Wound drain catheter

The wound drain catheter of the present invention is comprised of a drain portion connected to an outflow tube portion. The drain portion comprises a central core with plural T-shaped members projecting therefrom to form plural lumens having respective longitudinal grooves for fluid communication with the wound. This drain has a uniform cross-sectional area and is preferably made from a silicone elastomer having a durometer shore between 40 and 70 shore A. Such uniform cross-sectional area provides added strength to prevent the drain from breaking during its removal from the patient's body, and the silicone elastomer provides sufficient elasticity to permit the cross-sectional area of the drain to decrease by at least 30 percent when a pulling force is applied thereto, thereby reducing the gripping force of tissue surrounding the wound.

BACKGROUND OF THE INVENTION 
The present invention relates to wound drain catheters for draining fluid 
from, or supplying medication to, a closed deep wound. This invention also 
relates to a method for attaching a stainless steel trocar to a silicone 
outflow tube of a catheter. 
Virtually all wound drain catheters used in closed wounds comprise a drain 
portion for fluid communication with the wound and an outflow or extension 
tube portion. Typically, the tube portion is connected to a vacuum supply 
after (a) the drain has been placed in the wound and (b) the wound, or 
surgical incision, has been closed. The most common type of prior art 
drain comprises a length of tubing which is perforated by forming spaced 
apertures through the tubing wall. These apertures are usually in opposed 
pairs and, while the spacing between aperture pairs may vary, such 
aperture pairs are typically spaced by a distance equal to approximately 
twice the diameter of the tubing. One major problem with these prior art 
drains is that wound debris, such as clots, may block a number of the 
apertures, thereby substantially reducing the effectiveness of the drain. 
A more serious problem is that, as the wound heals, tissue tends to grow 
into the apertures. Such tissue growth not only blocks the apertures, but, 
in addition, when the physician removes the drain by applying a strong 
pulling force on the catheter, the portion of tissue that has grown into 
the apertures will be literally ripped from the patient's body. This 
causes severe discomfort to the patient and retards the healing process. 
Moreover, if the tissue growth into the aperture is extensive, the drain 
may break when the physician attempts to remove it, thereby leaving a 
portion of the drain in the patient's body. If this occurs, additional 
surgery may be required to extract the broken portion of the drain. 
A further disadvantage of prior art perforated drains is that their 
apertures tend to structurally weaken the drain. Since the cross-sectional 
area of the drain body is reduced at each of the apertures, the apertures 
create weak points in the drain tube wall. Further, when tensile forces 
are applied to the drain, the tensile stresses at the top and bottom of an 
aperture are particularly high, since the tensile forces are unable to 
pass across the aperture. That is, the material adjoining the aperture 
must carry the stresses which are unable to bridge the aperture in 
addition to its normal share of the stress. Thus, an area of 
discontinuity, such as an aperture, is commonly referred to as a "stress 
raiser". Perforated drains, therefore, are much weaker than their drain 
body cross-sectional area suggests, since each of the perforations creates 
a "stress raiser". 
Moreover, since perforated drains have a tubular structure, they tend to 
kink when bent or squeezed, as by movement of the patent. If this occurs, 
the effectiveness of the drain may be substantially impaired, thereby 
warranting premature removal of the drain. 
Wound drains made from a silicone elastomer are usually preferable to 
drains made from other materials, since silicone is highly biocompatible, 
soft, and flexible. In contrast, materials such as PVC are more rigid, and 
therefore, tend to irritate the wound. This causes substantial discomfort 
to the patient and inhibits healing. Further, PVC is less biocompatible 
than silicone. Materials such as natural rubber are seldom ued for closed 
wound drains because of toxicity problems. Thus, silicone is typically the 
most advantageous material for closed wound drains. However, silicone is 
not as strong as PVC, and thus, it tends to rupture more easily during 
drain removal from a closed, deep wound. This has limited the usefulness 
of silicone drains in many applications. 
For the purpose of illustrating the structural characteristics of a typical 
perforated drain, one exemplary form of prior art perforated drain, in 
common and widespread use, will be described. This exemplary drain has an 
outside diameter D, an inside diameter about one-half D, opposed pairs of 
perforations having a diameter of about one-half D, and an axial spacing 
of about 2D. Using well known mathematical formulas, it may be found that 
this exemplary drain has a lumenal drainage area of 0.196D.sup.2, a tissue 
contact drainage area of 0.196D.sup.2 units per unit D of length, and a 
drain body cross-sectional area of 0.0307D.sup.2 at each of the aperture 
pairs. These parameter values will be subsequently compared to 
corresponding parameter values for the present invention, in order to 
contrast the significant improvements in drain effectiveness and strength 
provided by the present invention. 
Non-perforated drains have been proposed for use in shallow surface wounds, 
such as those created by plastic surgery. For example, a drain of this 
type is illustrated in U.S. Pat. No. 3,860,008, issued to Miner et al. 
Another similar type of non-perforated drain is disclosed in U.S. Pat. No. 
105,038 (British), issued to Liddell. Both of these drains, however, are 
specifically designed to be patent to the atmosphere, rather than to an 
outflow tube. Thus, the drain is always exposed to infection causing 
organisms. Consequently, the problems associated with closed, deep wounds, 
such as providing an aseptic environment, and providing safe, reliable 
drain removal while maintaining drain effectiveness, are not addressed. 
Several techniques may be used to insert a wound drain catheter in the 
patient's body. For example, a surgeon may simply place the drain portion 
and a small part of the outflow tube portion in the wound, close the 
incision, and suture around the outflow tube portion. This technique is 
somewhat unsatisfactory, since it is difficult to completely seal the area 
around the outflow tube by suturing, and thus, the wound may become 
infected. A more satisfactory technique is to pass a trocar, preattached 
to the end of the outflow tube, through healthy tissue by entering the 
patient's body at a point within the wound and exiting at a point adjacent 
to the wound. The surgeon pulls the outflow tube portion through the 
tissue with the trocar until the catheter is properly positioned, with the 
drain in the wound. Since the outflow tube exits the body at a point 
adjacent the wound, the wound can be completely closed by suturing, 
thereby reducing the risk of infection. 
When outflow tubes made from silicone are used, the trocar and the tube 
sometimes separate, leaving the end of the outflow tube in the patient's 
body. If this occurs, the outflow tube must be removed and the procedure 
repeated. Such separation is due to the difficulty of attaching the trocar 
to the outflow tube. Typically, the end of the trocar includes a connector 
portion having annular ridges which grippingly engage the inner surface of 
the outflow tube. However, since a silicone catheter tube is soft and 
flexible, it tends to easily detach itself from the annular ridges when 
subjected to tensile force. Accordingly, there is a need for an improved 
method of attaching a silicone catheter tube to a trocar. 
SUMMARY OF THE PRESENT INVENTION 
The present invention comprises a wound drain which, in comparison with 
similarly sized prior art drains, has an increased tissue contact drainage 
area, and an increased lumenal flow drainage area. Thus, the drain of the 
present invention is substantially more effective than prior art drains. 
Further, the specific configuration of this drain provides an increased 
drain body cross-sectional area, and eliminates stress risers (weak 
points) in the drain body. This makes the drain of the present invention 
significantly stronger than comparably sized prior art drains, and 
therefore, it is less likely to break during removal. Moreover, this drain 
configuration reduces the risk that tissue growth will inhibit removal of 
the drain. Thus, the drain provides safety, reliability, and effectiveness 
not found in prior art drains. 
The wound drain of the present invention is fluted and, in a first 
embodiment, comprises a central core with four strut portions projecting 
radially therefrom. The radial strut portions are of equal size and are 
spaced at equal angles relative to each other. An overhang portion is 
provided at the end of each of the four strut portions, thereby forming 
four T-shaped members. These overhang portions from the periphery of the 
wound drain, and thus, the overhang portions and strut portions cooperate 
to form four channels or lumens which extend throughout the length of the 
drain. Viewed cross-sectionally, the overhang portions cooperate to form a 
segmented circle having gaps between adjacent overhang portions. The gaps 
extend longitudinally throughout the length of the drain, and thus, form 
grooves which permit fluid entry into the lumens. 
The grooves may have a width of about 0.05 to 0.2 times the diameter (D) of 
the drain. Since such width is significantly smaller than the apertures of 
perforated drains (typically 0.5D), the drain of the present invention is 
much more effective in preventing the entry of clots or tissue growth into 
the lumens. However, even though the width of the grooves is relatively 
small, their combined tissue contact drainage area is about 0.4D.sup.2 per 
unit D of length, assuming a groove width of 0.1D. In contrast, the 
previously described prior art perforated drain has a tissue contact 
drainage area of only 0.196D.sup.2 per unit D of length. Thus, the drain 
of the present invention has about twice the tissue contact drainage area, 
and therefore, is significantly more effective. 
The combined cross-sectional area of the lumens, that is, the lumenal flow 
drainage area, is equal to the total cross-sectional area of the drain 
less the drain body cross-sectional area. Thus, as an illustration, if the 
drain body cross-sectional area is assumed to be 0.411D.sup.2, the lumenal 
drainage area is 0.374D.sup.2. This is about 1.9 times the lumenal flow 
drainage area (0.196D.sup.2) of the previously described perforated drain. 
Thus, in addition to providing twice the tissue contact drainage area, the 
fluted drain of the present invention provides nearly twice the lumenal 
flow drainage area. 
This fluted drain is uniform in cross-section throughout its length, and 
therefore, stress risers and weak points in the drain are eliminated. 
Further, the above-mentioned drain body cross-sectional area of 
0.411D.sup.2 is about one-third greater than the cross-sectional area of a 
perforated drain at its opposed aperture pairs. Therefore, in addition to 
nearly doubling the tissue contact and lumenal flow drainage areas, the 
drain body cross-sectional area of the present invention is greater by a 
factor of approximately one-third. 
The increased area of the drain body and elimination of stress risers 
significantly increases the tensile strength of the drain and thereby 
reduces the risk that the drain might rupture during removal. Since this 
risk is particularly acute in drains made from a silicon elastomer, the 
present invention is particularly appropriate for this type of drain. 
Tests were conducted to compare the tensile strength of a typical, 
commercially available, 19 French (about 0.25 inch), round, perforated, 
silicone drain; a 10-mm flat, perforated, silicone drain; and a 19 French, 
fluted drain, made from a 50 Shore A silicone, and having four lumens. 
These tests showed that both of the perforated drains ruptured at a 
tensile force of about 8 to 10 pounds, while the fluted drain ruptured at 
22 pounds. Thus, the fluted drain of the present invention has more than 
twice the tensile strength of comparable perforated silicone drains. 
Although the increased tensile strength of the fluted drain provides added 
protection against a drain breaking off within the patient's body during 
removal, it is believed that this risk is even further reduced by other 
characteristics of the present invention. For example, the above-described 
tensile strength tests also showed that the cross-sectional area of the 
drain decreases rapidly when a pulling force is applied thereto. 
Specifically, it has been found that a pull force of only 2 pounds 
decreases the cross-sectional area of the drain by 50 percent, and that a 
pull force of 12 pounds decreases the cross-sectional area by 75 percent. 
A reduction in cross-sectional area of at least 30 percent in response to 
a two-pound pull force is considered to be advantageous. As the surgeon 
removes the drain, the pulling force causes it to "neck down", or reduce 
in cross-sectional area, along its length, thereby relieving the gripping 
force of the tissue and permitting the drain to be more easily removed. 
Moreover, since, as described above, the width of the grooves is 
relatively small, it is unlikely that tissue will grow into the lumenal 
flow path. However, even if such tissue growth does occur, it is believed 
that this will not restrict removal of the drain, since any such tissue 
growth will be along the grooves, and thus, the tissue will simply slide 
in the grooves when the drain is removed. This minimizes the danger of 
tissue damage and reduces discomfort to the patient. 
Although the above-described drain has four flutes, it will be understood 
that a different number of flutes may be used. However, it has been found 
that for drains manufactured from silicon having a durometer shore between 
40 and 70 shore A, providing four flutes has significant advantages over 
more or less members of flutes. For example, drains having more than four 
flutes require more raw materials for manufacture, and, while extra flutes 
may add a slight amount of strength, they offer few other advantages. On 
the other hand, drains having less than four flutes tend to kink easily. 
Further, they are susceptible to being squeezed or pinched by the movement 
of surrounding body tissue, thereby rendering them ineffective. It has 
been found that a three-fluted drain provides some kink resistance, and 
thus, may be appropriate in some cases. However, drains having less than 
three flutes are considered to be far less practical, since they are 
extremely susceptible to squeezing, pinching, and binding, and thus, do 
not function properly. The four-fluted drain, therefore, provides the most 
advantageous balance between kink resistance and the amount of raw 
material needed to form the drain. 
In a second embodiment of the present invention, the drain has a somewhat 
different configuration. Although this drain functions in the same manner 
as the drain of the first embodiment, its overhand portions, when viewed 
cross-sectionally, cooperate to form a segmented oval rather than a 
segmented circle. This drain is particularly appropriate for use between 
organs, or in other areas where surgeons typically prefer drains having an 
oval or flat profile. However, like the drain of the first embodiment, the 
drain of the second embodiment is specifically designed for use in 
draining closed, deep wounds. 
In either embodiment, the drain portion of the catheter is preconnected to 
the outflow tube portion. This may be accomplished by forming a butt joint 
between the ends of the drain and tube, and connecting them by a collar. 
However, since the lumens of the present invention are spaced about the 
periphery of the drain, rather than at its center, it is possible that the 
butt joint may close the end of the lumens, thereby prohibiting fluid flow 
from the drain into the outflow tube. Accordingly, the end of the drain, 
which is joined to the outflow tube, is undercut to provide a 
semi-spherical recess for fluid communication between the lumens and the 
outflow tube. Thus, fluid travels through the lumens, into the 
semi-spherical recess, and from the semi-spherical recess into the outflow 
tube. This prevents the butt joint from inhibiting proper operation of the 
drain. 
Another aspect of the present invention relates to a method of attaching a 
stainless steel trocar to an outflow tube made from a silicone elastomer. 
The connector portion of the trocar is coated with a primer which creates 
a bonding surface compatible with both stainless steel and silicone. Since 
the connector portions of trocars typically have annular ridges, the 
spaces between the ridges are filled with a silicone adhesive sealant 
prior to inserting the silicone outflow tube onto the connector portion. 
This provides a strong bond between the tube and connector portion 
throughout the length of the connector portion, and insures that the 
outflow tube will not separate from the trocar when the connector portion 
is passed through tissue.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
Referring to FIG. 1, the wound drain catheter 10 of the present invention 
includes a flexible drain portion 12 preconnected to a flexible outflow 
tube portion 14. The drain 12 and a small part of the tube 14 are placed 
in the patient's body 16 with the drain portion 12 in fluid communication 
with the wound 18. Preferably, the outflow tube 14 is connected to a 
sealed, sterilized suction device (not shown) for drawing fluid through 
the wound drain catheter 10. In addition, it is also preferable that the 
outflow tube 14 exit the patient's body 16 through an aperture 20 formed 
in healthy tissue, adjacent to the wound 18. Further, the outflow tube 14 
should have a smooth exterior to permit the surface tissue surrounding the 
aperture 20 to seal against the exterior of the tube 14, and thus, prevent 
air from passing therebetween. This permits the wound 18 to be completely 
closed, as by sutures 22, and covered with a dressing (not shown) to form 
an aseptic barrier, thereby sealing the wound from the atmosphere. Thus, 
since the drain 12 is patent only to the sterile suction device, and not 
to the atmosphere, risk of infection is reduced. 
The drain of the present invention is fluted, and is preferably radially 
symmetrical. In a first embodiment, the drain 12 comprises an elongate, 
cylindrical core portion 30 with four strut portions 32 projecting 
radially from the core 30 along its longitudinal axis. The radial strut 
portions 32 are of equal size and are spaced at equal angles relative to 
each other. Each of the outer ends of the strut portions 32 have 
respective overhang portions 34 which extend longitudinally throughout the 
length of the strut portions 32. Viewed cross-sectionally, as best seen in 
FIG. 3, the overhang portions 34 are thin arcuate members which extend an 
equal distance on either side of their respective strut portions 32. Thus, 
the overhang portions 34 and respective strut portions 32 combine to form 
four T-shaped members. The overhang portions 34 are sized to form a 
segmented circle at the periphery of the drain 12, with small gaps between 
adjacent overhang portions 34. Each of these gaps forms a longitudinal 
groove 36, parallel to the longitudinal axis of the core 30, and extending 
throughout the length of the drain 12, as shown in FIG. 2. The core 
portion 30, strut portions 32, and overhang portions 34 cooperate to form 
plural channels or lumens 38 along the length of the drain 12. The grooves 
36 permit fluid communication between a respective one of the lumens 38 
and the wound 18 (FIG. 1). Preferably, the width of the grooves 36 is 
approximately 0.05 to 0.2 times the outside diameter of the drain. This 
insures adequate tissue contact drainage area while inhibiting tissue 
growth or entry of debris, such as clots, into the lumens 38. 
Although the embodiment shown in FIGS. 2 and 3 is described as having four 
lumens 38, it will be recognized that a different number of lumens 38 may 
be provided by varying the number of strut portions 32 and respective 
overhang portions 34. For example, the triple lumen drain 12(a), shown in 
FIG. 4, utilizes three strut portions 32(a) and three respective overhang 
portions 34(a) to form three lumens 38(a). Other combinations will be 
apparent to those skilled in the art. However, for fluted drains 
manufactured from a 40-70 shore A silicone elastomer, it has been found 
that the number of lumens provided is critical. For example, drains having 
less than three lumens are far less practical, since they are extremely 
susceptible to punching, kinking, and squeezing. Moreover, drains having 
more than four lumens require additional raw material per unit of length 
if the T-shaped struts are of a sufficient thickness to provide enough 
strength to hold their shape. Such a drain would have a reduced lumen 
sectional area, with few compensating advantages. Further, while three 
lumen drains provide some kink resistance, it has been found that a four 
lumen drain provides the most advantageous balance between kink resistance 
and unit cost of manufacture. Thus, the four-fluted drain is particularly 
desirable. 
The fluted drain 12 of the present invention is uniform in cross-section 
throughout its length to eliminate stress raisers or weak points in the 
drain 12. Further, the drain 12 is preferably made from a highly 
biocompatible elastomer, such as silicone, having a durometer shore in the 
range of 40 to 70 shore A. This makes the drain 12 very soft and pliable, 
particularly at the lower end of the range, to reduce patient discomfort 
and irritation of the wound 18 (FIG. 1), while providing sufficient 
rigidity for added kink resistance. Moreover, this durometer shore rating 
permits the drain 12 to reduce in cross-sectional area when a relatively 
small pulling force is applied to remove the drain 12 from the wound 18. 
This characteristic of the drain 12 is illustrated in FIG. 5, which shows 
the drain 12 decreasing in cross-sectional area as the surgeon applies a 
pulling force thereto. Such decrease in cross-sectional area begins at the 
end of the drain 12 closest to the body opening 20 (FIG. 1) and 
progressively continues, as shown in phantom lines in FIG. 5, throughout 
the length of the drain 12. This relieves the gripping force of the 
tissue, and thereby makes the drain 12 easier to extract from the patient, 
reduces the risk of damage to the tissues surrounding the wound 18, and 
reduces the risk of drain breakage. 
The drain 12 is preferably radially symmetrical. As used herein, radially 
symmetrical means that for plural, equiangular radii extending from a 
central longitudinal axis, the number of such plural radii being equal to 
the number of drain lumens, there are corresponding parts of the drain on 
each of said plural radii, regardless of the orientation of such 
equiangular radii about such central axis, and regardless of the distance 
of such corresponding parts from the central axis. In the case of the 
drain 12, such corresponding parts of the drain will, additionally, be 
equidistant from the central axis, since the drain 12 is round. Such 
radial symmetry permits the drain to decrease in cross-sectional area 
uniformly along each of the plural radii, thereby reducing any tendency of 
the drain to twist in the wound as the drain is pulled therefrom. Further, 
such symmetry permits the drain to lie in the wound in any orientation and 
to drain from openings spaced equiangularly around its periphery for 
increased effectiveness. Moreover, it makes the compressive strength of 
the drain uniform along such radii. 
The ends of the drain 12 and outflow tube 14 may be connected together in 
abutting relationship by means of a flexible tubular collar 40, as shown 
in FIG. 7. This collar 40 spans the butt joint 39 and may be affixed to 
the drain 12 and tube 14 by a suitable adhesive material. However, in 
applying the adhesive, care must be exercised to prevent the adhesive from 
clogging the lumens 38. Preferably, the ends of the collar 40 are gently 
tapered towards the outer walls of the drain 12 and tube 14 to eliminate 
any projections which may cause tissue damage during removal of the 
catheter 10. Although the butt-type joint 39 is not essential, it is 
preferable, since it provides added strength and kink resistance at the 
connection. However, the butt joint 39 may tend to block the ends of the 
lumens 38 (FIGS. 2 and 3), and thus restrict fluid flow from the lumens 38 
into the tube 14. To prevent this from occurring, a portion of the core 30 
is removed by forming a semi-spherical cutout or recess 42 in the abutting 
end of the drain 12, thereby permitting fluid communication between the 
lumens 38 (FIGS. 2 and 3) and the semi-spherical recess 42. Thus, even if 
the butt joint 39 blocks fluid flow through the end of the lumens 38, the 
recess 42 provides an unrestricted flow path which permits fluid to travel 
from the lumens 38 into the recess 42, and from the recess 42 into the 
outflow tube 14. 
To insure a bond of sufficient strength between the tubular collar 40 and 
the drain 12, it is crucial that the overhang portions 34 conform to the 
interior wall of the collar 40 to permit contact therewith throughout a 
substantial portion thereof. In the embodiment described above, the 
overhang portions 34 contact the interior wall of the collar 40 through 75 
to 80 percent of its circumference. The precise percentage of 
circumferential contact will, of course, vary, depending on the width of 
the grooves 38. However, such percentage should be at least 50 percent to 
insure an adequate bond between the collar 40 and drain 12. 
In contrast to the round cross-sectional contour of the drain 12, a second 
embodiment of the present invention provides a drain 50 with an oval 
cross-sectional contour, as shown in FIGS. 7 and 8. Unless otherwise 
indicated, the term "closed curve" will be used generically as referring 
to any contour which will cooperate with the inside surface of a mating 
tube, such as the tubular collar 40. The drain 50 preferably is also 
radially symmetrical. However, since the drain 50 is oval, rather than 
round, the corresponding parts of the drain, referred to in the above 
definition of radial symmetry, will not be equidistant from the central 
axis. Thus, although both the drains 12,50 are radially symmetrical, the 
drain 50 differs from the drain 12 in this respect. The drain 50 also has 
diametrical symmetry, which, as used herein, means that for opposed radii 
(i.e., 180 degrees relative to each other) extending from a central axis, 
there are corresponding parts of the drain on such radii, equidistant from 
the central axis, regardless of the orientation of such radii about the 
axis. Of course, the drain 12 of the first embodiment also has diametric 
symmetry. Such symmetry has many of the same advantages as radial 
symmetry. 
The drain 50 functions in the same manner as the drain 12. Further, the 
drain 50, like the drain 12, is specifically designed for use in draining 
closed, deep wounds. However, the oval or flat configuration of the drain 
50 makes it particularly useful for draining areas between organs, or 
other areas where surgeons typically prefer drains having an oval or flat 
profile. 
The drain 50 comprises a central strut or core portion 52 perpendicularly 
connected at its ends to respective side strut portions 54,55. Respective 
overhang portions 56 are connected to each of the ends of the side strut 
portion 54. Similarly, respective overhang portions 57 are connected to 
each of the ends of the side strut portion 55. The struts 54,55 and 
overhang portions 56,57 form plural T-shaped members radiating from the 
core 52. As best seen in FIG. 8, the two pairs of overhang portions 56,57, 
respectively, cooperate to form a segmented oval. Further, like the 
overhang portions 34 of the drain 12, the overhang portions 56,57 of the 
drain 50 form longitudinal grooves 58 (FIG. 7) throughout the length of 
the drain 50. The pair of overhang portions 56 extend arcuately from the 
strut portion 54 and cooperate with the outer wall of the strut portion 54 
to form an essentially semi-circular lumen 60. In like manner, the pair of 
overhang portions 57 extend arcuately from the strut portion 55 and 
cooperate with the outer wall of the strut portion 55 to form a second, 
essentially semi-circular, lumen 61, in opposed relationship to the lumen 
60. Additionally, the overhang portions 56,57 extend on either side of the 
central strut portion 52, in parallel relationship thereto, to form a pair 
of essentially rectangular lumens 62,63 on opposite sides of the central 
strut portion 52. Thus, viewed from the perspective of FIGS. 7 and 8, the 
drain 50 has two side lumens 60,61, a top lumen 62, and a bottom lumen 63. 
Further, each of the lumens 60,61,62,63 has a respective longitudinal 
groove 58 for fluid communication with the wound. Therefore, drainage is 
provided from each of four sides of the drain 50. 
The drain 50 may be connected to an outflow tube by providing a suitable 
connector, formed in accordance with the teachings discussed in reference 
to FIG. 6. For example, referring to FIG. 9, a tubular collar 64 is 
adapted at one end 65 for connection to a round outflow tube 14 and at the 
other end 66 for connection to the oval drain 50. An annular flange 67, 
projecting inwardly from, and perpendicular to, the interior surface of 
the tubular collar 64, is provided a short distance from the end 66. The 
portion of the collar 64 between the flange 67 and end 66 is sized to 
receive the drain 50. Further, the portion of the collar 64 between the 
annular flange 67 and end 65 is tapered to provide a smooth transition 
between the drain 50 and tube 14. When the drain 50 is inserted into the 
collar 64, the annular flange 67 prevents the drain 50 from extending 
into, and thus, being squeezed by, the tapered transition portion of the 
collar 64. This prevents the ends of the lumens 60,61,62,63 from being 
accidentally closed when the catheter is assembled. However, it is 
possible that the flange 67 may block the ends of the lumens 60,61,62,63 
in the same manner that the butt joint 39 (FIG. 6) may block the lumens 38 
of the drain 12. Accordingly, it is preferable to provide a recess (not 
shown) in the end of the drain 50, formed according to the teachings 
discussed in reference to the recess 42 of FIG. 6. This recess functions 
in the same manner as the recess 42 to permit fluid communication between 
the drain 50 and tube 42, even if the lumens 60,61,62,63 are blocked by 
the flange 67. As an alternative to this recess, the flange 67 may be 
provided with slots (not shown) which are oriented to align with the 
lumens 60,61,62,63, respectively, and thus, provide a flow path from one 
side of the flange 67 to the other. 
The drain 50, as well as the drain 12 (FIGS. 2 and 3), may be formed in one 
step by well known extrusion processes. Thus, the drains 12,50 of the 
present invention may be manufactured at less cost than perforated drains. 
A drain constructed in accordance with FIGS. 1 to 9 provides approximately 
twice the tissue contact drainage area, twice the lumenal flow drainage 
area, and twice the tensile strength of comparable prior art perforated 
drains. Further, it substantially reduces patient discomfort, wound 
irritation, and tissue damage, particularly during removal of the drain. 
Moreover, this drain is safer and more reliable than comparable prior art 
drains, and may advantageously be manufactured from highly biocompatible 
material by a relatively low cost, one-step extrusion process. Thus, the 
drain of the present invention provides significant advances with respect 
to wound drain catheters for closed, deep wounds. 
Referring to FIG. 10, it is preferable, although not essential, to insert 
the catheter 10 (FIG. 1) in the patient's body by means of a trocar 70. 
The trocar 70 is a rod-shaped, stainless steel, surgical instrument having 
a blade portion 72 at one end and a connector portion 74 at the other end. 
The connector portion 74 has plural annular ridges 76 which grippingly 
engage the interior wall of the outflow tube 14 to attach the trocar 70 
and tube 14 together. However, as previously mentioned, this method of 
attachment has proven to be unsatisfactory for use with a silicone outflow 
tube 14, since the outflow tube 14 is often separated from the trocar 70 
when the connector portion is passed through body tissue. Accordingly, the 
present invention includes an improved method for attaching the trocar 70 
to the outflow tube 14. 
Although the outflow tube 14, discussed in reference to FIG. 10, is 
described as being made from silicone, it will be understood that the 
outflow tube 14, as discussed in reference to other drawings, may be 
formed from materials other than silicone. 
The improved method of attachment involves coating the connector portion 74 
with a primer 77 (FIG. 11) which creates a bonding surface compatible with 
both stainless steel and silicone. Such a primer 77 is commercially 
available from Hughson Chemicals, Lord Corporation, Erie, Pa., under the 
name Chemlok.RTM., manufacturer's designation V-B-311-312/Primer/(40G)/PI. 
After coating the connector portion 74 with the primer 77, the spaces 
between the annular ridges 76 are filled with a silicone adhesive sealant 
78, as shown in FIG. 11. The sealant filler 78 is commercially available 
as RTV Silicon Rubber Adhesive Sealant, manufactured by General Electric 
Company, Waterford, N.Y. The silicone outflow tube 14 is then inserted 
onto the connector portion 74, as shown in FIG. 12. The sealant filler 78 
provides a contact surface between the tube 14 and connector portion 74 
throughout the length of the connector portion 74, and thus creates an 
extremely strong bond between the tube 14 and trocar 70. The foregoing 
method of attachment, therefore, substantially reduces the risk that the 
outflow tube 14 may separate from the trocar 70 when the connector portion 
74 passes through tissue, and thus reduces the risk of procedure 
complications and injury to the patient.