Abstract:
Endotracheal and tracheostomy tubes have an inflatable cuff for sealing the trachea so that a patient may be ventilated through a respiratory lumen of the tube. As a result of sealing the trachea outside of the tube, liquids accumulate above the cuff. If these liquids are allowed to move into the lungs, they may cause ventilator acquired pneumonia (VAP). The liquids may be removed by suction applied to a suction lumen terminating in a port above the cuff, but suctioning can cause damage to the trachea if the tube is sucked up against the tracheal wall. A tracheal catheter having a unique method of attaching the balloon cuff is provided. The cuff is to attached so that an upper part (collar) of the cuff is used to cover the distal end of a suction lumen port. This allows the port to be located closer to the cuff and so provides more thorough liquid removal and reduces the possibility that the tube may suck itself onto the tracheal wall.

Description:
The present disclosure relates to a tracheal catheter or tube used for mechanical ventilation of a hospital patient, by insertion of the tube into the trachea of the patient. In particular, the present disclosure relates to a tracheal tube having means for irrigating and/or evacuating contaminated secretions accumulating above the tracheal tube cuff and thereby reducing the risk of such contaminated secretions entering the lungs of the patient. 
     There are two principle types of tracheal catheters or tubes; the endotracheal tube (ET tube) and the tracheostomy tube (trach tube). The ET tube is inserted through the mouth of a patient and guided past the vocal cords and glottis into the trachea. The trach tube is inserted directly into the trachea through a stoma created in the throat and the tracheal wall by surgical means and enters the trachea below is the glottis. Both types of tube have a relatively large main ventilating lumen that delivers the air from a mechanical ventilating device to the lungs. Both types of tubes typically terminate at a position above the carina, anterior to a position between the second and fourth thoracic vertebrate. Gases may then be introduced through the tracheal tube and into the lungs of the patient. 
     The primary purposes of tracheal intubation, are to mechanically ventilate the patient&#39;s lungs, when a disease prevents the patient from normal, breathing induced ventilation, or to apply anesthetic gases during surgical intervention. In order to create enough air pressure to accomplish such mechanical ventilation and to prevent escape of gases past the tube, it is necessary to seal the passageway around the tracheal tube. A seal may be produced by the use of an inflatable cuff or balloon formed integrally with and surrounding the tracheal tube. When the tracheal tube has been introduced into the patient&#39;s trachea, the inflatable cuff will normally be located about 3 to 5 centimeters above the carina and within the tube-like trachea. 
     The inflatable cuff is then inflated so as to engage the wall of the trachea and thereby seal the trachea and prevent gases being introduced through the tracheal tube from simply turning back up around the tube and passing out of the patients mouth and nose. While treatment of this sort has proved successful for patients having chronic or acute respiratory diseases, there is a constant risk of several complications. 
     In particular, many patients receiving tracheal intubation develop pneumonia, resulting from an infection of the lungs, possibly induced by contaminated, pooled secretions entering the trachea and the lungs after bypassing the inflatable cuff during intubation. This problem, ventilator acquired pneumonia or VAP, occurs with ET and trach tubes. It is more frequent in the case of ET tubes since when an ET tube is in place the epiglottis, which normally operates as a valve that selectively closes the entry into the trachea and lungs to prevent the introduction of secretions and particulate matter, is held in an open position and secretions which would normally be directed away from the trachea and into the digestive system, instead follow the path of the ET tube and pool above the inflatable cuff of the tracheal tube. 
     There is a risk of the infectious secretions reaching the lungs during the intubation, by aspiration of the secretions that are able to get past the tracheal tube cuff. However, the greatest risk of such infectious secretions reaching the lungs is upon the cessation of mechanical ventilation. In particular, when the need for tracheal intubation ends, the inflatable cuff of the tracheal tube is deflated so that the tracheal tube may be withdrawn from the patient. The infectious secretions which have pooled above the inflatable cuff are then released and are free to flow into the lungs, where bronchitis or pneumonia may rapidly develop. 
     To overcome these risks, it is known in the prior art to combine a single suction tube or lumen with a tracheal tube. The suction lumen is joined to the tracheal tube in a suitable manner, the end of the suction lumen terminating at a port in a position above the inflatable cuff. The suction lumen provides means for suction or evacuation of any pooled secretions which accumulate in the trachea above the inflatable cuff. Such prior art devices have the disadvantage that the suction lumen must terminate some distance above the upper or proximal shoulder of the cuff in order to allow for the attachment of the cuff to the tracheal tube body. This distance allows some volume of secretions to be, in effect, unreachable by the suction lumen. In addition, since the suction lumen port is spaced a distance from the cuff, such prior art tubes can allow the suction lumen port to adhere to the tracheal wall during suctioning, causing trauma to the tracheal wall and occluding the suction lumen port. 
     U.S. Pat. No. 4,840,173 to Porter III, describes an ET tube having a single suction tube merged thereto. In particular, this patent describes a device wherein the suction tube is laminated to the outside of the ventilation tube, so that the suction tube terminates at a position just above the inflatable cuff. The suction tube includes multiple openings which may be used to evacuate secretions which pool above the inflatable cuff. In addition, the inflatable cuff includes a section immediately adjacent to the end of the suction tube that is less flexible than the rest of the inflatable cuff, to ensure that the flexible material of the inflatable cuff is not sucked up against the suction tube openings. The tracheal tube described in the Porter III patent has the disadvantages noted above, that the single lumen suction tube terminates a distance above the upper surface of the cuff, allowing a certain volume of secretions to is remain above the cuff, even after suctioning. 
     US patent publication 2008/0053454 to Pasillas et al. describes an ET tube wherein the cuff is attached to the tube so that the proximal collar of the cuff is partially inverted, producing a double thickness collar. The publication teaches that this double thickness collar may help reduce or eliminate possible occlusion of the port and may help prevent the port from coming in contact with the tracheal wall. 
     What is needed is a tracheal catheter capable of suctioning secretions that have pooled above the inflatable cuff, more thoroughly than has been the case so far, with less chance that it will cause trauma to the tracheal wall. 
     SUMMARY 
     The present disclosure improves upon a tracheal catheter by attaching the cuff to the tube in a manner that overlays or covers part of the suction port. Part of the collar of the cuff may actually be located partially inside the suction lumen port, without obstructing the part of the suction lumen proximal to the suction lumen port. The proximal collar of the cuff may also block the part of the suction lumen that is distal to the port, instead of merely laying in or on the port. 
     In one embodiment, the tracheal tube is formed from a flexible cannula having a length, a distal end, and a proximal end. The cannula consists of a plurality of walls extending substantially along the length of the cannula, dividing the cannula into a plurality of separate lumens including a respiratory lumen, a suction lumen, a rinse lumen, and an inflation lumen. An inflatable cuff surrounds the cannula proximal to the distal end. The inflatable cuff is adapted to seal the trachea of a patient. The inflation lumen is in fluid communication with the inflatable cuff. The cuff is attached so that an upper part (collar) of the cuff partially overlays the suction lumen port. This allows the port to be located closer to the cuff and so provides better liquid removal and reduces the possibility that the tube may suck itself onto the tracheal wall. 
     Other objects, advantages and applications of the present disclosure will be made clear by the following detailed description of a preferred embodiment of the disclosure and the accompanying drawings wherein reference numerals refer to like is or equivalent structures. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a view of an ET tube of the prior art. 
         FIG. 2  is a cross-sectional view of the area of attachment of the cuff to the tube of  FIG. 1 . 
         FIG. 3  is a cross-sectional view of the area of attachment of the cuff to the tube of according to this disclosure. 
         FIG. 4  is a close-up side view of the suction port of  FIG. 3 . 
         FIG. 5  is a frontal close-up view of the suction port according to this disclosure. 
     
    
    
     DETAILED DESCRIPTION 
     Reference will now be made to the drawings in which the various elements of the present disclosure will be given numeral designations and in which the disclosure will be discussed so as to enable one skilled in the art to make and use the disclosure. It is to be understood that the following description is only exemplary of the principles of the present disclosure, and should not be viewed as narrowing the pending claims. In particular, though most references herein are to an ET tube since the problem of aspirated secretions is greater when using ET tubes, these teachings apply equally to trach tubes. Those skilled in the art will appreciate that aspects of the various embodiments discussed may be interchanged and modified without departing from the scope and spirit of the disclosure. 
     In manufacturing a tracheal tube, the main cannula is generally extruded by conventional means. As it is extruded in a never ending tube, the cannula is given three lumens; the main respiratory lumen, a cuff inflation lumen, and a suction lumen, separated by internal walls. There may be more lumens extruded into the cannula for additional functions, but the three recited are the lumens of concern for this disclosure. These lumens extruded into the cannula extend the entire length of the cannula. Once the cannula is cut to the proper length, the cuff inflation port and the suction port are located and “skived” or cut out, a technique that is well known to those skilled in the art. This allows liquid communication of each lumen (suction and inflation) through the wall of the cannula to its respective port, opening into the space outside the cannula. The remaining distal portion of the cuff inflation and suction lumens are then blocked below the skived port, generally with a sealing plug. The respiratory lumen extends the entire length of the cannula and is not skived out. 
     Turning to the drawings,  FIG. 1  illustrates a prior art ET tube  10  including an inflatable cuff  12 . Tube  10  includes a cannula  16  having an open proximal end  18  and an open distal end  20 . The cannula  16  defines a gas-conveying lumen  22  for mechanical ventilation of a patient. The proximal end  18  usually includes a connector  24  configured for attachment to a mechanical ventilator (not shown). An inflatable cuff  12  is mounted on the cannula  16  adjacent the distal end  20  of the cannula  16 , covering the skived out inflation lumen port(s)  31 . The cuff  12  is mounted on the cannula  16  by one or more collars. In  FIG. 1 , cuff  12  may be mounted on cannula  16  by a first or proximal collar  26  and a second or distal collar  28 . During the insertion of the tube  10 , the cuff  12  is at least partially collapsed. Once properly in place, the cuff  12  may be inflated via an inflation lumen  30  and cuff inflation port(s)  31  formed in or otherwise associated with the cannula  16 . The inflation lumen  30  may be coupled to an inflation line  32  terminating at its proximal end in a fitting  34  that allows inflation of the cuff  12  via the inflation lumen  30  and cuff inflation port(s)  31 . The cannula also includes a suction lumen  36  formed in or otherwise associated with the cannula  16 . The suction lumen  36  is in liquid communication with a suction lumen port  38  extending through the wall of the cannula  16  through which secretions or other matter accumulated on or proximate the cuff  12  may be removed. The suction lumen  36  extends to the distal end  20  of tubular body  16  and usually includes a sealing plug  39 . The suction lumen  36  may be blocked by the sealing plug  39  before the distal end  20  of tubular body  16  or just beyond opening  38 . An exterior suction tube  40  is connected to the suction lumen  36  for removing secretions or other matter through the port  38 . The suction tube  40  may include an end fixture  42  for attachment to a source of suction (not shown) including a cap  44 . 
     Referring to  FIG. 2 , a cross-sectional view of the cuff  12  and the area of is attachment of the collars  26 ,  28  to the cannula  16  of  FIG. 1  is shown. Both collars  26 ,  28  are attached around the cannula  16  and sealed and the suction port  38  is spaced some distance from the proximal collar  26 . There may be a sealing plug  39  in the suction lumen  36 , located distally of the port  38 . 
       FIG. 3  is a cross-sectional view of the cuff and area of attachment of an embodiment of the disclosed device. In some respects it is similar to the device of  FIG. 2 , however, the placement of the port  38  and the attachment of the proximal collar  26  are quite different. In this embodiment, a portion of the proximal cuff collar  26  partially covers or overlays the suction lumen port  38 . Part of the collar  26  may actually be located partially inside the port  38 , without obstructing the liquid communication between the port  38  and the suction lumen  36  proximal to the port  38 . This allows the port  38  to be located very close to the cuff  12  which should provide for more thorough suctioning of secretions from the subglottic space above the cuff. 
     The proximal collar  26  may also block the part of the suction lumen  36  that is distal to the port  38 , instead of merely laying in or on the port  38 . Purposely occluding the suction lumen  36  in this manner makes the sealing plug  39  unnecessary, though it may still be used to ensure that the suction lumen  36  distal to the suction port  38  is completely sealed. 
       FIG. 4  is a close-up side view of the suction port at the circle  4  of  FIG. 3 . In this view, the proximal part of the suction lumen  36  is open just above the cuff  12  and communicates with the suction lumen port  38 . The proximal collar  26  is attached to the cannula  16  in a manner that allows it to enter the port  38 . It may block the distal part of the suction lumen  36 . Since the collar  26  enters into the distal or lower portion of the open port  38 , it affects only the part of the suction lumen  36  distal to the port  38  while still allowing liquid communication between the proximal portion of the suction lumen  36  with the port  38 . 
       FIG. 5  shows a frontal close-up view of the suction lumen port  38 , partially is covered by the collar  26 . The proximal part of the suction lumen  36  is in liquid communication with the suction lumen port  38 . Note, in  FIGS. 2-5  the distal direction is to the left of the drawings. It should also be noted that although the port  38  shown in  FIG. 5  is oval shaped, the depicted shape is not meant as a limitation. The port may be round, square or any other shape that is functional. 
     The tracheal tube of the embodiments shown in  FIGS. 3-5  and described above allows for the suction lumen port to be placed in close proximity to the inflatable cuff. This allows for better, more thorough suctioning of secretions from the subglottic space. This also reduces the likelihood that the suction port will attach to the tracheal wall during the application of suction, and so reduces the chance of tracheal trauma. 
     The collar  26  is usually attached to the cannula  16  with an adhesive. A suitable adhesive is available from Dymax Corporation of Torrington, Conn. as item number 1163-M#F0024-FH076 though other suitable adhesives are available. This Dymax adhesive is an ultra-violet curable adhesive. Other methods of attaching the collars to the cannula may also be used. These include thermal bonding, solvent bonding, radio frequency and ultrasonic bonding and other means known to those skilled in the art. 
     In order to minimize leakage past the cuff and into the lungs, the disclosed tracheal tube desirably uses an improved cuff design. A tracheal tube using the cuffs taught in U.S. Pat. No. 6,526,977 or 6,802,317 results in much less leakage past the cuff into the lungs than conventional thick cuffs allow. The &#39;977 and &#39;317 cuffs are desirably made from a soft, pliable polymer such as polyurethane, polyethylene teraphihalate (PETP), low-density polyethylene (LDPE), polyvinyl chloride (PVC), polyurethane (PU) or polyolefin. The cuff should be very thin; with a thickness on the order of 25 microns or less, e.g. 20 microns, 15 microns, 10 microns or even as low as 5 microns in thickness, though at least 1 micron. The cuff should also desirably be a low pressure cuff operating at an inflation pressure of about 30 mmH 2 O or less, such as 25 mmH 2 O, 20 mmH 2 O, 15 mmH 2 O or less. 
     U.S. Pat. No. 6,802,317 describes a tracheal tube for obturating a patient&#39;s trachea as hermetically as possible, comprising: a cuffed balloon which blocks the trachea below a patient&#39;s glottis, an air tube, the cuffed balloon being attached to the air tube and being sized to be larger than a tracheal diameter when in a fully inflated state and being made of a soft, flexible foil material that forms at least one draped fold in the cuffed balloon when inflated in the patient&#39;s trachea, wherein the foil has a wall thickness below or equal to 0.01 mm and the at least one draped fold has a loop found at a dead end of the at least one draped fold, that loop having a small diameter which inhibits a free flow of secretions through the loop of the at least one draped fold. 
     U.S. Pat. No. 6,526,977 teaches a cuff for obturating a patient&#39;s trachea as hermetically as possible, comprising a cuffed balloon which blocks the trachea below a patient&#39;s glottis, an air tube, the cuffed balloon being attached to the air tube and being sized to be larger than a tracheal diameter when in a fully inflated state and being made of a sufficiently soft, flexible foil material that forms at least one draped fold in the cuffed balloon when fully inflated in the patient&#39;s trachea, wherein the at least one draped fold formed has a capillary size which arrests free flow of secretions across the balloon by virtue of capillary forces formed within the fold to prevent aspiration of the secretions and subsequent infections related to secretion aspiration. 
     Since the &#39;977 and 317 cuffs inhibit or arrest the free flow of secretion past the cuff, the secretions build up above the cuff and discontinuous or intermittent suctioning may be used. Intermittent suctioning is safer for the tracheal wall since it reduces the chance that the suction lumen inlet will adhere to the wall and subject it to the force of suction. 
     At the discretion of the caregiver and particularly immediately prior to removal of the tracheal tube, the subglottic space within the patient&#39;s trachea may be suctioned through the suction lumen  36  via the port  38  through the wall  25  of the cannula  16 . During this process, ventilation of the patient through the respiratory gas-conveying lumen  22  may of course continue unaffected. 
     Other arrangements are included in the spirit and scope of the disclosure. For example, the layout of the lumens within the cannula  16  may be altered, moreover, the suction lumen  36  may be formed in another wall or it may be a self contained lumen not embedded within any one of the walls of the cannula  16 . In addition, as alluded to above, other lumens may be present in the cannula  16 , such as rinse lumens to deliver fluid to loosen or dilute thick secretions prior to suctioning or lumens to deliver anesthesia or other medicaments. These additional lumens are not depicted though are understood by those skilled in the art. 
     As used herein and in the claims, the term “comprising” is inclusive or open-ended and does not exclude additional unrecited elements, compositional components, or method steps. 
     While various patents have been incorporated herein by reference, to the extent there is any inconsistency between incorporated material and that of the written specification, the written specification shall control. In addition, while the disclosure has been described in detail with respect to specific embodiments thereof, it will be apparent to those skilled in the art that various alterations, modifications and other changes may be made to the disclosure without departing from the spirit and scope of the present disclosure. It is therefore intended that the claims cover all such modifications, alterations and other changes encompassed by the appended claims.