Trocar port filter

A trocar assembly for exhausting gas from a body cavity comprises a trocar having a housing with a flow passage therethrough which terminates in an outlet fitting, and a filter mounted thereon. The filter includes a housing with a chamber, and an inlet and an outlet which communicate with opposite sides of the chamber to provide a flow passage therethrough. About the inlet is a fitting and there is a means on the inlet fitting mounting the filter on the outlet fitting of the trocar housing. Within the chamber is a filter means so that effluent gas passing through the trocar flow passage flows through the filter means prior to exiting through the outlet of the filter.

BACKGROUND OF THE INVENTION 
The present invention relates generally to trocars for exhausting 
insufflation gases from an abdominal cavity and, more particularly, to a 
filter for mounting on a trocar vent port. 
Recent developments in laparoscopic and endoscopic surgery have resulted in 
the increasing usage of insufflation with suitable gas, such as carbon 
dioxide CO.sub.2, to inflate the abdominal cavity like a balloon by 
expanding the peritoneum to bulge outwardly and separate from the organs 
inside the cavity as well as to separate the organs. The insufflation 
increases the working area for the surgeon in the normally confined 
abdominal cavity and allows better viewing within the cavity and 
instruments to be manipulated in the abdominal cavity with less 
obstruction. 
After such insufflation, an obturator, which is a sharp pointed instrument, 
is inserted into the cannula of a trocar to puncture the peritoneum with a 
lower risk of injuring organs. Thereafter, the obturator is withdrawn and 
a laparoscopic or endoscopic surgical instrument is inserted through the 
cannula to perform the desired surgery. 
A conventional system used for introducing the insufflation gases into the 
abdominal cavity includes a pneumoperitoneum needle connected to a gas 
source through a flexible conduit such as surgical rubber tubing. 
Another technique of insufflating the body cavity connects a source of 
pressurized gas to a valve fitting on the trocar through which, when 
opened, the pressurized gas may enter into the body cavity through the 
trocar cannula to insufflate the cavity. After the conduit has been 
insufflated with gas, the valve may be closed to seal the trocar passage, 
and the gas source may be removed from the valve fitting. 
After abdominal surgery is completed, the gas used to inflate the abdominal 
cavity must be vented from the abdominal cavity. One technique for venting 
these gases employs the use of a suction pump connected to a needle 
inserted into the cavity. An easier technique preferred by some surgeons 
is similarly to vent these gases through the trocar by releasing the valve 
on the housing of the trocar, and venting the gases to the surrounding 
atmosphere. However, these gases may carry bacteria, viruses, body fluids, 
etc., and, if unfiltered, these may be dispersed in the environment of the 
operating room suite, thereby increasing the chances of contamination of 
operating room personnel and the patient. 
It is an object of the present invention to provide a novel trocar port 
filter which prevents the outflow of particulate matter, microorganisms, 
and body fluids into the operating room, while allowing insufflation gases 
to flow out of the abdominal cavity at a high flow rate. 
It is also an object to provide such a filter which is relatively simply 
and quickly installed on the trocar port in an effective sealed 
engagement. 
Another object is to provide a filter which may be fabricated relatively 
easily and economically to enhance its usage as a disposable filter. 
SUMMARY OF THE INVENTION 
It has now been found that the foregoing and related objects may be readily 
attained in a trocar assembly for exhausting gas from a body cavity 
comprising a trocar having a housing with a flow passage which terminates 
in an outlet fitting, and a filter mounted thereon. The filter includes a 
housing providing a chamber, an inlet and an outlet communicating with 
opposite sides of the chamber to provide a flow passage therethrough, and 
a fitting about the inlet. The filter is coupled to the trocar by coupling 
means on the inlet of the filter housing and on the fitting of the trocar 
housing. Within the chamber is a filter means so that effluent gas passing 
through the trocar flow passage flows through the filter means prior to 
exiting through the outlet of the filter. 
Generally, the filter mounting means includes a resilient mounting member 
which has a passage through it. The passage has an inlet portion mounted 
and sealed on the outlet fitting of the trocar housing and an outlet 
portion mounted and sealed on the inlet fitting of the filter housing. 
Conveniently, the resilient mounting member is tubular. 
Preferably, the trocar housing includes a valve to selectively open and 
close the flow passage therethrough. Normally, the filter means includes a 
first filter element adjacent the inlet to filter relatively large 
particles and a second filter element oriented adjacent the outlet to 
filter relatively fine particles. These filter elements are generally 
hydrophobic. 
Preferably, the housing of the filter includes a pair of interengaging 
housing elements which have a base wall and a sidewall extending about 
their periphery. The base walls of these housing elements also have 
fittings about the inlet and outlet and are generally fabricated from 
synthetic resin.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
Turning first to FIG. 1, therein illustrated is a trocar generally 
designated by the numeral 10 having a housing 11 at one end and a tubular 
cannula 12 extending therefrom. A removable obturator 14 is telescopically 
mounted within the cannula 12 and extends beyond a distal portion of the 
cannula 12 into the abdominal cavity to initially pierce the peritoneal 
wall 16 of the cavity of a patient undergoing laparoscopic or endoscopic 
surgery. The proximal end of the obturator 14 is connected to the cover 13 
of the housing 11. After piercing the peritoneal wall 16, the obturator 14 
may be telescopically retracted from the lumen of the cannula 12 by 
releasing and lifting the housing cover 13. 
In order to insufflate the body cavity 16, a source of pressurized gas (not 
shown) is connected to a fitting 22 on the valve 18 of the trocar 10 
through which, when opened, the pressurized gas may enter into the 
interior of the housing 11 and cannula 12, to insufflate the abdominal 
cavity. After the peritoneal cavity has been properly insufflated, the 
valve 18 is closed to seal the trocar 10, and the gas source may be 
removed from the trocar value fitting 22. The trocar cannula 12 and 
housing 11 are sealed to prevent the gas in the body from escaping through 
the trocar. When it is desired to exhaust the gas from the abdominal 
cavity, a filter embodying the present invention and generally designated 
by the numeral 20 is connected to the trocar valve fitting 22, and the 
valve 18 is opened to vent the gas through the valve 18 and the filter 20. 
Turning in detail to FIGS. 2 and 3, the filter 20 includes a flexible pair 
of casing elements 35, 37 providing a housing with a cavity therein and a 
pair of hydrophobic filter elements 44, 46, seated in the cavity. Each 
casing element 35, 37 has a base wall 36 and a sidewall 38 extending about 
its periphery. The end portions 40, 42 of the two sidewalls 38 of the 
elements 35, 37, respectively, snap fit to form the housing as seen in 
FIG. 3. The end portion 40 of the casing element 35 is resiliently 
deflectable and seats within the end portion 42 of the casing element 37 
which is also resiliently deflectable. The base walls 36 have a coaxial 
aperture therein providing respectively, an inlet 32 and an outlet 48, and 
cylindrical fittings 28, 29 extend outwardly about the inlet 32 and outlet 
48 respectively to provide a flow passage through the filter. The fittings 
28, 29 each have a collar 34 about their outer end with a peripheral 
groove therein. 
The filter elements 44, 46 are disc-shaped and extend across the full 
diameter of the casing elements 35, 37 to ensure complete filtration of 
the exhaust gases passing through the filter 20. The filter element 44 is 
positioned adjacent the inlet 32 of the filter 20, and filters relatively 
large particles while the filter element 46 adjacent the outlet of the 
filter 20 filters the smaller particles which pass though the first filter 
element 44. Using two types of filter elements further ensures the proper 
filtering of vented insufflation gases and reduces the possibility of 
clogging the filter 20. 
The filter 20 may be removably mounted upon the trocar port fittings 22 by 
the resilient coupling 26 as shown in FIG. 3. As shown in FIG. 4, the 
coupling 26 has an annular passage 30 through its center and two 
peripheral grooves 50 are provided adjacent each end of the passage 30. 
The grooves 50 seat the two collars 24, at the ends of the trocar value 
fitting 22 and the two collars 34 at the end of the filter fitting 28, 
respectively, to provide an airtight seal between the filter 20 and the 
trocar 10 and retain the fittings 22, 28 therein. The flexibility of the 
coupling 26 enables it to accommodate reasonable dimensional variation in 
the trocar fittings 22. 
As will be appreciated, various materials may be employed for the 
construction of the filter housing. Most conveniently, the casing elements 
are molded from a synthetic resin such as polypropylene which is 
resiliently deflectable, relatively inexpensive to mold, and durable. 
The filter elements 44, 46 may be made from suitable material which will 
not be quickly blocked or saturated by vapors exiting the abdominal 
cavity. Thus, the elements 44, 46 are preferably hydrophobic filters and 
may be fabricated from a polytetrafluoroethylene (PTFE) material and 
should serve to filter particulate matter of a size ranging from about 0.2 
microns to about 0.5 microns. 
The relatively inexpensive cost of the filter of the present invention 
allows it to be disposable and thereby eliminates the possibility that a 
clogged, inactivated or poorly effective filter may be used in a 
subsequent laparoscopic procedure. 
Thus, it can be seen from the foregoing detailed description and the 
attached drawings that the novel trocar port filter of the present 
invention effectively prevents contamination by particulate matter in 
venting gases without the use of a vacuum pump or the like. The coupling 
of the filter may be readily and quickly installed onto the coupling 
trocar port fitting, and the filter can be readily removed and disposed.