Method of making a cuffed tube

A method of making a double-cuffed endotracheal tube is disclosed which includes forming a unitary double-cuff member, inserting and inverting one of the cuffs into the other cuff and connecting the cuffs on a plastic tube, and sealingly connecting the ends of the cuffs to the tube. A method of sealingly connecting one end of the inner cuff which is within the outer cuff to the tube includes inserting a pipe into the tube and through a sidewall opening in the tube, and flowing sealant material through the tube to seal one end of the inner cuff to the tube.

DESCRIPTION 
1. Technical Field 
This invention relates to a method of making a cuffed tube and more 
particularly to a method of making a double-cuffed retention tube. 
2. Background Art 
Single-cuff retention tubes, such as endotracheal tubes, are commonly used 
for artificial respiration of the unconscious or anesthestized patient. 
The cuff is generally pressurized sufficiently to provide a seal between 
the tube and the tracheal wall and to prevent inadvertant extubation 
during the respiration cycle. As is well known, damage to the tracheal 
walls can occur because of relatively high cuff pressures during prolonged 
use. Double-cuffed endotracheal tubes have been proposed in order to 
reduce injury to the trachea. It has been proposed to position a second 
smaller cuff within the main sealing cuff and connect the inner cuff with 
the ventilation lumen of the tube. In this way, the outer sealing cuff can 
be pressurized to a relatively low pressure or a pressure just necessary 
to provide a seal with the tracheal wall and hold the tube in place at 
times when minimum pressure is acting on the lungs. As the pressure in the 
lungs increases and decreases during the respiration cycle, the pressure 
inside the inner cuff will vary and, in turn, vary the pressure in the 
outer sealing cuff. In this way, pressures applied by the sealing cuff 
against the membranes of the trachea will vary in accordance with the 
pressures needed during the respiration cycle and the chance of injury to 
the trachea is reduced since high pressures are not continuously applied 
to the trachea. U.S. Pat. No. 3,481,339, for example, discloses a 
double-cuffed endotracheal tube. 
Such double-cuffed endotracheal tubes, however, are relatively difficult 
and expensive to manufacture. For example, a separate molding operation 
for each of the two cuffs is generally used. Also, in assembling the 
cuffs, each cuff has to be predeterminately positioned on the tube and 
sealingly connected to the tube, and this requires tedious and time 
consuming operations that increase the cost. 
DISCLOSURE OF THE INVENTION 
An object of the present invention is to provide an improved method of 
making a double-cuffed retention tube which is relatively simple and 
economical, and which in general, substantially overcomes the above 
problems. This is accomplished in accordance with one aspect of the 
present invention by forming a pair of integrally connected cuffs, 
inverting one of the cuffs and inserting it into the other cuff, and 
securing the ends of the cuffs in a desired location on a tube. In 
accordance with another aspect of the invention, one cuff is positioned 
within another cuff on a tube, and the ends of the cuffs are sealingly 
connected to the tube. An end of the inner cuff is sealingly connected by 
inserting a pipe into the tube with one end of the pipe extending through 
a sidewall opening in the tube, and then flowing a sealant material 
through the pipe to seal the one end of the inner cuff to the tube. 
These, as well as other objects and advantages of the present invention, 
will become apparent from the following detailed instruction and 
accompanying drawing.

DETAILED DESCRIPTION OF THE INVENTION 
Referring now to the drawing, and particularly to FIG. 1, a double-cuffed 
endotracheal tube 10 is shown including a plastic tube 12 having a pair of 
inner and outer balloon cuffs 14 and 16 disposed on tube 12 adjacent the 
distal end 18 of the tube. The proximal end 20 of tube 12 is adapted to be 
connected to a respirator. A tube 22 having a suitable or conventional 
one-way valve 24 is connected to tube 12 for inflating the outer cuff 16, 
as will be discussed hereafter. 
In making the endotracheal tube 12, cuffs 14 or 16 are postformed, 
preferably, both cuffs are integrally formed at the same time or in the 
same process to produce a unitary double-cuff member indicated generally 
at 26 in FIG. 2. The double cuff member 26 includes a generally 
cylindrical cuff connector portion 28 at one end of the member which is 
connected to one end of the cuff 16, a generally cylindrical center cuff 
connector portion 30 integrally connected between the opposite end of cuff 
16 and one end of cuff 14, and a proximal end generally cylindrical cuff 
connector portion 32 connected to the opposite end of cuff 14. The 
generally cylindrical or tubular connector portions 28, 30 and 32 of 
member 26 are formed such that they have an inner diameter approximately 
equal to the outer diameter of tube 12, and preferably, slightly less than 
the outer diameter of the tube to provide a snug fit with the tube. 
The double cuff member 26 may be formed of any suitable cuff material such 
as a suitable plastic and may be made of supple elastic or substantially 
non-elastic plastic or rubber, for example, silicone rubber, polyvinyl 
chloride, polyurethane or other plastic may be used to form member 26. The 
cuffs are formed so that they are inflatable and deflatable when gas 
pressurized and depressurized. The member 26 may be made by various well 
known manufacturing methods such as dip forming, blow molding, extrusion 
molding, injection blow molding or other methods. The cuffs 14 and 16 are 
preferably made from the same mold and/or the same parison. 
The tube 12 may be conventionally extruded from any suitable tube or 
catheter plastic material, for example, a natural or synthetic rubber or 
thermoplastic material such as polyvinyl chloride may be used. As seen in 
FIG. 3, the tube 12 has a main or ventilation lumen 34 extending entirely 
through the tube, and a relatively smaller auxiliary lumen 36 formed in 
the sidewall of the tube which is closed at the distal end and connected 
at the proximal end with the inflation tube 22 and one-way valve 24 (FIG. 
1). The tube 12 has at least one opening 38 through the sidewall which 
connects the inner cuff 14 in fluid communication with the main lumen 34. 
At least one opening 40 through the outer sidewall of the auxiliary lumen 
36 connects the outer cuff 16 in fluid communication with the auxiliary 
lumen and the inflation tube 22. Instead of extruding tube 12 with an 
auxillary lumen in the sidewall, an auxiliary lumen can be provided by 
attaching a separate tube to tube 12. 
The inner cuff 14 is made smaller than the outer cuff 16. The size of the 
small cuff is chosen such that, when it is fully inflated, and when 
maximum pressure is applied to the lungs the predeterminately pressurized 
outer cuff 16 will apply a desired maximum pressure to the trachea walls 
for sealingly holding the tube in place. When the inner cuff 14 is fully 
deflated or collapsed the outer cuff pressure is reduced to its minimum 
predetermined pressure which holds the tube in place during periods of low 
lung pressure. In the drawing, the cuffs are shown for illustration in 
their inflated condition for sake of clarity. 
The unitary cuff member 26 containing the inner and outer cuffs 14 and 16 
is applied to tube 12 by inverting and moving the cuff 14 into the 
interior of the outer 16 and then pulling the telescoped cuffs onto the 
end of the catheter or holding the telescoped cuffs and inserting the tube 
12 into the cuffs. During the insertion of cuff 14 into cuff 16, the cuff 
14 is inverted or turned inside-out (FIG. 3) and the cylindrical cuff 
portion 30 (FIG. 2) between the cuffs becomes folded back upon itself 
providing concentric proximal cylindrical cuff portions 30a and 30b. The 
outer surfaces of cuff 14 and cylindrical cuff portions 30b and 32, as 
viewed in FIG. 2, are on the inside or become radially inner surfaces when 
the cuffs are on the tube as shown in FIG. 3. The cuffs 14 and 16 are 
positioned on tube 12 so that the opening 38 is within the inner cuff 14 
and the opening 40 is within the outer cuff 16. The cuff portion 32 is 
shown wholly within cuff 16 and spaced proximally of portion 28. 
The proximal ends of cuffs 14 and 16, portions 30a and 30b, and the distal 
end of cuff 16, portion 28, are sealingly secured to the outer surface of 
tube 12 by any suitable or conventional means. For example, a suitable 
securing sealant material such as a tube material solvent or adhesive may 
be inserted between the cuff portion 30b and the tube 12, and between the 
inner surface of cuff portion 28 and the outer surface of tube 12 from the 
exterior of the tube. In some cases, induction heating may be employed to 
raise the temperatures of the plastic to a temperature sufficient to cause 
adhesion between the cuff portions 28 and 30b and tube 12. 
In order to sealingly secure the distal end or portion 32 of cuff 14 to the 
tube 12, a sealant, such as a suitable medical grade adhesive or a solvent 
is applied between to the inner surface of the connector portion 32 and 
outer surface of tube 12 to effect an adhesive connection between the 
distal end of cuff 14 and the tube 12. Where the tube 12 and cuffs 14 and 
16 are made of polyvinyl chloride, a solvent such as cyclohexanone 
provides a good solvent bond between the cuff and the tube. As is shown in 
FIG. 3, a hollow needle or tube 42 of small diameter is inserted into the 
distal end of tube lumen 34 to apply the sealant, such as the above 
solvent, to the facing surfaces of the cylindrical portion 32 of cuffs 14 
and the tube 12. The needle 42 may be connected at one end with a source 
of the solvent or cement which can be pressurized. The tip of the inserted 
end of the needle 42 is U-shaped or curved back upon itself. The tip end 
of the needle 42 is indicated at 44 and is curved so that the tip can 
enter and pass through hole 38 in the sidewall of the tube 12 and be 
adjacent to the distal end of the cuff 14 or cuff portion 32 for applying 
a sufficient amount of solvent. A drop of such sealant is shown for 
illustration at 46 in FIG. 3. The applied solvent is ejected from the 
needle 42 and distributes itself evenly as a result of surface tension so 
as to provide a good sealing connection between the distal end portion 32 
of cuff 14 and the tube 12. The needle 14 is then removed from hole 38 and 
the main lumen 34. 
Where desired, cement or solvent may be applied between the facing surfaces 
of the cylindrical cuff portions 30a and 30b just prior to inserting cuff 
14 into cuff 16. 
Since both cuffs can be made integrally from the same parison or mold, such 
a single operation reduces costs. Also, since the two cuffs 14 and 16 can 
be formed and applied to tube 12 while integrally connected, the location 
of the one cuff relative to the other cuff and to the tube 12 is 
substantially automatically and simultaneously obtained when one cuff is 
located after the cuffs are telescoped. This avoids the problem of 
positioning separate cuffs relative to each other and to the tube as in 
the past. 
The method of sealingly connecting the distal end or cuff portion 32 to the 
tube could also be employed where discrete or separate concentric cuffs 
are employed. Also, in some cases, the outer cuff portion 28 may be pulled 
proximally enough to permit insertion of a sealant material between 
portion 32 and the tube 12 from outside the device 10. In some cases, it 
is possible to position the folded-back portion 30 at the distal end of 
tube 12 with the portion 28 proximally of the portion 30. 
In use, the double-cuff 14, 16, is disposed in the throat. The outer cuff 
may be inflated to a relatively low pressure and the distal end 20 of tube 
12 connected to a respiration system that applies intermittent positive 
gas pressures to the main lumen and lungs of the patient to thereby effect 
lung ventilation. As gas or air pressure increases in the lungs the inner 
cuff 14 inflates thereby increasing the sealing pressure applied to the 
trachea walls by the outer cuff 16. As the lung pressure decreases, the 
inner cuff 14 deflates thereby reducing the pressure applied to the 
trachea walls by the outer cuff 16. This cycle continues during 
respiration so that the relatively high pressure applied to the trachea 
walls is intermittent instead of continuous. 
Where a separate inflation tube having a separate inflation lumen is used 
instead of the integral auxiliary lumen 36, the separate inflation tube 
can extend along the outer or inner surface of the tube 12 and be 
connected directly to the outer cuff 16. 
As various changes may be made in the above described construction and 
method without departing from the scope of the invention, it is intended 
that all matter contained in the above description and shown in the 
accompanying drawing be interpreted as illustrative and not in a limiting 
sense.