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Description  |
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The present invention relates generally to an endotracheal tube control
device, and more specifically to a magnetically controllable stylet for
assisting in the insertion of an endotracheal tube.
BACKGROUND OF THE INVENTION
In a number of medical circumstances including routine surgery and
intensive care, spontaneous respiratory capability is diminished, and a
breathing assist is required. This breathing assist involves the forcing
of air into the lungs by positive pressure. Positive pressure ventilation
is supplied by a small bag of air or oxygen mixture squeezed by an
anesthesiologist or by a bellows or piston in a mechanical ventilator. To
insure that the air actually goes into the lungs rather than the esophagus
and stomach and to insure that an open airway is always present during
surgery or mechanical ventilation in the intensive care unit, a tube is
inserted into the trachea such that the distal tip is well below the vocal
cords. This tube, called an endotracheal tube, may be inserted through the
mouth or the nose but must bend anteriorly in the throat in order to enter
the trachea and avoid the esophagus. Once the tube is in place in the
trachea, a circumferential balloon-cuff above the distal tip of the
endotracheal tube is inflated with air. This balloon-cuff seals the tube
in the trachea by filling the area between the tracheal wall and the
endotracheal tube. Such an arrangement allows positive pressure to be
applied and the lungs inflated by the anesthesiologist or mechanical
ventilator. The balloon-cuff also protects the trachea from any foreign
material from the mouth or regurgitated from the stomach.
Ever since the endotracheal tubes were introduced, anesthesiologists and
other physicians have experienced difficulties placing endotracheal tubes
into the trachea, a procedure called intubation. Of all procedures done in
the intensive care unit related to maintaining ventilation of critically
ill patients, intubation of the trachea is associated with the greatest
number of complications. Very few physicians other than anesthesiologists
have any proficiency at inserting endotracheal tubes. Usually, intubation
involves the use of a device called a laryngoscope.
In order to insure that the endotracheal tube goes into the airway to
trachea instead of the esophagus, the anesthesiologist must visualize the
vocal cords by extending the patients head slightly and by elevating the
jaw of the patient with the laryngoscope. In his position behind the
patient's head, he can place the tube between the vocal cords, into the
trachea below. One of the principle dangers of this procedure is that it
almost always requires that the patient be temporarily paralyzed.
Paralysis of the patient facilitates visualization of the vocal cords by
relaxing the jaw muscles and preventing the patient from retching or
otherwise interfering with the placement of a large piece of metal (the
laryngoscope) down his throat. Unfortunately it also eliminates any
contribution that the patient might take towards his own breathing.
Failure to place the endotracheal tube rapidly can result in death if the
patient cannot be ventilated by a mask placed tightly over his mouth and
nose in between attempts to intubate with the laryngoscope. Ventilating a
patient by mask and positive pressure from a bag of oxygen also requires
particular skill and practice and is nearly impossible with some patients
and without proper equipment.
Even experienced anesthesiologists have difficulty intubating certain
patients. Patients with the following problems are particularly difficult
to intubate:
(1) short muscular neck
(2) receding jaw
(3) large, thickened tongue
(4) high arched palate
(5) cleft lip or palate
(6) cervical or temperomandibular arthritis (common in elderly patients,
prevents adequate extention of the neck in order to see the vocal cords)
(7) post surgical scars or burns to the face, neck, or mouth
(8) pharngeal or laryngeal tumors
(9) inflammation of the epiglottis or tonsils
(10) facial fractures
(11) thyroid disease (colloid, goiter, substernal thyroid)
(12) deviation of the epiglottis, vocal cords, or trachea from the midline
by stricture or kyphoscoliosis.
Such patients are difficult to intubate under the best of circumstances,
that is, in the operating room prior to elective surgery. At this time the
anesthesiologist has time and appropriate equipment and other skilled
persons to give the patient 100% oxygen prior to putting him to sleep and
paralyzing him. The patient can be properly positioned and counseled to
know what to expect. Even if his intubation is prolonged and difficult, he
is put to sleep first by intravenous medication and is not aware of the
complication. Intubating patients in the intensive care unit, emergency
room, coronary care unit, or elsewhere outside the operating room is much
more difficult. Unlike the well-prepared, sedated, and pre-oxygenated
patient on the operating room table, the intensive care patient or
emergency room patient is often in great respiratory and cardiovascular
distress at the time endotracheal intubation is mandatory. He may be so
short of breath that he refuses to lie down or allow a tight fitting mask
on his face. Time and skill are of great importance, as is experience
obviously, to overcome unexpected anatomic problems in choking,
suffocating, uncooperative, frightened patients. Some types of lung
disease leave the lungs so stiff that adequate ventilation with a mask is
not possible. Since the patient is already in respiratory distress despite
the usual administration of oxygen by a loosely fitted mask, the rapid
institution of an intravenous sedative and paralyzer is a gamble that an
endotracheal tube can be inserted swiftly in spite of unexpected
anatomical problems which could interfere with intubation, and should
intubation not be successful, that an appropriate mask, oxygen source,
anesthesia bag, and skill are at hand to ventilate the paralyzed patient
in between intubation attempts or until more skilled persons and/or
equipment are available. Should the endotracheal tube be inadvertently
placed in the esophagus, the forcing of air into the esophagus can result
in rupture of the stomach or, more commonly, the inducement of vomiting.
Gastric contents may then go into the airway and severely damage the
lungs.
Skill with a laryngoscope only comes with constant practice. It is
therefore not surprising that only anesthesiologists and certain intensive
care physicians are capable of intubating the trachea proficiently. On
occasion, an endotracheal tube can be inserted into the nose and blindly
advanced into the throat and through the vocal cords without paralyzing
the patient. This technique is particularly useful in the patient with
acute respiratory distress because it requires only local anesthesia to
the nose and allows the patient to continue with his own breathing,
although it is not totally adequate for him, during the insertion of the
endotracheal tube. Obviously, this blind technique requires even more
skill and practice to avoid inserting the tube into the esophagus or
injuring the patient. In addition, this nasal approach is often impossible
for anatomic reasons even if an experienced person is making the attempt.
These problems have been discussed in part and a proposed device disclosed
in U.S. Pat. No. 4,063,561 issued Dec. 20, 1977. The device disclosed
therein is a newly constructed endotracheal tube which includes therein
metallic material within the walls of the tube and which may be affected
by external magnetic devices placed over the larynx of the patient
externally. Obviously, the cost of manufacturing individual tubes with
metallic wire in the walls would be much greater than the cost of
manufacturing the present invention, which can be used with any existing
endotracheal tube, is reusable indefinitely, and has no expensive parts.
The above mentioned patent further discloses a possibility of enclosing
frictionally a metallic block within the tube lumen which is secured to
the end of a flexible wire whereby an ordinary endotracheal tube can be
inserted into the throat and the entire tube manipulated by an external
magnet into the trachea. All endotracheal tubes must be stiff enough to
prevent excessive collapse when they bend. For this reason, normal
endotracheal tubes cannot be manipulated externally with a necessarily
small piece of metal within the lumen of the tube. Such an arrangement
could be potentially dangerous. The block of metal could become dislodged
from the wire and drop into the trachea. Further, such a metallic plug may
become stuck upon its withdrawal at the point of anterior bend of the
endotracheal tube in the nose or mouth, completely occluding the airway.
The problems arising from this arrangement are further apparent from the
fact that the emphasis in the above mentioned patent is upon the creation
of a new endotracheal tube. The attraction of a magnet, no matter how
large, for a piece of metal is still a function of the mass of both pieces
of metal. The size of the metallic plug as illustrated in the patent
cannot be large enough to manipulate a normal endotracheal tube because it
must fit into the lumen of the tube. Increasing the size of the magnet
outside will not overcome the distances involved or the stiffness of the
ordinary tube.
The above disadvantages are overcome by the present invention wherein a
very flexible stylet, instead of a whole endotracheal tube, is controlled
by an external magnet by incorporating a second magnet into the distal end
of the stylet. This small magnet on the distal tip of the stylet has
opposite polarity to the external magnet, thus increasing their attraction
and providing consistant alignment and direction toward the vocal cords.
The stylet may be inserted through the mouth or nose in almost any body
position and is of a dimension of fit within a standard endotracheal tube
without completely occluding its lumen. After the distal tip of the stylet
is within the trachea, the endotracheal tube is advanced over the stylet
into the trachea, and the stylet quickly removed. Accordingly, it can be
seen that the stylet acts as a flexible intubating guide for the
endotracheal tube. To facilitate removal of the stylet from the
endotracheal tube, the diameter of the stylet is much smaller than the
lumen of the endotracheal tube. The magnet at the tip of the stylet may be
constructed out of many small magnets. When stuck together, they function
exactly like one long magnet, but when bent around a tight turn will
articulate with one another and allow flexibility and easy withdrawal once
the endotracheal tube has been advanced over the stylet into the trachea.
This arrangement of many small articulating magnets functioning as one
magnet is especially useful as the size of the endotracheal tube
decreases. Larger endotracheal tubes do not require the articulation of
small magnets at the distal tip of the stylet because there is adequate
space in the lumen to withdraw the stylet without the magnet becoming
lodged in the tube at its point of bend in the posterior pharynx. The
flexible stylet may be inserted originally into the mouth or nose and
directed into the trachea before the endotracheal tube is advanced over
it, or the stylet and endotracheal tube may be advanced as a unit or
alternately, as long as the stylet stays several inches in front of the
tip of the endotracheal tube. In any case, once the tube has been advanced
into the trachea, the stylet is quickly removed, the balloon-cuff of the
tube inflated, and positive pressure ventilation initiated. Paralysis is
never necessary. Local anesthetic agents may be sprayed or applied to the
nose, throat, and tongue prior to insertion of the stylet. Mild sedation
may be given, but the patient continues to breathe for himself and may
remain in the sitting position if he desires.
Besides a system of nasal or oral tracheal intubation, the stylet is
constructed to be not only very flexible and responsive to the external
magnet but also to be at least twice the length of a standard endotracheal
tube. This extra length provides the ability to change one endotracheal
tube that may be defective or too small with a new endotracheal tube,
again without paralysis or a laryngoscope. In this case the stylet is
inserted (using the end opposite the magnetic tip) into the old
endotracheal tube and the old tube removed when the stylet is in the
trachea. Then a new tube can be advanced over the stylet and the stylet
withdrawn. This procedure is rapid, does not require an external magnet,
and is far safer and easier than removing the old tube and necessitating
the insertion of a new tube by sedation, paralysis, and a laryngoscope.
The stylet is constructed of a material which is spring-like and slides
easily inside the endotracheal tube, bends easily but can be pushed,
confers enough rigidity to allow guidance for an endotracheal tube, but is
very responsive in a magnetic field.
Accordingly, it is the purpose of this invention to provide an endotracheal
tube insertion system which does not require the risky technique of
paralysis, can be used by anesthesiologists to intubate patients with
difficult anatomical problems through the nose or mouth, can be used by
relatively unskilled medical personnel in emergencies when an
anesthesiologist is not present, can be used in a variety of positions,
including supine, sitting and lateral decubitus, and can be used and
reused indefinitely on standard endotracheal tubes. This endotracheal tube
insertion system provides for a flexible stylet, having a magnet attached
to one end, to be guided into the trachea by means of an external magnet
with opposite polarity. The endotracheal tube is advanced over the stylet
so as to enter the trachea with the subsequent removal of the stylet.
It is a further object of this invention to provide a stylet guiding means
which may be used to quickly replace one endotracheal tube for another
without paralysis or the use of a laryngoscope.
BRIEF DESCRIPTION OF THE DRAWINGS
These and other objects of the invention will become apparent from the
following description when taken in conjunction with the drawings wherein
FIG. 1 is a perspective view of the three components preferably used with
the present invention;
FIG. 2 is a perspective view of one embodiment of the stylet of the present
invention;
FIG. 3 is an enlarged view of a section of the stylet of FIG. 2;
FIG. 4 is a sectional view of one embodiment of the external magnet used
with the stylet of the present invention;
FIGS. 5, 6 and 7 illustrate the steps which are taken in using the present
device for performing intubation orally;
FIGS. 8 and 9 show like steps which are taken when the insertion is through
the nostril;
FIG. 10 is a sectional view of a further embodiment of the stylet of the
present invention; and
FIG. 11 shows the interaction between individual magnets used in the stylet
of FIG. 10.
Before proceeding with the description of the invention, reference should
be made to the term "stylet" as used in the medical profession. A
definition and a discussion of a stylet may be found in "Understanding
Anesthesia Equipment" pages 274 and 275 authored by Jerry A. Dorsch, M.D.
and Susan E. Dorsch, M.D., The Williams and Wilkins Company. In that
discussion, it is stated that a stylet is a device which fits inside an
endotracheal tube. It aides in directing the insertion of the tube by
making the tube more rigid and allowing its shape to be changed. In the
present invention, a stylet is used as herein indicated in that it is a
device that fits inside an endotracheal tube and is used to help direct
the tube. However, as defined herein, it is not designed to make the tube
more rigid nor to change the shape of the tube. Accordingly, for the
present purposes a stylet is defined as a flexible device which fits
within a tube and may be passed therethrough. More specifically, the
stylet of the present invention involves a flexible device having a magnet
located at one end thereof. The stylet is springlike and is so constructed
that it bends easily but can be pushed along its length.
BRIEF DESCRIPTION OF THE PREFERRED EMBODIMENTS OF THE INVENTION
Turning now more particularly to the drawings, there is shown in FIG. 1 the
three items which may be used in performing an intubation of the trachea
using the stylet of the present invention. As illustrated, a standard
endotracheal tube 11 comprising a plastic tube body 13 has a beveled
insertion end 15 and an inflatable balloon 17. The balloon is inflated in
a standard manner by the inflating syringe 19. The opposite end of the
tube 13 terminates in a connector which may be secured to a breathing
assist system. This is all known equipment used in the standard procedure
as described hereinabove. The present invention provides a stylet 23,
which will be more specifically shown and described as the description
proceeds, and an exterior magnet 41. Magnet 41 is preferrably a housing of
plastic material 43 having a magnet secured therein with one end having a
concave face 45.
Turning now more specifically to FIG. 2, there is illustrated one
embodiment of a stylet of the present invention. This stylet is most
useful with endotracheal tubes having an internal diameter larger than 8.0
mm.
The main body 25 of the stylet is comprised of a coiled spring of a
non-magnetic material such as stainless steel or other non-magnetic
material. Such a tube could be constructed of a suitable plastic material
manufactured so as to conform to the characteristics of a coiled spring. A
magnet 27 is secured to the other end of the spring. Magnet 27 may be
encased within an inert housing 29 (FIG. 3) such as stainless steel,
plastic etc., which is then secured to one end of stylet 25 by means of a
weld or adhesive or the like.
FIG. 3 is an enlarged partial illustration indicating the spring bellows 31
which is secured between the housing 29 and the body 25 of the stylet.
Such bellows are commercially available and provide additional flexibility
at the distal end of the stylet. This further aids the ability of the
distal end to bend as shown in the dotted lines of FIG. 2 when it is
subjected to exterior magnetic forces.
FIG. 4 shows one embodiment of exterior magnet 41. The magnet may be
encased in an inert housing 42 of a material such as plastic or the like.
As indicated, one face of housing 42 is concave for purposes which will
become apparent as the description proceeds.
FIGS. 5, 6 and 7 illustrate the use of the device when intubation is
practiced orally. FIG. 5 shows the stylet 23 being inserted with the
magnetic end entering into the throat of the patient. When the stylet is
so inserted, the end will assume a position approximately as shown in the
dotted lines 39. If allowed to follow this course, the stylet will tend to
enter the esophagus instead of the trachea. However, as indicated, the
magnet 41 is placed exteriorly in the midline adjacent to the prominence
of the thyroid cartilage, or "Adam's Apple". This is easily
distinguishable on the patient and places the magnet in a proper spot for
attracting the magnetized end of the stylet 37 into the tracheal passage
as indicated in the solid line form. As shown in FIG. 6, the stylet is
then inserted into the tracheal cavity by sliding it along inside the
endotracheal tube. The tube is then guided along by the stylet as shown
until it, too enters the tracheal passage. The stylet is then removed as
shown in FIG. 7, leaving the endotracheal tube in position with the
trachea.
FIGS. 8 and 9 illustrate that the same procedure may be used when the
nostril is dilated and the stylet and the tube may then be inserted
therethrough following the same procedure for locating the stylet and,
subsequently, the endotracheal tube into position.
Turning more specifically to FIGS. 10 and 11, there is shown therein an
alternate embodiment of the stylet of the present invention. The main body
of the stylet is comprised of a similar coiled spring 55 which extends
substantially the length of the stylet. A rounded cup 57 of an inert
material such as teflon may be secured within one end of the coiled spring
55 by means of an adhesive or the like. The other end of coiled spring 55
has inserted therein a series of small magnets beginning with magnet 59 at
one end and terminating at the other end with magnets 60 and 61. These
magnets have a diameter slightly smaller than the internal diameter of the
section of coil spring 55 which encases them. Spring 55 is made larger at
this section to allow the magnets to interact as shown in FIG. 11. The
magnets terminate in a larger magnet 63 which has a reduced section 61
which fits within the end of the coil spring and is secured thereto by
means such as by soldering or with an adhesive. Also, to provide a smooth
insertion area, an inner hemispherical segment 65 is secured to the outer
end of magnet 63 by means such as an adhesive. In order to present the
stylet in an understandable dimensional view, the following parameters are
typical of a desired stylet.
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DIMENSION PARAMETER-INCHES
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A 27
B 1/4
C .8125
D 1/8
E 1/16
F 1/16
G 3/16 O.D.
H 1/4 O.D.
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FIG. 11 illustrates one of the reasons for providing the separate
individual magnets as shown in FIG. 10. While the magnets do not totally
part from each other because of the extreme force exerted between them,
they may partially separate as illustrated in FIG. 11. This partial
separation allows the terminal end of the stylet having the magnets to
provide more flexibility and, thus, greater ease in drawing the stylets
into the tracheal passage. This embodiment, when using the stylet with
smaller diameter endotracheal tubes, allows the small magnets to function
as one magnet, but articulate with each other, whereby the removal of the
stylet from the smaller endotracheal tube is greatly eased. One of the
reasons why this invention is now practical is due to the development of
extremely high magnetic material such as cobalt and the like. This reduces
the necessary size of the magnets while still realizing the necessary
magnetic force, since the use of a magnetic material such as cobalt in the
stylet itself increases the attraction between the exterior magnet and the
end of the stylet to a very large degree. The use of only a metallic
material for a stylet would reduce the ability to direct the end of the
stylet into the trachea.
The above description and drawings are illustrative only since material
substitution and dimension variations are possible without departing from
the invention. Accordingly, the invention is to be limited only by the
scope of the following claims.
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