U.S. patent application number 15/889821 was filed with the patent office on 2019-02-21 for methods and devices for detecting bowel perforation.
This patent application is currently assigned to Sentire Medical Systems, LLC. The applicant listed for this patent is Sentire Medical Systems, LLC. Invention is credited to M. Robert GARFIELD, III, Balakrishna HARIDAS, David KRASNE, David LEONARD, Tony SCALICI.
Application Number | 20190053749 15/889821 |
Document ID | / |
Family ID | 46969863 |
Filed Date | 2019-02-21 |
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United States Patent
Application |
20190053749 |
Kind Code |
A1 |
SCALICI; Tony ; et
al. |
February 21, 2019 |
METHODS AND DEVICES FOR DETECTING BOWEL PERFORATION
Abstract
The present disclosure relates to methods and devices to detect
perforation of the bowel, for example, resulting from surgical
procedures, such as laparoscopy, diagnostic procedures, such as
colonoscopy, medical conditions, such as diverticulitis, and
trauma. The present disclosure also relates to filtration systems
and electrical connector assemblies for use in the methods and
devices.
Inventors: |
SCALICI; Tony; (Delray
Beach, FL) ; LEONARD; David; (Madison, AL) ;
KRASNE; David; (New York, NY) ; HARIDAS;
Balakrishna; (Mason, OH) ; GARFIELD, III; M.
Robert; (Cincinnati, OH) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Sentire Medical Systems, LLC |
New York |
NY |
US |
|
|
Assignee: |
Sentire Medical Systems,
LLC
Kalamazoo
MI
|
Family ID: |
46969863 |
Appl. No.: |
15/889821 |
Filed: |
February 6, 2018 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
13442266 |
Apr 9, 2012 |
9907505 |
|
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15889821 |
|
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|
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61473592 |
Apr 8, 2011 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
A61B 17/3474 20130101;
A61B 5/0002 20130101; A61B 2505/05 20130101; G01N 21/3504 20130101;
A61M 13/003 20130101; B01D 39/00 20130101; A61B 5/4255
20130101 |
International
Class: |
A61B 5/00 20060101
A61B005/00; B01D 39/00 20060101 B01D039/00; A61B 17/34 20060101
A61B017/34 |
Claims
1. A bowel perforation detection device comprising: a sample
delivery unit comprising an aspirate filtering means; a sensing
unit comprising a gas-detecting means, a pump, a processor, and a
display; and a connecting means connecting the sample delivery unit
and the sensing unit.
2. The device of claim 1 wherein said aspirate filtering means
comprises a first filter and a second filter.
3. The device of claim 2 wherein said first filter is a hydrophobic
porous membrane filter having pore sizes ranging from about 100
microns to about 500 microns.
4. The device of claim 2 wherein said second filter is a
hydrophobic filter having minimum pore size of 0.2 microns or a
hydrophilic filter having a minimum pore size of 0.01 microns.
5. The device of claim 1 wherein said aspirate filtering means
comprises: an outer housing section; an inner tubing section, a
portion of which is perforated; a sleeve comprising an absorbent
wicking material disposed between the perforated tubing and the
outer housing; a hydrophobic liquid filter having pore sizes
ranging from about 100 microns to about 500 microns; and a
gas/microbial filter.
6. (canceled)
7. The device of claim 1 wherein said gas-detecting means is
selected from the group consisting of contact gas sensors,
non-contact gas sensors, and combinations thereof.
8. The device of claim 1 wherein said gas-detecting means is
selected from the group consisting of a carbon dioxide gas sensor,
a methane gas sensor, a hydrogen gas sensor, a sulfide gas sensor,
a nitrogen gas sensor, and combinations thereof
9.-13. (canceled)
14. A method for detecting a bowel perforation injury, said method
comprising: obtaining an aspirate sample from a abdominal or pelvic
cavity of a patient; filtering said aspirate sample to separate a
gas component of the sample; analyzing said gas component using a
gas-detecting means to determine the concentration of gases in the
sample; wherein an elevated level of a gas normally present in the
bowel and not normally present in the abdominal or pelvic cavity
indicates the presence of a bowel perforation injury.
15. The method of claim 14 wherein said gas-detecting means is
selected from the group consisting of contact gas sensors,
non-contact gas sensors, and combinations thereof.
16. The method of claim 14 wherein said gas-detecting means is
selected from the group consisting of carbon dioxide gas sensors,
methane gas sensors, hydrogen gas sensors, sulfide gas sensors,
nitrogen gas sensors, and combinations thereof.
17.-18. (canceled)
19. The method of claim 14 wherein filtering said aspirate sample
comprises passing the aspirate through a first filter for
separating liquid from aspirate and a second filter for separating
gas and microbes from aspirate.
20. The method of claim 19 wherein said first filter is a
hydrophobic porous membrane filter having pore sizes ranging from
about 100 microns to about 500 microns.
21. The method of claim 19 wherein said second filter is a
hydrophobic filter having minimum pore size of 0.2 microns or a
hydrophilic filter having a minimum pore size of 0.01 microns.
22. The method of claim 14 wherein filtering said aspirate sample
comprises passing the sample through a filtration assembly
comprising: an outer housing section; an inner tubing section, a
portion of which is perforated; a sleeve comprising an absorbent
wicking material disposed between the perforated tubing and the
outer housing; a hydrophobic liquid filter having pore sizes
ranging from about 100 microns to about 500 microns; and a
gas/microbial filter.
23. The method of claim 14 wherein said gas component is selected
from the group consisting of carbon dioxide, methane, hydrogen,
sulfide, nitrogen, and mixtures thereof.
24. A filter assembly comprising: an outer housing section; an
inner tubing section, a portion of which is perforated; a sleeve
comprising an absorbent wicking material disposed between the
perforated tubing and the outer housing; and a first filter.
25. The filter assembly of claim 24, wherein the first filter is a
hydrophobic liquid filter having pore sizes ranging from about 100
microns to about 500 microns.
26. The filter assembly of claim 24, further comprising a second
filter.
27. The filter assembly of claim 26 wherein said second filter is a
hydrophobic gas/microbial filter having minimum pore size of 0.2
microns or a hydrophilic gas/microbial filter having a minimum pore
size of 0.01 microns.
28. The filter assembly of claim 24 wherein said absorbent wicking
material is selected from the group consisting of cellulose fiber
mats and hydrophilic urethane foams.
29. (canceled)
Description
CROSS-REFERENCE TO RELATED APPLICATION
[0001] This application is a continuation of U.S. application Ser.
No. 13/442,266 filed Apr. 9, 2012, which issued as U.S. Pat. No.
9,907,505 on Mar. 6, 2018 and claims priority to U.S. Provisional
Application for Patent Ser. No. 61/473,592 filed Apr. 8, 2011, the
entire contents of which are incorporated herein by reference.
FIELD OF THE DISCLOSURE
[0002] The present disclosure relates to methods and devices to
detect perforation of the bowel, for example, resulting from
surgical procedures, such as laparoscopy; diagnostic procedures,
such as colonoscopy; medical conditions, such as diverticulitis;
and trauma. The present disclosure also relates to filtration
systems and electrical connector assemblies for use in the methods
and devices.
BACKGROUND OF THE DISCLOSURE
[0003] Bowel perforation injuries can occur as the result of
surgical procedures; diagnostic procedures; medical conditions; and
trauma. The cost to repair a bowel perforation suffered during
laparoscopic surgery is minimal if that perforation is identified
and treated during that surgery. The cost of reparation, as well as
patient morbidity and mortality are far greater if a bowel
perforation is not detected at the time of surgery. Cost and
morbidity increase as time to diagnosis/intervention increases.
Patients suffering undetected bowel perforations during
laparoscopic surgery require additional surgery to treat the
perforation. Additional diagnostic procedures, hospitalization and
surgical intervention such as, CT scan, exploratory laparotomy or
laparoscopy, colostomy, ileostomy, reanastomosis, antibiotic
treatment, hospitalization/ICU treatment, and infectious disease
consultation may also be required. The negative effects from a
delay in treating bowel perforations can range from mild
peritonitis to septic shock. Sepsis and septic shock can lead to
hypoxia, renal failure, other major organ dysfunction and
death.
[0004] Laparoscopic surgeries are performed to treat a variety of
conditions in the abdominal and pelvic area, including but not
limited to, exploratory biopsies, cholecystectomy, hysterectomy,
hernia repair, ovarian cyst removal, and prostatectomy.
Additionally, laparoscopic surgeries are being performed more
routinely on patients who might previously have received open
laparotomies, for example, in patients who have had previous
abdominal surgeries with known adhesions, and for more complex
surgeries, such as those involving large tumors, reconstructive
surgeries, complex partial nephrectomies, surgeries to treat
inflammatory pathological conditions, and all robotic assisted
procedures.
[0005] Robotic-assisted laparoscopic procedures are also being used
with increased frequency in gynecological, urological and other
laparoscopic surgical procedures. This further increases the number
and complexity of laparoscopic surgeries that are routinely
performed. Lack of surgeon feel, as well as reduced visualization
associated with robotic assisted laparoscopic procedures can
contribute to the risk of bowel perforation and decrease the
possibility of immediate detection.
[0006] Bowel perforation injuries are a risk associated with
laparoscopic surgery. They can occur during initiation of the
procedure as a Veress needle or trocar is introduced blindly into
the abdominal cavity or during intraoperative dissection and
cauterization. Bowel perforation injuries are not easily visualized
by medical personnel during surgery due to optical limitations of
the surgical equipment. Since the bowel moves during surgery, an
area of injury can become positioned outside of the field of vision
of the surgeon. Because of the difficulty in visualizing bowel
perforations at the time of injury, there is an increased chance
that the injury will not be detected during the procedure leading
to the above-described negative health effects and increased costs
of treatment.
[0007] In addition to surgical bowel perforations, patients may
suffer trauma or ruptured diverticula causing bowel perforations
that are difficult to diagnose by CT scan and clinical examination.
Diagnosis relies on CT scans which can result in false negatives
and clinical findings often present 24-28 hours after the onset of
the infectious process. Bowel perforation is a surgical emergency.
Time to diagnosis and treatment are directly correlated with
morbidity/mortality and patient outcome.
[0008] There remains a need in the art to be able to detect bowel
perforation. Optimally, such detection should occur near the time
of injury, for example, during a laparoscopic procedure. This need
and others are met by the present invention.
SUMMARY OF THE DISCLOSURE
[0009] The present disclosure relates to methods and devices for
detecting bowel perforation injuries. Such methods and devices
involve detecting in an abdominal or pelvic cavity an elevated
concentration, as compared to the ambient concentration or a
previously recorded concentration, of at least one gas normally
found in the bowel. As described herein, a bowel perforation
detection device, also referred to as a bowel perforation detection
system, can include: a sample delivery unit comprising an aspirate
filtering means; a sensing unit comprising a gas-detecting means, a
pump, a processor, and a display; and a connector, for example, an
electromechanical connector, to link the sample delivery unit and
the sensing unit.
[0010] The aspirate filtering means can comprise a first filter for
separating liquid from aspirate and a second filter for separating
gas and microbes from aspirate. The first filter can be a
hydrophobic porous membrane filter having pore sizes ranging from
about 100 microns to about 500 microns. The second filter can be a
hydrophobic filter having a minimum pore size of 0.2 microns or a
hydrophilic filter having a minimum pore size of 0.01 microns. The
aspirate filtering means can also be a filtration system which
includes an outer housing section; an inner tubing section, a
portion of which is perforated; a sleeve comprising an absorbent
wicking material positioned between the perforated tubing and the
outer housing; and the above-described filters. The absorbent
wicking material can be a hydrophilic polyurethane foam or a
cellulose fibrous material with capillary wicking
characteristics.
[0011] The gas-detecting means can be one or more gas sensors.
User-interactive software can be provided for control of the gas
sensors. Any sensors known to those skilled in the art that are
capable of detecting the desired gases may be used in the practice
of the invention. For example, the gas sensors can be contact gas
sensors, non-contact gas sensors, and combinations thereof. Gases
that can be detected include, but are not limited to, hydrogen,
methane, carbon dioxide, sulfide, and nitrogen. Thus, devices of
the invention may include one or more of a carbon dioxide gas
sensor, a methane gas sensor, a hydrogen gas sensor, a sulfide gas
sensor, and/or a nitrogen gas sensor. The carbon dioxide and
methane gas sensors can be infrared sensors and the hydrogen gas
sensor can be a solid state sensor. The gas-detecting means can be
configured to detect the concentration of gases in real-time.
[0012] As described herein, a method for detecting a bowel
perforation injury can include steps of: obtaining an aspirate
sample from an abdominal or pelvic cavity of a patient; filtering
said aspirate sample to separate a gas component of the sample from
a liquid component (if present) and a microbial component (if
present); analyzing said gas component using a gas-detecting means
to determine the composition of the gas contained in the abdominal
or pelvic cavity; wherein an elevated level of a gas normally
present in the bowel and not normally present in the abdominal or
pelvic cavity indicates the presence of a bowel perforation injury.
The method for detecting a bowel perforation injury can be
accomplished using the devices described herein.
[0013] Also described herein is an electromechanical connector. The
connector can be used to connect the sample delivery unit and the
sensing unit of the bowel perforation detection device. The
connector can comprise a first section comprising an insert molded
curvilinear conducting element; and a second section comprising a
paired pin conductor set. The connector can be an injection molded
threaded coupler with a simple standard luer connection containing
a metallic conducting strip that is insert molded with the main
connector body. This metallic conducting strip will preferentially
mate with its counterpart on the sensing unit only when the luer
connector is properly threaded on to the sensing unit.
DESCRIPTION OF THE DRAWINGS
[0014] FIG. 1A shows a configuration of the bowel perforation
detection system disclosed herein.
[0015] FIG. 1B shows another configuration of the bowel perforation
detection system.
[0016] FIG. 2 is an exemplary operating room layout for use with
the methods and devices disclosed herein.
[0017] FIG. 3 is a schematic depiction of a bowel perforation
detection method as disclosed herein.
[0018] FIG. 4 is a table of calculations for determining bowel gas
concentrations in a gas sample.
[0019] FIG. 5 shows the configuration of a single stage embodiment
of the bowel perforation detection system disclosed herein.
[0020] FIG. 6 shows the configuration of another single stage
embodiment of the bowel perforation detection system disclosed
herein.
[0021] FIG. 7 shows the configuration of a two stage embodiment of
the bowel perforation detection system disclosed herein.
[0022] FIG. 8 shows the configuration of another two stage
embodiment of the bowel perforation system disclosed herein.
[0023] FIG. 9 is an exploded view of a filter-tubing system as
disclosed herein.
[0024] FIGS. 10A-10C provide perspective and exploded views of
filter assembly/filtration unit as disclosed herein. FIG. 10D is a
cross-sectional view of the assembly of a central perforated
tubing.
[0025] FIGS. 11A and 11B provide perspective and exploded views,
respectively, of another filter assembly/filtration unit as
disclosed herein. FIG. 11C provides another perspective view of the
filter assembly/filtration unit as disclosed herein and FIG. 11D is
a cross-sectional view along line A-A of FIG. 11C.
[0026] FIGS. 12A and 12B provide perspective and exploded views,
respectively, of the filtration system. FIG. 12C provides another
perspective view and FIG. 12D is a cross-sectional view along line
A-A of FIG. 12C.
[0027] FIGS. 13A and 13B provide perspective and exploded views,
respectively, of the filtration system. FIG. 13C provides another
perspective view and FIG. 13D is a cross-sectional view along line
A-A of FIG. 13C.
[0028] FIG. 14 is an exploded view of an electrical connector
disclosed herein.
[0029] FIG. 15 is a schematic view of an electrical connector
disclosed herein.
[0030] FIGS. 16A and 16B provide perspective views of a sensing
module as disclosed herein.
[0031] FIG. 17 shows a sensing module as disclosed herein.
[0032] FIGS. 18A and 18B provide an exploded view and perspective
view of a sensor arrangement as disclosed herein.
[0033] FIGS. 19A-19E show exploded view, perspective view, and
cross-sectional view of a sensing chamber assembly as disclosed
herein.
[0034] FIGS. 20A and 20B each provides a perspective view of
another sensing module disclosed herein.
[0035] FIG. 21 shows another sensing module as disclosed
herein.
[0036] FIGS. 22A and 22B provide exploded view and perspective view
of another sensor arrangement as disclosed herein
[0037] FIGS. 23A-23E provide exploded view, perspective view, and
cross-sectional view of another sensing chamber assembly as
disclosed herein.
[0038] FIG. 24 is a table of sensor selection results.
[0039] FIG. 25 is a graphical view of a user-screen interface for
the devices disclosed herein.
[0040] FIG. 26 is a logic-flow of the user interaction for the
devices disclosed herein.
[0041] FIG. 27 is another logic-flow of the user interaction for
the devices disclosed herein.
[0042] FIG. 28 is an algorithm flow for the devices disclosed
herein.
[0043] FIG. 29 is a photograph of a bypass filter construction as
disclosed herein.
[0044] FIG. 30 is a photograph of a bypass filter construction as
disclosed herein.
[0045] FIG. 31 is a photograph of the wicking function of a bypass
filter construction as disclosed herein.
[0046] FIG. 32 is a view showing various gas concentrations over
the length of the human intestinal tract.
DETAILED DESCRIPTION
[0047] The methods and devices disclosed herein can detect the
presence and/or measure the concentration gases that are present in
the bowel but not normally present in the abdominal or pelvic
cavities. By detecting and measuring these gases, the methods and
devices can be used to diagnose the presence and location of a
bowel perforation.
[0048] The device disclosed herein can access the abdominal or
pelvic cavity, for example, by having a medical device that is
positioned in the cavity connected thereto, such as a Verress
needle or trocar connected to the device via a Luer Lock. The gas
detection device can gently suction a small sample of the air from
the abdomen. The device measures for one or more of methane,
hydrogen, carbon dioxide, sulfide, and other fermentable gases that
are released by bacterial metabolism, such as nitrogen and sulfide
acetate. These gases form and are exclusive to the bowel and are
not present in the abdominal cavity. These gases exist in different
concentrations in each section of the small and large bowel, as
shown in FIG. 32. When these bowel gases are discovered in the
abdominal cavity, it alerts the physician that a bowel leak or a
perforation can exist. The device can also be calibrated based on
ambient concentrations of gases for comparison purposes, for
example, in order to identify whether an elevated gas concentration
in the abdominal cavity could be the result of trace amounts of the
gas in the ambient atmosphere of an operating room. The device can
also be utilized to detect changes in gas concentrations in the
abdominal cavity over time, for example, throughout the course of a
laparoscopic surgical procedure.
[0049] The device can also analyze the concentration of the
different gas types that are present in the abdominal cavity, for
example, in order to identify the presence of an abnormally high
concentration of a gas and the most likely area of the bowel where
that concentration of gases normally resides and escaped into the
abdominal cavity. The device can include a processor that
identifies the most likely section of the bowel that has been
perforated based upon the relative concentrations of bowel gasses,
or may be provided with a reference chart so that the physician can
direct attention to the most likely area of injury.
[0050] The bowel perforation detection device disclosed herein can
include a sample delivery unit and a sensing unit. The sample
delivery unit and sensing unit can be linked via a connector, for
example, an electromechanical connector.
[0051] The sample delivery unit can include a means for filtering,
for example, a means for filtering aspirate contained in the
abdominal and pelvic cavities. The abdominal cavity is a dry space
and the sampled aspirate is typically composed mainly of gas.
However, the aspirate can contain residual quantities of liquid and
can also contain microbes. The filtering means is provided in order
to separate any liquid and microbial components of the aspirate
from the gas components of the aspirate prior to analysis by the
gas sensing means. Separation of liquid components of aspirate is
necessary in order to prevent damage to or interference with the
gas detecting means, especially when the gas detecting means is a
gas sensor. Separation of microbial components of the aspirate is
needed in order to contain microbes in the sample delivery unit to
prevent contamination of the sensing unit and gas detecting means.
By preventing contamination of the sensing unit and gas detecting
means, these parts of the device can be reused with other patients
and in other procedures.
[0052] The filtering means can be a filtration system comprising at
least one filter, for example one, two, three, or more filters. The
filters of the filtration system can be a coarse hydrophobic filter
for fluid separation, i.e., filtering any liquid component present
in the aspirate, and a fine filter, for example, a gas filter, to
remove particles and other contaminants, for example, microbes,
from the aspirate. The sample delivery unit can be pre-sterilized
and positioned in the sterile area during a surgical procedure. The
sample delivery unit can be disposable.
[0053] The sensing unit can include a gas-detecting means. The
sensing unit can be positioned in the non-sterile area of the
operating room and can be reused.
[0054] The gas-detecting means can be, for example, at least one
gas sensor. Depending on the type of gas to be detected, the
gas-detecting means can comprise more than one sensor, for example,
a separate gas sensor for detecting each of carbon dioxide,
methane, hydrogen, sulfide, and/or nitrogen. The sensor(s) can be
configured to detect these gases sequentially or simultaneously.
The sensor(s) can be positioned on a sensor board which may be
housed in a chamber. The gas-detecting means can be positioned in
the sample delivery unit and results of the gas detection can be
transmitted to a separate display unit via a connected or wireless
communications interface. The unit can also be provided with an
audible alarm that is programmable to indicate when a particular
gas concentration exceeds a threshold concentration.
[0055] The sensing unit can also include elements related the
transport of a gas sample through the unit, for example, tubing for
transporting the gas sample from the connector to the gas-detecting
means and clearing a tested sample, an exhaust or vent system for
discarding the gas sample, and a pump for drawing the aspirate
sample through the sample delivery unit and the sensing unit. The
sensing unit can also include a processor and display unit for
outputting the gas-detecting results.
[0056] The connector between the sample delivery unit and the
sensing unit can be an electromechanical connector. The
electromechanical connector can include an electrical switch to
indicate connection between the sample delivery unit and the
sensing unit. In some configurations, the connector can be
positioned so that a first portion of the connector, for example, a
male portion, is positioned as part of the sample delivery unit and
a second portion of the connector, for example, a female portion,
is positioned as part of the sensing unit. Alternatively, the
connector can be positioned completely within the sample delivery
unit.
[0057] The detection system described herein can make use of
several features designed to aid ease of use. For example, the
design of the sensing unit, coupling mechanisms, and location of
the sensing unit within an operating room can be configured for
ease of use by an operator. For example, the device can be located
on a battery charging dock on the wall of the operating room in an
appropriate location and docked when ready to use and connected to
a tubing connector as part of hand-off from within sterile field.
An alternate device location is a hand held unit prepped on
non-sterile tray with sterile connector tubing etc sealed in its
packaging. The device can also be positioned on an insufflation
delivery and monitoring stack.
[0058] User interface simplicity can be achieved in the design by
providing the user a simple button system that allows for a usage
sequence in a minimal number of steps, for example, two or three
steps. A three-button system can provide an easy method for using
the device, for example, as follows: Button A--On/Off Button
B--Calibrate (meaning calibrate baseline gas levels in ambient air
to measure sample against) and Button C--Start/Stop (meaning turn
the pump on to draw in the gas sample for measurement. The software
algorithms controlling the pump in the sensing unit can stop the
pump automatically once it has drawn enough sample gas in and can
also be configured to contain a manual stop option.
[0059] The devices disclosed herein can also be designed to have
reusable sections, for example, a reusable sensing unit or display
unit for use across patients and procedures. Since the device
involves transport of gaseous and liquid contents through the
tubing, this becomes an especially challenging problem which has
been addressed in this system.
[0060] Management of the intra-device sterile boundary (i.e., the
flow path) is critical and can been accomplished by incorporating a
two-stage filtration system, also referred to as a filter system,
as the filtering means into the sample delivery unit. The
filtration system can be integrated into tubing that connects the
device at its distal end to a Veress needle or trocar inserted into
the abdominal or pelvic cavity of a patient. The two-stage
filtering unit can contain a microbial filter and a gas filter
system in conjunction with a liquid bypass absorption element that
reliably prevents the ingress of intra-abdominal contaminants
(e.g., liquids, and bacteria) from contacting the gas-detecting
means, e.g., the gas-sensors. This filtration system can greatly
reduce or eliminate the possibility of contaminating the sensors
and sensing unit. A third stage gas filter can also be incorporated
into the sensor for use during a calibration cycle, i.e, a cycle of
the device to detect the ambient carbon dioxide content in an
insufflated patient.
[0061] The device can be designed to accommodate aspirate volumes
as needed to enable detection, for example, from about 50 cc of
asipirate to about 500 cc. Since the aspirate can contain residual
amounts of liquid in addition to gas (e.g., bowel gas if
perforation has occurred, and atmospheric gases resulting from hiss
test ingress of outside air), the system can be designed to
eliminate liquid ingress via a two-stage liquid bypass filter and
in conjunction with a software algorithm controlling the pump such
that the liquid breakthrough pressure of the filters is not
exceeded by the pump. Thus, the device can achieve filtration of
aspirate to separate the liquid and gas phase, and retain enough
pressure differential to achieve transport of gas phase to the
sensing unit without exceeding the liquid breakthrough pressure of
the filter itself.
[0062] The system can be designed to accurately detect minute
quantities of bowel gases in a sample that are above the threshold
levels (ambient concentrations). Bowel gas concentrations are
50,000-290,000 PPM for CO.sub.2, 600-470,000 PPM for H2, and 0
260,000 PPM for CH.sub.4. Ambient values for each of these gases
are 360 PPM, 0.5 PPM, and 2 PPM respectively. The gas-detecting
means for each of the gas species in the present device can detect
gas concentration elevations of about 1 PPM above ambient
concentrations for H2, 10 PPM for CH.sub.4, and 100 PPM for
CO.sub.2, at the sensing unit. The gas concentrations for various
sample volumes are shown in FIG. 4.
[0063] The bowel perforation detection device disclosed herein is
now described with reference to the figures.
[0064] FIGS. 1A and 1B provide perspective and exploded views of
the device 10. In general, devices of the invention will comprise a
sample delivery unit 20 and a sensing unit 30. As shown in FIGS. 1A
and 1B, the sample delivery unit 20 can include a luer 21, a means
for filtering aspirate that is a filtration unit 22, tubing 23, and
a section, for example, a male section 41, of the connector 40. The
luer is adapted to be connected to surgical device for accessing
the abdominal or pelvic cavities and for obtaining an aspirate
sample for passing through the sample delivery unit to the sensing
unit 30, for example, a Veress needle or trocar (not shown). The
luer can also be provided with a one way valve 24 in order to
prevent return of sampled aspirate into the abdominal or pelvic
cavity.
[0065] As shown in FIGS. 1A and 1B, the sensing unit 30 can include
a housing unit, shown as top housing unit 3I0a and bottom housing
unit 310b, a section, for example, a female section 42, of the
connector 40, a gas-detecting means, a pump 32, a processor 50,
tubes 37a (FIGS. 1A and 1B) and connectors 37b (FIG. 1B) for
transporting the sample through the sensing unit, an
exhaust/pressure relief system 38 for venting sampled gas, a
battery 39, and a display unit 36. As shown in FIGS. 1A and 1B, the
gas detecting means can be a sensor board 33 having at least one
gas sensor 34 that is housed in a sensing chamber 35. The sensing
chamber can have ports for transporting the gas sample into and out
of the chamber. The chamber can also have a pressure relief valve.
The pump 32 is provided to draw the aspirate sample from the
abdominal or pelvic cavity, through the sample delivery unit, and
into the sensing unit. The number, position, shape, and length of
tubes 37a and connectors 37b in the sensing unit are not
particularly limited and can be adjusted as understood by one of
ordinary skill in the art to transport the gas sample through the
sensing unit 30 and sensing chamber 35.
[0066] FIGS. 1A and 1B show alternate configurations for the
sensing chamber. As shown in FIG. 1A, the sensing unit has a single
sensing chamber. A single sensing chamber configuration is
discussed in more detail below with reference to FIGS. 16A, 16B,
17, 18A, 18B, and 19A-19E. As shown in FIG. 1B, the sensing unit
has two sensing chambers and each chamber can contain different
types of gas sensors. A two sensing chamber configuration is
discussed in more detail below with reference to FIGS. 20A, 20B,
21, 22A, 22B, and 23A-23E. FIGS. 1A and 1B also show alternate
positions for the connection of the sample delivery unit and the
sensing unit.
[0067] The bowel perforation detection system described herein can
be configured as a single-stage unit, e.g., a system in which the
sample delivery unit and the sensing unit are physically connected.
Alternatively, the system can be can be configured as a two-stage
unit, e.g., a system in which the sample delivery unit and sensing
unit are separate, stand-alone units, or parts of the sample
delivery unit and sensing unit are separate. System architectures
for single-stage and two-stage units are explained with reference
to FIGS. 5-8.
[0068] FIG. 5 shows a system architecture for a single-stage unit
bowel perforation detection system as described herein. A
disposable sample delivery includes tubing with a one way valve, at
the needle coupling/needle luer, a coarse hydrophobic filter for
fluid separation, and a fine gas filter to remove particles,
microbes, and other contaminants. The sample delivery unit also
contains a coupling to connect to the sensing unit which
incorporates an electrical conducting insert that serves as a
switch which is triggered if the connector is properly assembled
(e.g., threaded) onto the sensing unit. The reusable sensing unit
shown in FIG. 5 includes three gas sensors (for example, one for
each of CO.sub.2, CH.sub.4, and H.sub.2) in series, a pump, valves,
mother board, embedded software, screen display, and switches/user
control buttons, as needed, integrated in to a single housing for
use. The number of sensors included in the sensing unit can be
adjusted based on the number of gases desired for detection.
Sensors specified for this application can be contact based
requiring direct interaction with the gaseous species
(electrochemical and catalytic technologies) to enable
concentration measurement. Contact based sensors require more
sophisticated software algorithms for driving each sensor (which
can be different for each sensor), sensing, and signal
conditioning. This system architecture provides for real time
intermittent or continuous analysis of the sample and simultaneous
detection by the gas sensors.
[0069] FIG. 6 shows an alternative system architecture for a
single-stage unit bowel perforation detection system as described
herein. The system architecture shown in FIG. 6 is similar to that
shown in FIG. 5. The architecture shown in FIG. 6 is designed for
utilizing non-contact technologies, such as infrared (optical)
methods, for sensing gas concentrations. This system architecture
incorporates a similar modular hierarchy with the sample delivery
unit containing the valves, filters, tubing, and electromechanical
connector, and the sensing unit containing all of the hardware and
software used for gas sensing. Non-contact sensors require less
sophistication in terms of software algorithms for sensing and
signal conditioning. This system architecture also allows for
real-time sensing and sequential activation of the gas sample.
[0070] FIG. 7 shows a system architecture for a two-stage bowel
perforation detection system. A two-stage system can be desired in
clinical settings where real time tracking of bowel gas leakage
risk is not possible, or not required. In these settings, system
architecture shown in FIG. 7 can be used, which makes use of the
same general principles and design specifications shown in the
system architectures of FIGS. 5 and 6. In the system architecture
shown in FIG. 7, the first stage contains the sample delivery unit
along with a portable pump to collect the gas into a collection bag
for storage. The filtered sample gas will be taken offline for
sensing and display of the results. For example, the sample is
delivered from the sample delivery unit to a collection bag and the
collection bag is then disconnected from the sample delivery unit
and attached to the sensing unit for transfer of the sample to the
sensing unit. The time required to acquire and test a sample with
this system is greater than a single-stage unit. This architecture
may be useful, for example, in settings where real-time results are
not required or desired. This can decrease the cost of the system
for both the sample delivery unit and the gas-detecting means in
the sensing unit.
[0071] FIG. 8 shows another system architecture for a two-stage
unit. This system architecture addresses the issue of having tubing
cross a sterile barrier, by eliminating the tubing connection from
the sample delivery unit to the sensing unit. In this design, the
sample delivery unit includes the gas-detecting means and
associated components (e.g., pump, tubing, exhaust) communication
between the sampling-sensing unit (disposable) and the display is
provided as a separate unit that is connected to the combined
sample delivery-sensing unit via a wireless communications
interface. Testing results are transmitted via the wireless
communications interface for processing and display on the separate
display unit.
[0072] These above-described system architectures take into account
the various requirements including and not limited to various
considerations such as sterile barrier, preferential gas transport,
shielding of sensing elements from body fluids and other
contaminants, pumping requirements, software control algorithms to
address ease of use, handling, reliability and accuracy to avoid
false positives and false negatives, and disposability of the
appropriate modules that do get contaminated. A person of ordinary
skill in the art will recognize variations of these system
architectures based on these factors.
[0073] In addition to features that ensure no fluid ingress into
the sensing unit, the filter tubing also incorporates an
electromechanical connector. The connector can include a mechanical
coupling to the sensing unit that also serves as an electrical
switch that completes the sensor control circuit when properly
connected. This is designed to ensure that the sensing units are
not activated without the filter in place, i.e., the unit will not
function without filter connected
[0074] The sample delivery unit can include a filtering means,
tubing for transporting the sample through the unit, and a luer
adapted for connection to a device for obtaining an aspirate
sample, for example, a trocar or Veress needle. The filtering means
can be a filtration system comprising at least one filter. The
purpose of the filtering means is to separate the liquid,
microbial, and gaseous components of aspirate in the abdominal and
pelvic cavities. The tubing can be suitable for use in surgical
procedures and is not particularly limited by material and
size.
[0075] The primary function of the filtering means of the present
systems are to eliminate any liquid phase components of the
aspirate as close to the luer-Veress needle/trocar connecton as
possible. This can be achieved by using at least one filter as the
filtering means. When using a filter as the filtering means, it is
also necessary to avoid liquid clogging at the filter, which can
trap gas distal to the filter, and to prevent contaminants from
entering the sensing unit.
[0076] The filtration requirement for transporting bowel gases over
a substantial length of tubing has several challenges. These
include the need to completely eliminate liquid from entering the
gas sensing unit, avoiding clogging of gas filters with liquid and
trapping gas near the needle and ensuring that no bacterial
contaminants enter the sensing unit. Preventing the entry of
bacterial contaminants into the sensing unit is necessary in order
to ensure reusability of the sensing unit.
[0077] Filter performance characteristics are measured by various
types of parameters. Water Breakthrough or Water Entry Pressure
(WEP) is a measurement of the pressure required to push water
through a hydrophobic filter and is a measure of filter integrity.
The bubble point of a filter measures the pressure required to
remove liquid from the largest pore of the filter. Flow rate
measures the flow of liquid or air through the filter at a given
pressure. Housing Integrity is the pressure that the filter housing
will withstand before it bursts. Filtration efficiency is a measure
of the performance of the filter by comparing the "challenge" with
the "filtrate". The selection of the appropriate filter for an
application is determined by the composition of the media to be
filtered, the desired filtrate, the pressure drop, and flow rate
requirements.
[0078] Additionally, for systems as described herein which must be
designed for use within a sterile area, methods of sterilization
are also considered. Filter unit materials can be used which allow
for both Gamma sterilization and Ethylene Oxide sterilization.
[0079] Based on the above-described goals, a two-stage filtration
strategy can be selected. The first stage can involve a first
filter for liquid filtration, i.e., separation of the liquid phase
from the aspirate. The first filter can be a hydrophobic porous
membrane filter with pore sizes ranging from 100-500 microns. Such
filters are commercially available from manufacturers as Pall
Medical.RTM., GVS.RTM., PSI.RTM., Millipore.RTM.. The second stage
can include a second filter for gas and microbial filtration and
can be a hydrophobic or a hydrophilic filter depending on the size
of the contaminants. For a hydrophilic filter, the minimum pore
size can be 0.01 microns. For a hydrophobic filter, the minimum
pore size can be 0.2 microns.
[0080] The presence of these two types of filters does not
eliminate all potential clogging risk. Since tubing diameters can
be very small, there is a potential risk of clogging or entrapment
of liquid aspirate at the first filter, resulting in trapping of
the gases on the upstream side of the filter. In this situation the
only way to continue to transport gas through the tubing lumen is
to increase the pump pressure and exceed the liquid breakthrough
pressure for the liquid membrane filter, which then poses a risk of
liquid reaching the gas sensing unit. An alternate approach can be
to employ a sophisticated pump control (e.g., on-off cycling
techniques similar to the antilock braking systems in an
automobile) algorithms can be developed based on the LBP pressure
cutoffs to create a break in the liquid barrier or agitate the
trapped liquid just enough to transport gas through.
[0081] In order to avoid the above-described problems, the sample
delivery unit can be provided with a filter-tubing system
containing a one way valve in series with tubing (internal
diameters from 2 mm to a high of 12 mm). FIG. 9 shows an exploded
view of a sample delivery unit including a luer 21 for connecting
to a surgical device (e.g., Veress needle or trocar), a one-way
valve 24, a filtration unit 22 having one end adapted to connect to
the one way valve and another end adapted to connect to tubing 23,
and a male section 41 of the connector for connection to the
sensing unit.
[0082] A filtration unit 22 as shown in FIG. 10A and FIG. 10C can
include a rigid outer case/housing 220, a perforated section of
tubing 223 that transports the aspirate, an absorbent wicking
material sleeve 224 between the perforated inner tube and outer
casing, a first filter 221, for example, a liquid hydrophobic large
pore (100-500 micron) filter, and a second filter 222, for example,
a 0.2 micron hydrophobic or hydrophilic gas/microbial filter,
downstream from the first filter. The filtration unit has a lumen
through which the aspirate sample passes. The filtration unit can
also have a spacer 226 positioned between the liquid filter 221 and
gas filter 222. The spacer 226 can have recessed portion(s) for
positioning of the filter(s). The filtration unit can have a
housing cap 227, which can have a recess for positioning of a
filter and an end adapted to connect to tubing. As shown in FIG.
10A, a portion of the perforated tubing 223 can protrude from
housing 220 for connection to the one way valve.
[0083] The perforated section of tubing 223 can have a shoulder
portion 228. The shoulder portion can be integrally formed with the
perforated section and formed of the same material. Alternatively,
the shoulder portion can be a separate component positioned at an
end of the perforated tubing. The shoulder portion can have a
recessed area for positioning a filter.
[0084] FIGS. 10A and 10B provide perspective and exploded views,
respectively, of the filtration unit. FIG. 10C provides another
perspective view and FIG. 10D is a cross-sectional view along line
A-A of FIG. 10C. FIG. 10D depicts the assembly of a central
perforated tubing (shown with multiple perforations around the
circumferential and axial direction, the absorbent sleeve, the
outer rigid housing that will resist the vacuum pressure applied
without buckling in, and the two-stage filter discs for liquid and
gas respectively.) As shown in FIG. 10D, an external portion of the
filtration unit can be formed by the housing 220, the shoulder
portion 228, the spacer 226, and the housing cap 227, which can be
hermetically sealed.
[0085] This entire assembly comprises a liquid bypass absorption
mechanism to prevent liquid entrapment clogging which features the
perforated inner tube which allows liquids to be wicked into the
absorbent sleeve. Various absorbent materials such as cellulose
fiber mats, and hydrophilic urethane foams can be used to achieve
the wicking functionality. The wicking functionality allows for
liquids to be moved away from the gas flow path and maintain an
open lumen for gaseous species transport. The tubing end that
couples to the sensing unit has a mechanical connector containing
an electrical conductive element that is engaged with a female
mating connector on the housing to complete the sensing
circuit.
[0086] An alternative filter housing design can have only the
liquid filter 221 within the filtration assembly (as shown in FIG.
11B) and place the gas filter at the coupling site with the sensing
device (not shown). This configuration can allow for lower driving
pressures at the pump by eliminating or reducing the pressure
differential resulting from the length of tubing (approximately 2-3
meters) used for transport of gas species. This feature can enable
the selection of smaller and lower pressure capacity pumps for the
sensing unit. FIGS. 11A and 11B provide perspective and exploded
views, respectively, of the filtration system. FIG. 11C provides
another perspective view and FIG. 11D is a cross-sectional view
along line A-A of FIG. 11C.
[0087] The filtration unit 22 shown in FIG. 11A can include a rigid
outer case/housing 220, a perforated section of tubing 223 that
transports the aspirate, an absorbent wicking material sleeve 224
between the perforated inner tube and outer casing, and a filter
221, for example, a liquid hydrophobic large pore (100-500 micron)
filter. The filtration unit has a lumen through which the aspirate
sample passes. The filtration unit can have a housing cap 227,
which can have a recess for positioning of a filter and an end
adapted to connect to tubing. A portion of the perforated tubing
223 can protrude from housing 220 for connection to the one way
valve.
[0088] The perforated section of tubing 223 can have a shoulder
portion 228. The shoulder portion can be integrally formed with the
perforated section and formed of the same material. Alternatively,
the shoulder portion can be a separate component positioned at an
end of the perforated tubing. The shoulder portion can have a
recessed area for positioning a filter.
[0089] As shown in FIG. 11D, an external portion of the filtration
unit can be formed by the housing 220, the shoulder portion 228,
and the housing cap 227, which can be hermetically sealed.
[0090] Another configuration for the disposable filter tubing
system 22, as shown in FIG. 12A, can be provided to address
scenarios in which larger quantities of aspirate are desired for
testing purposes. In this embodiment, a thin-walled absorbent
sleeve 224 and housing 220 can be extended all along the length of
the tubing 223 and transport tubing to provide the desired
volumetric pore capacity to filter large amounts of aspirate as
desired. The filtration unit shown in FIG. 12B includes one filter
221. However, this filter assembly design can also incorporate
multiple filters, for example, liquid and gas membrane filters at
the end close to the sensing device. The filtration unit can also
include a housing unit 220, housing cap 227, and spacer. A portion
of the perforated tubing 223 can protrude from housing 220 for
connection to the one way valve.
[0091] FIGS. 12A and 12B provide perspective and exploded views,
respectively, of the filtration system. FIG. 12C provides another
perspective view and FIG. 12D is a cross-sectional view along line
A-A of FIG. 12C.
[0092] Another configuration for the filter assembly 22 is
described with reference to FIG. 13A. This filter assembly contains
an injection molded rigid housing 220 with a first filter 221, for
example, a liquid filter membrane (100-500 microns-hydrophobic).
This configuration does not contain a liquid bypass feature in
place of which, a larger volume chamber 229 within housing 220 is
provided with a flared filter surface area to increase flow and
prevent liquid entrapment and clogging. Housing caps 227, adapted
to connect to tubing, can also be included in the filter assembly.
FIGS. 13A and 13B provide perspective and exploded views,
respectively, of the filtration system. FIG. 13C provides another
perspective view and FIG. 13D is a cross-sectional view along line
A-A of FIG. 13C.
[0093] All the embodiments of the filter-tubing assembly can
contain an electrical coupling connector integrally assembled into
the tubing. The electrical coupling connector, also referred to as
an electromechanical connector, is shown in FIGS. 14 and 15. The
mechanical connection can be a bayonet fitment requiring rotation,
for example, a 90 degree or a 45 degree rotation, to bring the
conductive elements in contact between the tubing connector of the
sample delivery unit and its mating counterpart on the sensing unit
housing to complete the sensing circuit. The electrical coupling
itself can be facilitated by providing electrodes, for example,
curvilinear copper or steel electrodes that are insert molded into
the plastic connector at the end of the tubing. The curvilinear
electrodes can also be stamped from sheet metal and bonded to the
plastic connector surface using alternate methods such as adhesive
bonding, thermal bonding, and ultrasonic welding. Matching pin
electrodes can be located on the female side of the connector
located within the sensing unit. The pin electrodes can be in turn
connected internally to the circuit that contains the sensors,
pumps, mother board, and screen display. This circuit can remain
open when the tubing side connector is not assembled to the sensing
side connector coupling. When the tubing side connector is threaded
on to the sensing side, the rotational lock (e.g., bayonet or
standard threaded connection) can bring the electrical conducting
strip and pins in alignment, thus completing the circuit. This
circuit closure can be detected by a smart software algorithm
indicating that the device is ready for use and that the tubing is
connected correctly. The loss or presence of this connection will
also be monitored by the software algorithm during intermittent or
continuous gas sensing modes to ensure that tubing connections are
correct and working as desired real time.
[0094] The sensing unit can be a hand held device with a housing
unit, for example, a rigid plastic injection molded housing,
containing an onboard battery pack for power, user interaction
screen interface, processor, for example, a processor for signal
conditioning, embedded software, pump, flow and pressure sensors,
an enclosed sensing chamber with gas sensors, a pressure relief
valve as appropriate for venting, and tubing for gas transport. The
sensing unit is described in detail with reference to FIGS. 16A,
16B, 17, 18A, 18B, and 19A-19E.
[0095] FIGS. 16A and 16B show a sensing unit 30 for use in a
single-stage system architecture, for example, as shown in FIGS. 5
and 6. The sensing unit 30 can have a sensing module housing 310
containing a linear array of gas sensors 34 inside a sensing
chamber 35. The sensing unit can also include a display 36 and
battery 39. Although the system architectures shown in FIGS. 5 and
6 have different modes of gas detecting, the hardware remains the
same across both. Although the size of the sensing module housing
is not particularly limited, the housing as shown in FIG. 16A is
about 210.times.115.times.63 mm.
[0096] Gas ingress can be achieved when the processor (not shown)
starts the pump 32 which opens a one-way valve 320 and enables
transport of gas through the internal secondary filter 321. Gas
passes through the in-series flow sensor 322 and is transported to
the sensing chamber 35 wherein the gas sensors 34, for example,
CO.sub.2, CH4, and H2 sensors, are sequentially turned on based on
the sensor response/reaction times to enable concentration
measurement. The sensors are connected to a single electronic board
33 containing the electronics required for signal conditioning
(e.g., power supply, amplification, and filtering) and other
control requirements for the sensors. A pressure relief valve 380
is provided in the event the pressures inside the collection
chamber exceed a critical value. Once the measurements are
completed gases are vented through the pump 32. The sensing unit
can also include a pressure sensor 323 for detecting the pressure
exerted by the pump 32. An internal secondary filter 321 can be
provided for use during calibration of the sensing unit, e.g.,
detecting ambient gas concentrations.
[0097] FIG. 17 shows a configuration of the sensing chamber 35
with, gas sensors 34, connection base assemblies 340, and sensor
board 33 for the system architecture as shown in FIGS. 5 and 6. For
simultaneous sensing of the gases, infra-red (IR) sensors are used
for CH4 and CO.sub.2, and electrochemical sensors are utilized for
H2. Unlike semiconductor sensors (for H.sub.2) which require
heating of the gas, this configuration can utilize simultaneous
measurement of all the ppm levels thereby reducing the read time of
the entire sensing unit. For sequential sensing, the IR sensors
(CH.sub.4 and CO.sub.2) are triggered first in the order of
sensing. The H2 sensor is triggered later in order to avoid
interactions between the heat produced by the sensor and the
CH.sub.4/CO.sub.2 sensors which use IR methods. For example, in
sequential sensing, heat produced by a solid state
semiconductor-type H.sub.2 sensor will not affect the IR sensors
for detecting CH.sub.4 and CO.sub.2.
[0098] FIGS. 18A and 18B depict the layout of the gas sensors 34,
their connection base 340 assemblies, and sensor board 33. FIGS.
19A-19E show perspective, exploded, and cross-sectional views of
the sensing chamber 35.
[0099] FIGS. 16A, 16B, 17, 18A, 18B, and 19A-19E show a sensing
chamber containing three gas sensors. However, the dimensions of
the sensing chamber and number and type of sensors contained in
each chamber can be changed based on the type of sensor and gas to
be detected, as understood by a person of ordinary skill in the
art.
[0100] Another configuration for the sensing unit, as shown in
FIGS. 20A, 20B, and 21, is to utilize two separate sensing chambers
35, for example, one chamber for the IR based CH.sub.4/CO.sub.2
sensors, and another chamber for semiconductor sensors, primarily
H2, and optionally semiconductor based sensors for CH.sub.4 (shown
in the figures as four sensor locations). In this configuration,
perfect thermal isolation can be achieved by separation of the
sensing volumes into two chambers, at the expense of some risk due
to splitting of the gas flow stream. The sensing unit can also
include a display 36 and battery 39.
[0101] Gas ingress can be achieved when the processor (not shown)
starts the pump 32 which opens a one-way valve 320 and enables
transport of gas through the internal secondary filter 321. Gas
passes through the in-series flow sensor 322 and is simultaneously
transported to the first sensing chamber and the second sensing
chamber as it passes through a connector 37b. The sensors within
each chamber can be connected to a single electronic board 33
containing the electronics required for signal conditioning (e.g.,
power supply, amplification, and filtering) and other control
requirements for the sensors. A pressure relief valve 380 can be
provided for each chamber in the event the pressures inside the
collection chamber exceed a critical value. Once the measurements
are completed gases are vented through the pump 32. The sensing
unit can also include a pressure sensor 323 for detecting the
pressure exerted by the pump 32. An internal secondary filter 321
can be provided for use during calibration of the sensing unit,
e.g., detecting ambient gas concentrations.
[0102] FIGS. 22A and 22B depict the layout of the gas sensors 34,
their connection base 340 assemblies, and sensor board 33 as used
in the sensing unit configuration shown in FIGS. 20A, 20B, 21.
FIGS. 23A-23E provide perspective, exploded, and cross-sectional
views of the sensing chambers 35 of the sensing unit shown in FIGS.
20A, 20B, and 21.
[0103] FIGS. 20A, 20B, 21, 22A, 22B, and 23A-23E show a sensing
chamber containing two gas sensors. However, the dimensions of the
sensing chamber and number and type of sensors contained in each
chamber can be changed based on the type of sensor and gas to be
detected, as understood by a person of ordinary skill in the
art.
[0104] The pump housed within the sensing unit is designed to be
capable of delivering the pressure differentials required to
transport gas while avoiding exceeding the liquid breakthrough
pressure for the liquid membrane filters used in the tubing.
Engineering flow calculations can be conducted to determine the
pressure differential required to generate adequate flow of gas and
liquid. Using the following flow calculation input parameters,
Veress needle lumen of 0.4 mm, Initial length of the tube from
Veress needle to filter 24 mm, tubing OD--12 mm, ID 9 mm, worst
case filter parameters (0.2 um pore dia hydrophobic filter, 0.12 mm
thick, 0.01 um pore diameter, hydrophilic, 0.12 mm thick, OD 2*tube
dia=24 mm.), total tubing length of 8 ft, and an internal (to
sensing unit) 0.2 um pore dia hydrophobic filter, 0.12 mm thick, a
pressure differential of 0.92 mBar (91.89 N/m.sup.2) is required to
achieve gas flow, and a differential of 50.99 mBar (5099 N/m.sup.2)
is required to transport liquid over this distance. Thus, to avoid
liquid ingress, a pump capacity of 5 mBar was selected to ensure
safe and preferential transport of gas species, when combined with
the liquid bypass filter design. Numerous commercial pump suppliers
provide pumps in this range of pressure differential capacities
(e.g. KNF Inc, Pfeiffer, etc).
[0105] For selection of gas sensors, a detailed weighted Pugh
Matrix method for each gas was utilized in conjunction with the
following metrics, sensing range, warm-up time, operating
temperature, response time, accuracy, least count/resolution,
sensor life, power consumption, calibration intervals, size, and
other sensor compatibility issues. The Pugh matrix results can also
be adjusted based on secondary factors such as manufacturing cost,
service cost, design time, and parts availability. FIG. 24
identifies acceptable sensor technologies for the present devices
and methods. These technologies in various combinations can be
utilized for the various system architectures chosen for the
sensing unit designs.
[0106] The user interface is designed to be an extremely simple
sequence to enable a layperson to work with the device/sensing
unit. The high level and low level (software level) interactions
are designed and depicted in FIGS. 25-28.
[0107] At the highest level, i.e., the user-screen interface, the
interaction involves tactile engagement with the touch screen
display on the front of the hand held unit. This on-screen logic
sequence is graphically depicted in FIG. 25 (actual display).
[0108] The device can make use of two options for the logic flow
underlying the high level user interaction (FIG. 26--Option 1 and
FIG. 27--Option2). At this level the user interaction involves the
following steps. [0109] Turn on the device [0110] Displays the
welcome screen [0111] A warning is displayed if the battery charge
is low (software interrupt requiring low power). Low
Battery--Recheck/Recharge If battery power is adequate, the
software algorithm will proceed to run an internal "Self-Test" to
ensure that all the sensors and pump are working within the
designed operating parameters. [0112] If battery power is adequate,
screen displays the message "Calibrating to Ambient" (denoting the
process of establishing the baseline levels of gases in the
environment.) [0113] Calibration complete (In this option 1,
calibration feedback and success is explicitly communicated to the
user. In option 2, calibration is a background process and not
necessarily communicated.) [0114] Message to user to connect the
tubing. [0115] If the tubing is connected correctly this completes
the active sensing circuit. Message to user "Connection Found"
[0116] Message to user that system is "Ready" [0117] User presses
"Start" to initiate gas collection [0118] Message to user "Testing"
[0119] If adequate gas is collected based on flow meter monitoring
and/or pressure sensors, results are displayed for each of the
gases. If not, "Flow error message" with note to check tubing
connections. [0120] Retest option displayed for user to run test
again.
[0121] The low level software algorithm is designed to bridge the
communication between the user-and device touch screen and the
required commands at the digital-analog interface to communicate
with the various pieces of hardware in the sensing system. FIG. 28
depicts the preferred software algorithm flow with appropriate
checks to address various risks and failure modes potentially
encountered in operation of the sensing unit.
[0122] The methods and devices disclosed herein can be used during
various stages of or continuously throughout laparoscopic surgery.
These surgical stages include pre-insufflation, intraprocedure and
post-insufflation, and post-abdominal/pelvic procedures.
[0123] The pre-insufflation stage of laparoscopic surgery involves
blind placement of a Veress needle or trocars into the abdominal or
pelvic cavities. During this surgical stage, surgeons insert a
hollow needle into the abdomen or, alternately, a trocar through an
incision, and must ensure that they do not damage/perforate the
bowel. The present methods and devices can be used during this
stage to conduct an aspiration and sensing test after placement of
the needle/trocar to determine if a bowel perforation injury has
occurred.
[0124] Intra-procedure and post-insufflation stage refers to the
surgical stage during which surgeons conduct the abdominal/pelvic
procedure and just prior to closing the patient. Carbon dioxide gas
is typically used to insufflate the abdominal cavity, also referred
to as creating a pneumoperitoneum. The present detection system can
be used to detect for the presence of other gaseous species,
including hydrogen, methane, sulfide, and nitrogen, in the abdomen
or pelvic cavities via discrete or real-time testing. The device
can also be used to detect for elevated concentrations of these
gases as compared to a baseline or previously measured level.
[0125] The system described herein can be used after completion of
abdominal/pelvic procedures. For the example, the present systems
and methods can be used to identify bowel perforation injuries in
patients who have already undergone surgery and present various
symptoms during the post-operative recovery period. In these
patients, the presence of perforation and the precise confirmation
of the same is extremely important given the major ramifications of
such an event which if true results in exploratory surgery,
creation of a colostomy and immediate major impact on the quality
of life. In addition to this, the patient has to undergo another
surgery after resolution of an infection resulting from the
perforations, this time to reverse the colostomy. The application
of the bowel perforation detection technology can be facilitated
via a paracentesis procedure with ultrasound guidance, used to
aspirate abdominal gas contents to enable diagnosis of the presence
of bowel perforation with a high degree of reliability.
[0126] The methods and devices disclosed herein can also be used
for repeated sampling and detecting during a surgical procedure.
For example, for a laparoscopic surgery, the device can be
connected to the medical device inserted into the abdominal cavity
prior to insufflation to perform repeated sampling and
gas-detecting during the surgery, and disconnected after completion
of the procedure and immediately prior to removal of the medical
device from the abdominal cavity. The methods and devices can be
adapted to sample and detect gas at pre-determined intervals, for
example, by programming the device, or can be adapted for on-demand
sampling and testing by a user. The timing and number of samples
obtained and analyzed can be adapted depending on the type of
procedure, for example, laparoscopic surgery or diagnostic
procedures, as would be understood by a person of ordinary skill in
the art.
[0127] The present systems and methods can also be used to detect
bowel perforation injuries occurring in other situations, for
example, trauma and non-laparoscopic surgeries. For example, the
device can be used in conjunction with exploratory aspiration
procedures done with paracentesis needles and enable detection of
bowel gases in the abdomen.
[0128] The bowel perforation detection system can be setup by the
operating room staff in a very short period of time with a
connections-to-measurement time window of about two minutes or
less. However, this does not limit the use of the device by the
surgeons over a longer time window if desired by the needs of the
physician or the procedure. This is critical because there is very
little time available between needle placements and initiation of
pneumoperitoneum. As a result of this rapid overall performance
envelope for connection-to-measurement, the system incorporates
rapid mechanical connections/couplings that can be accomplished by
the surgeon, surgeons assistant, and scrub/circulating nurses, a
very simple user interface, (involving aspirate-sense-results
display steps), software algorithms and gas sensors that work in
conjunction to deliver readings on the digital display rapidly to
the user.
[0129] The bowel perforation detection system can be used in a
surgical operating room setting during laparoscopic procedures and
includes features that address the unique requirements of the
connections with the Veress needle using a tubing coupler, crossing
the sterile field to make a connection with a non-sterile sensing
unit that is reused across procedures and patients. The sterile end
of the tubing is handled by staff that are within the sterile
operating field (e.g., surgeon, surgeon's assistant, scrub nurse),
while the non-sterile end is handled by the circulating nurse or
other assisting staff
[0130] During usage of the system once connected to the Veress
needle, the surgeon performs a common clinical maneuver called a
Hiss test prior to connecting the system to the needle. The purpose
of this test is to ensure that the outside air is entering the
abdomen and will do so if the needle tip is indeed in the
peritoneal cavity. One of the consequences of this Hiss test is
that outside air will mix with any bowel gases (if present) in the
abdominal cavity which will dilute the bowel gas concentrations.
However, the benefit of the Hiss test is that it will ensure that
any trapped bowel gas in various pockets within and between
abdominal or pelvic organs will be freed up and available for
aspiration. Typically several hundred cc of air is brought into the
peritoneal cavity during a hiss test. To accommodate this dilution
level, the sensors and software programming can be configured to
detect small elevations/changes in gas concentrations above
baseline values.
[0131] The following list provides exemplary steps for possible
usage of the present system. Staff within the sterile field can
include a Surgeon (S), a Surgeon Assistant (SA), and a Scrub Nurse
(SN). Staff outside sterile field can include a Circulating Nurse
(CN). FIGS. 2 and 3 provide view of an operating room layout and
flowchart of a laparoscopic surgery using the present system. The
exemplary steps are as follows: [0132] The device and tubing are
prepared on surgical tray for use. [0133] The tubing is sealed in
sterile packaging (e.g., double tyvek pack/pouch). [0134] New
tubing filter/cartridge is connected to device (the tubing can be
packed and--delivered including the Filter which is also a onetime
use). [0135] Surgeon (S/SA) performs standard Veress needle
insertion (without insufflation of CO.sub.2). [0136] Tubing is
delivered into sterile field (CN)--standard drop in sterile
technique. [0137] Tubing is connected to Veress needle via Luer-Lok
connection. Anyone inside the sterile field can execute this
connection. [0138] The other end of the tubing is transferred by
SN/SA/S to CN. [0139] CN can connect tubing to device/filter via
connection. [0140] CN can confirm with staff within the sterile
field that a secure connection is made to the Veress needle. [0141]
CN can implement/start the device. [0142] CN reads device feedback
to decision makers (e.g., S/SA). [0143] S/SA interprets device
feedback and determines next step. [0144] Insufflation of CO.sub.2
followed by trocar placement is next step if surgery can proceed;
[0145] Tubing is disconnected from the Veress needle. [0146] Tubing
is disconnected from the system and discarded. [0147] The system
filter is removed/replaced device cleaned. [0148] The system is
cleaned and retuned to base/docking station.
[0149] Alternative step orders or additional steps based on the
specific type of procedure can be made. Additionally, surgeons can
alter the order of certain steps based on personal preference.
[0150] The device can allow surgeons to avoid delay in treating
bowel perforation and the complications related to seepage of bowel
contents into the abdominal cavity. The device may also be utilized
to detect bowel perforation from ruptured diverticulitis or trauma
in closed abdomens.
[0151] This same device and method may be used as an adjunct to
other modalities in detecting these perforations caused by trauma
or rupture diverticulitis. The methods and devices described herein
can also be used when the abdomen is closed and a perforation is
suspected from a ruptured diverticulum or trauma. A 27 gauge needle
can be placed through the abdominal wall and connected to the
device for a sample of abdominal gases to be analyzed.
EXAMPLES
Example 1
[0152] Filter-Tubing Assembly Testing
[0153] A liquid bypass filter assembly is tested for the ability of
the perforated tubing-absorbent sleeve assembly to achieve lateral
fluid absorption in order to ensure a viable gas flow lumen. FIG.
29 is a photographic of the materials for use in the test. These
include a Veress needle, colored water for visualization, a length
of polyurethane medical grade tubing with a perforated section, a
sheet of absorbent cellulose non-woven material, a rigid plastic
housing, silicone sealant, and a syringe to serve as the pump. As
shown in FIG. 30, the prototype bypass filter is constructed by
inserting the perforated tube into the clear plastic housing.
Following this, the absorbent cellulose wicking material is packed
into the annular cavity created between the perforated section and
the plastic housing. The ends of the plastic housing are sealed
with silicone adhesive to prevent leakage from the annular
space.
[0154] The testing process is shown in FIG. 31. Testing is
initiated by connecting the tubing at one end to a Veress needle
and the syringe at the other end using standard luer lock
connectors (manufactured by Qosina Corporation.RTM.). Following
this, suction is applied by drawing back on the syringe plunger to
draw fluid through the distal end of the Veress needle, which is
positioned in the colored water. As soon as the liquid front
reached the absorbent section, it is immediately absorbed laterally
into the cellulose sleeve, in the circled area of FIG. 31.
Furthermore, even in the absence of a membrane filter, while the
fluid is drawn into the syringe, the absorbency of the sleeve is so
pronounced that it can wick fluid from the syringe back into the
filter assembly. This example demonstrates the engineering
functionality of the liquid bypass filter design.
[0155] While the foregoing disclosure has been described in some
detail for purposes of clarity and understanding, it will be
appreciated by one skilled in the art from a reading of this
disclosure that various changes in form and detail can be made
without departing from the true scope of the disclosure and
appended claims.
* * * * *