve is shown to have a
relatively small internal diameter section 40 joined to a
relatively large diameter section 41. One marginal end 42 of the
section 41 is slightly smaller than the remainder of the section 41
so that the marginal end 42 snugly embraces the hub 27.
The small internal diameter section 40 is shown to have an internal
diameter which is only slightly larger than the outside diameter of
the interior marginal end 31 of the cannula 21. An end wall or
diaphram 43 closes off one end of the section 40. The valve 30 is
composed of a pierceable, resealable, elastomeric material and thus
the end 37 can pierce through the end wall 43 with which it is in
alignment; when the end 37 is withdrawn the end wall 43 will reseal
and thus the end wall 43 will be closed off again. More
specifically, the valve 30 is composed of a styrene-butadiene
copolymer although other suitable materials can be used. Formed
integrally with the inside of the section 40 is an annular valve
ring or seal 44. The inside diameter of the valve ring 44 is
slightly less than the outside diameter of the interior marginal
end 31 of the cannula 21. When the venipuncture is made, the valve
30 being in the initial position shown in FIG. 3, air in the
cannula 21 can be vented through the open cannula end 37, through
the restricted passage or space between the section 40 and the
outside of the interior marginal end 31; the air then passes
through the space between the section 41 and the outside of the
interior marginal end 31; from there the air can pass through air
vent holes 45 and 46 into the passageway 23' and from there to the
atmosphere. In FIG. 3 the terminal end 47 of the section 41 is
shown to be spaced from the interior surface of the end wall 24,
and the tip of the end 37 is shown to be spaced a relatively long
distance from the interior surface of the end wall 43 of the
section 40. When the valve 30 is moved from the initial position
shown in FIG. 3 by the closure 39 of the evacuated container 38,
the terminal end 47 of the section 41 is moved into abutment with
the end wall 24 of the holder 22 and the end wall 43 of the valve
30 is moved to a position relatively close to the tip of the end
37. In the position shown in FIG. 5, the valve ring 44 is in
sealing engagement with outside of the interior marginal end 31.
Accordingly, neither air nor blood can pass around the valve ring
44.
The holder 22 is preferably composed of a substantially rigid,
transparent material. As the valve 30 is also sufficiently
transparent, when the venipuncture is made, a blood telltale can be
seen at the open end 37. The user can then move the evacuated
container 38 further into the passageway 23' until the end 37 of
the cannula 21 has pierced through the end wall 43 of the valve 30
and has penetrated into the closure 39, as shown in FIG. 6. In this
position the open end 37 is sealed off by the closure 39. An
indicator 48 in the form of an annular ring is formed integrally
with the inside surface of the transparent holder body 23. As the
container 38 is being moved from the position shown in FIG. 5 to
the position shown in FIG. 6 by the user, the user can visually
observe the position of the terminal end 49 of the closure 39
relatively to the indicator 48. When the terminal end 49 of the
closure is brought into alignment with the indicator 48, the end 37
is embedded in the closure 39 (FIG. 6). As the container 38 and its
closure 39 are being moved from the position shown in FIG. 5 to the
position shown in FIG. 6, the valve 30 buckles eccentrically with
respect to the cannula interior marginal end 31. As shown in FIG.
6, this eccentric buckling takes place essentially only in the
section 41. As the internal diameter of the valve section 41 is
considerably greater than the external diameter of the interior
marginal end 31 of the cannula 21, the cannula 21 does not
essentially inhibit eccentric buckling of the section.
When the container 38 is moved still further into the passageway
23' from the position shown in FIG. 6 to the position shown in FIG.
7, the cannula opening at the end 37 communicates with the space
within the evacuated container 38, thereby enabling flow of blood
from the patient, through the cannula 21 and out of the open end 37
into the container 38. In this position, the valve 30 is buckled
eccentrically to even a greater extent than shown in FIG. 6. In the
position shown in FIG. 7, the end 49 of closure 39 is shown in
abutment with a conical internal surface 18 of a conical section
19. The conical surface 18 serves as a stop when the container 38
is moved from the position shown in FIG. 6 to the position shown in
FIG. 7. When the sample of blood has been collected, the container
38 is withdrawn from the passageway 23' and the valve 30 returns to
the position shown in FIG. 5. It is preferred to coat the interior
of the valve 30 with silicone or other suitable lubricants so that
the marginal end 42 of the valve 30 can more easily slide on the
hub 27 as the valve 30 is being shifted from the position shown in
FIG. 3 to the position shown in FIG. 5 and so that the interior
marginal end 31 will not impede either the compression,
specifically the eccentric buckling, or the subsequent extension of
the valve 30.
When the assembly is to be used, the closure 33 is removed and the
container 38 is inserted into the passageway 23' of the holder 22
as shown in FIG. 3. Thereafter, the sheath 28 is removed and
venipuncture is made. As soon as the venipuncture is made, the user
will see a small telltale of blood at the open end 37. The air that
is in the cannula 21 is vented through the restricted passage, the
section 41, the air holes 45 and 46, and the passageway 23' to the
atmosphere. The restricted passage permits only a very low rate of
blood flow but it is sufficient to provide the blood telltale. The
space within the section 40 is made as small as practical so that
the amount of blood that can pass into it when the valve 30 is in
the position shown in FIG. 5 if very small. As soon as the blood
telltale appears, the container 38 is moved to the position shown
in FIG. 5, thereby sealing off the opening at the end 37 from the
atmosphere. The container 38 can now be moved to the position shown
in FIG. 6. When the sample of blood is ready to be collected, the
container 38 is moved to the position shown in FIG. 7, at which
blood can pass through the open end 37 into the space within the
container 38. When the sample of blood has been collected, the
container 38 is removed from the passageway 23'. As the cannula 21
leaves the closure 39, the closure 39 automatically reseals to
maintain the sterility of the blood collected in the container 38.
The valve 30 automatically returns to the position shown in FIG. 5
because of its resilience and the end wall 43 automatically
reseals. In the position shown in FIG. 5, blood cannot flow past
the valve ring 44 into the space between the section 41 and the
interior marginal end 31. As soon as the blood sample has been
collected, the marginal end 29 of the cannula 21 can be withdrawn
from the patient's vein. However, should it be desired to take two
or more samples, this can be done without making another
venipuncture because the open end 35 of the cannula 21 can be left
in the patient's vein until all the samples have been collected. In
particular, assuming a second sample is to be collected, a second
container with its closure is inserted into the passageway 23'
either to the position shown in FIG. 6 and from there to the
position shown in FIG. 7, or directly to the position shown in FIG.
7. When the second sample has been collected, the container and its
closure are removed from the passageway 23' and valve 30
automatically returns to the position shown in FIG. 5. In like
manner, additional samples can be collected.
In the embodiment of FIGS. 8 and 9, the same reference characters
are used as in the embodiment of FIGS. 1 and 3 through 7, together
with the letter a, to designate components having the same general
construction, function and relative location. In FIG. 8, there are
shown fragmentary portions of a cannula 21a and a holder 22a. A
valve 30a differs from the valve 30 in that, instead of having air
vent holes 45 and 46, marginal end 42a of the valve 30a has a
groove 50. The groove 50 and hub 27a provide an air passage. The
valve 30a is shown in FIG. 8 to be in a position corresponding to
the initial position of the valve 30 in FIG. 3 in which there is
communication with the atmosphere via groove 50. When the valve 30a
is moved to a position corresponding to the position of the valve
30 in FIG. 5, an air seal is provided by the hub 27a and the inside
surface of the valve 30a beyond the groove 50.
In the embodiment of FIGS. 10 and 11, the same reference characters
are used as in the embodiment of FIGS. 1 and 3 through 7, together
with the letter b, to designate components having the same general
construction, function and relative location. In FIG. 10 there are
shown fragmentary portions of a cannula 21b and holder 22b. Valve
30b differs from the valve 30 in that it has no air vent holes 45
and 46. However, hub 27b has a projection or spacer 51. Marginal
end 42b embraces the hub 27b, but a groove or air passage 52, 53 is
provided at each side of the projection 51 between the marginal end
42b and the hub 27b. The valve 30b is shown in a position in which
the air passages 52 and 53 provide communication with the
atmosphere. When the valve 30b is moved to a position corresponding
to the position of the valve 30 in FIG. 5, the terminal end 47b of
the valve 30b is in sealing abutment with the inside surface of the
end wall 24b, thereby preventing communication with the
atmosphere.
In the embodiment of FIGS. 12, 13 and 14, the same reference
characters are used as in the embodiment of FIGS. 1 and 3 through
7, together with the letter c, to designate components having the
same general construction, function and relative location. FIGS. 12
and 14 depict fragmentary portions of cannula 21c and holder 22c,
together with valve 30c. The valve 30c is shown in its initial
position in FIG. 12 corresponding to the position of the valve 30
in FIG. 3, and the valve 30c is shown to be in different position
in FIG. 13 corresponding to the position of the valve 30 in FIG. 5.
The valve 30c does not have a valve ring or seal as does the valve
30. However, the hub 27c has stepped sections 54 and 55. The hub
section 54 has a slightly smaller diameter than the hub section 55.
In assembling the valve 30c onto the hub 27c it is brought up
against shoulder 56 provided by the section 55. An internal groove
57 in the hub 27c extends along the entire length of the hub
section 54 and extends along part of the length of the hub section
55. When the valve 30c is in the position shown in FIG. 12, air can
pass out of the open end 37c of the cannula 12c, through the space
between small internal diameter section 40c and the interior
marginal end 31c of the cannula 21c through the space between the
large diameter section 41c, through the air passage provided by the
groove 57, and through passageway 23' to the atmosphere. When the
valve 30c is moved from the position shown in FIG. 13 by moving the
container 38 and its closure 39 further into the passageway 23c',
marginal end 42c is moved into embracing and sealing relationship
with the hub section 55 beyond the groove 57, thereby closing off
the groove 57.
In the embodiment of FIGS. 15 through 21, the same reference
characters are used as in the embodiment of FIGS. 1 and 3 through
7, together with the letter d to designate components having the
same general construction, function and relative location. In FIG.
15, there are shown fragmentary portions of a cannula 21d and a
holder 22d. A one-piece valve 30d differs from the one-piece valve
30 in several respects. The valve 30d is shown to have a body with
columns 60 and 61. The two columns 60 and 61 are shown to be
diametrically opposite each other. Each column 60 and 61 is shown
to be generally T-shaped in construction. The vertical bar part of
each T-shaped column extends in a radial direction and the
horizontal bar part of each T-shaped column extends in a
directional perpendicular to the associated vertical bar part. The
columns 60 and 61 are shown to be equally spaced apart. It is
preferred to use two columns but it is within the spirit of the
invention to use more than two columns, if desired. The columns are
preferably identical in length, cross-sectional area, shape and are
symetrically located relative to the center line of the cannula
21d. This provides outward buckling as the valve 30d is moved from
the position of FIG. 16 through the position of FIG. 17 to the
position of FIG. 18. Accordingly buckling of columns 60 and 61 is
completely free and unimpeded because there is no contact between
the columns and the cannula 21 d during distention of the valve
30d. Likewise, resilient extension or straightening out of the
columns 60 and 61, due to their construction and the nature of the
material of which the valve 30d is composed, is also completely
free and unimpeded because there is no contact between the columns
and cannula 21d during extension of the valve 30d.
The one ends of the columns 60 and 61 are integrally joined by an
annular collar or ring 62 which is slideably received by hub
portion or hub 27d. The other ends of the columns are joined to a
ring-shaped section 63 which is joined to a relatively small
internal diameter section 40d. The buckling of the valve 30d takes
place essentially entirely in the columns 60 and 61. When the
columns 60 and 61 are completely buckled as shown in FIG. 18, the
columns 60 and 61 are buckled in two different directions as is
evident by a comparison to FIG. 17.
As in the embodiment of FIGS. 1 and 3 through 7, the section 40d is
provided with an internal annular valve ring 44d for the same
purpose. It is apparent that upon making the venipuncture, air can
be vented to the atmosphere through the space between the cannula
31d and the side wall 65 above the valve ring 44d, through the
space between columns 60 and 61, and through the space between the
container 38 and the inside of the tubular body 23. The valve is
closed off when in the position of FIG. 16. As in the other
embodments, the valve 30d, and in particular the end of the section
40d is provided with an end wall 43d, in alignment with the cannula
21d, which is pierceable and resealable. As in the other
embodiments the blood telltale is visible through the transparent
holder 22d and the transparent valve 30d. The valve 30d is
preferably composed of the same material as the other embodiments
of the valve.
The embodiments of the blood collecting assembly shown in FIGS. 8
and 9, 10 and 11, 12, 13 and 14, and 15 through 21 are used in the
same manner as the blood collecting assembly of the embodiment of
FIGS. 1 and 3 through 7.
While it is evident that a valve as exemplified in the drawings in
all the various embodiments is particularly useful when it is
desired to make more than one venipuncture, the holder shown in the
drawings can also be used without a valve. The holder is injection
molded to the cannula; specifically, the holder has an end wall
with an integral outwardly extending projection or hub and an
inwardly extending projection or hub. The end wall and these hubs
are injection molded about a substantial portion of the length of
the cannula to provide solid holding of the cannula. The tapering
section which joins the end wall and the tubular body makes an
included angle of about 56.degree. and is preferably between about
40.degree. and 90.degree.. This enables the venipuncture to be made
at a more shallow angle of approach. This range of angles allows
the exterior marginal end of the cannula to be relatively short,
such as one inch, and this results in a cannula of shorter than
usual length which affords the user greater control, and is less
costly to manufacture in the first place. The relatively short
exterior marginal end means that for a cannula of a given outside
diameter and a given wall thickness, the exterior marginal end is
more rigid. By way of example not limitation, the outside diameter
of the holder body is about 0.80 inch, but it can be within a range
of between about 0.550 inch and 0.850 inch. The wall thickness of
the tubular body, the tapering section and the end wall are each
about 0.05 inch, the outwardly extending hub is about 0.35 inch in
length, the inwardly extending hub is about 0.25 inch in length and
the interior marginal end of the cannula is about 0.65 inch in
length.
Various modifications of the foregoing embodiments will suggest
themselves to those skilled in the art, and all such of these are
within the scope of the invention which is best defined by the
appended claims.
* * * * *