A stone extraction device for hepatobiliary surgery

Abstract

The present invention relates to the field of medical devices, and particularly to a stone extraction device for hepatobiliary surgery. The technical problem of the prior art is that the existing stone extraction device has the disadvantage that the stone is likely to fall off from the lumen of the endoscope. A stone extraction device for hepatobiliary surgery includes a lumen tube, etc.; both ends of the lumen tube are divided into a head end and a tail end, and a plurality of limiting brackets are fixedly connected to the lumen tube. An extension tube is slidably connected between the plurality of limiting brackets. A plurality of inclined slots are formed in the extension tube, and a limiting mechanism is arranged on the lumen tube. The limiting mechanism is used to limit the extension tube. The slotted support rod rotates to push the perforating rod to pierce into the stone. A plurality of perforating rods pierce into the stone, so as to further limit the stone, so that the stone is adsorbed more firmly, and thus the stone is not likely to fall off when the doctor removes it subsequently.

Description

Technical Field

[0001] The present invention relates to the field of medical devices, and particularly to a stone extraction device for hepatobiliary surgery. Background Art

[0002] Solid masses formed in the catheter lumen of the human body or animal body or in the lumen of a cavity organ (such as the kidney, ureter, gallbladder or bladder, etc.), mainly seen in the gallbladder, bladder and renal pelvis, and also seen in the lumen of the pancreatic duct, salivary gland duct, etc. The stone is composed of inorganic salts or organic substances, and generally has a core in the stone, which is composed of exfoliated epithelial cells, bacterial masses, parasite eggs or worms, fecal masses or foreign bodies.

[0003] The treatment method for biliary tract stones is generally by surgery. Usually, an opening is made on the abdominal cavity of the human body, and then the stones in the biliary tract are removed by using an endoscope. During this process, the stones often collide with the inside of the liver and gallbladder when being removed through the lumen of the endoscope, causing the stones to fall off from the lumen of the endoscope. It requires the doctor to operate the endoscope multiple times to completely remove the stones, thus increasing the operation time and operation difficulty of the doctor. Summary of the Invention

[0004] In order to overcome the drawback that the existing stone extraction device has the problem that the stone is easily detached from the lumen of the endoscope, the technical problem of the present invention is: to provide a stone extraction device for hepatobiliary surgery that can more stably extract stones from the liver and gallbladder.

[0005] The technical solution is: a stone extraction device for hepatobiliary surgery, including a lumen tube. The two ends of the lumen tube are respectively a head end and a tail end. A plurality of limiting brackets are fixedly connected to the lumen tube. A telescopic tube is slidably connected between the plurality of limiting brackets. A plurality of inclined slots are opened on the telescopic tube. A limiting mechanism is arranged on the lumen tube for limiting the telescopic tube. A suction mechanism is arranged on the lumen tube for sucking the stones in the liver and gallbladder.

[0006] Furthermore, the limiting mechanism includes a rotating ring. An annular groove is formed on the inner side of the head end of the cavity tube. The rotating ring is rotatably connected to the annular groove on the head end of the cavity tube. A torsion spring is rotatably connected between the cavity tube and the rotating ring. Three fixing bolts are fixedly connected to the inner side of the head end of the cavity tube. Swing rods are rotatably connected to the three fixing bolts. A chute is formed at one end of each swing rod. Three fixed round rods are fixedly connected to the rotating ring. The fixed round rods are slidably connected to the chutes at one end of the swing rods. The other ends of the swing rods are engaged with the inclined grooves on the extension tube. An inflatable cavity is fixedly connected to the inner side of the head end of the cavity tube. The interior of the inflatable cavity is a hollow structure. The other end of the inflatable cavity is fixedly connected to the tail end of the cavity tube. The inflatable cavity is communicated with the tail end of the cavity tube. An arc-shaped push rod is slidably connected to one end of the inflatable cavity. One end of the arc-shaped push rod is fixedly connected to the rotating ring.

[0007] Furthermore, the suction mechanism includes an annular tube. The annular tube is fixedly connected to the inner side of the head end of the cavity tube. The annular tube is a hollow structure. Two suction pipes are fixedly connected to the annular tube. The annular tube is communicated with the two suction pipes. The other ends of the two suction pipes are fixedly connected to the tail end of the cavity tube. The suction pipes are communicated with the tail end of the cavity tube. A number of extension cavity seats are fixedly connected to the annular tube. The extension cavity seats are communicated with the annular tube. The end of the extension cavity seat away from the annular tube is fixedly connected to the head end of the cavity tube. The head end of the cavity tube is communicated with the extension cavity seats. A blocking support rod is slidably connected to each extension cavity seat. A fixed cam disk is fixedly connected to the rotating ring. The end of the blocking support rod away from the extension cavity seat is in contact with the fixed cam disk. A compression spring is fixedly connected between the extension cavity seat and the blocking support rod.

[0008] Furthermore, a perforating mechanism is further included. The perforating mechanism is arranged at the head end of the cavity tube. The perforating mechanism is used to limit the stones. A number of fixed support plates are fixedly connected to the inner side of the head end of the cavity tube. Grooved support rods are rotatably connected to the number of fixed support plates. Transverse grooves are formed at both ends of each grooved support rod. A number of through holes are formed in the head end of the cavity tube. Perforating rods are slidably connected to the through holes formed in the head end of the cavity tube. The perforating rods are slidably connected to the transverse grooves at one end of the grooved support rods. A fixed curved tube is fixedly connected to the blocking support rod. The fixed curved tube is slidably connected to the transverse groove at the other end of the grooved support rod.

[0009] Furthermore, it also includes an expansion mechanism, which is arranged on the extension tube and is used to intercept stones. A recessed ring is opened at one end of the extension tube, and an inflatable bag is fixedly connected to the recessed ring of the extension tube. A plurality of shaping limit rods are fixedly connected inside the recessed ring of the extension tube. An inflatable branch tube is fixedly connected inside the extension tube, and the inflatable branch tube is connected to the inflatable bag. One end of the inflatable branch tube away from the inflatable bag is fixedly connected to the tail end of the cavity tube, and the inflatable branch tube is connected to the tail end of the cavity tube.

[0010] Furthermore, the shaping limit rod is made of soft plastic material and has deformation capability.

[0011] Furthermore, the surface of the inflatable bag is coated with a smooth layer.

[0012] Beneficial effects: 1. The doctor will first insert the cavity tube into the liver and gallbladder of the body through a small incision in the body, transmit the real-time image to the display screen through the endoscope, and then use the air pump to inflate the inflatable cavity from the tail end of the cavity tube. The air filled into the inflatable cavity will push the arc-shaped push rod to move, and the movement of the arc-shaped push rod drives the rotating ring and the fixed round rod to rotate. The fixed round rod rotates along the slide groove of the swing rod to push the swing rod to rotate. The swing rod rotates and disengages from the extension tube, and the swing rod no longer jams the extension tube. Then the doctor pushes and rotates the extension tube, and the extension tube moves forward to evacuate the blocked stones, so as to facilitate better absorption of the stones later. Then continue to use the air pump to inflate the inflatable cavity, and the rotating ring continues to rotate to drive the fixed cam disk to rotate. The fixed cam disk rotates to squeeze the blocked support rod to move, and the blocked support rod no longer blocks the extension cavity seat. The doctor uses suction to absorb the stones close to the head end of the cavity tube through the suction tube, the annular tube and the extension cavity seat, so that the doctor can better remove the stones later.

[0013] 2. When the stone is adsorbed, the fixed cam plate pushes several blocking rods to move, and the blocking rod drives the fixed curved tube to move together. The fixed curved tube moves along the transverse groove at one end of the slotted rod to drive the slotted rod to rotate. Under the guidance of the through hole at the head end of the cavity tube and the transverse groove at the other end of the slotted rod, the slotted rod rotates to push the perforating rod toward the stone. Several perforating rods penetrate the stone, thereby further limiting the stone, so that the stone is adsorbed more firmly, and the stone is not easy to fall when the doctor takes it out later.

[0014] 3. After using the extension tube to disperse the stones, the doctor continues to push the extension tube forward through the stones, and then inflates the inflation branch tube. The air on the inflation branch tube extends to the inflation balloon, and the inflation balloon expands to squeeze and deform the shaping limit rod. After that, the inflation of the inflation branch tube is stopped. The inflation balloon expands to intercept the stones between the inflation balloon and the head end of the cavity tube, so as to avoid the omission of the non-adsorbed stones when the cavity tube and the extension tube are pulled out together, and then the stones can be more stably removed from the patient's liver and gallbladder. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 The first partial three-dimensional structure diagram of the present invention.

[0016] Figure 2 The second partial three-dimensional structure diagram of the present invention.

[0017] Figure 3 The sectional three-dimensional structure diagram of the present invention.

[0018] Figure 4 The sectional three-dimensional structure diagram of the limit mechanism of the present invention.

[0019] Figure 5 The sectional three-dimensional structure diagram of the extension cavity seat, the blocking support rod and the compression spring of the present invention.

[0020] Figure 6 The first partial three-dimensional structure diagram of the suction mechanism and the perforation mechanism of the present invention.

[0021] Figure 7 The sectional three-dimensional structure diagram of the inflation cavity and the arc-shaped push rod of the present invention.

[0022] Figure 8 The second partial three-dimensional structure diagram of the suction mechanism and the perforation mechanism of the present invention.

[0023] Figure 9 For the present invention Figure 8 The enlarged three-dimensional structure diagram of A in

[0024] Figure 10 The sectional three-dimensional structure diagram of the extension tube of the present invention.

[0025] Figure 11 For the present invention Figure 10 The enlarged three-dimensional structure diagram of B in

[0026] Meanings of the reference numerals in the figures: 1 - cavity tube, 2 - limiting bracket, 3 - extension tube, 41 - rotating ring, 42 - torsion spring, 43 - fixing bolt, 44 - swing rod, 45 - fixed round rod, 46 - inflatable cavity, 47 - arc-shaped push rod, 51 - annular tube, 52 - air extraction tube, 53 - extension cavity seat, 54 - blocking support rod, 55 - fixed cam disc, 56 - compression spring, 61 - fixed support plate, 62 - slotted support rod, 63 - perforated rod, 64 - fixed curved tube, 71 - air bag, 72 - shaping limiting rod, 73 - inflatable branch tube. Detailed implementation manners

[0027] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0028] Embodiment 1: A stone extraction device for hepatobiliary surgery, as Figures 1 - 8 shown, includes a cavity tube 1. The two ends of the cavity tube 1 are respectively a head end and a tail end. A plurality of limiting brackets 2 are welded on the cavity tube 1. A sliding connection is provided between the plurality of limiting brackets 2 with an extension tube 3. The extension tube 3 is used to disperse the blocked stones. A plurality of inclined slots are opened on the extension tube 3. A limiting mechanism is provided on the cavity tube 1, and the limiting mechanism is used to limit the extension tube 3. A suction mechanism is provided on the cavity tube 1, and the suction mechanism is used to suck the stones in the liver and gall.

[0029] The limiting mechanism includes a rotating ring 41. An annular groove is opened inside the head end of the cavity tube 1. The rotating ring 41 is rotatably connected to the annular groove on the head end of the cavity tube 1. A torsion spring 42 is rotatably connected between the cavity tube 1 and the rotating ring 41. Three fixing bolts 43 are welded inside the head end of the cavity tube 1. A swing rod 44 is rotatably connected to each of the three fixing bolts 43. A chute is opened at one end of each swing rod 44. The swing rod 44 is used to limit the extension tube 3. Three fixed round rods 45 are fixedly connected to the rotating ring 41. The fixed round rod 45 is slidably connected to the chute at one end of the swing rod 44. The other ends of the swing rods 44 are respectively caught in the inclined slots on the extension tube 3. An inflatable cavity 46 is welded inside the head end of the cavity tube 1. The inside of the inflatable cavity 46 is a hollow structure. The other end of the inflatable cavity 46 is welded to the tail end of the cavity tube 1. The inflatable cavity 46 is communicated with the tail end of the cavity tube 1. One end of the inflatable cavity 46 is slidably connected with an arc-shaped push rod 47. One end of the arc-shaped push rod 47 is fixedly connected to the rotating ring 41.

[0030] The suction mechanism includes an annular tube 51. The annular tube 51 is welded to the inner side of the head end of the cavity tube 1. The annular tube 51 is of a hollow structure. Two air extraction tubes 52 are welded to the annular tube 51. The annular tube 51 is in communication with the two air extraction tubes 52. The other ends of the two air extraction tubes 52 are fixedly connected to the tail end of the cavity tube 1. The air extraction tubes 52 are in communication with the tail end of the cavity tube 1. A number of extension cavity seats 53 are welded to the annular tube 51. The extension cavity seats 53 are in communication with the annular tube 51. One end of the extension cavity seat 53 away from the annular tube 51 is fixedly connected to the head end of the cavity tube 1. The head end of the cavity tube 1 is in communication with the extension cavity seat 53. A blocking support rod 54 is slidably connected to each extension cavity seat 53. A fixed cam disk 55 is fixedly connected to the rotating ring 41. One end of the blocking support rod 54 away from the extension cavity seat 53 is in contact with the fixed cam disk 55. An extrusion spring 56 is fixedly connected between the extension cavity seat 53 and the blocking support rod 54.

[0031] At first, under the action of the torsion spring 42, the rotating ring 41 pushes the fixed round rod 45. The fixed round rod 45 snaps the swing rod 44 into the inclined groove of the extension tube 3. Under the action of the extrusion spring 56, the blocking support rod 54 is in contact with the fixed cam disk 55, and the extension tube 3 is limited through the swing rod 44, so that when the cavity tube 1 enters the human body, it can drive the extension tube 3 to move together. When the doctor needs to remove the stones in the patient's liver and gallbladder, the doctor will first insert the cavity tube 1 into the liver and gallbladder of the body through a small incision in the body, transmit the real-time image to the display screen through the endoscope, and then the doctor manually pushes the cavity tube 1 to move onto the stones. When the head end of the cavity tube 1 touches the stones, the doctor uses an air pump to inflate the inflatable cavity 46 from the tail end of the cavity tube 1. The air filled into the inflatable cavity 46 will push the arc-shaped push rod 47 to move. The movement of the arc-shaped push rod 47 drives the rotating ring 41 and the fixed round rod 45 to rotate. The torsion spring 42 is compressed. The rotation of the fixed round rod 45 pushes the swing rod 44 to rotate along the chute of the swing rod 44. The swing rod 44 rotates and disengages from the extension tube 3. The swing rod 44 no longer blocks the extension tube 3. Then the doctor pushes and rotates the extension tube 3. The extension tube 3 moves forward to disperse the blocked stones, so as to better adsorb the stones subsequently. Then continue to use the air pump to inflate the inflatable cavity 46. The rotating ring 41 continues to rotate and drives the fixed cam disk 55 to rotate. The rotation of the fixed cam disk 55 squeezes the blocking support rod 54 to move. The blocking support rod 54 moves and no longer blocks the extension cavity seat 53. The doctor uses suction to adsorb the stones close to the head end of the cavity tube 1 through the air extraction tube 52, the annular tube 51 and the extension cavity seat 53, so as to facilitate the doctor to better remove the stones subsequently. Then the doctor pulls the cavity tube 1, the extension tube 3 and the stones back together and withdraws them from the small incision made in the body. Finally, the doctor turns off the air extraction pump on the air extraction tube 52. The extension cavity seat 53 no longer adsorbs the stones, and the stones fall from the head end of the cavity tube 1.

[0032] Embodiment 2: On the basis of Embodiment 1, as Figure 9 shown, it further includes a perforating mechanism. The perforating mechanism is arranged at the head end of the cavity tube 1. The perforating mechanism is used to limit the position of the stone. A plurality of fixing support plates 61 are welded inside the head end of the cavity tube 1. A plurality of slotted support rods 62 are rotatably connected to the plurality of fixing support plates 61. Transverse slots are formed at both ends of each slotted support rod 62. A plurality of through holes are formed at the head end of the cavity tube 1. Perforating rods 63 are slidably connected to the through holes at the head end of the cavity tube 1. The perforating rods 63 are slidably connected to the transverse slots at one end of the slotted support rods 62. The perforating rods 63 are used to perform puncture and limit the position of the stone. A fixed curved tube 64 is welded and connected to the blocking support rod 54. The fixed curved tube 64 is slidably connected to the transverse slot at the other end of the slotted support rod 62.

[0033] When adsorbing the stone, the fixed cam disc 55 pushes a plurality of blocking support rods 54 to move. The blocking support rods 54 drive the fixed curved tube 64 to move together. The fixed curved tube 64 moves along the transverse slot at one end of the slotted support rod 62 to drive the slotted support rod 62 to rotate. Under the guidance of the through holes at the head end of the cavity tube 1 and the action of the transverse slot at the other end of the slotted support rod 62, the slotted support rod 62 rotates to push the perforating rod 63 to pierce into the stone. A plurality of perforating rods 63 pierce into the stone, so as to further limit the position of the stone, so that the stone is adsorbed more firmly, and thus when the doctor takes it out later, the stone is not easy to fall off. After the stone is taken out, the fixed cam disc 55 resets. Under the action of the compression spring 56, the blocking support rod 54 and the fixed curved tube 64 reset together. The reset of the fixed curved tube 64 drives the slotted support rod 62 and the perforating rod 63 to reset together.

[0034] Embodiment 3: On the basis of Embodiment 2, as Figures 10 - 11 shown, it further includes a spreading mechanism. The spreading mechanism is arranged on the extension tube 3. The spreading mechanism is used to intercept the stone. A concave ring is formed at one end of the extension tube 3. An air bag 71 is fixedly connected to the concave ring of the extension tube 3. A smooth layer is coated on the surface of the air bag. The smooth layer on the surface of the air bag 71 can reduce the friction between the air bag 71 and the inner wall of the liver and gallbladder. A plurality of shaping limiting rods 72 are fixedly connected inside the concave ring of the extension tube 3. The shaping limiting rods 72 are made of soft plastic material and have the ability to deform. An air inflation branch pipe 73 is fixedly connected inside the extension tube 3. The air inflation branch pipe 73 is communicated with the air bag 71. The end of the air inflation branch pipe 73 away from the air bag 71 is fixedly connected to the tail end of the cavity tube 1. The air inflation branch pipe 73 is used to inflate the air bag 71. The air inflation branch pipe 73 is communicated with the tail end of the cavity tube 1.

[0035] After using the extension tube 3 to evacuate the calculus, the doctor continues to push the extension tube 3 forward through the calculus. When the extension tube 3 moves through the calculus to a certain position, the doctor inflates the inflation branch tube 73, and the air on the inflation branch tube 73 extends to the inflation balloon 71. The inflation balloon 71 expands and squeezes the shaping limiting rod 72 to deform. Then, the inflation of the inflation branch tube 73 is stopped. The inflation balloon 71 expands to intercept the calculus between the inflation balloon 71 and the head end of the cavity tube 1, so as to avoid the omission of the non-adsorbed calculus when the cavity tube 1 and the extension tube 3 are pulled out together, and further stably remove the calculus from the patient's liver and gallbladder. When the doctor pulls out the cavity tube 1 and the extension tube 3, the air in the inflation balloon 71 is released and the deformed shaping limiting rod 72 is bent back to a parallel shape. Then, the extension tube 3 is pulled back. When the extension tube 3 is retracted to a certain position, the swing rod 44 is reinserted into the inclined groove of the extension tube 3.

[0036] Although the embodiments of the present invention have been shown and described, for those of ordinary skill in the art, it can be understood that various changes, modifications, substitutions and variations can be made to these embodiments without departing from the principle and spirit of the present invention. The scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A stone removal device for hepatobiliary surgery, characterized in that: The invention comprises a cavity tube (1), wherein the two ends of the cavity tube (1) are divided into a head end and a tail end, the cavity tube (1) is fixedly connected to a plurality of limit brackets (2), an extension tube (3) is slidably connected between the plurality of limit brackets (2), the extension tube (3) is provided with a plurality of inclined grooves, the cavity tube (1) is provided with a limit mechanism, the limit mechanism is used to limit the extension tube (3), and the cavity tube (1) is provided with a suction mechanism, the suction mechanism is used to suck stones in the liver and gallbladder; The limiting mechanism comprises a rotating ring (41), an annular groove is formed on the inner side of the head end of the cavity tube (1), the rotating ring (41) is rotatably connected to the annular groove on the head end of the cavity tube (1), a torsion spring (42) is rotatably connected between the cavity tube (1) and the rotating ring (41), three fixing bolts (43) are fixedly connected to the inner side of the head end of the cavity tube (1), the three fixing bolts (43) are rotatably connected to swing rods (44), one end of each swing rod (44) is formed with a sliding groove, and three fixed round rods (45) are fixedly connected to the rotating ring (41), the fixed round rods (45) are ) is slidably connected to the slide groove at one end of the swing rod (44), the other end of the swing rod (44) is stuck in the inclined groove on the extension tube (3), the inner side of the head end of the cavity tube (1) is fixedly connected to an inflatable cavity (46), the interior of the inflatable cavity (46) is a hollow structure, the other end of the inflatable cavity (46) is fixedly connected to the tail end of the cavity tube (1), the inflatable cavity (46) is communicated with the tail end of the cavity tube (1), one end of the inflatable cavity (46) is slidably connected to an arc-shaped push rod (47), one end of the arc-shaped push rod (47) is fixedly connected to the rotating ring (41); The suction mechanism comprises an annular tube (51), the inner side of the head end of the cavity tube (1) is fixedly connected with the annular tube (51), the annular tube (51) is a hollow structure, two air extraction tubes (52) are fixedly connected to the annular tube (51), the annular tube (51) is communicated with the two air extraction tubes (52), the other ends of the two air extraction tubes (52) are fixedly connected to the tail end of the cavity tube (1), the air extraction tubes (52) are communicated with the tail end of the cavity tube (1), a plurality of extension cavity seats (53) are fixedly connected to the annular tube (51), the extension cavity seats (53) are communicated with the annular tube (51), and the extension cavity seats (53) are connected to the annular tube (51). One end of the extension cavity seat (53) away from the annular tube (51) is fixedly connected to the head end of the cavity tube (1), and the head end of the cavity tube (1) is communicated with the extension cavity seat (53). A blocking support rod (54) is slidably connected to each of the extension cavity seats (53). A fixed cam disk (55) is fixedly connected to the rotating ring (41). The rotating ring (41) has a plurality of protrusions. One end of the blocking support rod (54) away from the extension cavity seat (53) is in contact with the fixed cam disk (55). A compression spring (56) is fixedly connected between the extension cavity seat (53) and the blocking support rod (54).

2. A stone removal device for hepatobiliary surgery according to claim 1, characterized in that: The invention also comprises a perforating mechanism, which is arranged at the head end of the cavity tube (1) and is used for limiting the position of the stone. A plurality of fixed support plates (61) are fixedly connected to the inner side of the head end of the cavity tube (1), and a plurality of the fixed support plates (61) are rotatably connected to slotted support rods (62). Both ends of each slotted support rod (62) are provided with transverse grooves. A plurality of through holes are provided at the head end of the cavity tube (1), and a perforating rod (63) is slidably connected to the through holes provided at the head end of the cavity tube (1). The perforating rod (63) is slidably connected to the transverse groove at one end of the slotted support rod (62). A fixed curved tube (64) is fixedly connected to the blocking support rod (54), and the fixed curved tube (64) is slidably connected to the transverse groove at the other end of the slotted support rod (62).

3. The stone removal device for hepatobiliary surgery according to claim 2, characterized in that: The extension tube (3) further comprises an expansion mechanism, the expansion mechanism being arranged on the extension tube (3) and being used for intercepting stones. A recessed ring is provided at one end of the extension tube (3), an inflatable bag (71) is fixedly connected to the recessed ring of the extension tube (3), a plurality of shaping limit rods (72) are fixedly connected inside the recessed ring of the extension tube (3), an inflatable branch tube (73) is fixedly connected inside the extension tube (3), the inflatable branch tube (73) is communicated with the inflatable bag (71), one end of the inflatable branch tube (73) away from the inflatable bag (71) is fixedly connected to the tail end of the cavity tube (1), and the inflatable branch tube (73) is communicated with the tail end of the cavity tube (1).

4. A stone removal device for hepatobiliary surgery according to claim 3, characterized in that: The shaping limit rod (72) is made of soft plastic material and has deformation capability.

5. A stone removal device for hepatobiliary surgery according to claim 4, characterized in that: The surface of the inflatable bag (71) is coated with a smooth layer.

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