Method and apparatus for relieving excess insufflation pressure

A method and apparatus for relieving insufflation pressure in a body cavity (18) in excess of a predetermined value are provided. A conduit assembly (24) extends from the body cavity (18) through the surface (61) of a fluid reservoir and has a port (63) positioned beneath the fluid surface (61). The relief pressure is selected by setting the relative positioning of the open end (63) and fluid surface (61). The apparatus avoids insufflation gas leakage problems associated with known insufflation pressure relief devices.

FIELD OF THE INVENTION 
This invention pertains to an improved apparatus for relieving insufflation 
pressure in excess of a predetermined value during surgical procedures 
wherein a body cavity is insufflated. 
BACKGROUND OF THE INVENTION 
Certain surgical procedures involve insufflation, i.e., introducing a gas 
such as certain inert gases or air into a body cavity. One such procedure 
is laparoscopic surgery. Laparoscopic surgery is a minimally invasive type 
of surgical procedure wherein surgical instruments and imaging equipment 
are inserted into a body cavity through an access cannula, thereby 
avoiding the need for large incisions. In such procedures, it is common to 
introduce a gas into the body cavity to separate a wall of the body cavity 
or other tissue from the surgical site. Sufficient clearance is thus 
provided to facilitate insertion and manipulation of the surgical 
instruments and viewing equipment. 
It is important to monitor the introduction of the insufflation gas and the 
insufflation pressure in the body cavity during surgery. For example, a 
reduction in patient vital signs may result if the insufflation pressure 
is too high. It is thus desirable to maintain the insufflation pressure 
within a range where adequate insufflation is provided substantially 
without affecting the patient's vital signs. In addition, pressurized 
insufflation gas may spread from the surgical site into the patient's body 
resulting in post-surgery pain. Moreover, a high insufflation gas delivery 
rate can result in rapid depletion of the gas source, i.e., a gas 
canister, necessitating changing or replenishing of the source and 
prolonging surgery. For these and other reasons, it is useful to account 
for the insufflation gas and monitor the insufflation pressure. 
Heretofore, the insufflation pressure has commonly been regulated by using 
a mechanical pressure relief valve which opens, thereby partially venting 
the body cavity, when the insufflation pressure reaches a predetermined 
limit. One such type of mechanical valve involves the use of a biasing 
device such as a spring to provide a back pressure such that the valve 
remains closed until the insufflation pressure is sufficient to overcome 
the back pressure. Thus, in theory, the insufflation pressure can be 
maintained below a desired limit in such devices by selecting an 
appropriate biasing device or device setting. 
However, it has been found that such mechanical pressure relief valves may 
leak under normal operating conditions. It is often desired to maintain 
the insufflation pressure within a narrow pressure range during surgery. 
For example, during laparoscopic surgery, surgeons commonly insufflate the 
body cavity to approximately 14 mm Hg. However, it is generally desired to 
keep the insufflation pressure below about 16 mm Hg to avoid 
over-insufflation problems such as described above. Thus, pressure relief 
valves may be exposed to pressures near the selected relief pressure 
during surgery. Known mechanical pressure relief valves may leak as the 
insufflation pressure approaches the relief pressure and therefore fail to 
provide abrupt and positive pressure relief. As a result, the surgeon's 
ability to monitor the insufflation pressure and account for the 
insufflation gas may be impaired. In addition, the total amount of 
insufflation gas required during surgery may be increased due to the 
leakage. Moreover, because such mechanical pressure relief valves 
generally do not provide a visual indication when the relief pressure is 
exceeded, the surgeon may continue to introduce insufflation gas not 
knowing that the relief pressure has been exceeded, thereby possibly 
posing a risk to the patient and further increasing gas usage. 
It is a further disadvantage of known mechanical pressure relief valves 
that such valves utilize moving parts which may malfunction or require 
maintenance. Moreover, some known mechanical pressure relief valves are of 
relatively complicated construction. Such valves thereby increase costs, 
particularly when used in disposable medical applications. 
SUMMARY OF THE INVENTION 
The present invention provides a method and apparatus for relieving 
insufflation pressure in a body cavity in excess of a predetermined value. 
The invention provides abrupt and positive pressure relief and reduces 
leakage problems associated with prior art devices. The invention also 
provides a visual indication when the relief pressure is exceeded, thereby 
increasing safety and reducing gas usage. In addition, an apparatus 
constructed in accordance with the present invention does not require 
moving parts thereby avoiding maintenance and reducing the likelihood of 
malfunction. Moreover, the present invention provides an apparatus which 
is of simple construction and may be produced inexpensively. The present 
invention therefore lends itself to disposable applications such that post 
use sterilization is unnecessary and contamination concerns are reduced. 
According to one aspect of the present invention, an apparatus for 
relieving insufflation pressure in a body cavity in excess of a 
predetermined value is provided. The apparatus comprises a receptacle 
containing a fluid and an insufflation gas exhaust assembly. The exhaust 
assembly extends into the fluid contained in the receptacle and has a 
first end positioned a predetermined distance beneath the top surface of 
the fluid contained in the receptacle such that insufflation gas is 
exhausted from the body cavity via the first end of the exhaust assembly 
when the insufflation pressure exceeds the predetermined value. That is, 
the fluid exerts a back pressure on the exhaust assembly such that 
insufflation gas does not flow through the port unless the insufflation 
pressure exceeds the back pressure. Thus, the relief pressure can be 
selected by setting the predetermined distance between the top surface of 
the fluid in the receptacle and the first end of the exhaust assembly, 
e.g., by changing the fluid level in the receptacle or by moving the first 
end relative to the top surface of the fluid. The exhaust assembly can 
comprise a tube which is adapted for interconnection to an exhaust port 
from the body cavity. The exhaust assembly preferably includes a conduit 
which is fixed with respect to the receptacle such that the predetermined 
distance is set by adding or subtracting fluid from the receptacle. The 
receptacle can comprise a bag or other rigid or non-rigid container. 
Preferably, the receptacle is at least partly transparent, i.e., the 
receptacle is wholly or partially comprised of transparent or translucent 
material. Additionally, the receptacle is preferably formed from 
inexpensive materials, such as certain plastic materials, as it is 
desirable to dispose of the receptacle after use. Calibration markings may 
be provided on the receptacle to assist in setting the fluid level. The 
fluid surface can be exposed to the ambient atmosphere. The fluid should 
be a sterile solution such as sterile saline solution. 
According to another aspect of the present invention, an insufflation 
system is provided. The system comprises an insufflation gas source, an 
inlet assembly for one-way delivery of gas from the gas source to a body 
cavity, and an outlet assembly for one-way venting of insufflation gas 
from the body cavity. The outlet assembly extends from the body cavity 
into a fluid contained in a receptacle and includes a first end submerged 
a predetermined distance beneath the surface of the fluid contained in the 
receptacle. The fluid may comprise a sterile fluid such as sterile saline 
solution. 
According to a further aspect of the present invention, a method for 
relieving excess insufflation pressure in a body cavity is provided. The 
method includes the steps of providing an insufflation gas exhaust 
assembly including a receptacle containing a fluid and an exhaust line 
extending from a body cavity into the fluid, and establishing one-way 
insufflation gas communication from the body cavity to the receptacle via 
the exhaust line. The step of establishing can be accomplished by 
pressurizing the body cavity such that insufflation gas flows therefrom 
and/or opening a valve or cover to allow flow through the conduit 
assembly. 
According to a still further aspect of the present invention, a method for 
venting a body cavity is provided. The method comprises the steps of 
setting the relative positioning between a first end of an exhaust line 
extending from a body cavity and the top surface of a fluid contained in a 
receptacle so that the first end is positioned a preselected distance 
beneath the surface and establishing one-way insufflation gas 
communication from the body cavity to the receptacle via the exhaust line. 
Insufflation gas thus flows from the body cavity to the first end of the 
exhaust line when the insufflation pressure exceeds a predetermined value. 
The relative positioning between the first end and the fluid surface can 
be selected by changing the fluid level in a receptacle or by moving the 
first end of the exhaust line. The method can further include the step of 
flowing insufflation gas from a gas source to the body cavity.

DETAILED DESCRIPTION OF THE INVENTION 
Referring to FIG. 1, an insufflation system constructed in accordance with 
the present invention is generally identified by the reference numeral 10. 
The system 10 comprises an insufflation gas source 12, a gas delivery 
conduit assembly 14, and a pressure relief assembly 16. A control unit 15 
for controlling gas flow from the gas source 12 may be included within gas 
delivery conduit assembly 14. 
The system 10 can be used in connection with any insufflation application 
wherein it is desired to relieve insufflation pressure in excess of a 
preselected value. In the illustrated embodiment, the system 10 is 
depicted in a typical laparoscopic surgery setting. In such a setting, for 
example, a body cavity, generally identified by the reference numeral 18, 
of a patient 20 may be insufflated to provide clearance between the 
surgical site and the abdominal wall or other surrounding tissue, thereby 
facilitating manipulation of surgical tools and viewing equipment. 
An insufflation gas is delivered from the gas source 12 to the body cavity 
18 through the gas delivery assembly 14. The gas source 12 can be a 
canister of a known insufflation gas, such as C0.sub.2, and can be 
incorporated into a gas cart (not shown) or provided separately. A valve 
22 is provided to regulate the flow of gas from the gas source 12. The gas 
source 12 and/or control unit 15 can further include a gas flow or 
pressure meter and/or a gauge to monitor the remaining gas supply. 
The gas delivery assembly 14 sealably engages an outlet of the gas source 
12 and extends into the body cavity 18 to deliver the insufflation gas 
thereto. Only one-way gas flow should be permitted through the gas 
delivery assembly 14 to avoid contamination of the gas source 12 or 
upstream components. The assembly 14 may comprise a single gas line or a 
series of gas lines. For example, the insufflation gas may be delivered to 
the body cavity 18 through a cannula which can also be used to provide 
access to the surgical site for surgical tools, viewing equipment and the 
like, thereby reducing the required number of incisions. Thus, the 
insufflation gas may be routed to the body cavity 18 through a gas line 
from the source 12, internal passageways of a surgical instrument, and a 
cannula. Alternatively, a separate conduit assembly dedicated to delivery 
of the insufflation gas may be provided, and the gas source 12 may be 
interconnected to an inlet port of an access cannula 29, as shown. 
A pressure relief assembly 16 is provided to relieve insufflation pressure 
in the body cavity 18 in excess of a predetermined value. The assembly 16 
comprises a gas outlet conduit subassembly 24 extending from the body 
cavity 18 and a fluid reservoir subassembly 32 for selectively relieving 
excess insufflation pressure. The gas outlet subassembly 24 may comprise a 
series of gas lines for selectively delivering insufflation gas from the 
body cavity 18 to the fluid reservoir subassembly 32, or the gas outlet 
subassembly 24 may be provided by way of a single tube. In the illustrated 
embodiment, the gas outlet subassembly 24 comprises a length of flexible 
tubing 26 which sealably engages an exhaust port 28 of the access cannula 
31. The tubing 26 should have a width sufficient to accommodate flow of 
insufflation fluid therethrough with little resistance. For example, the 
tubing 26 can have an inside diameter of about 1/4-3/16 inch. The tubing 
26 can be sealably attached to the cannula 31 by way of a standard "LUER" 
lock, frictional engagement, or other means. If desired, a valve or cover 
can be included in the gas outlet subassembly 24 to selectively close 
fluid communication between the body cavity 18 and the reservoir 
subassembly 32. 
Generally, the reservoir subassembly 32, which will be described in greater 
detail below, comprises a fluid reservoir and an insufflation fluid 
passageway separated from the reservoir by a substantially fluid 
impermeable barrier. The insufflation fluid passageway extends through the 
reservoir fluid surface and has an open end a predetermined distance 
beneath the surface. It will thus be appreciated that the reservoir fluid 
will fill the insufflation fluid passageway to the level of the surface of 
the reservoir if the pressure in the insufflation fluid passageway is 
equal to the pressure exerted on the surface of the reservoir. If the 
pressure in the insufflation fluid passageway is greater than the pressure 
on the surface of the reservoir, the level of reservoir fluid in the 
insufflation fluid passageway will be reduced accordingly. Thus, because 
insufflation pressure is communicated from the body cavity 18 to the 
insufflation fluid passageway, insufflation fluid can pass from the body 
cavity 18, through the open end of the insufflation fluid passageway, and 
to the surface of the reservoir when the insufflation pressure is 
sufficiently greater than the pressure on the surface of the reservoir. At 
the surface, the insufflation fluid may be vented to the ambient 
atmosphere or the fluid may be collected and/or filtered. 
The parameters involved in determining the relief pressure of the pressure 
relief assembly thus include the density of the reservoir fluid, the 
pressure exerted on the surface of the reservoir and the distance between 
the reservoir surface and the open end of the insufflation fluid 
passageway. It will therefore be appreciated that many configurations of 
the reservoir subassembly 32 are possible. For example, the reservoir 
subassembly 32 can comprise a bottle, beaker, bag or other receptacle and 
the reservoir surface can be exposed to the ambient atmosphere or to 
non-atmospheric pressure. A flexible bag or other inexpensive, easily 
disposed receptacle is preferred as it is desirable to dispose of the 
receptacle after use to avoid sterilization costs and attendant risks. The 
insufflation fluid passageway can be an integral portion of a receptacle 
or may be provided by way of a conduit which is moveable relative to such 
a receptacle. The distance between the reservoir surface and the open end 
of the insufflation fluid passageway can therefore be adjusted by changing 
the reservoir fluid level or by moving such a moveable conduit relative to 
the receptacle. 
As shown, separate cannulas 29 and 31 are provided to allow separate access 
to the body cavity 18 for assemblies 14 and 16 and to allow for one-way 
insufflation gas flow throughout the system 10. This construction provides 
a number of advantages. First, since the pressure relief assembly 16 does 
not communicate with the gas delivery assembly 14 (other than via body 
cavity 18), accurate regulation of the insufflation pressure in the body 
cavity 18 is insured. It has been found that systems which attempt to 
regulate the insufflation pressure in a body cavity by monitoring pressure 
in an insufflation gas delivery line can be inaccurate due to differences 
between the pressure inside the body cavity and in the delivery line. Such 
differences result at least in part from back pressure reflected from the 
inlet port to the body cavity which is normally somewhat restricted. The 
present invention avoids this problem by positioning the reservoir 
subassembly 32 downstream from the body cavity 18 in a one-way flow system 
10. The illustrated construction also lends itself to disposable, add-on 
applications. That is, the pressure relief assembly 16 or portions thereof 
can be provided separately and disposed of after use. Other advantages 
will be apparent to those skilled in the art. 
In the embodiment of FIGS. 1 and 2, the reservoir subassembly 32 comprises 
a receptacle 44 such as a bag formed from flexible elastomeric material. 
Preferably, the receptacle 44 is at least partly transparent to allow 
viewing into the receptacle 44. The receptacle 44 can conveniently be 
constructed by attaching two thin sheets together at portions thereof, 
e.g. by heat sealing, RF bonding, adhesive bonding or other technique, to 
form an internal fluid retaining space 46. The illustrated receptacle 44 
includes an insufflation gas conduit portion 48 and a reservoir portion 50 
wherein the portions 48 and 50 are separated by a substantially fluid 
impermeable barrier 51. The barrier 51, which can be formed by sealing the 
front and back walls of the receptacle 44 together, extends downwardly 
from a top edge 52 of the receptacle 44. A gap 54 is provided in the 
barrier 51 or between the barrier 42 and a bottom wall 56 of the 
receptacle 44 to allow fluid communication between the portions 48 and 50. 
Preferably, the gas conduit portion 48 has relatively small volume as 
compared to the reservoir portion 50 such that a change in fluid level in 
the gas conduit 48 results in a smaller change in the fluid level in the 
reservoir portion 50. 
Insufflation gas is introduced into the conduit portion 48 through adapter 
tube 58. The adapter tube 58, which is sealably disposed within a 
peripheral seal 60 of the receptacle 44 above the fluid surface 61, is 
adapted to sealably engage tubing 26 from the body cavity 18 of the 
patient 20. The adapter tube 58 and the tubing 26 may be interconnected by 
way of a locking assembly such as a "LUER" lock, frictional engagement or 
other means. In the illustrated embodiment, the adapter tube 58 and tubing 
26 are friction fitted so that a seal is formed between the adapter tube 
58 and tubing 26 when they are mated. The illustrated receptacle 44 also 
includes a second tube 62 which extends through the peripheral seal 60 
above the fluid surface 61 into the reservoir portion 50 of the receptacle 
44. The tube 62 allows venting of the insufflation gas and can be used to 
add fluid to the receptacle 44. 
The receptacle 44 may be adapted to be hung out of the way during surgery, 
thereby conserving operating theater space and reducing the likelihood of 
tilting or spilling of the receptacle 44 or its contents. As illustrated, 
the receptacle 44 is provided with a bulge 64 including a sealed opening 
66 for this purpose. The receptacle 44 can thus be hung from an IV or 
plasma bag stand 65 or other hanger assembly. Preferably, the opening 66 
is positioned at or near a longitudinal axis 68 of the receptacle 44 so 
that the axis 68 tends to orient vertically when fluid is added to the 
receptacle 44. 
As shown in FIG. 2, markings can be provided on the receptacle 44 for use 
in setting the desired relief pressure. Because the relief pressure is 
proportional to the distance D between the open end or port 63 of the 
insufflation gas conduit portion 48 and the surface 61 of the reservoir 
fluid, the relief pressure can be set at a desired level by filling the 
receptacle 44 with the fluid until the fluid reaches the appropriate 
level. Various fluid levels and/or associated relief pressure settings can 
thus be conveniently calibrated by placing markings directly on the 
receptacle 44. Calibration can be accomplished experimentally or by using 
known formulas, e.g., relating 1 mm Hg to a depth of the reservoir fluid. 
It will be appreciated that many different reservoir fluids can be used in 
accordance with the present invention. However, the reservoir fluid should 
be a sterile fluid such as 7% sterile saline solution to reduce the 
likelihood of contamination in the event that the fluid enters the body 
cavity 18. 
Referring to FIG. 3, a front view of a receptacle 70 constructed in 
accordance with an alternative embodiment of the present invention is 
shown. The receptacle 70 can comprise a bottle, beaker, bag or other 
container. Preferably, the receptacle 70 is at least partly transparent to 
allow viewing of the reservoir fluid 72 therein and to allow viewing of 
bubbles rising through the fluid 72 when the predetermined relief pressure 
is exceeded. In the illustrated embodiment, the receptacle 70 is formed 
from two sheets of clear plastic which are sealed together at peripheral 
portions thereof to define an internal fluid retaining space. For ease of 
construction, the illustrated receptacle 70 is formed from sheet materials 
which can be sealably attached together by heat sealing or RF welding. 
Alternatively, the sheets could be attached together by an adhesive or 
other means. 
Insufflation fluid from a body cavity is introduced into the receptacle 70 
by way of a conduit assembly including a tube 74 and a channel 76. The 
tube 74, which is in fluid communication with the body cavity, extends 
through a bottom edge 78 of the receptacle 70 and has an open end 80 
within the channel 76. A seal 84 is provided in the bottom edge 78 about 
the tube 74 to substantially prevent leakage of reservoir fluid 72. Any 
suitable means may be utilized to provide the seal 84. In the illustrated 
embodiment, the seal 84 comprises a widened portion wherein the sheet 
materials of the receptacle are heat sealed or RF welded together. 
Preferably, the open end 80 is positioned above the surface 82 of the 
reservoir fluid 72 to reduce the likelihood that fluid 72 will flow 
through the tube 74 to the body cavity. 
The channel 76 extends downwardly from a top edge 86 of the receptacle 70 
and has a port 88 positioned a predetermined distance D beneath the 
surface 82. The channel 76 has an inside width W.sub.i greater than an 
outside width W.sub.o of the tube 74 such that insufflation fluid can flow 
therebetween. It will be appreciated that the channel 76 is sealed at an 
upper edge 90 so that insufflation fluid flowing from the body cavity can 
only escape from the conduit assembly through port 88. In this regard, the 
channel 76 may comprise, for example, a tube having a sealed upper end. In 
the illustrated embodiment, the channel 76 is formed by sealing portions 
of the sheet materials of the receptacle 70 together, e.g., by heat 
sealing or RF bonding. Preferably, the channel 76 is positioned along a 
vertical centerline 92 of the receptacle 70 to reduce horizontal movement 
of the center of gravity and tilting of the receptacle 70 due to flow of 
reservoir fluid 72 into or out of the channel 76. The illustrated 
configuration has also been found to reduce or eliminate the incidence of 
undesired clinging of the opposing sheet materials of the receptacle 70, 
which clinging could obstruct the flow of insufflation fluid. 
The receptacle 70 further includes at least one opening through a wall of 
the receptacle 70 above the surface 82 to allow introduction of reservoir 
fluid 72 to the receptacle 70 and escape of insufflation fluid therefrom. 
In the illustrated embodiment, wherein the channel 76 is provided by 
sealing the sheet materials of the receptacle 70 together such that 
insufflation fluid cannot flow around the channel 76 above the surface 82, 
openings are provided in the receptacle 70 on both sides of the channel 
76. As shown, the openings comprise tubes 94 sealably extending through 
the top edge 86 of the receptacle 70. The illustrated receptacle also 
includes a hole 96 positioned on or near the centerline 92 to allow the 
receptacle to be hung from an IV stand or other hanger, thereby conserving 
space in the operating theater. In addition, the illustrated receptacle 
includes markings 98 on a surface thereof to aid in setting the reservoir 
fluid level. 
In operation, an insufflation system constructed in accordance with an 
embodiment of the present invention can be used as follows. Operating room 
personnel can first remove a disposable bag and tubing from protective 
packaging using aseptic techniques. The bag and connected tubing can then 
be passed outside of a sterile field, retaining a free end of the tubing 
in the sterile field. The bag can be hung on an IV stand or other hanger 
and filled with sterile saline solution to the desired relief pressure as 
indicated by markings on the bag. The free end of the tubing can then be 
connected to the vent port of a cannula extending from a body cavity of a 
patient. Insufflation fluid is delivered from a source to the body cavity, 
e.g., by opening valves, to provide the desired insufflation pressure. 
When in use, bubbles will be seen rising through the reservoir fluid 
whenever the set relief pressure is exceeded. After use, the tubing should 
be detached from the cannula, or fluid communication between the bag and 
cannula should otherwise be closed, prior to removing the cannula from the 
patient. The bag and tubing, which are of simple construction, can be 
discarded after use in accordance with accepted medical procedures. 
The present invention has a number of advantages over known insufflation 
systems. The present invention provides an insufflation system capable of 
abrupt and positive pressure relief. An apparatus constructed and used in 
accordance with the present invention can thus function near the selected 
relief pressure substantially without leakage of the insufflation gas. A 
physician's ability to monitor the insufflation pressure and account for 
the insufflation gas is therefore enhanced. In addition, the likelihood of 
depleting the insufflation gas source during surgery is reduced thereby 
avoiding time consuming interruptions during surgery. The present 
invention also provides a visual indication, i.e., bubbles, when the 
relief pressure is exceeded. Moreover, the present invention provides a 
pressure relief apparatus of simple construction which lends itself to 
disposable applications. The present invention also provides a pressure 
relief apparatus which can be constructed without moving parts which may 
malfunction or require maintenance. Additional advantages of the present 
invention will be apparent to those skilled in the art. 
While the present invention has been described in relation to specific 
embodiments thereof, additional alternative embodiments apparent to those 
skilled in the art in view of the present disclosure are intended to fall 
within the scope of the present invention as further defined by the claims 
set forth below.