Abstract:
The present invention is a catheter having a tube and including mechanisms that provide precision control over insertion and retraction of the catheter tube. The catheter is particularly adapted for introduction into the pulmonary system. The catheter includes an insertion depth control mechanism that acts as a stop and provides a tactile indication to the person inserting the catheter tube that a predetermined position has been reached. The catheter also includes an anti-bunching mechanism to prevent bunching of a protective sleeve disposed around the catheter tube, thereby reducing interference from the sleeve during insertion of the catheter tube.

Description:
PRIORITY CLAIM 
   This application is a continuation of and claims the benefit of U.S. patent application Ser. No. 09/610,644, filed Jun. 12, 2000, now U.S. Pat. No. 6,702,789 which is a continuation of U.S. patent application Ser. No. 09/038,465, filed Mar. 11, 1998, now abandoned which claims priority to provisional U.S. patent application Ser. No. 60/040,678, filed Mar. 11, 1997. 

   CROSS REFERENCE TO RELATED APPLICATIONS 
   This application is related to the following commonly-owned co-pending patent application: “CATHETER HAVING INSERTION CONTROL MECHANISM”, Ser. No. 10/768,265, filed Jan. 30, 2004. 
   TECHNICAL FIELD 
   The present invention relates to medical catheters, and more particularly to catheters used to remove substances from, or introduce substances into, the pulmonary system or gastrointestinal tract of a patient. 
   BACKGROUND OF THE INVENTION 
   In certain medical treatment situations, catheters must be precisely introduced into a patient&#39;s pulmonary system or gastrointestinal tract for various functions. For example, a patient may require involuntary aspiration of secretions from the patient&#39;s lungs. In this situation, a suction catheter can be introduced into the patient&#39;s airway and lungs to remove the secretions via suction through the catheter. In addition, a patient may require introduction of various substances into the body through such catheters. For example, a patient may require the introduction of a lavage solution into the lungs to loosen secretions without interfering with ventilation. 
   Respiratory distress frequently occurs in infants and small children, especially prematurely born infants. Premature infants may require repeated pulmonary intervention. When an infant or small child is unable to effectively breathe on their own, intubation and involuntary ventilation is provided via an endotracheal tube. In caring for infant patients, it is necessary to periodically suction out secretions that would otherwise accumulate in the infant&#39;s lungs. This requires periodic involuntary removal of secretions from the lungs via a small suction catheter tube without injury to the lungs. Suctioning and/or introduction of therapeutic substances may take place intermittently during ventilation. 
   Suctioning is generally accomplished by introducing and advancing one end of a flexible suction catheter tube into the endotracheal tube and applying suction to the other end of the catheter tube. To reduce the extent of airway occlusion, the catheter tube is typically withdrawn from the endotracheal tube when the catheter is not in use. 
   Before the catheter tube is advanced through the endotracheal tube, the catheter tube may be “exposed” within the catheter assembly. However, many catheters include a flexible sleeve that covers the span of tubing between the fittings of a catheter to avoid the introduction of microbial pathogens during intubation. The sleeve encloses the catheter tube and preserves the sterility of the tube in a closed system. The sleeve remains fixed to the fittings of the catheter. The sleeve is flexible so that the catheter can be advanced by manipulating the catheter from the outside of the sleeve. Thus, the catheter may be intermittently introduced without breaking the sterile field created by the sleeve around the catheter. 
   Precise control over the placement of the catheter tube is also required to reduce the risk of injury during placement. The catheter must be advanced far enough to effectively reach the lungs without damaging tissue by overextension of the catheter. The use of a catheter having a protective sleeve further impacts control over the catheter during placement. As the catheter is fully advanced, the sleeve may bunch, making precise control more difficult. Thus, there is a need for a catheter having a mechanism for controlling insertion depth while preventing bunching of the protective sleeve as the catheter is inserted. 
   SUMMARY OF THE INVENTION 
   The present invention is a catheter having a tube and including mechanisms that provide precision control over insertion and retraction of the catheter tube. The catheter is particularly adapted for introduction into the pulmonary system. The catheter includes an insertion depth control mechanism that acts as a stop and provides a tactile indication to the person inserting the catheter tube that a predetermined position has been reached. The catheter also includes an anti-bunching mechanism to prevent bunching of a protective sleeve disposed around the catheter tube, thereby reducing interference from the sleeve during insertion of the catheter tube. 
   In one embodiment, the insertion depth control mechanism comprises an insertion control member that is adjustably positioned on the catheter tube. The insertion control member includes a releasable catch to permit adjustment of its position along the catheter tube. When placed in a predetermined position that corresponds to a predetermined insertion depth, the insertion control member acts as a stop against a connector or other form attached to the tube. When the insertion control member reaches the connector or form during insertion of the tube, it bumps against the connector or form and stops the advancement of the catheter tube at a predetermined length. This resistance provides a tactile response, or feel, to a person inserting the catheter, which indicates that the catheter tube has been inserted to the predetermined depth. The insertion control member can comprise a number of different shapes. 
   In one embodiment, the anti-bunching mechanism comprises a sleeve spreader including an outer surface concentrically disposed around the catheter tube and adjacent a tube opening of a distal connector attached to the catheter. The sleeve spreader deflects the sleeve away from the tube opening of the distal connector and prevents it from bunching at the tube opening, thereby avoiding interference with advancement of the catheter tube. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a perspective view of a catheter of the present invention including a connector for a ventilation apparatus. 
       FIG. 2A  is a perspective view of a first embodiment of an insertion control member of the present invention. 
       FIG. 2B  is a cross-sectional view of the insertion control member shown in  FIG. 2A  taken transversely through the center of the insertion control member. 
       FIG. 3  is a cross-sectional side view of a second embodiment of an insertion control member of the present invention. 
       FIG. 4  is a cross-sectional view of a sleeve spreader of the catheter shown in  FIG. 1 . 
       FIG. 5A  is an elevational view of a second embodiment of a sleeve spreader of the present invention. 
       FIG. 5B  is a cross-sectional view of the sleeve spreader shown in  FIG. 5A . 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
   While the present invention will be described fully hereinafter with reference to the accompanying drawings, in which a particular embodiment is shown, it is to be understood at the outset that persons skilled in the art may modify the invention herein described while still achieving the desired result of this invention. Accordingly, the description which follows is to be understood as a broad informative disclosure directed to persons skilled in the appropriate arts and not as limitations of the present invention. 
     FIG. 1  is an exploded view of a suction catheter  20  and associated attachments for use in a typical ventilator circuit. The suction catheter  20  incorporates an insertion depth control mechanism and an anti-bunching mechanism as described herein. The suction catheter  20  includes a catheter tube  21 , a proximal end  22  having a proximal connector assembly  24 , and a distal end  26  having a distal spreader connector  28 . The proximal connector assembly  24  includes a sleeve collar  30 , a vacuum valve  32 , and a terminal connector  34 . The distal spreader connector  28  includes a sleeve collar  35  and a generally cone-shaped extension  36  that extends toward the proximal end  22  of the catheter  20 . The cone-shaped extension includes a tube aperture  37 . The catheter tube  21  passes through the tube aperture  37 . The distal spreader connector  28  has a fitting  38  that can be connected to an adapter device  39 . To complete the ventilation circuit, the adapter device  39  is connected to a conventional ventilation adapter  40  that includes an endotracheal tube  42  having an end opening  44 . Other components may be used in connection with the suction catheter  20  without departing from the present invention, such as those disclosed in U.S. Pat. No. 5,642,726, which is incorporated herein by reference. 
   The catheter tube  21  of the suction catheter  20  is surrounded by a flexible external sleeve  46  that spans from the proximal connector assembly  24  to the distal spreader connector  28 , as shown in  FIG. 1 . The external sleeve  46  is attached to the proximal connector assembly  24  within the sleeve collar  30  and the distal spreader connector  28  within the sleeve collar  35 . The sleeve  46  may be banded to the sleeve collars  30  and  35  or adhered thereto. The external sleeve  46  encloses the catheter tube  21  to preserve its sterility during use in a closed system. 
   During intubation, the catheter tube  21  of the suction catheter  20  is introduced into the endotracheal tube  42  through the distal spreader connector  28  and the adapter device  39  and advanced to a predetermined depth. The depth of insertion is controlled by an insertion control member  50 . During insertion of the catheter tube  21 , the insertion control member  50  acts as a stop against the cone-shaped extension  36  of the distal spreader connector  28 , thus stopping the advancement of the catheter at a predetermined length. The insertion control member  50  also provides a tactile feel to the operator when it bumps against the extension  36 , thereby signaling to the operator that the proper depth has been reached. 
   In the embodiment depicted in  FIG. 1 , the insertion control member  50  has a generally barreled shape as shown in  FIGS. 2A and 2B . The insertion control member  50  includes two flattened grip portions  52  and a tube passage  54 . As shown in  FIG. 2B , the tube passage  54  has an elongated cross-section near the center of the insertion control member  50 . The catheter tube  21  passes through the tube passage  54  and the elongated configuration of the tube passage  54  grips the catheter tube  21  to hold the insertion control member  50  at a predetermined position along the catheter tube  21 . The catheter tube  21  may include indicia to help facilitate depth adjustment of the catheter tube  21  via the insertion control member  50 . The position of the insertion control member  50  can be adjusted by an operator pinching the insertion control member  50  at the flattened grip portions  52  to flex the elongated cross-section of the of the tube passage  54  to form a relatively wider cross-section. The wider cross-section allows the operator to slide the insertion control member  50  to a new position on the catheter tube  21 . When the insertion control member  50  is repositioned, the operator releases the flattened grip portions  52  so that the cross-section of the tube passage  54  returns to its elongated configuration. Alternatively, the cross-section of the tube passage  54  may include other features to help grip the catheter tube  21 , such as teeth or other projections. 
     FIG. 3  shows an alternate embodiment in the form of an insertion control assembly  60 . The insertion control assembly  60  includes a threaded sleeve  62  having a thru-hole  64  and external threads  66  on one end of the sleeve  62 . The thru-hole  64  has a tapered surface  68  that accepts a tapered collet  70 , as shown in  FIG. 3 . The tapered collet  70  includes a channel  72  therethrough. A mating nut  74  includes a thru-hole  76  and internal threads  78  that are adapted to engage the external threads  66  of the threaded sleeve  62 . The catheter tube  21  passes through the thru-hole  64  of the threaded sleeve  62 , the channel  72  of the tapered collet  70 , and the thru-hole  76  of the mating nut  74 . When the threaded sleeve  62  and the mating nut  74  are engaged and tightened, the threaded sleeve  62  deflects and compresses the tapered collet  70  around the catheter tube  21 , thereby securing the insertion control assembly  60  to the catheter tube  21 . 
     FIG. 4  is a cross-sectional view of the distal spreader connector  28  shown in  FIG. 1 . As the catheter tube  21  is advanced through the distal spreader connector  28  and the adapter device  38 , the external sleeve  46  begins to bunch up near the distal spreader connector  28 . The cone-shaped extension  36  of the distal spreader connector  28  acts to spread or deflect the sleeve  46  as the catheter tube  21  is advanced and prevent the sleeve  46  from interfering with the tube opening or aperture  37  of the extension  36  of the distal spreader connector  28 . The sleeve  46  is attached to the distal spreader connector  28  between the collar  35  and the extension  36 , as shown in  FIG. 4 . 
     FIGS. 5A and 5B  show an alternate embodiment in the form of a distal spreader connector  80 . In this embodiment, the distal spreader connector  80  includes a set of four tapered ribs  82  that extend from an extension  84 . The tapered ribs  82  provide further deflection and spreading of the sleeve  46  as the catheter tube  21  is advanced. Accordingly, the distal spreader connector  80  deflects the sleeve adjacent to the tube opening of the distal spreader connector. 
   While the specific embodiments have been illustrated and described, numerous modifications come to mind without significantly departing from the spirit of the invention and the scope of protection is only limited by the scope of the accompanying Claims.