CA1266598A

CA1266598A - Method of making a grooved medical tube

Info

Publication number: CA1266598A
Application number: CA000498038A
Authority: CA
Inventors: Richard Gerry Brownell Sr.; James Lawrence Fehl
Original assignee: Sherwood Medical Co
Current assignee: Covidien AG
Priority date: 1984-12-19
Filing date: 1985-12-18
Publication date: 1990-03-13
Also published as: JPH056468B2; ES8707687A1; DK573285D0; IE58470B1; AU574032B2; US4628783A; IE853076L; EP0191234B1; DK162741C; JPS61154573A; ES550073A0; DK573285A; DE3572595D1; DK162741B; EP0191234A1; AU5076385A

Abstract

Abstract of the Disclosure A method of making a suction catheter having grooves and suction holes in the grooves is disclosed which includes the step of clamping a lube to effect a bulge and moving a knife longitudinally of the tube to skive the outer portion of the bulge to form a groove after clamping pressures are removed. Holes are formed inthe bottom walls of the grooves, Skiving apparatus is disclosed which includes aclamping device for positioning and bulging a tube adjacent one end, and a kniferelatively movable longitudinally of the tube to skive the bulge.

Description

:~p~

This invention re]a-tes to medical tubes and more particularly to the method of making a medical tube especially adapted for use as a suction cathater.

Medical tubes, such as suction catheters, are used in a variety of applications, for example, they are used for tracheobronchial and nasopharyngeal suctioning, as well as for other suctioning applications. Such cathe-ters may be made with an open distal end and generally with a plurality of suction openings in the sidewall of the tube adjacent the distal end.
1~
Suction catheters have been provided with distal ends of various configurations in order to prevent or reduce invagination of the mucousa or body cavity wall tissue into the suction openings so as to prevent or reduc~ occulsion of the suction openings, as well as, damage and discomfort to the patient. Some thermoplastic tubes have been heated and post-formed in a die so that the distal end of the catheter has an annular radial flange. Suction openings are formed adjacent the flange so that the flange spaces the walls of the body cavity 2U from the suction openings when the catheter is in use. However, because of the ~lange, the maximum usable size and fluid flow rate of the catheter for a given size body cavity or passage, i3 less than it would be if no flange was required.

In some cases longitudinal ridges and valleys are post-formed at the distal end of the catheter tube and suction openings are formed in the valleys so that the ridges space the openings from the body tissue. However, the valleys and ridges generally result in a catheter having a distal portion of greater 3~ outer diameter than the rest of the catheter or a portion of the lumen at the distal end of reduced size, neither of which is desirable.

U.S. patent No. 4,330,497 discloses a method of making a suction catheter having longitudinal grooves and suction ~k opening in the bottom wall of the grooves and that does not require radial flanges or ridge and valleys at the distal end of the catheter. While this patent discloses a method for producing desirable catheters that avoid the above-mentioned disadvantages, it requires the coextrusion of two different plastic materials, one forming the tube and the other forming a longitudinal strip in the outer ~all of the tube during extrusion. The strip must be subsequently .I.u l!;

3~
- la -removed to provlde the gr-ooves In the outer wall of the tube.
Suctlon openlngs are then formed In t~e bottom walls of the grooves. These steps, however, tend to Increase the cost and complexlty of manufacture.

Catheter tlps have been separately molded, such as by InJectlon moldlng, and then bonded or adheslvely connected to the end of a catheter tube. Such a constructlon, however, has the dlsadvantages of requlrlng the use and storage of a solvent or adheslve and the assembllng step, and presents the posslblllty of tlp separatlon In use.

The present Inventlon provldes an Improved method of maklng a medlcal tube havlng a groove formed In the outer wali of the tube and whlch method avolds or reduces the above-mentloned problems of prlor art methods.

The present Inventlon also produces an effectlve and economlcal method of maklng a suctlon catheter havlng a groove In the outer wall of the catheter adJacent Its dlstal end and a suc-tlon openlng formed In the bottom wall of the groove and whereln preclslon control over the length and depth of the groove Is obtalned. In accordance wlth one aspect of the present Inven-tlon, a portlon of a reslllent tube Is expanded by applylng forces thereto, and a sklver and the tube ar-e relatlvely moved to effect sklvlng of an outer wall portlon of the expanded portlon of the tube so that when the applled forces are removed, the tube has a groove In the outer wall thereof.

In accordance wlth another aspect of the present Inven-tlon, a method of maklng a suctlon catheter Is provlded whlch Includes maklng a reslllent tube In the above-descrlbed manner and then formlng a suctlon openlng In the bottom wall of the groove.
Stlll another aspect of the Inventlon Is an apparatus provlded for maklng a groove In the outer wall of a medlcal tube In an especlally slmple, economlcal and accurate manner.

Accordlng to the present Inventlon there Is provlded a method Gf formlng a groove In the exterlor wa~l of a medlcal tube comprlslng the steps of appIylng predetermlned forces to a tube to expand a portlon of the tube, sklvlng the expanded portlon to remove an outer part of the wall thereof to thereby provlde a groove In the outer surface of the tube. Sultably, sad step of applylng forces Includes posltlonlng the portlon of the tube between a palr of clamplng members, and movlng at least one of the clamping members toward each the to compress the predeter-mlned portlon of the tube therebetween and effect the expanded portlon. Deslrably, sald sklvlng step Includes effectlng rela-tlve movement between a knlfe and the tube so that the knlfe cutsthe radlally outer part of the wall of the expanded portlon and whereby the groove has a bottom wall of less thlckness than por-tlons of the sldewall of the tube adJacent the groove. Prefer-ably, the method further Includes the step of forming an openlng extendlng through the bottom wall of the groove. Sultably, the expanded portlon extends radlally outwardly of the outer surface of the clamplng members, and sald sklvlng step Includes movlng a cuttlng blade longltudlnally of the tube and In a plane spaced from the clamplng member to cut the radlally outer portlon of the wall of the expanded portlon from the tube, and the step of removlng the forces from the tube Includes movlng at least one of the clamplng members to free the tube. Deslrably, the method of the clamplng members have faclng surface confIguratlons such that the tube Is predetermlnately located thereby between the clamplng members prlor to the step of applylng the compressive forces to the tube. Preferably, at least one clamplng members has a faclng surface conflgurat~on that Is arcuate and the tube has an arcuate outer surfaces portlon whlch fIts wlthln the arcuate surface of the one clamplng member to predetermlnately locate the tube rela-tlve to the clamplng members and the knlfe.

_ 2a -in one embodIment of the present Inventlon sald step of applying forces to the tube Includes squeezlny a predetermlned portlon of the tube between a palr of clamplng members to effect a palr of expanded portlons at the opposlte sldes of the tube and whlch extend rad~ally outwardly beyond the opposed outer surfaces of the tube, and whereln the sklvlr19 step Includes movlng a palr of cuttlng blades longltudlnally of the tube to remove a radlally outer portlon of the wall o~ each of the expanded ~ortlon to form sald groove and a groove on the opposed slde of the tube when the compresslve forces are removed. Deslrably, the tube whlch Is at least partlally collapslble, and of flexlble and reslllent mate-rlal and substantlally returns to 'ts normal conflguratlon after forces have been removed therefrom. Sultably, the tube ~s ~ormed from extruded ~hermoplastlc materlal or the tube Is formed of an elastomerlc materlal.

The present Inventlon also provldes the method of mak-Ing a suctlon catheter comprlslng the steps of provlding a flexl-ble tube, posltlonlng the tube between a palr of relatlvely mov-able clamplng Jaws, effectlng relatlve movement between at least one Jaw to squeeze a predetermlned longltudlnally extendlng por-tlon of the tube between the Jaws so as to form a bulge on the tube whlch extends out~ardly beyond the outer surface of the tube effectlng relatlve movement between a knlfe and the tube so that the knlfe sklves the outer surface of the wall of the bulge to effect an elongate groove In the outer wall of the tube when the tube Is released from the Jaws, effectlng relatlve movement of the Jaws so as to release the tube therefrom, and formlng at least one openlng through the bottom wall of the groove that con-neGts wlth the lumen of the tube. Suitably, the sklver effects a substantlally flat elongate area on the bulge. Preferably, the tube has substantlally constant Inner and outer dlameters throughout Its length and Is at least partlally collapsed to ~orm the bulge.

- 2b -In one embodlment of the present Inventlon the step of squeezlng the predetermlned portlon of the tube Includes effect-lng a second bulge on the slde opposlte the slde on whlch flrs named bulge is effected, and sklvlng the second bulge to effect a second elongate groove In the outer wall of the tube when the tube Is released from the Jaws, and formlng at least one openlng through the bottom wall of the second groove whlch connects wlth the lumen of the tube. Sultably, a second knlfe Is provlded, and the second knlfe Is moved wlth the flrst named knlfe to effect slmultaneous sk I v I ng of the bulges. Des I rably, ~he kn I ves have cuttlng edges extendlng substantlally normal and parallel to the longltudinal axls of the tube and are moved In a longltudlnal dlrectlon relatlve to the tube so that sklvlng cuts and removes outer parts of both bulges and effects substantially flat elon-gate outer surface areas whlle the predetermlned portion of the tube Is squeezed, and removlng the tube from bet~een the Jaws so that the flat surface areas become elongate grooves In the outer wall of the tube.
The present Inventlon agaln provldes sklvlng apparatus for produclng at least one groove In a dlstal end portlon of a medlcal tube comprlslng a palr of clamplng members, one of sald clamplng members belng movable toward and away from the other of sald clamplng members, sald clamplng members havlng spaced faclng surfaces for recelvlng a tube whlch Is at least partlally col-lapslble, means for movlng at least one of sald clamplng members toward and away from sald other clamplng member to at least par-tlally collapse the tube so that a portlon thereof bulges radl-ally outwardly of portlons of the tube not partlally collapsed,and tube cuttlng means Includlng a cuttlng element for cuttlng the materlal of the tube, and means for movlng sald element lon-gltudlnally of the tube to sklve a radlally outer wall portlon of the bulge. Sultably, sald clamplng members have faclng surfaces engageable wlth opposed sldes of the tube to at least partlally collapse the tube and effect a second bulge on the partlally col-- 2c -lapsed tube at a locatlon dlametrlcaily opposlte the flrst named bulge and whlch extends radlally outwardly beyond the radially outer surface of tube, and whereln sald tube cuttlng means Includes a second cuttlng element, an~ sald means for movlng sald element Includes means for movlng sald second cuttlng element longltudlnally of the tube to sklve a radlally outer wall portlon of the second bulge. Deslrably, the faclng surface of at least one of sald clamplng members Is shaped In relatlon to a surface of a tube to be clamped therebetween such that sald faclng surfaces of the clamplng members located the tube for sklvl ng . Preferably, a~ least one of ~a I d ~ac I ng surf~ces of sald clamplng members Include an arcuate surface for receivlng portlons of a tube to be sklved. Deslrably, sald cuttlng elements are mo~able slmultaneous longltudlnally of a tube to be sklved and are spaced from each other to cut only the bulges of the tube.

The pr-esent Inventlon In a further aspect thereof pro-vldes a method of maklng a reslilent flexlble medlcal tube havlng a groove In the exterlor surface of the wall of the tube and an openlng through the bottom wall of the groove connect!ng the groove wlth the lumen of the tube comprlslng the steps of apply-lng predetermlned forces to a reslllent flexlble tube to expand a portlon of the wall of the tube, sklvlng the expanded wall por-tlon to remove an outer part of the wall thereof, removlng theapplled forces to thereby allow the expanded wall portlon to return to Its unexpanded condltlon and effect a groove havlng spaced opposed sldewalls and a bottom wall In the exterlor sur-face of the wall of the tube where the outer part of the wall was ~0 removed, and formlng an openlng extendlng through that portlon of the wall of the tube that forms the bottom wall of the groove to connect the groove wlth the lumen of the tube.

The present Inventlon In a stlll further aspect thereof provldes a method of formlng a groove In the exterlor surface of the wall of a reslllent flexlble medlcal tube comprlslng the - 2d -steps of applylng prede-termlned forces to a reslllent flexlble tube to expand a portlon of the wall of the tube, sklvlng the expanded wall portion to remove an outer part of the wall thereof, removlng the applied forces to thereby allow the expanded wall portlon to return to Its unexpanded condltlon anc effect a groove havlng spaced opposed sldewalls and a bottom wall In the exterlor surface of the wall of the tube where the outer part of the wall was re~oved, said step of applylng forces Includlng posltlonlng the tube between a palr of clamplng mem-bers, and movlng at least one of the clamplng members toward theother to compress a predetermlned portlon of the tube therebe-tween and effect at least a partlal collapse of the tube lumen and a bulge wlth the expanded portlon of ~he wall thereon, sald sklvlng step Includlng effectlng relatlve movement between a knlfe and the tube so that the knlfe cuts the radlally outer part of the wall of the expanded portlon and whereby the groove has a bottom wall o~ less thlckness than portlons of the sldewall oF
the tube adJacent the groove, and formlng an openlng extendlng through the bottom wall of the groove subsequent to removlng sald applled forces.

The present Inventlon further provldes a method of formlng a groove In the exterlor surface of the wall of a resll-lent flexlble medlcal tube comprlslng the steps of applylng pre-determlned forces to a reslllent flexIble tube to expand a por-tlon of the wall of the tube, sklvlng the expanded wall portlon to remove an outer part of the wall thereof, and removlng the applled forces to thereby allow the expanded wall portlon to return to Its unexpanded condltlon and e~ect a groove havlng spaced opposed sldewalls and a bottom wall In the exter~or sur-face of the wall of the tube where the outer part o~ the wali removed, sald step of applylng forces Including posltlonlng the tube between a palr of clamplng members, and movlng at least one of the clamplng members toward the other to compress a predeter-mlned portlon of the tube therebetween and effect at least a par-tlal collapse If t~e tube lumen and a bulge wlth the expanded - 2e -portlon of ti~e wall thereon, sald sklvlng step Includlng ef~ect-lng relatlve movement between a knlfe and the tube so that the knlfe cuts the radlally outer part of the wall of the expanded portlon and whereby the groove has a bo-ttom wali of less thlck-ness than por~lons of the sldewall of the tube adJacent thegroove, the expanded portlon extendlng radlally outwardly of the outer surface of the clamplng members, sald sklving step Includ-lng movlng a cuttlng blade longltudlnally of the tube and In a plane spaced from the clamplng member to cut the radlally outer part of the wall of the expanded portlon from the tube, sald step of removlng the forces from the tube Includlng movlng at least one of the clamplng members to free the tube.

The present Inventlon also provides a method of formlng a groove In the exterlor surface of the wall of a reslllent flex-lble medlcal tube comprlslng the steps of applylng predetermlned forces to a reslllent flexlble tube to expand a portlon of the wall of the tube, sklvlng the expanded wall portion to remove an outer part of the wall thereof, and removlng the applled forces to thereby allow the expanded wall portlon to return to Its unex-panded condltlon and effect a groove havlng spaced opposed slde walls and a bottom wall In the exterlor surface of the wall of the tube where the outer part of the wall was removed, sald step of applylng forces Includlng posltlonlng the tube between a palr of clamplng members, and movlng at least one of the clamplng mem-bers toward the other to compress a precietermlned portlon of the tube therebetween an effect at least a partlal collapse of the tube lumen and a bulge wlth the expanded portlon of the wall thereon, sald skivlng step Includlng e~fectlng relatlve movement between a knlfe and the tube so that the knlfe cuts the radlally outer part of the wall of the expanded portlon and whereby the groove has a bottom wall of less thlckness than portlons of the sldewall of the tube adJacent the groove, of the clamplng members havlng faclng surface conflguratlons such that the tube Is prede-termlnate~y located thereby between the clamping members prlor tothe step o~ applylng the compresslve forces to the tube.

- 2f -In a further aspect thereof the present Inventlon pro-vldes a method of formlng a groove In the ex~erlor surface of the wall of a reslllent flexlble medlcal tube comprlslng the steps of applylng predetermlned forces to a reslllent flexlble tube to expand a portlon of the wall of the tube, sklvlng the expanded wall portlon to remove an outer part of the wall thereof, and removlng the applled forces to thereby allow the expanded wall portlon to return to Its unexpanded condltlon and effect a groove havlng a spaced opposed sldewalls and a bottom wali In the exte-rlor sur face o~ the w~ll of the tube where the outer part of thewall was removed, sald step oF applylng forces to the tube Including squeezlng a predetermlned portlon of the tube between a palr of clamplng members to effect a palr of expanded portlons at the opposlte sldes of the tube and whlch bulge radlally outwardly beyond the opposed outer surfaces of portlons of the tube whlch are not squeezed, sald sklvlng step Includlng movlng a palr of cuttlng blades longltudlnally of the tube to remove a radlally outer portlon of the wall of each of the expanded portlons to form sald groove and a groove on the opposed slde of the tube when the applled forces are removed.

In another aspect thereof the present Inventlon pro-vldes the method of maklng a suctlon cathe~er comprlslng the steps of provldlng a reslllent flexlble tube, posltlonlng the tube between a palr of relatlvely movable clamplng members, effectlng relatlve movement between at least one member and the tube to squeeze a predetermlned longltudlnally extendlng portlon of the tube between the members so as to form a bulge on the tube whlch extend outwardly beyond the outer surface of the portlons of the tube whlch are not squeezed, effectlng relatlve movement between a knlfe and the tube so that the knlfe sklves the outer surface of the wall of the bulge to effect an elongate groove In the outer wall of the tube having spaced opposed sldewalls and a bottom wall when the tube Is released from the members, effectlve relatlve movement of the members so as to release the tube there-from, and formlng at least one openlng through the wall of the tube such that the groove connects wlth the openlng and the lumen of the tube.

The present Inventlon also provldes apparatus for pro-duclng a reslllent suctlon ca~heter havlng a suctlon openlng In the sldewall of the catheter tube whlch has walls on opposed sldes thereo~ to prevent Invaglnatlon of tlssue Into the openlng comprlslng a palr of clamplng members, control means for movlng sald clamplng members relatlvely toward and away from each other, sald clamplng rnembers havlng spaced faclng surfaces for recelvlng a reslllent tube whlch Is at least partlally collapslbie, sald clamplng members ~elng relatlvely movable toward each other to at least partlally collapse the tube when placed therebetween so that a portlon of the tube bulges radlally outwardly of portlons of the tube not partlally collapsed, tube cuttlng means Includlng a cuttlng element for sklvlng materlal of the tube, means for effectlng relatlve movement between the cuttlng element and the tube for movlng sald element relatlvely longltudlnally of the tube In the plane parallel to the longltudlnal axls of the tube to sklve a longltudlnal radlally outer wall portlon only from the bulge to form a flat longltudlnally extendlng area, sald clamplng members belng movable relatlvely away from each other to allow the flat area of the tube to form a groove having sldewalls and a bottom wall, and means for formlng an openlng through the bottom wall of the formed groove, sald clamplng members havlng faclng surfaces engageable wlth opposed sldes of the tube to at least partlally collapse the tube and effect a second bulge on the par-tlally collapsed tube at a locatlon dlametrlcally opposlte the flrst named bulge whlch extends radlally outwardly beyond the rad~ally outer surface of tube not partlally collapsed, sald tube cuttlng means Includlng a second cuttlng element, and sald means for movlng sald elemen-t Includlng means for movlng sald second cuttlng element longltudlnally of the tube to sklve a radlally outer longltudlnalIy extendlng wall portlon of the second bulge.

- 2h -In another aspect thereof the present Inventlon pro-vldes apparatus for produclng a reslllent suctlon catheter havlng a suctlon openlng In the sldewall oF the catheter tube whlch has walls on opposed sldes thereof to prevent Invaglnatlon of tlssue Into the openlng comprlslng a palr of clamplng members, control means for movlng sald clamplng members relatlvely toward and away from each other, sald clamplng members havlng spaced faclng sur-faces for recelvlng a reslllent tube wh~c~l Is at least partlally collapslble, sald clamplng members belng relatlvely movable toward each other to at least partlally col~apse the tube when placed therebetween so that a portlon of the tube bulges radlally outwardly of portlons of the tube not partlally collapsed, tube cuttlng means Includlng a cuttlng element for sklvlng materlal of the tube, means for effectlng relatlve movement between the cut-tlng element and the tube for movlng sald element relatlvely lon-gltudlnaliy of the tube In a plane parallel to tl1e longltudlnal axls of the tube to sklve a longltudlnal radlally outer wall por-tlon only from the bulge to form a flat longltudlnally extendlng area, sald clamplng members belng movable relatlvely away from each other to allow the flat area of the tube to form a groove havlng sldewalls and a bottom wall, and means for formlng an openlng through the bottom wall of the formed groove, sald cut-tlng elements belng movable slmultaneous longltudlnally of a tube to be sklved and spaced from each other to cut only the bulges of the tube.

In a stlll further aspect thereof the present Inventlon provldes a method of formlng a groove In the exterlor surface of the wall of a reslllent flexlble medlcal tube comprlslng the steps of applylng predetermlned forces to a resillent flexlble tube to expand a portlon of the wall of the tube, sklvlng the expanded wall portlon to remove an outer part of the wall thereof, removlng the appl!ed forces to thereby allow the ~5 expanded wall portlon to return to Its unexpanded cond!tlon and effect a groove havlng spaced opposed sldewalls and a bottom wall .

i$~ 8 In the exterlor surface of the wall of the tube where the outer part of the wall was removed, sald step of applylng forces Includlng posltlonlng the portlorl of the tube between a palr of clamplng members, and movlng at least one of the clamplng members toward the other to compress a predetermlned portlon of the tube therebetween and effect at least a partlal collapse of the tube lumen and a bulge wlth the expanded portlon of the wall thereon, sald sklvlng step Includlng eFfectlng relatlve movement between a knlfe and the tube so that the knlFe cuts the radlally outer part of the wall of the expanded portlon and whereby the groove has a bottom wall of less thlckness than portlons of the sldewall of the tube adJacent the groove, the knlfe cuttlng the outer part of the wall of the expanded portlon to form an elongated sectlon which Is substantlally flat In both lateral and longltudlnal directlons.

Fig. 1 is an elevational view of a suction catheter made in accordance with the present invention and shown connected through a vacuum control member to a schematically illustrated source of suction;

Fig. 2 is an enlarged cross-sectional view taken along ~ line 2--2 of fig~ 1;

Fig. 3 is an enlarged left end view of the catheter of Fig. l;
:1. t) Fig. 4 is an elevational view partly in section of a step in the method of making the catheter of Fig. 1, Fig. 5 is a pPrspective view, on a reduced scale, of apparatus used in making the medical suction of Fig. 1 tube ln accordance with one aspect of the present invention;

Fig. 6 is a perspective view of the clamps shown in Fig. 5 and a tube adapted to be received between the clamps in

2~ accordance with a step in the method of making the catheter of Fig. l;

Fig. 7 is an enlarged end view showing tne tube inserted between the clamps of Fig. 6;

Fig. 8 is a p~rspective view of the clamps and tube of Fig. 6 after the tube has been inserted between the clamps and clamping forces applied to compress the tube;

3~ Fig. 9 is an enlarged cross-sectional view taken along line 9--9 of Fig. 8;

Fig. 10 is a right sideview of a portion of the apparatus of Fig. 5 illustrating the relative relationship between the knives, clamps, and tube during the start of tne 3~

skiving operation performed by the apparatus;

Fig. 11 is a persp~ctive view of the knives, clamps and tube during the skiving operation of the apparatus of Fig. 5;

Fig. 12 is an enlarged cross-sectional view similar to Fig. 9, but showing the tube after it has been skived;

Fig. 13 is a perspective view of the tube after the skiving step of Fig. 11 and after removal from the clamps; and lU
Fig. 14 is cross-sectional view taken along line 14~-14 of Fig. 13 along with a punch aligned with the tube grooves for forming suction holes in the tube.

Referring now to the drawings and more particularly to Figs. 1-3, a medical tube in the form of a suction catheter is indicated generally at 10 which includes a flexible hollow shaft or tube 11. Catheter 10 has a distal end portion 12 adapted for insertion into a body cavity, such as the trachea of a patient, and a proximal end 3~

- 3a -portion 14 connected to a source of suction I 6 through a vacuum or suction control venting valve 18. The suc-ion source 16 may be a conventional hospi-ial source of suction and -ihe valve 18 may be any suitabie or conventional suction control device that can be used to vary the suciion applied to the catheter 10.
Catheter tube has n lumen 20 extending throughout its length and which is open a~ both ends. The lumen is connected at the proximal end por-iion 14 with a main lumen 22 of ~he suction control valve 18 that, in turn, is connected in fluid communication wi th the suction source 16 by a iube 19. Control valve 18 has a vent port 24 that can be covered or partially covered by the thumb of the operator for 10 allowing air from the atmosphere -io enter the control valve in a controlled manner so as to control the negative pressure or suction within i-ube lumen 20. The port 24 can t)e completely occluded for maximum negative pressure or vacuum, partially opened to to effect a lower vacuum, or cornpletely opened to further reduce or elim-inate the vacuum in lumen ~û.
The distal end portion 12 of tube 11 is provided wi-ih a pair of elongated, longitudinally extending grooves 26 and 28 in the outer surface or wall of tube 11 at diametrically opposite locations on the tube, as seen in Fig. 2. The bottom walls of grooves 26 and 28 are indicated at 3û and 32, respectively, and are provided with at least one suction opening or hole, two holes 34 and two holes 36, are shown respec-20 tively disposed in grooves 26 and 28 for illustration. Each of the bottom walls 30 and 32 has, of course, a radial thickness less than that of portions of the tube 11 adjacent both sides of the groove. The tube lumen 20 is not reduced in size at ihe distal end of the tube but rather, is of substaniially constant diameter or size through-out its length thereby avoiding any fluid flow restriction. Also, the outer diameter of the tube 11 is substantially constani throughou- the length of tube except at the grooves and has no radial enlargement at i--s distal end 12.
Wii-h this construction the distal end portion of the catheter 10 may be inserted into the trachea and controlled suction applied to the catheter so thatmucous and other fluids may flow into the open distal end of lumen 20 as well as the 30 sidewall suction openings 36 and 38. Because the openings are in the bottom walls oF the grooves 26 and 28, the side walis of the grooves space the mucosa or cavity wall tissue of the paiient from the sidewall openings preventing invagination ofiissue into the openings and continously providing fluid flow paths from the trachea into the tube lumen 20. The suction catheter 10 may be, for exarnple, passed through an endotracheal tube where such a tube had been previously inserted in the patient.
The present invention is particularly concerned with the method of mak-ing 1he catheier lû and to the apparatus used in the method. In makina cathe-ter 10, the tube I I may be initially Formed from -~ubing of plastic or rubber. Tube I I may be cut from extruded or otherwise formed pias~ic tubing, for example, a tubing made of a thermoplas~ic rna~erial whicb includes a poiyvinyl chloride, polyurethane, poly-ethiene, or o-lher suitable plastic or mixture of plas~ics, that may used as a catheter or other medical tube ma~erial. Elastol-ners such as synthe~ic rubber and silicone rubber may also be used. In ~he rnanufacture of suction catheters, the material may be flexible and somewhat pliable, resiliently compressible and such that the tube material can be cu-l either in its natural condition or in ansoftened condition. As used herein, "tube" is intended to mean either a discreet tube or the soiidified extru-10 date tubing as il comes from an extruder where the tube is formed by the extrusionprocess.
Fig. 4 shows the tube 11 in its initial state, that is, for example, after being cut frorn a -Ihermoplastic extrudate or tubiny, such as froln a tubular plasticized, polyvinyl chloride extrudate, and after being inserted in~o a conventional melt or suitable heated mold 39 to smoothly round the cut or sharp edges formed by cutting the tube 11 frorn the plastic extrudate. The smoothly rounded end provides the distal end in the completed catheter 10 as idicated in Figs. I and 3.
The method of forming each of the grooves 26 and 28 includes expanding a portion of the tube radially outwardly of the outer surface of other portions of the 20 tube and skiving an outer section or part of the expanded tube por~ion. Expanding or bulging a portion of the tube, is accomplished in the preferred method by compress-ing or partially collapsing a predetermined portion of the tube. The skiving is prefer-ably accomplished by relatively moving a knife and the tube, longitudinally of the tube, to cut or skive an elongate outer wall portion of the expanded or bulging por-tion of the tube.
Fig. 5 shows a skiving apparatus for cutting or skiving distal end portion 12 of the tube 11 to provide the grooves 26 and 28 in the finished catheter 10. Sl<iv-ing apparatus 40 includes a tube clamping device 42 having a pair of similar, opposed clamping jaws or clamps 44 and 46 for receiving, holding and clamping or compress-3û ing the tube 11 to expand or bulge portions of tube 11, as will be further describedhereafter. The clamps are operated between predetermined open and closed positions by a pair of actuators or motors 48 and 50, respectively, which may be conventional air, vacuum or hydraulic motors or other suitable actuators. As shown for example, the motors 48 and 50 are pressurized air actuated motors connected to a pressurized air source 51 through an air flow control valve 52. The actuators 48 and 5û are fixed to a plate or table 53 such as by bolts.

rhe skiving device 40 also includes a skiver or tube cutting device 54.
Skiver 54 includes a kni-fe holder 56 to which is attached a pair of knives or cutting blades 57 and 58, such as by bolts (not shown) The knife holder 54 is guided forlinear rnovement longitudinally of the tube 11 during skiving operations by any suit-able guide mernber, for exarnple, a member 59 is shown for illustration as having a groove in which the holder 56 is slidable. The guide member 59 is secured to plate 53, such as bolts, so that the knife holder 56 and knives 57 and 58 are accurately guided for movement longitudinally of the -lube 11 when -Ihe tube is held by clamps 44 and 46. Holder 56 is moved by an air motor or actuator 60 mounted to plate 5310 and connected to move the holder. Skiver actuator 6û may be controlled by an air flow controi valve 62 connected to the pressurized air source 51. Each of the actua-tors 48, 5û, and 6û rnay be actuated, for example, in a forward direction by air pres-suri~atioo and returned by an internal spring to the rearward or deactuated position.
The valves 52 and 62 may be conventional valves of the rnanually controlled type or they may be automatically controlled as desired.
In utilizing the skiving apparatus 40 to forrn grooves 26 and 28 in the outer surface of the distal end portion 12 of the tube 11 after the distal tip of the tube has been rnelt molded as in Fig. 4, the tube is inserted, distal end first, between the relatively rnovable clamps 44 and 46 o-f skiving apparatus 40. The tube 11 may 20 be inserted and the proximal end portion held by hand as shown in Fig. 5. Fig. 6 illustrates the tube 11 just prior to insertion between the jaws in the clamping device 42. Preferably, the tube 11 is inserted into the clamps until the distal end extends slightly out of the clamps as in Fig. 5. The opposed facing s~lamping surfaces of the clamps L~4 and 46 have arcuate portions 64 and 66 respectively which form arcs sub-stantially connplementary to arcuate portions on the outer surface of tube 11. When the clamps ore in the open or unactuated position, as in Fig. 6 and 7, the tube 11 can be guided into accurate position between the clamping members 44 and 46 by the - facing arcuate surfaces 64 and 66. The facing surface of the clamp 44 also has a pair of longitudinally extending flat parallel surfaces 68 and 69 at the upper and 30 lower edges of the clamp. Similarly, the facing surface of clamp 46 has a pair of longitudinally ex~ending flat parallel surfaces 70 and 71 and which respectively face and are in lateral alignment with flat surfaces 68 and 69 of jaw 44. These flat fac-ing surfaces o-f the clamps engage and move opposed sides of the tube 11 toward each other to cornpress and effect bulging of the tube 11 in preparation for skiving il, as will be described.
Af ler the tube 11 is inserted into the space between the clamps 44 and 46, as in Fig. 7, so that the arcuate surfaces 64 and 66 acturately locate and hold 5~

the tube 11 in ~l~e desired position, the clarnps 44 and Li6 are actoQted by actuators 48 and S0 ~Fig. 5) so that they rnove relative -to each o~her and the tube 11 to apply clarnping forces to the opposed sides of the tube as seen in Figs, 8- 10, thereby com-pressing the predeterrnined por~ion of -Ihe tube and causing upper and lower diametric-ally opposecl radial protrusions or bulges 72 and 74. As best seen in FigO 9, the facing flat surfaces 68 and 7û of the cla,nps ;nove relative to each other and ~ube 11 such that they sqoeeze or compress an upper portion of ~ube 11 causing the bulge 72 while the faciny surfaces 69 and 71 of the clamps move relative to each other and tube 11 so as to squeeze or compress the lower diametrically opposed portion of tube 11 and effect the bulge 74.
In Fig. 9, the rnovement of the clamps 44 and 46 relative!y toward each other are limited, such as by suitable stops or the like (not shown) to provide a pre-determine clarnping pressure. As shown, a pressure is applied so that the tube lumen 20 does not fully close and the inner wails of the tube become generally eliptical.
As shown, the lumen 2û, is no longer of the same configuration and cross-section as in its original or unclamped shape, ~hat is, the inner walls of the lumen 2û are no longer round at the clamped portion of the tube but facing walls of the tube do not contact each other although they may do so depend upon the clalnping pressure applied to the tube. It is seen from Figs. 7 and 9 that the tube 11, before being squeezed by the clamp 44 and 46 is circular in cross-section and its outer diameter is less than the vertical height of the clamps 44 and 46 and the outer wal I or surface of tube 11 does not extend above or below the upper and lower surfaces of the clamps. However, after the tube is clamped or compressed, as best shown in Fig. 9, the diametrically opposed bulges 72 and 74 do extend above and below the upper and lower surfaces of the clarnps.
In Fig. 70, the knives 56 and 58 are shown positioned for longitudinal movement rig7hrwardly to effect skiving the longitudinally extending bulges 72 and 74. In Fig. I I, the knives 56 and 58 are shown effecting the skiving, that is, cutting longitudinal chips indicated at 76 and 78 from the outer wall or surfaces of the bulges 72 and 74 of the tube. The knives are moved by actuator 60 as controlled by valve 62. Tube 11 in Fig. 12 is shown clamped between the clamps 44 and 46 and after having been skived by the l<nives 56 and 58. It will be seen that in the clamped con-dition of the tube, the knives, which rnove longitudinally along the tube, cut off the radially outer portions or tops of the bulges 72 and 74 so that the remaining outer surfaces of the bulges are flot. These flats, which are indicated at 80 and 82 in Fig.
12, are flat both lonaitudinally along the tube as well as laterally or in a direction norrnal ~o the longitudinal axis of the tube.

$~

Af~er skiviny tube I i, the clamF)s 44 and 46 are returned to the normally open posi~ion~ the position shown in Fig. 6 and 7. The tube I I may then be pulled longiiudinally out of ~he clamps. I~ue to the resilency oF the tube 11, the dis~al end portion will be re~urned to its original shape ~naturally or mechanically assisted) so that tl)e lumen 2û in ~he distal end portion of the -lube will return to its originql shape, in this case, the lurnen walls become circular again. The tube 11 will appear as shown in Fig. 13. Because the tube was squeezed or clarnped to effect bulging as in Fig. 9, the fla-l areas or portions 80 and 82 af~er sl<iving as shown in Fig. 12, becorne the curved or generally arcuate grooves 26 or 28, as best seen in Figs. 2 and 14, 10 when the clampillg pressures are removed From the tube as when it is removed from the clamps of clamping device 42.
After the tube 11 is provided with grooves 26 and 28, the suction openings or holes 34 and 36 (Fig. 2) are formed. This may be accomplished by aligning a hol-low punch, such as indicated at 84, with the grooves 26 and 28, as seen in Fig. 14 and then moving the punch 84 through both of the bottom walls 30 and 32, such as during a single stroke of the punch, to produce the holes 34 and 36. Where desired, other rnethods of Forming the suction openings may be used, for example, a mandrel maybe inserted into the tube lumen 20 and individual punches used to punch the suction openings.
The tube clamping device 42 of skiving apparatus 40 performs the func-tions of receiving and holding a tube accurately in the desired location for process-ing since the outer surfaces of the clamps 44 and 46 conform to the engaging outer portion of the tube (Fig. 7). While the surfaces are arcs oF circles when the tube is circular in section, the facing surfaces of the clamps may be shaped differentlywhere the outer surface of the tube is normally noncircular, such as e!iptical or the like. The clamps of the clamping device 42 not only squee7e or collapse the walls of the tube to effect the described bulging of the tube for skiving or cutting the grooves in the outer surface or walls oF the bulges but also serve to accurately locate and hold the tube during skiving to obtain accurately controlled grooves. While the fac-30 ing surfaces of -the clamps are shown complementary to the surfaces of the tube, it is not necessary for the facing surfaces of the clarnps to be compiementary to the tube or to each other in order that the clamps locate and position to tube for skiving.
Preferably, the cutting edge of each knife is straight and extends normal to the longitudinal axis of the tube (Fig. 5, 10 and 11). The knives 56 and 58 of device 42 are positioned so that when moving longitudinally along the tube to effect skiving, they do not engage the clamps 44 and 46. since the tube is bulged by clamp-ing forces and such that the bulge extends radial Iy outward beyond the normal outer .~r~ 9~3 surface of the tube, and -the knives 56 and 58 move only longitud1nally, the tube is cut only where -the bulge occurs.
Thus skiving apparatus many be made simply and economically and yet produce accurately controlled and located grooves. Catheters made by the above described me~hod and apparatus are effective and atraumatic.
!, Where desired, one of the clamps, such as clamp 44 may be made stationery so that only one clamp is movable to thereby eliminate the need for one of the actuators 48 and 50. Also, while two grooves 26 and 28 are advantageously similtaneously formed in diametrically opposite sides of the tube by apparatus 40, a single knife could be used to skive one groove at a time if desired. Also, a suction tube could be provided with one or more than two grooves as desired.
1~;

g

Claims

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE
PROPERTY OR PRIVILEGE IS CLAIMED ARE DE

1. A method of making a resilient flexible medical tube having a groove in the exterior surface of the wall of the tube and an opening through the bottom wall of the groove con-necting the groove with the lumen of the tube comprising the steps of applying predetermined forces to a resilient flexible tube to expand a portion of the wall of the tube, skiving the expanded wall portion to remove an outer part of the wall thereof, removing the applied forces to thereby allow the expanded wall portion to return to its unexpanded condition and effect a groove having spaced opposed sidewalls and a bottom wall in the exterior surface of the wall of the tube where the outer part of the wall was removed, and forming an opening extending through that portion of the wall of the tube that forms the bot-tom wall of the groove to connect the groove with the lumen of the tube.

2. The method of claim 1 wherein said step of applying forces includes positioning the tube between a pair of clamping members, and moving at least one of the clamping members toward the other to compress a predetermined portion of the tube therebetween and effect at least a partial collapse of the tube lumen and a bulge with the expanded portion of the wall thereon.

3. The method of claim 2 wherein said skiving step includes effecting relative movement between a knife and the tube so that the knife cuts the radially outer part of the wall of the expanded portion and whereby the groove has a bottom wall of less thickness than portions of the sidewall of the tube adjacent the groove.

4. A method of forming a groove in the exterior sur-face of the wall of a resilient flexible medical tube comprising the steps of applying predetermined forces to a resilient flexi-ble tube to expand a portion of the wall of the tube, skiving the expanded wall portion to remove an outer part of the wall thereof, removing the applied forces to thereby allow the expanded wall portion to return to its unexpanded condition and effect a groove having spaced opposed sidewalls and a bottom wall in the exterior surface of the wall of the tube where the outer part of the wall was removed, said step of applying forces including positioning the tube between a pair of clamping mem-bers, and moving at least one of the clamping members toward the other to compress a predetermined portion of the tube therebe-tween and effect at least a partial collapse of the tube lumen and a bulge with the expanded portion of the wall thereon, said skiving step including effecting relative movement between a knife and the tube so that the knife cuts the radially outer part of the wall of the expanded portion and whereby the groove has a bottom wall of less thickness than portions of the sidewall of the tube adjacent the groove, and forming an opening extending through the bottom wall of the groove subsequent to removing said applied forces.

5. A method of forming a groove in the exterior sur-face of the wall of a resilient flexible medical tube comprising the steps of applying predetermined forces to a resilient flexi-ble tube to expand a portion of the wall of the tube, skiving the expanded wall portion to remove an outer part of the wall thereof, and removing the applied forces to thereby allow the expanded wall portion to return to its unexpanded condition and effect a groove having spaced opposed sidewalls and a bottom wall in the exterior surface of the wall of the tube where the outer part of the wall removed, said step of applying forces including positioning the tube between a pair of clamping members, and mov-ing at least one of the clamping members toward the other to com-press a predetermined portion of the tube therebetween and effect at least a partial collapse if the tube lumen and a bulge with the expanded portion of the wall thereon, said skiving step including effecting relative movement between a knife and the tube so that the knife cuts the radially outer part of the wall of the expanded portion and whereby the groove has a bottom wall of less thickness than portions of the sidewall of the tube adja-cent the groove, the expanded portion extending radially out-wardly of the outer surface of the clamping members, said skiving step including moving a cutting blade longitudinally of the tube and in a plane spaced from the clamping member to cut the radi-ally outer part of the wall of the expanded portion from the tube, said step of removing the forces from the tube including moving at least one of the clamping members to free the tube.

6. A method of forming a groove in the exterior sur-face of the wall of a resilient flexible medical tube comprising the steps of applying predetermined forces to a resilient flexi-ble tube to expand a portion of the wall of the tube, skiving the expanded wall portion to remove an outer part of the wall thereof, and removing the applied forces to thereby allow the expanded wall portion to return to its unexpanded condition and effect a groove having spaced opposed sidewalls and a bottom wall in the exterior surface of the wall of the tube where the outer part of the wall was removed, said step of applying forces including positioning the tube between a pair of clamping mem-bers, and moving at least one of the clamping members toward the other to compress a predetermined portion of the tube therebe-tween an effect at least a partial collapse of the tube and a bulge with the expanded portion of the wall thereon, said skiving step including effecting relative movement between a knife and the tube so that the knife cuts the radially outer part of the wall of the expanded portion and whereby the groove has a bottom wall of less thickness than portions of the sidewall of the tube adjacent the groove, of the clamping members having facing sur-face configurations such that the tube is predeterminately located thereby between the clamping members prior to the step of applying the compressive forces to the tube.

7. The method of claim 6 wherein at least one clamping members has a facing surface configuration that is arcuate and the tube has an arcuate outer surfaces portion which fits within the arcuate surface of the one clamping member to prede-terminately locate the tube relative to the clamping members and the knife.

8. A method of forming a groove in the exterior sur-face of the wall of a resilient flexible medical tube comprising the steps of applying predetermined forces to a resilient flexi-ble tube to expand a portion of the wail of the tube, skiving the expanded wall portion to remove an outer part of the wall thereof, and removing the applied forces to thereby allow the expanded wall portion to return to its unexpanded condition and effect a groove having a spaced opposed sidewalls and a bottom wall in the exterior surface of the wall of the tube where the outer part of the wall was removed, said step of applying forces to the tube including squeezing a predetermined portion of the tube between a pair of clamping members to effect a pair of expanded portions at the opposite sides of the tube and which bulge radially outwardly beyond the opposed outer surfaces of portions of the tube which are not squeezed, said skiving step including moving a pair of cutting blades longitudinally of the tube to remove a radially outer portion of the wall of each of the expanded portions to form said groove and a groove on the opposed side of the tube when the applied forces are removed.

9. The method of claim 1 wherein the lumen of the tube is at least partially collapsible, and the tube is of flexible and resilient material which substantially returns to its normal configuration after said forces have been removed therefrom, and said groove extends longitudinally of said tube.

10. The method of claim 1 wherein the tube is formed from extruded thermoplastic material.

11. The method of claim 1 wherein the tube is formed of an elastomeric material.

12. The method of claim 1 wherein said step of skiving includes cutting the expanded portion to form an elongate sub-stantially flat surface while the predetermined forces reapplied to form a substantially arcuate groove when the predetermined forces are removed.

13. The method of claim 12 wherein the tube is nor-mally substantially circular in cross-section.

14. The method of claim 1 wherein said tube has a lumen which extends through said expanded wall portion.

15. The method of making a suction catheter comprising the steps of providing a resilient flexible tube, positioning the tube between a pair of relatively movable clamping members, effecting relative movement between at least one member and the tube to squeeze a predetermined longitudinally extending portion of the tube between the members so as to form a bulge on the tube which extend outwardly beyond the outer surface of the portions of the tube which are not squeezed, effecting relative movement between a knife and the tube so that the knife skives the outer surface of the wall of the bulge to effect an elongate groove in the outer wall of the tube having spaced opposed side walls and a bottom wall when the tube is released from the members, effective relative movement of the members so as to release the tube there-from, and forming at least one opening through the wall of the tube such that the groove connects with the opening and the lumen of the tube.

16. The method of claim 15 wherein the skiver effects a substantially flat elongate area on the bulge.

17. The method of claim 16 wherein the tube has sub-stantially constant inner and outer diameters throughout its length and is at least partially collapsed to form the bulge.

18. The method of claim 15 wherein the step of squeez-ing the predetermined portion of the tube includes effecting a second bulge on the side opposite the side on which first named bulge is effected, and skiving the second bulge to effect a sec-ond elongate groove in the outer wall of the tube when the tube is released from the clamping members, and forming at least one opening through the bottom wall of the second groove which con-nects with the lumen of the tube.

19. The method of claim 18 wherein a second knife is provided, and the second knife is moved with the first named knife to effect simultaneous skiving of the bulges.

20. The method of claim 19 wherein the knives have cutting edges extending substantially normal and parallel to the longitudinal axis of the tube and are moved in a longitudinal direction relative to the tube so that skiving cuts and removes outer parts of both bulges and effects substantially flat elon-gate outer surface areas while the predetermined portion of the tube is squeezed, and removing the tube from between the clamping members so that the flat surface areas become elongate grooves in the outer wall of the tube.

21. Apparatus for producing a resilient suction catheter having a suction opening in the sidewall of the catheter tube which has walls on opposed sides thereof to prevent invagi-nation of tissue into the opening comprising a pair of clamping members, control means for moving said clamping members rela-tively toward and away from each other, said clamping members having spaced facing surfaces for receiving a resilient tube which is at least partially collapsible, said clamping members being relatively movable toward each other to at least partially collapse the tube when placed therebetween so that a portion of the tube bulges radially outwardly of portions of the tube not partially collapsed, tube cutting means including a cutting ele-ment for skiving material of the tube, means for effecting rela-tive movement between the cutting element and the tube for moving said element relatively longitudinally of the tube in the plane parallel to the longitudinal axis of the tube to skive a longitu-dinal radially outer wall portion only from the bulge to form a flat longitudinally extending area, said clamping members being movable relatively away from each other to allow the flat area of the tube to form a groove having sidewalls and a bottom wall, and means for forming an opening through the bottom wall of the formed groove, said clamping members having facing surfaces engageable with opposed sides of the tube to at least partially collapse the tube and effect a second bulge on the partially col-lapsed tube at a location diametrically opposite the first named bulge which extends radially outwardly beyond the radially outer surface of tube not partially collapsed, said tube cutting means including a second cutting element, and said means for moving said element including means for moving said second cutting ele-ment longitudinally of the tube to skive a radially outer longi-tudinally extending wall portion of the second bulge.apparatus for producing a resilient suction catheter having a suction open-ing in the sidewall of the catheter tube which has walls on opposed sides thereof to prevent invagination of tissue into the opening comprising a pair of clamping members relatively toward and away from each other, said clamping members having spaced facing surfaces for receiving a resilient tube which is at least partially collapsible, said clamping members being relatively movable toward each other to at least partially collapse the tube when placed therebetween so that a portion of the tube bulges radially outwardly of portions of the tube not partially col-lapsed, tube cutting means including a cutting element for skiv-ing material of the tube, means for effecting relative movement between the cutting element and the tube for moving said element relatively longitudinally of the tube in the plane parallel to the longitudinal axis of the tube to skive a longitudinal radi-ally outer wall portion only from the bulge to form a flat longi-tudinally extending area, said clamping members being movable relatively away from each other to allow the flat area of the tube to form a groove having sidewalls and a bottom wall, and means for forming an opening through the bottom wall of the formed groove, said clamping members having facing surfaces engageable with opposed sides of the tube to at least partially collapse the tube and effect a second bulge on the partially col-lapsed tube at a location diametrically opposite the first named bulge which extends radially outwardly beyond the radially outer surface of tube not partially collapsed, said tube cutting means including a second cutting element, and said means for moving said element including means for moving said second cutting ele-ment longitudinally of the tube to skive a radially outer longi-tudinally extending wall portion of the second bulge.

22. Apparatus for producing a resilient suction catheter having a suction opening in the sidewall of the catheter tube which has walls on opposed sides thereof to prevent invagi-nation of tissue into the opening comprising a pair of clamping members, control means for moving said clamping members rela-tively toward and away from each other, said clamping members having spaced facing surfaces for receiving a resilient tube which is at least partially collapsible, said clamping members being relatively movable toward each other to at least partially collapse the tube when placed therebetween so that a portion of the tube bulges radially outwardly of portions of the tube not partially collapsed, tube cutting means including a cutting ele-ment for skiving material of the tube, means for effecting rela-tive movement between the cutting element and the tube for moving said element relatively longitudinally of the tube in a plane parallel to the longitudinal axis of the tube to skive a longitu-dinal radially outer wall portion only from the bulge to form a flat longitudinally extending area, said clamping members being movable relatively away from each other to allow the flat area of the tube to form a groove having sidewalls and a bottom wall, and means for forming an opening through the bottom wall of the formed groove, said cutting elements being movable simultaneous longitudinally of a tube to be skived and spaced from each other to cut only the bulges of the tube.

23. A method of forming a groove in the exterior sur-face of the wall of a resilient flexible medical tube comprising the steps of applying predetermined forces to a resilient flexi-ble tube to expand a portion of the wall of the tube, skiving the expanded wall portion to remove an outer part of the wall thereof, removing the applied forces to thereby allow the expanded wall portion to return to its unexpanded condition and effect a groove having spaced opposed sidewalls and a bottom wall in the exterior surface of the wall of the tube where the outer part of the wall was removed, said step of applying forces including positioning the portion of the tube between a pair of clamping members, and moving at least one of the clamping members toward the other to compress a predetermined portion of the tube therebetween and effect at least a partial collapse of the tube lumen and a bulge with the expanded portion of the wall thereon, said skiving step including effecting relative movement between a knife and the tube so that the knife cuts the radially outer part of the wall of the expanded portion and whereby the groove has a bottom wall of less thickness than portions of the sidewall of the tube adjacent the groove, the knife cutting the outer part of the wall of the expanded portion to form an elongated section which is substantially flat in both lateral and longitudinal directions.

24. The method of making a suction catheter comprising the steps of providing a resilient flexible tube, positioning the tube between a pair of relatively moveable clamping members, effecting relative movement between at least one member and the tube to squeeze a predetermined longitudinally extending portion of the tube between the members so as to form a bulge on the tube which extend outwardly beyond the outer surface to the portions of the tube which are not squeezed, effecting relative movement between a knife and the tube so that the knife skives the outer surface of the wall of the bulge to effect an elongate groove in the outer wall of the tube having spaced opposed sidewalls and a bottom wall when the tube is released from the members, effecting relative movement of the members so as to release the tube there-from, and forming at least one opening including forming an open-ing after the skiving step and after the tube has been released from the clamping members.