Note: Descriptions are shown in the official language in which they were submitted.
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Background of the Invention
This invention relates to improvements in tubes which
are inserted into the body. More particularly, the invention
involves the prevention of leakage from the vent lumen of a
double-lumened nasograstric tube.
Nasogastric tubes are commonly used in hospitals and
nursing homes to remove fluids from the stomach or to administer
nutritives or medicines to a patient.
Nasogastric tubes are used, for example, postoperatively
to prevent pooling of liquids in the stomach during recovery of
the digestive function. They are also used in treatment of
bleeding ulcers to remove blood from the stomach. They are also
used for protecting gastric suture lines, for preventing and
treating paralytic ileus, to decompress the stomach in
circumstances which create outside pressure on the stomach, and
in a host of other conditions.
The tube is conventionally a ~lexible plastic tube which
is passed through the nasal canal, through the p~larynx, and then
down the esophagus into the stomach or small intestine. The
lower or distal end of the tube in the stomach includes several
openings or suction eyes to allow the passage of fluids.
~When the tube is used for removing fluids from the
; stomach, the upper or proximal end of the tube is connected
through a collector vessel to a vacuum pump system. Stomach
fluids are drawn through the openings in the distal end of the
tube, and into the collector vessel.
The openings in the distal end of the tube tend to
become clogged. There are two major causes of such clogging.
Debris in the stomach tends to be drawn into the openings.
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Further, as suction is applied to the nasogastric tube, the
distal end of the tube drifts in the direction of the openings
toward the wall of the stomach. Should the tube engage the wall
of the stomach, occlusion of the openings may occur as the soft
stomach lining (gastric mucosa) is drawn into the openings. Not
only is the action of the tube blocked, but serious damage may be
done to the wall of the stomach.
To help prevent blockage of the openings of a
nasogastric tube, a double-lumened tube is generally used. The
double lumened tube contains both a suction tube or lumen and a
vent tube or lumen parallel to the suction lumen. Generally,
both lumens are provided in a single tube, the vent lumen being a
tube-within-a-tube. The vent lumen includes at least one small
orifice into the suction lumen near their distal ends, to permit
atmospheric air to be drawn through the vent lumen into the
suction lumen.
A common commercially available double-lumened
nasogastric tube is sold by Sherwood Medical Company under the
trademark Salem Sump. The Salem Sump tube is formed as a
tube-within-a-tube. The proximal end of the vent lumen is a
pigtail about one foot long. The distal end of the vent lumen
- ~ includes both an aperture into the suction lumen and a pair of
openings into the stomach in its outer wall, on the side of the
tube opposite the suction openings. The use and operation of the
Salem Sump tube is described in an article by Edwina A.
McConnell, in Nursing magazine, volume 7, number 9, September
1977, at pages 54-7, reprinted in Nursing 82.
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When food or medication is passed down ~he suctionlumen, the vent lumen is clamped or plugged, or air pressure is
applied afterwards to clear the vent lumen. The present
invention is primarily concerned with the functioning of a
double-lumened nasogastric tube when suction is applied to the
suction lumen.
During normal suctioning operation of the nasogastric
tube, a small amount of atmospheric air is drawn through the vent
lumen into the suction lumen at their distal ends, and is mixed
with the stomach fluid as it is drawn from the stomach. During
normal operation air bubbles will be visible in the stomach fluia
as it passes through the tubing to the collector vessel. Should
the suction tube openings become occluded, the presence of
atmospheric air modifies the intensity of vacuum pressure spiking
at the point of occlusion. Therefore, risk of damage to the
stomach wall is reduced. Presence of atmospheric air at the
point of occlusion also provides inducement for the tube to
separate from the obstruction, thereby permitting the tube to
resume normal operation.
The size of the orifice between the vent lumen and the
suction lumen is chosen carefully to avoid interference with the
normal operation of the suction lumen, and to diminish sudden
spiking of vacuum pressure within the suction lumen should its
openings become occluded. Other aspects of the system are also
chosen carefully to balance efficiency of suctioning against the
danger of occlusion. For example, either the suction on the pump
is set to a low value, about 30-40 millimeters of mercury, or the
pump is set to run intermittently (such as five seconds on and
five seconds off at about 80-120 millimeters of mercury). These
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settings are selected so that the vacuum p~essure at t~le suction
openings is maintained below the level of capillary fragility, 25
millimeters of mercury. Should the stomach lining be drawn into
the suction openings at a higher suction, serious damage to the
lining can occur.
It will be seen that proper operation of the double
lumen nasogastric tube depends on the continuous availability of
atmospheric air to the suction openings through the aperture
between the suc~ion tube and the vent tube at their distal ends.
Unfortunately, double lumen nasogastric tubes frequently
do not operate as intended. When stomach pressure is greater
than atmospheric pressure, gastric reflux or leakage can occur,
causing stomach fluids to escape through the vent lumen and out
the pigtail onto the patient. Stomach pressure sufficient to
cause gastric reflux is relatively common. It can be caused by
as simple a force as coughing. It may also be caused, for
example, by an overfilled stomach or by external pressure on the
stomach caused by fluids in the abdominal cavity.
Reflux through the vent lumen of a double-lumened tube
causes problems associated with the spillage of liquids through
the pigtail and may also inter~ere with proper operation of the
nasogastric tube.
The leakage of fluids due to gastric reflux can create
severe medical problems. Stomach fluids are very acidic and will
contribute to skin breakdown on contact. Leaking stomach or
intestinal fluids can cause contamination of wounds, tubing and
catheters. The leakage can be a source of hospital acquired
(nosocomial) infections. Other medical problems can include
inaccurate measurement of gastric secretions.
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Spillage of stomach fluids causes further hospital
problems. The burden of handling leakage or spills due to
gastric reflux is usually the responsibility of the nursing
staff. ~he recommended procedure is to wash the patient and
change the patient's gown and bedliners following a period of
leakage. Removal of equipment connections to the patient may
also be required. This consumes a great deal of nursing time and
adds to the cost of care. Unfortunately, the patient and bed are
not always changed immediately following an episode of gastric
reflux. Failure to change the patient may be the result of
limited nursing resources or may be because the patient can not
be removed from critical intravenous tubes, monitoring equipment
or the like. The patient may thus be required to lie in the
soiled bed for inordinate time periods, which causes patient
discomfort, and may cause fear and additional medical problems.
Gastric reflux also may clog the vent lumen, either by
drawing solid particles into the lumen or by drawing sufficient
liquid into the vent lumen that the low or intermittent suction
being applied to the suction lumen is insufficient to clear the
vent lumen. Blockage of the vent lumen can lead to loss of
function of the nasogastric tube and can result in stomach
lesions and pooling of gastric fluids.
Gastric reflux has long been recognized as a pro~lem
with double-lumened nasogastric tubes. The génerally recommended
procedure for preventing reflux is to place the pigtail above the
patient's midline, and to place the collection trap of the
suction tube below the patient's midline. Unfortunately, the
recommended placement of the tubes is not always practical, and
even with such placement gastric reflux may occur. Maintaining
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the pigtail above the patient's midline generally involves
pinning it to the patient's pillOwr thereby severely Limiting his
or her head movement and adding significantly to discomfort. If
the outlet of the vent tube is below the patient's midline (the
approximate level of liquid in the patient's stomach), the vent
tube can act as a siphon.
Nurses have developed a number of unorthodox techniques
for precluding gastric reflux from the vent lumen of a
double-lumened nasogastric tube. These include placing a stopper
(such as a golf tee or a pencil tip) in the pigtail of the vent
lumen, tying a surgicaL glove over the pigtail, or allowing the
leakage to pool onto a napkin or into a receptacle. The first
two methods defeat the function of the vent lumen. The third is
tedious, further restricts patient movement, and frequently fails.
Summary of the Invention
One of the objects of this invention is to provide a
method and device for preventing the leakage of stomach fluids or
gastric secretions from the vent lumen of a double-lumened
nasogastric tube while maintaining the intended function of the
vent lumen during evacuation of the stomach.
Another object of this invention is to provide such a
method and device which prevent clogging of the vent lumen.
Another object of this invention is to provide such a
method and system in which proper operation of the system is
independent of the placement of the pigtail of the vent lumen,
thereby enhancing patient comfort.
Another object of this invention is to provide such a
~e~hod and device which are inexpensive and easy t~ use
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Another object of this invention is to provide
such a device which may be utilized as a plug for the vent
tube when the suction tube is used for administering food
and medication and which may close the vent and suction
lumens when the nasogastric tube is disconnected from
suction.
Other objects of this invention will be apparent
to those skilled in the art in light of the foll~wing
description and accompanying drawings.
In one aspect o~ the present invention there is
provided a nasogastric suction tube sized for insertion of
the distal end of the tube through the nasal canal and
esophagus into the stomach or small intestine of a
patient, the tube comprising a suotion lumen having
proximal and distal ends, the suction lumen having opening
means in its distal end and means at its proximal end for
attaching the suction lumen to a suction source; a vent
lumen having a proximal and distal ends, the proximal end
of the vent lumen being open to ambient, the vent lumen
having opening means in its distal end for allowing air to
enter the distal end of the suction tube; and one-way
valve means in the vent lumen for closing the vent lumen
to trap a closed column of air in the vent lumen when the
pressure differential between pressure at the proximal end
of the vent lumen and pressure at the distal end of the
vent lumen is less than a predetermined value and for
opening the vent lumen to permit ambient air to pass
through the vent lumen when the pressure differential
between pressure at the proximal end of the vent lumen and
,
pressure at the distal end of the vent lumen exceeds the
predetermined value.
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In a related aspect of the invention there is
provided a nasogastric suction tube sized for insertion of
the distal end of the tube through the nasal canal and
esophagus into the stomach of small intestin~ of a
patient, the tube comprising a suction lumen having
proximal and distal ends, the suction lumen having open
means in its distal end in communication with a space
about the distal end of the tube and means at its proximal
end for connecting the suction lumen to a suction source;
a vent lumen having proximal and distal ends, the vent
lumen having opening means in its distal end in
communication with the space about the distal end of the
tube; and one-way valve means in the vent lumen ~or
closing the vent lumen to trap a closed column of air in
the vent lumen when the pressure differential between
pressure at the proximal end of the vent lumen and
pressure at the distal end of the vent lumen is less than
a predetermined value and for opening the vent lumen to
permit air to pass through the vent lumen when the
pressure dif~erential between pressure at the proximal end
of the vent lumen and pressure at the distal end of the
vent lumen exceeds the predetermined value.
In another aspect of the present invention there
is provided in a nasogastric suction tube sized for
insertion of the distal end of the tu~e through the nasal
canal and esophagus into the stomach or small intestine of
a patient, the tube comprising:
a. a suction lumen having proximal and distal
ends, the suction lumen having opening means in its distal
end and means at its proximal end for attaching the
suction lumen to a suction source, and
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b. a vent. lumen having proximal and distal ends,
the vent lumen having opening means in its distal end for
allowing air to enter the distal end of the suction tube
and being open to ambient at its proximal end, the
improvement comprising
c. means ~or preventing siphoning of fluids
through the vent tube, the means ~or preventing siphoning
comprising one~way valve means for closing the vent lumen
to trap a closed column of air in the vent lumen when
pressure at the distal end of the vent lumen is equal to
or greater than ambisnt pressure at the proximal end of
the vent lumen.
In a related aspect the invention provides in a
nasogastric suction tube sized for insertion of the distal
end of the tube through the nasal canal and esophagus into
the stomach or small intestine of a patient, said tube
comprising:
a. a suction lumen having proximal and distal
ends, the suction lumen having opening means in its distal
end and means at its proximal end for connecting the
suction lumen to a suction source, and
b. a vent lumen having proximal and distal ends,
the vent lumen having opening means in its distal end in
communication with the space about the distal end of the
suction tube and being in communication with an air source
at its proximal end, the improvement comprising
c. valve means for closing the vent lumen to
~; trap a closed column of air in the vent lumen when
pressure at the distal end of the vent lumen is greater
that pressure at the proximal end of the vent lumen.
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In yet another aspect of the present invention
there is provided a valve for use in a vent lumen of a
double-lumened nasogastric tube having a suction lumen
including a proximal end of the suction lumen and a vent
lumen including a proximal end of the vent lumen, the
valve comprising: a hollow stem portion sized to fit
frictionally into the enlarged end of the vent lumen; a
head portion rigidly connected to the hollow stem portion;
opening means in the head portion for admission of ambient
air into the head portion: one-way valve means in the head
portion for preventing fluid flow through the head portion
from the hollow stem through the opening means to the
ambient and for permitting ambient air to flow through the
head portion from the opening means through the stem
portion; and a tapered second stem portion rigidly
attached to the head porkion and sized to fit frictionally
with the proximal end of the suction lumen for closing the
proximal end of the suction lumen when the suction lumen
is removed from a suction source.
In yet another related aspect the invention
provides a valve for use in a vent lumen of a
double-lumened nasogastric tube having a suction lumen
including a proximal end of the suction lumen and a vent
lumen, the valve comprising: a hollow stem portion sized
to fit ~rictionally into the end of the vent lumen; a head
portion rigidly connected to the hollow stem portion;
opening means in the head portion for admission of air
into the head portion; one-way valve means in the head
portion for preventing fluid flow through the head portion
from the hollow stem portion through the opening means and
for permitting air to flow through the head portion from
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the opening means through the hollow stem portion; and atapered second stem portion attached to the head portion
and sized to fit frictionally with the proximal end of
the suction lumen when the suction lumen is removed from
a suction source.
Finally, in accordance with the method of the
present invention, generally stated, a method is
provided for removing fluids from a body cavity of a
patient by means of a novel double-lumened tube having a
proximal end and a distal end, the tube including a
suction lumen and a vent lumen, the method being
characterized by the prevention of reflux through the
vent lumen. The method comprises a step of inserting
into the cavity of the patient the distal end of the
tube, and a step of applying suction to the proximal end
of the suction lumen. The vent lumen includes a valve
which passes atmospheric air into the distal end of the
tube through the vent lumen when pressure at the distal
end of the vent lumen is less than atmospheric pressure
and closes the vent lumen when pressure at the distal
end of the vent lumen equals or exceeds atmospheric
pressure, thereby providing a closed column of air in
the vent lumen and preventing fluid from escaping from
the cavity through the vent lumen.
The pressure differential at which the valve opens
is preselected by the design of the valve to be quite
small, so that the valve opens whenever pressure at the
distal end of the vent lumen is slightly less than
ambient.
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Preferably, the valve is a separate one-way valve
inserted into a pigtail at the proximal end of the vent lumen
prior to the step of inserting the tube into the cavity of the
patient, Preferably, the body cavity is the stomach or upper
intestine and the tube is a nasogastric tube.
By inserting the valve into the vent lumen pigtail
before the tube is inserted into the stomach, a column of air is
entrained in the vent lumen as the tube is inserted. Gastric
reflux through the vent tube is therefore prevented during
insertion of the tube as well as during operation. The solid
stem of the valve may also be placed in the proximal end oE the
suction lumen during insertion of the tube into the patient, to
provide a closed system. This method may also be used whenever
the proximal end of the suction tube is removed from the suction
source, for example to check the return of the patient's
gastro-intestinal function to normal or to permit movement of the
patient.
If liquids are administered through the suction tube,
the valve will preven~ reflux of the liquids through the vent
tube, without capping the vent tube.
The valve is preferably configured to permit easy
insertion and removal of the valve from the pigtail and to permit
easy closing of the proximal ends of ~he vent and suction lumens
when the tube is removed from the suction source. The preferred
valve includes a hollow stem portion sized to fit snugly in the
pigtail, a hollow head portion, opening means in the head portion
for admission o~ ambient air into the head portion, one-way valve
means in the head portion, and a solid connection means for
closing the proximal end of the suction lumen when the suction
~L30S~Q~;
lumen is removed from a suction source. The solid connecton
means is preferably a solid stem portion which may be inserted
into the proximal end of the suction lumen when it is removed
from the suction source, to close the system.
Preferably, the one-way valve comprises a perforated
restriction plate mounted in the head portion below the opening
means. A flexible disc below the restriction plate is normally
closed, but opens in response to a drop in pressure in the hollow
stem.
The valve also functions to prevent siphoning. Because
the valve prevents siphoning, the distal end of the vent lumen or
pigtail may be allowed to hang free without regard to its
position relative to the patient's midline.
FIGURE 1 is a somewhat diagramatic view of a nasogastric
tube of the present invention, attached to a suction device and
inserted into the stomach of a patient for evacuating the stomach.
FIGURE 2 is a view in elevation of the nasogastric tube
of FIGURE 1, partially broken away, showing a valve portion
thereof.
FIGURE 3 is a sectional view of the valve portion of the
nasogastric tube of FIGURES 1 and 2.
FIGURE 4 is a top plan view of a restriction plate
portion of the valve of FIGURE 3.
; FIGURE 5 is a top plan view of a flexible disc valve
; portion of the valve of FIGURE 3.
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Descr ~ Embodiment
Referring now to the drawings, and in paeticuLar to
FIGURE 1, reference nùmeral 1 indicates one illustrative
embodiment of nasogastric tube of the present invention. The
tube 1 is shown inserted through the nose 3, pharynx 5, and
esophagus 7 into the stomach 9 of a patient 11. The upper or
proximal end of a suction lumen 13 of the tube 1 i~ connected by
a 5-in-1 adaptor 14 and tubing 15 to a collection vessel 17,
which is in turn connected to an internlittent suction pump 19 by
tubing 20. The arrangement of FIGURE 1 is standard and
well-known in the art except for the modified nasogastric tube 1.
The nasogastric tube 1 is a commercially available Salem
Sump tube 21, having inserted in the pigtail 23 of its vent lumen
25 a one-way valve 27 in accordance with the present invention.
As is well known in the art, a Salem Sump tube 21
includes a quarter-inch diameter flexible plastic tube, about
forty-seven inches long. The tube is divided by an internal wall
or septum into the suction lumen 13 and the vent lumen 25. The
lower or distal end of the tube 21 is closed.
The exterior wall of the suction lumen 13 is perforated
as indicated at 29, to provide a single hole 3.0" from the distal
end of the tube 21, and four pairs of holes 2.5", 2.0", 1.5" and
1.0ll from the distal end of the tube. The vent lumen 25 is
perforated as indicated at 31, to provide vent holes 0.5" from
the distal end of the tube 21: two holes which extend through the
exter~ior of the tube 21 and an aperture which extends'through the
septum separating the vent lumen 25 from the suction lumen 13.
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The sizes of the holes 29 and 31 are carefully chosen to prevent
the suction at the holes 29 from exceeding about 25.0 mm of
mercury under normal operating suction, to protect the lining of
the stomach.
The upper or proximal end of the suction lumen 13 is
flared, to accept a standard 5-in-1 adaptor 14. The proximal end
of the vent lumen 25 terminates in a pigtaiL 23, a separate piece
of tubing tightly inserted into an opening 33 cut in the exterior
wall of the vent lumen 25 and spaced 1.5" from the proximal end
of the tube 21. The proximal end of the pigtail 23 is flared.
To distinguish the vent tube from the suction tube, the pigtail
; 23 is colored blue.
The valve 27 has a height of about 2.5" and a maximum
diameter of about 0.75". It includes two body parts 35 and 37, a
perforated disk 39, and a flexible disc valve 41.
The body parts 35 and 37 are molded of aluminum. For
purposes which will become apparent, the first body part 35 is
anodized blue and the second body part 37 is anodized a
contrasting color such as gray.
The first body part 35 includes a one-inch long stem
part 43 and a head part 45. The exterior of the stem part 43 is
i~ tapered to fit snugly into the flared end of the pigtail 23, and
the exterior of the head part 45 is threaded. A bore 47 extends
a~ially through the stem part 43 to a cylindrical chamber 49 in
.
the head part 45.
The second body part 37 includes a one-inch long stem
part 51 and a head part 53. The exterior of the stem part 51 is
tapered to fit snugly into the flared end of the suction tube 13
and into the pigtail 23. A bore 55 extends axially into the stem
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part 51 of the second body part to a cylindrical chamber 57 in
the head part 53. The end of the stem part 51 is solid. The
interior of the head par~ 53 is threaded to mate with the
exterior threads on the head part 45 of the Eirst body ~art 35.
An annular ledge 59 spaces the disk 39 from the bottom of the
chamber 57. Four holes 61 extend through a sho~lder 63 between
the stem 51 and head 53. The holes 61 provide a passage between
the chamber ~7 and the ambient atmosphere.
The disk 39 is made of aluminum. It includes four air
passages 65 and a central mounting hole 67 through it. It is
held to the ledge 59 of the second body part by the upper face of
the head part 45 of the first body part 35 when the first and
second body parts are screwed together. The disk 39 separates
the chamber 49 from the chamber 57.
The flexible disc valve 41 is made of resilient rubber.
It includes a tail 69 and a cap 71. The proximal end of the tail
69 includes a step 73 for spacing the center of the cap 71 from
the disc 39, and a protuberance 75 for frictionally holding the
flexible disc valve in the central mounting hole 67 of the disk
39. The periphery of the cap 71 includes a rim 77 which engages
the face of the disk 39 when pressures on opposite sides of ~he
disk are equal.
In assembling the valve 27, the tail 69 of flexible disc
valve 41 is pulled through the mounting hole 67 of the disk 39
until the step 73 seats on the disk and the protuberance 75
engages the opposite side of the disk, to mount the flexible disc
valve 41 securely on the disk. In this position, the rim 77 of
the flexible disc valve prevents fluid flow from its side of the
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disk 39 to the other side, but permits air fLow in the opposite
direction with a very small pressure differential, on the order
of two millimeters of mercury.
The assembled disk 39 and valve 41 are then dropped into
the second body part 37, with the tail 69 extending into the bore
55 and the margin of the disk 39 seated on the ledge 59. The
first body part is then screwed tightly into the second body part
to complete the assembly.
All passage of fluid (including air) through the valve
27 between the ambien~ atmosphere and the outlet of bore 47 is
through holes 61, chamber 57, holes 65, chamber 49, and bore 47.
As previously noted, flow from the bore 47 to the atmosphere is
blocked by the flexible disc valve 41.
The blue stem 43 of valve 27 is preferably inserted into
the blue pigtail 23 of the tube I before the tube 1 is inserted
into a patient. The valve 27 is held frictionally in the pig~ail
23 to form an air-tight fit with the vent lumen 25. Upon
insertion of the tube 1 into the patient, the valve 27 ensures
that the entire vent lumen 25 forms an air column and prevents
liquids from being drawn into the vent lumen. The flared
proximal end of the suction tube 13 is placed over the gray stem
51 of the valve to close the system and prevent reflux of gastric
fluids through either lumen.
The tube 1 is inserted into the patient in the usual
manner. The proper length of tube is measured and marked. The
distal end of the tube is lubricated and inserted through a
nostril until it reaches the pharynx. The patient then swallows
while the tube is advanced into the stomach. After testing to De
sure that ~he distal end of the tube is in the stomach, the
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proximal end of the tube is taped to the patient's nose. The
proximal end of the tube is then removed from the stem 51 and
connected through 5-in-1 connector 14 and collection vessel 17 to
a standard suction pump 19. The pump 19 is set to provide either
intermittent suction of eighty to one hundred twenty millimeterS
of mercury, or to provide continuous suction of thirty to forty
millimeters of mercury.
The holes 61 and 65 in the valve 27 are sized to permit
unrestricted flow through the valve 27 and vent lumen 25.
So long as pressure at the openings 31, at the distal
end of the vent lumen 25 within the stomach, is less than
atmospheric pressure, the tube 21 acts precisely like a Salem
Sump tube without the valve 27. Atmospheric air is drawn through
the valve 27 and vent lumen 25 into the distal end of the suction
tube 13 and/or irlto the stomach 9. A small amount of atmospheric
air is drawn through the vent lumen 25 into the suction lumen 13
and is mixed with the stomach fluid as it is drawn from the
stomach. Should the suction tube openings 29 become occluded,
the presence of atmospheric air at the distal ends of the vent
lumen 25 and the suction lumen 13 modifies the intensity of
vacuum pressure spiking at the point of occlusion, thereby
reducing risk of damage to the stomach wall and providing
opportunity for the tube 21 to separate from the occlusion and to
resume operation.
When pressure at the distal end of the vent tube 25
equals or exceeds atmospheric pressure, the flexible disc valve
41 immediately blocks fluid flow through the valve 27. Gastric
fluids are therefore blocked by the column of air in the vent
lumen 25 from rising in the vent lumen.
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It will ~e seen that while the valve 27 is closed, it
greatly reduces the chances that gastric reflux will cause
particles to clog the vent lumen 25. The column of air in the
vent lumen 25 is maintained at the same pressure found at the
openings 31, and this pressure is greater than oe equal to
atmospheric pressure. When pressure in the stomach is greater
than atmospheric pressure, gastric fluids wilL rise a short
distance into the vent lumen 25 to compress the air column until
air pressure and gastric pressure are approximately balanced.
Should the suction openings 29 become occluded, the increased air
pressure in the vent lumen 25 speeds the flow of the viscous
gastric fluid out of the vent lumen 25, to permit air to reach
the points of occlusion and break the suction, thereby tending to
reduce or level the high vacuum spiking at the point of occlusion
and reducing trauma to gastric mucosa. If vacuum within the
suction lumen is sufficiently increased by occlusion, the valve
27 will open.
If pressure within the stomach is reduced below
atmospheric pressure, the valve 27 immediately opens.
It will be seen that the positioning of the pigtail 23
and valve 27 relative to the midline of the patient does not
affect the operation of the valve 27 and the nasogastric tube 1.
Both gastric reflux and siphoning are prevented even thouyh the
pigtall 23 is not pinned to the patient's pillow but is allowed
to hang ~ree below patient midline.
If liquids are passed down the suction lumen 13, the
valve 27 prevents gastric reflux of the liquids. In accordanCe
with standard practice, the suction pump 19 is disconnected for
several minutes after administration o~ nutrients or medication
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through the tube 21. The valve 27 may also be removed for
irrigatiOn of the tube 1 by injecting saline through the vent
lumen 25.
The valve may also be removed for connecting the pigtail
to the 5-in-1 connector 14 to seal the system when the suction
tube is removed from the suction pump tubing 15. Preferably,
however, the system may be sealed by removing the 5-in-1
connector from the suction lumen and leaving it connected to the
suction pump tubing 15; the solid stem 51 of the valve 27 is
placed in the proximal end of the suction lumen 13 to seal the
system. This arrangement permits air to be drawn into the
patient's stomach if stomach pressure drops below atmospheric
pressure.
Numerous variations in the present tube and its use,
within the scope of the appended claims, will be apparent to
those skilled in the art in light of the foregoin~ description
and accompanying drawings.
Merely by way of example, the valve 27 may be made of
different materials. Other one-way valves may be used in the
valve 27. Indicator means may be provided in the valve 27 to
indicate that stomach pressure has exceeded atmospheric
pressure. Although the preferred embodiment of valve opens at a
very slight pressure differential across it, the magnitude of the
operating differential may be varied somewhat to suit the needs
of a particulax application, in accor~ance with known valve
design. The solid stem~may instead be female, for receiving the
adaptor 14 to close the system.
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~30S;0~S
The valve 27 may be formed as an integral part of the
pigtail 23, although some advantages may be lost, in particular
the ability to purge the system easily by removing the valve and
injecting saline through the pigtail. One way to retain the
ability to purge the system is to form a one-way duckbill valve
of the same material as the tube and bond it into the upper end
of the pigtail with the duckbill extending into the pigtail.
The tube may be of different design and may include
additional lumens (the term "double-lumened" being understood to
include multiple-lumened tubes), although the design of the Salem
Sump tube offers advantages in the practice of the invention.
Although the tube is described as a nasogastric tube inserted
into the stomach, the invention may be applied to the suctioning
Of other body cavities, particularly the upper intestine, where
reflux may be a problem.
These variations are merely illustrative.
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