Luer cap

A luer cap for use on ports of medical devices such as cardiotomy reservoirs and blood sets. The cap comprises an outer wall (10) having a generally circular cross-sectional shape. An inner wall (12) and end wall (20) define an internal port receiving cavity (13). The inner wall (12) is threaded to mate with threads or a flange on a female luer port. The mating surfaces of the luer cap and the luer port can be sterilized through a hollow tubular portion (18), end wall (20), and outer wall (10) of the luer cap.

BACKGROUND OF THE INVENTION 
This invention relates to an improved luer cap for medical devices, 
principally for use on medication ports, connecting ports, and injection 
ports of medical devices. 
Many medical devices such as cardiotomy reservoirs, blood sets, and 
oxygenators have ports for access to the devices. Since many of the 
devices process a patient's blood for a variety of medical treatments, 
e.g., oxygenation of blood during a heart-lung bypass operation, it is 
frequently necessary that a physician, nurse, or medical technician have 
access to the device to add medication to the patient's blood or to take a 
blood sample. Because of this need, many medical devices have ports which 
are covered by a protective cap. When access is necessary, the caps are 
removed to uncover the port. 
The major problem with prior art port caps is the inability to sterilize 
through the cap once it is placed on a port in the manufacturing process. 
An additional problem is that, prior to this invention, no luer cap was 
available through which sterilization could occur and which would not leak 
air or liquid when subjected to a positive or negative pressure during 
operation of the device. 
The term "luer" is derived from the name of a German instrument maker who 
developed a medical syringe in the Nineteenth Century. The term "luer-lok" 
is defined in Dorland's Illustrated Medical Dictionary, 25th Edition, as 
"a glass syringe for intravenous and hypodermic use, with a metallic tip 
and locking device to hold the needle firmly in place." 
FIGS. 3 and 4 of U.S.A. Standard Z70.1-1955, "Dimensions of Glass and Metal 
Luer Tapers for Medical Applications," show respectively female luer lock 
and male luer lock connectors. Burd U.S. Pat. No. 4,133,312 shows a luer 
lock connection used with a blood tubing set. 
The structure of U.S.A. Standard Z70.1-1955, "Dimensions of Glass & Metal 
Luer Tapers for Medical Applications", (FIG. 4 of the Standard), and the 
structure of the blood tubing set connector of Burd U.S. Pat. No. 
4,133,312 cannot perform the sterilizing function of the present invention 
since their tubular portions are open. Additionally, the U.S.A. Standard 
and Burd U.S. Pat. No. 4,133,312 are connectors for fluid flow and cannot 
perform a capping function like the present invention. 
Before this invention, a practice was to supply medical devices with 
sterile ports covered by protective tabs. Caps for these ports were 
supplied separately. Before the medical device was placed into operation, 
the tabs on the ports were removed and the caps put in place. There was 
concern on the part of medical personnel for maintenance of sterility of 
the system when the caps were put in place. A reason that medical devices, 
prior to this invention, were not supplied with the port caps in place was 
that the gas used to sterilize the medical device could not pass through 
the cap and reach, and therefore sterilize, the portion of the device 
(port area) covered by the cap. 
Thus, there is a need to provide a luer cap for ports of medical devices 
through which sterilization can occur and which will not leak air or 
liquid when subjected to a positive or negative pressure during operation 
of the device. The ability of the luer cap to not leak air or liquid 
during positive or negative pressurization of the medical device is 
significant since many medical devices operate above (positive) or below 
(negative) atmospheric pressure. If the device is subjected to a negative 
pressure, and the luer cap leaks, the potential for airborne contamination 
entering the device is high. If the device is subjected to a positive 
pressure, and the luer cap leaks, blood or other body fluid could escape 
from the device to the potential severe detriment of the patient. 
A cap which is simple in design is also desirable for ease of molding and 
manufacture. 
It is, therefore, an object of this invention to provide an improved luer 
cap for medical devices which is of simple design, and when placed on a 
port of a medical device, the port can be sterilized through the luer cap. 
It is a further object of this invention to provide an improved luer cap 
which will not leak air or liquid when subjected to a positive or negative 
pressure during use of the device. 
These objects are satisfied by the present invention which incorporates a 
luer cap design which is permeable to ethylene oxide gas (ETO) and can be 
placed on a device prior to ETO sterilization. The design is also capable 
of withstanding the positive or negative pressures that the medical device 
may be subjected to during use. 
SUMMARY OF THE INVENTION 
The luer cap of the present invention is a male luer cap capable of 
providing an engagement with an external wall of a female luer port; the 
female luer port can be either externally threaded or have a single 
projection or flange at its distal end. After the male luer cap is engaged 
with the female luer port, all mated surfaces are capable of being 
sterilized by ethylene oxide gas sterilization through the male luer cap. 
The luer cap has a wall thickness and is made of a plastic material such 
that efficient ETO sterilization occurs. The connection between the male 
luer cap and the female luer port is sufficiently secure to enable 
pressurization of the connection during use of a medical device which uses 
the luer cap of this invention. 
The present invention male luer cap comprises a generally circular 
cross-sectional outer wall. There is an inner wall which is internally 
threaded and an end wall which define an internal port receiving cavity. 
The end wall extends into the cavity and defines a hollow tubular portion 
which has an open end and a closed end. Sterilizing gas passes through the 
outer wall, the hollow tubular portion, and the end wall to sterilize all 
interior surfaces of the male luer cap and female luer port. The cap is 
fabricated of a plastic which is permeable to ethylene oxide gas and which 
enables ethylene oxide gas to pass through the cap and effect 
sterilization. The preferred plastic is manufactured and supplied by 
Celanese Corporation under the trade name CELCON, and is generically an 
acetal copolymer. The preferred thickness of the hollow tubular portion 
and the preferred thickness of the end wall is in the range 0.018 to 0.022 
inches.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
The preferred embodiment of the luer cap of this invention is illustrated 
in FIGS. 1-4. 
Referring to FIG. 1, the inventive luer cap is shown in perspective view 
with an outer wall 10 of generally circular cross-sectional configuration. 
There is a knurled portion 14 on the outer wall 10 to aid in manually 
grasping the luer cap and also to aid in removing the luer cap from the 
mold during fabrication of the luer cap. 
Referring to FIG. 2, the luer cap of FIG. 1 is shown in longitudinal 
section taken along line 2--2 of FIG. 1. An internal port receiving cavity 
13 is defined by an inner wall 12 and an end wall 20. The inner wall 12 
has threads 16 exterior to and surrounding a hollow tubular portion 18. 
The hollow tubular portion 18 of the luer cap is closed by end wall 20 at 
one end and is open to the atmosphere at the end of the hollow tubular 
portion 18 which is opposite end wall 20. 
In the preferred embodiment which is shown in FIG. 2, the end wall 20 is 
shown at the distal end of hollow tubular portion 18, but the end wall 20 
can be at any vertical location along hollow tubular portion 18. 
During ethylene oxide gas sterilization of a medical device having a female 
luer port with a luer cap of this invention attached to it, ethylene oxide 
gas passes inside and down hollow tubular portion 18 and passes through 
hollow tubular portion 18 to sterilize the mated surface of the female 
luer port. The sterilizing gas also passes through end wall 20 to aid 
sterilization at mating points 23 and 25. 
The exterior surface of the female port and the threads 16 of the male luer 
cap are sterilized by ethylene oxide gas permeating through wall 10. Wall 
10 is of such a material and thickness so that the sterilizing gas can 
permeate through wall 10, yet wall 10 is structurally strong. 
The preferred plastic from which the luer cap of this invention is 
fabricated is CELCON, a trade name of a generic acetal copolymer 
manufactured and supplied by Celanese Corporation. CELCON has an inherent 
lubricity which prevents it from binding with rigid plastics such as 
polycarbonates and plexiglass which are used in many medical devices. The 
preferred wall thickness of hollow tubular portion 18, end wall 20, and 
outer wall 10 is 0.020 inch, and the preferred range is 0.018 to 0.022 
inches. It has been found that these wall thicknesses result in the luer 
cap being sufficiently permeable so that enough ETO can pass through the 
cap to effect sterilization. 100% ETO gas is required for sterilization, 
not a mixture of ETO gas and freon as is sometimes used in the 
sterilization art. 
Referring to FIG. 4, the male luer cap of the present invention with outer 
wall 10 is shown in perspective view with portions broken away as it 
prepares to engage with outer wall 21 of female luer port 22. When the 
male luer cap of the present invention is engaged with the female luer 
port 22, internal threads 16 of the male luer cap mate with the external 
threads 24 of outer wall 21 of female luer port 22, and hollow tubular 
portion 18 of the male luer cap mates with axial bore 26 of the female 
luer port. Alternatively, internal threads 16 of the male luer cap can 
mate with a female luer port which has a single flange circumferentially 
formed around the distal end of female luer port 22. 
Because the design of the present invention includes hollow tubular portion 
18 with end wall 20, and because of the nature and thickness of the 
material used in its fabrication (CELCON having a thickness in the range 
of 0.018 to 0.022 inches), during ETO sterilization, ethylene oxide gas 
migrates inside and down and through hollow tubular portion 18 and through 
end wall 20 to sterilize axial bore 25 of female luer port 22. Thus, the 
mated surfaces of the male luer cap and the female luer port are 
sterilized prior to shipment with the male luer cap shipped in place. 
Referring to FIG. 5, a commercial cardiotomy reservoir with overhead inlets 
is shown in partial cutaway perspective view. The device is manufactured 
and sold by the Artificial Organs Division of Travenol Laboratories, Inc., 
Deerfield, Ill. as a Model 1470 Cardiotomy Reservoir. It is used in 
conjunction with a heartlung machine to store and filter blood returned 
from the surgical field. 
The cardiotomy reservoir of FIG. 5 consists of an outer plastic housing 28 
with three overhead noncommunicating suction inlets 30, 32, and 34. These 
suction inlets are connected to blood suction lines that remove blood from 
the surgical field during open heart surgery. 
Luer caps of the present invention are shown at 36, 38, and 40 covering 
female luer ports 42, 44, and 46 which are used for the administration of 
blood, fluids, and medication; the ports are also used to monitor pressure 
within the device. Prior to the male luer cap of this invention, the caps 
36, 38, and 40 had to be shipped separated from the luer ports 42, 44, and 
46 of the cardiotomy reservoir, and the luer caps were placed on the 
reservoir in the operating room. This is less desirable than having the 
caps in place and sterilized when the reservoir is unpackaged and ready to 
use. 
The present invention satisfies a long felt need for a luer cap through 
which sterilization can occur enabling shipment of medical devices with 
luer caps in place. It also satisfies the need for a cap which will hold 
pressure under operating conditions of the various medical devices with 
which the present invention can be used. The design is simple and easy to 
mold and manufacture. 
While the present invention has been disclosed in connection with the 
preferred embodiment thereof, it should be understood that there may be 
other embodiments, which fall within the scope of the invention as defined 
by the following claims.