U.S. patent number 3,848,604 [Application Number 05/332,823] was granted by the patent office on 1974-11-19 for suction catheter.
This patent grant is currently assigned to Physician's Medical Patent Development Corporation. Invention is credited to Marvin A. Sackner.
United States Patent |
3,848,604 |
Sackner |
November 19, 1974 |
SUCTION CATHETER
Abstract
A suction catheter comprising an elongated flexible plastic tube
having a lumen running interiorly thereof and defining an opening
at the distal end. Means are provided at the proximal end for
connecting the catheter to a source of vacuum. The distal end of
the tube is provided with laterally extending flange means and a
plurality of apertures are defined through the tube into the lumen
immediately proximal of the flange means for producing a flow of
gas over the flange means to provide a gaseous cushion between the
flange means and the wall of a body cavity into which the catheter
is to be inserted thereby assisting in maintaining a spaced
relationship therebetween.
Inventors: |
Sackner; Marvin A. (Miami
Beach, FL) |
Assignee: |
Physician's Medical Patent
Development Corporation (Newark, NJ)
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Family
ID: |
26892054 |
Appl.
No.: |
05/332,823 |
Filed: |
February 16, 1973 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
|
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196602 |
Nov 8, 1971 |
|
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Current U.S.
Class: |
604/119 |
Current CPC
Class: |
A61M
25/007 (20130101); A61M 25/0021 (20130101); A61M
25/0068 (20130101); A61M 1/84 (20210501); A61M
2025/0073 (20130101) |
Current International
Class: |
A61M
25/00 (20060101); A61M 1/00 (20060101); A61m
025/00 () |
Field of
Search: |
;128/348,349R,35R,351,239,240,241,242,245,276-278 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
Primary Examiner: Truluck; Dalton L.
Attorney, Agent or Firm: Holman & Stern
Parent Case Text
This application is a continuation-in-part of application Ser. No.
196,602 filed Nov. 8, 1971 now abandoned.
Claims
I claim:
1. A suction catheter of a size suitable for insertion into a body
cavity containing a gas such as the nose, mouth or
laryngotracheobronchial tree, comprising an elongated tube formed
of a flexible material having a lumen running interiorly thereof,
said tube having a distal end with an opening for placing said
lumen in communication with the interior of the body cavity and a
proximal end adapted to place said lumen in communication with a
source of pressure lower than that existing at the distal end of
said tube, regulation means for controlling, from said proximal
end, the suction applied at said distal end, aperture means near
said distal end extending through said tube into said lumen, and
flange means extending laterally from said tube adjacent said
aperture means and between said aperture means and said opening to
maintain said aperture means spaced from the walls of said body
cavity thereby aiding in preventing occlusion of said aperture
means upon application of suction to said catheter.
2. A suction catheter according to claim 1 wherein the area of said
aperture means is sufficient to permit only a nominal vacuum at
said opening upon application of suction to said catheter.
3. A suction catheter according to claim 1 wherein said flange
means is a continous ring extending about the periphery of said
tube contiguous to said distal end, and said aperture means is
immediately proximal of said ring, whereby flow of gas over said
ring provides a gaseous cushion between said ring and the wall of
the body cavity into which the catheter is inserted to assist in
maintaining a spaced relationship therebetween.
4. A suction catheter according to claim 3 wherein the edge of said
opening and flange means are smoothly rounded.
5. A suction catheter according to claim 1 wherein said aperture
means comprises a plurality of equally circumferentially spaced
apertures.
6. A suction catheter according to claim 5 wherein the diameter of
said apertures is sufficient to produce a nominal vacuum at said
opening means when a vacuum of 160 mm. Hg is applied to the
proximal end of said tube.
7. A suction catheter according to claim 6 wherein for a tube
having an outside diameter of 0.181 .+-. 0.004 inches and a wall
thickness of 0.028 inches, said flange means has an outside
diameter of 0.265 .+-. 0.010 inches and a radius of 0.035 inches,
said aperture means comprises four equally circumferentially spaced
apertures having a diameter of 0.059 .+-. 0.002 inches, the distal
edge of each of which is proximal of said flange means no more than
0.015 inches.
8. A suction catheter according to claim 6 wherein for a tube
having an outside diameter of 0.221 .+-. 0.004 inches and a wall
thickness of 0.032 inches, said flange means has an outside
diameter of 0.31 .+-. 0.010 inches and a radius of 0.035 inches,
said aperture means comprises four equally circumferentially spaced
apertures having a diameter of 0.063 .+-. 0.002 inches, the distal
edge of each of which is proximal of said flange means no more than
0.015 inches.
Description
The instant invention relates to a catheter construction and
relates more particularly to a suction catheter for insertion into
a body cavity. The catheter of this invention is useful in many
body cavities such as the rectum and the stomach. However, since
one of the primary uses for suction catheters resides in suctioning
of the nasopharyngeal airway and the tracheobronchial tree, the
emphasis herein will be directed to this application. Suctioning of
the tree is usually accomplished by passing a suction catheter
through an endotracheal tube or tracheostomy tube down into the
tracheobronchial tree. A great majority of the suction
catheterization done in hospitals today is done in the Intensive
Pulmonary and Coronary Care Units. Many patients in these units
have tracheostomy tubes inserted. Because tracheostomy patients
have difficulty in bringing up the foreign matter, i.e., secretion
and mucus, from the tree, these patients require suctioning between
30 and 60 times a day. This, of course, is deep suctioning of the
tracheobronchial tree.
The trachea is a tubular structure 4 to 5 inches long which
consists of 16 to 20 U-shaped cartilages separated by fibrous
connective tissue. The trachea branches off into two bronchus, the
right mainstem bronchus which is wider and shorter and less abrupt
in its divergence from the trachea than the left, and the left
mainstem bronchus which is longer but smaller in caliber than the
right. It is very difficult to suction the left bronchus because of
its sharp divergence from the tracheobronchial path. The cartilage
ring of the trachea continues into the bronchial tubes until it
reaches approximately 1 mm. thickness in diameter. The innermost
lining of the tracheobronchial tree is called the mucous membrane
and is composed of areolar and lymphoid tissue and presents a well
marked inner membrane supporting a stratified epithelium. The next
layer is the sub-mucosa layer and is composed mainly of a mixed
layer of blood vessels, nerves and mucous glands.
In 1956 Plum and Dunning, Technics for Minimizing Trauma to the
Tracheobronchial Tree after Tracheotomy, New Eng. J. Med.
254:193-200, reported that non-interrupted vacuum during
tracheobronchial suctioning might lead to severe mucosal damage.
They pointed out that if the suction catheter adhered to the mucosa
and was pulled directly away from it, such a technique was
tantamount to a crude biopsy. Indeed, they often found blood
aspirate which contained muscosal tissue with routine suctioning of
the tracheobronchial tree of patients. Further, in a necropsied
series of tracheostomized patients who had been repeatedly
suctioned, they noted scattered hemorrhages and edema in the right
but not the left bronchus. In addition, extensive microscopic
damage was found even in those areas that appeared grossly normal.
These areas showed loss of epithelial covering 0and a submucosa
which was edematous, hermorrhagic and heavily infiltrated with
acute inflammatory cells. They produced similar lesions in cats
both with continuous and to a lesser extent with interrupted
suctioning procedures.
More recently, Amikam et al., Bronchofiberscopic Observations of
the Tracheobronchial Tree During Intubation, Am. Rev. Resp. Dis.
105:747-755, 1972, conducted a prospective bronchofiberscopic study
of the tracheobronchial damage associated with prolonged
endotracheal intubation. Mucosal hemorrhages and erosions distal to
the tip of the endotracheal tube both in the trachea and right
bronchus within a few hours after intubation were noted. Since it
has long been recognized that straight suction catheters invariably
enter the right bronchus, the location of these lesions was
consistent with the suction catheter damage observed by Plum and
Dunning, supra. Indeed, in one patient in whom the endotracheal
tube had been placed within the right bronchus by error, these
lesions were only present in the right and not in the left
bronchus.
The foregoing damage occurs basically because the suction catheters
commercially available at the present time are end hole and side
hole catheters. When the suction catheter comes into close contact
with the mucosa, the catheter with the vacuum regulating device
closed, elvates the mucosa and invaginates it into the end or side
holes of the suction catheter. Following cessation of the vacuum,
the mucosa invaginated by the suction catheter usually will display
two responses. In most instances, the area invaginated becomes
immediately hemorrhagic. In some instances the area becomes pale
white and within ten to twenty seconds, hemorrhagic. Mucosa
hemorrhages are the result of ischemia due to the occlusion of the
vascular supply resulting from the invagination of the mucosa into
the end or side holes of the suction catheter. These lesions serve
as a nest for bacteria. Basically, the suction catheters on the
market will allow a little mucus to enter the side or end holes,
and when full vacuum is applied, it causes full suction to be
applied on the side or end hole that is not partially occluded.
This traumatizing effect results in erosion of the epithelial
tissue, edema of the mucosa and submucosa layers and can lead to
erosion and ulceration of the submucosa which, of course, causes
bleeding and is dangerous to the patient. In many instances, the
findings are not as noticeable macroscopically as microscopically
when examined by the pathologist.
It is the primary object of the instant invention to provide a new
catheter construction which overcomes to a major extent the
foregoing and other such disadvantages.
A further object of this invention is the provision of a catheter
which includes means to provide an air cushion surrounding the
distal tip to assist in maintaining a spaced relationship the
distal tip to assist in maintaining a spaced relationship between
the eyes of the catheter and the wall of the airway into which the
catheter is inserted.
Yet another object of this invention is the provision of a catheter
construction which includes a flange means surrounding the distal
end of the catheter and small side holes immediately proximal of
the flange means to produce a laminar air cushion over the flange
means which promotes centering of the catheter within the airway,
the flange means itself also providing a mechanical impediment
assisting in preventing the end hole of the catheter from
contacting the side wall of the airway. These two factors prevent
the damage caused by indrawing of the mucosa into the eye of the
catheter. Thus, the catheter of the instant invention minimizes
damage to the tracheobronchial mucosa which is caused by presently
available suction catheters and aids in minimizing bacterial
colonization in patients who require suctioning of the
tracheobronchial tree.
Other and further objects of this invention will be obvious to
those skilled in the art from the following detailed description
which makes reference to the accompanying drawing illustrating a
preferred embodiment of the instant inventive concepts.
FIG. 1 is an elevational view, partly broken away for illustrative
clarity, of a suction catheter incorporating the instant inventive
concepts; and
FIG. 2 is a fragmentary longitudinal cross-sectional view taken
along lines 2--2 of FIG. 1 and showing the airflow around the
distal tip of such a catheter in a body airway.
In order to test the efficiency and safety of commercially
available suction catheters, and compare the same to the catheter
of the instant invention, various experiments were designed as
follows.
Animal Experiments - Forty mongrel dogs were anesthetized with
pentobarbital 25 mg per Kg such that spontaneous respiration was
preserved. A flexible bronchofiberscope was passed directly into
the tracheobronchial tree, the mucosa examined and control 35 mm.
still photographs or 16 mm. cine obtained. The following
commercially available suction catheters of 14F and 18F diameter
were directed into a major or lobar bronchus: 1) Bard Parker
Reg-U-Vac, 2) Superior Safety Control, 3) Davol Red Rubber, 4)
American Hospital Vacutrol, 5) Cutler Resoflex, 6) Bard With
Airport Adaptor, 7) Rusch, 8) Argyle, 9) USCI, 10) Pharmaseal, and
11) Abbott free part. Each catheter was employed in a minimum of
three animals. In 10 dogs, attempts were made to produce lesions
during bronchofiberscopic observation by forcing the tip of the
catheter against the bronchial mucosa without use of vacuum. The
catheters were connected to a Puritan Vacuum Apparatus and
different levels of vacuum (40 to 200 mm. Hg.) were briefly and
repetitively applied by occluding the proximal vacuum bled hole or
vacuum regulator of the catheter as in a clinical situation.
Model Airway - To simulate what was seen in the animal experiments,
a finer was cut from a latex glove and mounted on a ring stand to
function as a model of an airway. Catheters were passed along the
wall of this model and patterns observed when vacuum was
applied.
Efficiency of suction - This was tested by immersing one or more of
the eyes of the catheter into a beaker of water and timing the rate
of removal of the fluid.
Airflow patterns around catheter - Flow of cigar smoke generated in
sidearm flask was observed flowing past the head of the catheter
and into the side ports. The catheter was housed in a Plexiglas
cylinder approximately 2 inches in diameter and 18 inches long. The
suction applied to the catheter from a source external to the
cylinder was responsible for pulling the smoke from the reservoir
into the catheter.
Th following results were realized with the commercially available
catheters.
Animal Experiments - All commercially available catheters tested
gave similar results. In no instance did touching the tip of the
catheter to the mucosa without application of vacuum produce
grossly visible lesions. When vacuum was applied, and the eyes of
the catheter came into close proximity with the bronchial mucosa,
the mucosa elevated and invaginated into the side hole or end hole
or both depending upon the configuration of the catheter tip.
Following cessation of vacuum, the area of mucosa invaginated by
the suction catheter displayed two responses. In most instances,
the area became hemorrhagic immediately but rarely it first became
pale white and within 10 to 20 seconds hemorrhagic. Lesions were
produced at all levels of vacuum from 40 to 200 mm. Hg, but were
more readily induced at the higher settings. At the time the mucosa
occluded all eyes of the catheter, the vacuum regulator indicated
full vacuum.
In catheters with single holes or with two holes placed
In catheters with single holes or with two holes placed in the same
plane, damage generally was easier to produce. In catheters with
combined end and side holes, slight damage was often produced when
only the side hole came into contact with the mucosa. Greater
damage was found when the side hole contacted the mucosa and the
end hole was also touching the mucosa or occluded by
secretions.
Model Airway - When vacuum was applied to end hole cathethers, and
the catheter was drawn along the latex wall of the model, immediate
collapse of the simulated airway was seen. When a catheter with an
end and side hole was used, minimal local indrawing of the latex
wall into the side hole was seen. Graded occlusion of the end hole
with bone wax produced accentuation of this phenomenon, and
complete occlusion of the end hole as analogous to occlusion with
secretions or contact of the end hole with bronchial mucosa gave
the same result as a single end hole cathether. Catheters with
parallel side holes and a closed end produced similar collapse of
the latex wall.
Efficiency of suction - The end hole of the catheter was placed
into a beaker of water and vacuum was applied. In both the end hole
plus a close by proximal side hole, prompt removal of the water
occurred. In catheters in which two side holes were staggered at a
distance from the tip, (Saklad Catheter, Davol) no water was taken
up through the end hole; only when the side holes were placed in
the water, did the catheter function efficiently.
The foregoing results confirm the observations of Plum and Dunning,
supra, that the tracheobronchial mucosa may be damaged by suction
catheters. Even with brief interrupted suction, as soon as the eye
of the suction catheter contacts the mucosa, hemorrhage and
erosions of the mucosa are produced. This is because the vascular
supply is occluded by the border of the eye of the catheter as the
mucosa is invaginated into the eye of the catheter. The frequency
of these lesions appears to be directly related to the magnitude
and the length of time that the vacuum is applied. Moreover, these
lesions cannot be prevented unless such low levels of vacuum for
brief time intervals are applied, that there is a complete loss of
efficiency for aspiration of secretions. Plum and Dunning found
mucosal damage in cats suctioned with standard catheters both with
continuous suction and to a lesser extent with optimal brief
periods of interrupted suction. Thus, it is apparent that the
design of present day suction catheters is unacceptable because no
provision is made for preventing the eyes from contacting the wall
of the airway being suctioned.
Although gross lesions were not observed by bronchofiberscopy after
stroking the mucosa with the tip of the suction catheter this does
not exclude damage which might be present microscopically. Indeed,
Hilding, Time-lapse Relation to Changes in the Respiratory
Epithelium After Minimal Trauma, Acta Otolaryng. 57:352-366, 1964,
has shown that light stroking of extirpated trachea with a cotton
swab causes progressive loosening from one another of the columnar
cells and cleavage from the underlying cells with complete
exfoliation of the columnar layer over a 1 to 24 hour period.
Destruction of ciliated epithelium by the suction catheter
suppresses mucous clearance. This predisposes the tracheobronchial
tree to obstructive crusting. Further, the destruction of the
mucous clearance mechanism might also explain the high incidence of
bacterial colonization in intubated and tracheostomized patients
who are usually subjected to suctioning.
The foregoing investigations suggested that protection of the
mucosa from suction catheter damage was only possible if the holes
of the catheter could be prevented from contacting the mucosa. The
prototype of the instant invention was a rubber "O ring" cemented
to the cut-off end of a straight plastic catheter. The basic
concept behind this construction was that the O-ring would
physically prevent a single end hole from contacting the sides of
the airway. However, this prototype was unsuccessful because
contact of the end hole with a bronchial bifurcation or flush to
the mucosa of a small airway gave the same damage as the end hole
catheters.
The tip was then modified according to the preferred embodiments of
the instant inventive concepts. In order to better understand the
same, reference is made to the drawings wherein a catheter
construction according to this invention is designated generally by
the reference numeral 10. The catheter 10 includes an elongated
tube 12 having a distal end 14 and a proximal end 16 with a lumen
18 running interiorly thereof and defining an opening means 20 at
the distal end.
The tube 12 can be made of any non-toxic material, preferably a
relatively flexible plastic material such as natural or synthetic
rubber, polypropylene, polyethylene, polyvinyl chloride, nylon or
the like. The particular material is not critical and those skilled
in this art can readily select suitable materials to provide
adequate flexibility and resilience for the intended use.
Any conventional means may be provided at the proximal end for
connecting the catheter to a source of pressure lower than that
existing at the distal end of the tube in use, usually a vacuum. In
the embodiment of FIG. 1 a bulbous portion is shown at the proximal
end for connection of the catheter 10 to the tubing from a source
(not shown) of vacuum or the like. An eye 22 may be provided as a
relief hole so that the user can make and break the negative
pressure through the lumen 18 in a well known manner.
The tube 12 is provided with a laterally extending continuous
flange means 24 contiguous to and surrounding the distal end. In
the manufacture of the catheter, this bead or flange means can be
formed in a number of ways. A conventional catheter made from
thermoplastic material can be heated to provide a large ring at the
free end thereof, or a preformed ring can be thermoplastically
sealed or adhesively attached to the distal end of the tube.
Preferably, however, the flange means is intergrally formed at the
distal end of the tube and has an arcuate peripheral surface as
shown in the drawing.
Immediately proximal of the flange means 24, aperture means 26
extend through the tube 12 into the lumen 18. Preferably, the
aperture means comprises a plurality of equally circumferentially
spaced apertures, four such apertures being shown in the
illustrative embodiment in the drawings.
The aperture means, in combination with the flange means function
to produce a laminar flow of gas from the airway, schematically
shown at 28 in FIG. 2, over the flange means to produce a gaseous
cushion between the flange means 24 and the wall of the body cavity
or airway 28 into which the catheter 10 is to be inserted, thereby
assisting in maintaining a spaced relationship therebetween and
helping to center the distal tip of the catheter in the airway. The
flow of gas into the opening means 20, and the laminar flow over
the flange means 24 into the aperture means 26 is schematically
shown in FIG. 2 by the arrows 30.
Selection of the optimum dimensions for a catheter construction
which satisfies the instant inventive concepts may be accomplished
by those skilled in the art having the foregoing teachings
available to them. The size of the proximal side holes or apertures
26 can be readily determined for a given size catheter by forming
the holes just large enough to give a slight sensation of vacuum
when the end hole or opening means 20 is touched to the cheek of
the face during the application of 160 mm. Hg of vacuum at the
proximal end of the tube. This subjective test can be readily
reproduced, and basically comprises formation of the aperture means
in such a manner as to produce a nominal vacuum at the opening
means during the application of such a vacuum to the catheter.
As exemplary of optimum dimensions, for a 14F catheter wherein the
tube has an outside diameter of 0.181 .+-. 0.004 inches and a wall
thickness of 0.028 inches, the flange means has an outside diameter
of 0.265 .+-. 0.010 inches and a radius of 0.035 inches and the
aperture means comprise four equally circumferentially spaced
apertures having a diameter of 0.059 .+-. 0.002 inches, with the
distal edge of each of the apertures which is proximal to the
flange means being no more than 0.015 inches therefrom. Actually,
it is desirable to have the aperture means as close to the proximal
edge of the flange means as possible, zero spacing being optimum.
However, from a practical standpoint, since these apertures are
punched with a tubular die, obviously having a wall thickness, the
ideal positioning is limited by the thickness of the die wall.
For an 18F suction catheter wherein the tube has an outside
diameter of 0.221 .+-. 0.004 inches and a wall thickness of 0.032
inches, the flange means has an outside diameter of 0.31 .+-. 0.010
inches and a radius of 0.038 inches, with the aperture means
preferably comprising four equally circumferentially spaced
apertures having a diameter of 0.063 .+-. 0.002 inches, the distal
edge of each of the apertures again being placed as closely as
possible to the proximal edge of the flange means in order to
produce the desired air flow as illustrated in FIG. 2.
Again, the foregoing dimensions are given as optimum illustrations
for 14F and 18F suction catheters. Those skilled in the art can
select proper dimensional relationships to produce the desired
functional characteristics from the teachings herein.
Subjection of a catheter according to the instant inventive
concepts to the foregoing experiments produced the following
results.
Animal experiments - In the trachea, main bronchi, and lobar
bronchi of animals, the suction catheter of this invention tended
to remain in the center of the airway such that no damage could be
detected by bronchofiberscopic observation. However, mucus left the
walls of the airway to be aspirated by the catheter. When the
catheter was impacted into a segmental or subsegmental bronchus,
vacuum from the catheter caused the segment to be evacuated by the
catheter and the airway collapsed around the catheter. However,
even under these conditions, minimal or no erosions were visible by
bronchofiberscopy.
Model Airway - The suction catheter hereof was tested in the latex
finger model of the airway. There was little or no collapse of the
latex wall toward one of the proximal side holes or apertures as
the catheter was drawn back and forth along the wall. Thus, the
design of this catheter prevented the wall from being suctioned
into a side hole thereof. The 14F catheter performed better under
this test because of a more favorable relation of the thickness of
the flange eans to the size of the apertures than the 18F model.
The thickness of the flange means in the 18F catheter was limited
by the desire not to increase the overall diameter to a size that
would be unacceptable to passage through nasopharyngeal and
edotracheal tubes. Graded occlusion of the end hole or opening
means by bone wax did not produce significant collapse of the latex
wall of the model. Complete occlusion of the end hole caused
depression of the latex wall but no invagination of this material
into one of the small side apertures.
Efficiency of suction - Immersion of the end hole of the catheter
of this invention into the surface of the water such that the side
apertures were exposed to air produced prompt removal of water as
soon as vacuum was applied. The efficiency of suction of the fluid
under this condition was about 30% slower than when the entire
catheter tip was immersed in the water.
Air flow around catheter - The air flow pattern around the catheter
was revealed by smoke which flowed around the tip when vacuum was
applied. Air flowed through the end hole or opening means and
around the flange means to produce an air cusion over the surface
of the flange means in order to enter the proximal side apertures
as schematically illustrated in FIG. 2.
Thus, it will now be seen that there is herein provided an improved
suction catheter which satisfies all of the objectives of the
instant invention, as set forth above, including many advantages of
great practical utility and commercial importance. It shall be
understood that the foregoing illustrative embodiments are intended
as exemplary and that various modifications and changes may be made
without departing from the instant inventive concepts.
* * * * *