Br. J. Surg. Vol. 63 (1976) 440-445
An experimental evaluation of the types of material used for bile duct drainage tubes ACHILLES APALAKiS* SUMMARY
A comparison has been carried out of the properties of latex, silicone, red rubber and polyvinyl chloride ( P VC) T tubes draining the common bile duct in dogs. The tubes remained in the animals for 15-98 days. Bile cultures, liver function tests, cholangiograms and the histology of the common bile ducts were studied, and the changes in the physical properties of tubes implanted in the experimental animals, and of those after 1 month’s incubation in human bile, were assessed. The elasticity of the tubes was also measured and the tissue reaction around them observed. Finally, the tissue reaction following implantation in mice of tubes which had been incubated in human bile for 1 month was investigated, and compared with that when new tubes were used. Polyvinyl chloride tubes caused the least reaction in both the common bile duct and the peritoneal cavity. However, the lack of tissue tract formation around them, owing to their inertness, and their rapid development of rigidity make them unsuitable for use in biliary surgery. Red rubber tubes were found to be the most irritant. While silicone tubes proved to have desirable physical properties compared with latex tubes, they did, however, disintegrate easily with improper handling on suturing and were slow to produce a satisfactory tract, the latter fact suggesting that they would be unsuitable for short ferm biliary drainage. It appears that the latex tube is the tube of choicefor drainage periods of up to 3 months, while silicone tubes are preferable when intubation for longer periods is necessary. Red rubber tubes may be the alternative for routine short term drainage if a latex tube is not available. DRAINAGE of the common bile duct was first performed by Abbe in 1892, using a rubber catheter, and in 1904 Deaver described the T tube. The use of drainage in the biliary system, particularly for long periods, has been increasing in recent years as a result of progress in hepatobiliary surgery, and tubes of various materials have been advocated. i n clinical practice each has been shown to have advantages as well as disadvantages, and the ‘ideal’ tube remains to be found. It is the purpose of this article to describe a series of experiments undertaken to compare the properties of four of these materials: red rubber, polyvinyl chloride (PVC), latex and silicone rubbert.
Materials and methods Thirty-eight healthy dogs weighing 12-18 kg were operated on under pentobarbitone sodium anaesthesia (25mg/kg) using an aseptic technique. In all the animals a right paramedian incision was used, and 440
the common bile duct was opened longitudinally. The tube under test, sized between 6 and 12 FG according to the size of the bile duct, was inserted and the duct was closed with 4/0catgut. Ampicillin, 500 mg, was instilled into the abdominal cavity. A skin flap was raised to the right of the skin incision and the long limb of the tube was brought through a stab wound, positioned under the flap for a distance of 6-8 cm and fixed in two or three places by sutures. It was then brought to the skin surface via a separate stab wound and was connected to a bag to permit bile collection. Operative cholangiograms were obtained. After 3-4 days the tube was ligated flush with the skin, cut off and buried. In this way it was possible to observe the degree of intraperitoneal tissue reaction around it with the passage of time. This technique was used in an effort to imitate as far as possible the conditions in biliary drainage in man. Abdominal drainage was not used because of the problem of restraint of the dogs and as it was supposed that a period of 3-5 days would be adequate for a satisfactory periductal seal to be produced. When the animals were sacrificed further cholangiography was done, and specimens of the bile ducts were examined histologically. In the second part of this work portions of silicone, red rubber, latex and PVC tubes were incubated in human bile at body temperature for 30 days. The tubes were then washed with distilled water and small pieces from each type of tube were implanted into the paravertebral muscles of 4 mice, which were sacrificed after 1 month. Specimens of tissue surrounding the tubes were taken for a qualitative assessment of the resulting histological changes. A similar study of tissue reaction was performed after implantation of pieces from new tubes. Lastly, an assessment was made of the change in the elastic properties of the implanted tubes by manually comparing their stiffness with that of unused tubes. To try to confirm this subjective assessment the tube specimens were also tested mechanically using an instron tensometer. Two or three specimens of the intracholedochal portion of 20 tubes were tested after sacrifice of the animal, making a total of 50 tests. The ultimate breaking load was measured in kg, and the total elongation at rupture of a 1-cm gauge length of each tube was measured in cm. An index of elasticity, being the slope of the load/extension curve
* St George’s Hospital, London. t The latex tubes were produced by Warne Surgical Products, the silicone polymer tubes by Medical Suppliers, the polyvinyl chloride tubes by Portex and the red rubber tubes by John Bell of Croydon.
Material for bile duct drainage tubes over the initial approximately linear portion, and a proof load of 20 per cent, which it is felt would be a better measure of the change in the elastic properties of the tubes, was also calculated. The technique gave satisfactory, reproducible results with unused tubes.
Results Common bile duct drainage Thirteen dogs died, giving an overall mortality of 34.2 per cent. None of them died from biliary obstruction. The principal cause of death was, not unexpectedly, biliary peritonitis, from which 6 dogs died between the third and thirteenth postoperative days (Table I ) ; 3 with a silicone tube, 2 with PVC and 1 with a latex tube. In all cases the tube was found to be in place. Biliary peritonitis occurred primarily in the groups of dogs in which silicone and PVC had been used: 5 deaths among 22 dogs in comparison with the 1 death in the red rubber and latex groups (16 dogs). Another death was due to disintegration of a silicone tube around the silk stitch securing it. The causes of the remaining 6 deaths were considered to be irrelevant to this study. Twenty-five dogs survived until sacrificed, but in 4 the tube was not found, presumably because the animal had removed it, and in 2 dogs histological results were not obtained. Nineteen specimens were thus available for histological examination. All the tubes were well tolerated by the dogs except 2 (30P and 37s) in which a loss of weight was noticed (1 and 2 kg respectively), and in dog 37s the silicone tube was found to have slipped back into the abdominal cavity, which contained free bile. Necropsy findings Seven of the surviving dogs were sacrificed 2-3 weeks after operation, 9 at 4-6 weeks and the remaining 9 at 12-14 weeks. A skin reaction was noticed in 7 dogs; 4 with either a red rubber or latex tube, 2 with PVC and 1 with a silicone tube. A widespread peritoneal reaction was found in 2 dogs from the red rubber and latex groups. More dense and numerous adhesions were observed in animals with a red rubber tube, and the least in animals with a PVC tube. It was difficult to quantify the difference between silicone and latex tubes as both produced approximately the same intraperitoneal reaction, and well-marked tracts were observed in both groups. Five out of 6 animals with a latex tube had a good tract, while in the sixth a reasonable one was observed after 15 days. Silicone tubes produced a good (Fig. 1) and a reasonable tract after 92 and 46 days respectively, while no tract was observed after 19 days, A good tract was found in all the animals with a rubber tube. Finally, PVC tubes produced poor tracts in 2 of the 6 dogs, but only after the tubes had remained in place for 3 months. Laboratory investigations and cholangiography Bile specimens were taken from the gallbladder of 20 dogs at sacrifice, and in 18 positive cultures were obtained (90 per cent). There was no relationship between the incidence of bile infection and the histo-
Fig. 1. Good tissue tract formation around a silicone tube after 13 weeks’ implantation in a dog. Table I: OUTCOME IN 38 DOGS IN WHICH DRAINAGE OF THE COMMON BILE DUCT WAS PERFORMED Type of tube Outcome Red rubber Latex Silicone PVC Total 7 9 13 9 38 Number of dogs Number 6 6 6 7 25 surviving 3 1 4 Tube lost Histology 6 5 3 5 19 obtained in Cause of death
in 13 dogs Biliary peritonitis Tube pulled out Tube disintegrated Technical reasons Undetermined
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1
3
--
I
1
-
2 l
-
1
2
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-
_
1
-
6
3 1 1
2
logical findings. Similarly, no relationship was found between the type of the organism and the type of the tube. The commonest bacteria were Escherichia coli and faecal streptococci. Abnormal liver function tests at sacrifice were found three times (Table ZZ), and in the case of dog S37 this was due to biliary peritonitis, as has already been mentioned. Seventeen cholangiograms were obtained at sacrifice in the 25 surviving dogs; in 4 dogs the tube had been extruded and in the remaining 4 the cholangiograms were technically unsuccessful. In 4 dogs a moderate to significant proximal bile duct dilatation was shown, without evidence of obstruction. N o relationship was found between the cholangiography findings and the liver function tests or the histological findings. Dogs with PVC tubes presented minimal cholangiographic changes (Table ZZ). Histological appearances Segments from the common bile duct in 19 surviving dogs, taken just proximal and distal to the T tube, 441
Achilles Apalakis Table I1 : LIVER FUNCTION, BILE CULTURE AND CHOLANGIOGRAPHY FINDINGS Alkaline Bilirubin phosphatase G PT (IUjl) Cholangiography Dog (mg/100 ml) ( K A units/100 ml)
0.7
9
21
Severe common bile duct dilatation
R1 I
0.7
60
65
Normal
R14 R15 R27 R33
0.5
20 21
11 10 10
Minimal dilatation
R7
0.7 0.7 0.3
21 124
25
5
5
5 8 5
5 12
Y
4
30 6
8
SI 3 S3 I s37
0.8
0.6 0.9
5 12 280
P3 P4 P20
0.1 0.2 0.0
6
5
12 10
10
P26 ~ 3 0 P34
0.4 0.3 0.7
2 2 8
19
-
Proximal dilatation Normal Slight dilatation Slight dilitation Mild dilatation Proximal dilatation and some dilatation of main ducts Minimal dilatation -
Moderate dilatation Normal Slight proximal dilatation Normal Minimal dilatation
8
-
22 4
Normal Minimal dilatation
Bile culture E. coli, Proteus, faecal streptococci E. coli, faecal streptococci N o growth Staph.vlococcirs pyogenes E. coli E. coli, faecal streptococci Pseudomonos pyocyanea, streptococci Faecal streptococci E. coli E. coli
No growth Faecal streptococci Klebsiella E. coli Klebsiellu, Proteus Klebsiella E. coli, faecal st reptococci E. coli E. coli E. coli, faecal streptococci
R = Red rubber; S = silicone; L = latex; P = PVC. Normal ranges in dogs for liver function tests are: bilirubin 0.1-1.0 mg/100 ml, alkaline phosphatase 7-35 K A units/100 ml, alanine transaminase (GPT) 25-50 lU/l (Street, 1975).
were studied histologically. PVC tubes proved to be the most inert, evoking the minimal histological changes. There were no significant differences in the histological findings with silicone, latex and red rubber tubes, which produced inflammation and fibrosis in a number of animals, and no relationship was detected between these findings, the incidence of bile infection and the results of the liver function tests. From the histological observations on the muscular tissue of mice with implanted tubes it was concluded that red rubber caused the most tissue reaction, while PVC was more inert than latex or silicone (Figs. 2-5). Elasticity findings All the PVC tubes were palpably rigid and hard while the silicone tubes appeared to be unchanged both after removal from the dogs and after incubation in human bile. Two red rubber tubes after 85 and 86 days’ implantation respectively were darkened i n colour and dilated, while all those incubated in human bile were harder and darker. Two latex tubes after 86 and 98 days’ implantation were found to be dark in colour, suggesting some change in the material. While the grips holding the tube specimens for the loading tests tended to distort them, thus affecting the elasticity measurements somewhat, the results confirmed the initial tactile assessment in most of the specimens. In the case of the PVC tubes there was a marked increase in proof stress and stiffness over those 442
of the unused materials, while for the latex and silicone tubes there was no significant change in the elastic properties. The results of the measurements on the rubber tubes varied considerably, and owing to the small number of specimens available for testing no firm conclusions could be drawn (Tables 111, I V ) .
Discussion The majority of surgeons experienced in biliary surgery recommend and practise T tube drainage of the common bile duct after exploration (Maingot, 1974), and for this purpose the red rubber tube has long been employed satisfactorily. However, where a long term intubation is required, it has become apparent that red rubber tubes have a number of undesirable properties: they gradually disintegrate, are prone to become obstructed by bile (Cantor, 1964) and may act as a local irritant, producing much tissue reaction. Furthermore, Brudenell(l954) reported that red rubber supports bacterial growth, with the consequent danger of cholangitis, while its liability to perish in hot climates has been pointed out by Nunn (1954). Latex rubber has proved to have better physical properties, and in many hospitals has replaced red rubber tubes, at least for short term drainage of the common bile duct. It has long been known that the presence within the bile duct lumen of red rubber or latex tubes may produce an irritative reaction, perhaps with stricture, especially in long
Material for bile duct drainage tubes
Fig. 2. Mouse tissue reaction to a PVC implant; there is a narrow fibrous capsule with minimal tissue reaction. ( x 75.)
Fig. 4. Mouse tissue reaction to a red rubber implant; there is a wider fibrous capsule and a wide zone of granulation tissue. ( x 75.)
Fig. 3. Mouse tissue reaction to a silicone implant showing a narrow fibrous capsule and a narrow zone of granulation tissue. ( X 75.)
Fig. 5. Mouse tissue reaction to a latex implant. This is similar to that shown with PVC and silicone, but there is as more extensive inflammatory exudate between the muscle bundles. ( x 75.)
Table Ill: MEASUREMENTS OF THE BREAKING LOAD AND ELASTIC PROPERTIES OF THE TUBES IMPLANTED IN THE DOG BlLE DUCT Total extension Breaking 20% Load (kg)/ of I-cm proof load extension gauge length load Duration (cm) 0%) (kg) (cm) Assessment by inspection of study Dog (d ) I U I U I U I U of tube Swollen and darkened 6.7 8.3 1.4 1.9 8.8 R7 91 5.1 7.0 8.9 Swollen and darkened 5.6 4.8 1.1 1.5 10.8 4.4 6.6 8.8 92 R11 2.5 Unchanged 4.1 0.7 0.7 9.4 12.3 2.9 2.9 34 R14 Unchanged 2.5 5.1 1.0 0.7 9.2 12.3 34 3.6 2.9 R15 Unchanged 8.1 7.4 0.8 1.1 5.8 8.0 21 2.6 3.6 R27 Unchanged 9.5 10.0 10.0 9.8 2.0 2.1 21 7.2 6.8 R33 7.8 8.8 9.5 10.6 10.2
13.6 10.4 11.5 14.0 10.1
0.6 0.6 0.5 0.6 0.5
0.5 0.8 0.7 0.6 0.6
2.9 2.8 2.9 2.3 2.9
3.3 3.5 2.7 2.7 3.0
Change in colour Change in colour Unchanged Unchanged Unchanged
5.8
9.0 6.4 8.4
9.6 9.6 9.1
1.2 1.3 1.5
1.3 1.4 1.4
3.6 3.5 3.0
3.3 3.1 3.3
Unchanged Unchanged Unchanged
3.0 3.1 3.2 3.2 3.2 3.2
3.7 7.0 5.8 4.1 6.9 4.6
4.6 9.1 9.3
4.0 2.5 1.8 2.0 1.8 3.6
1.5 0.9
100.0
10.2 6.3 5.0 5.0
L5 L19 L22 L24 L36
86 98 34 40 36
3.5 4.6 4.3 4.3 3.0
S13 S3 I s37
92 46 19
5.5 4.0 5.3
5.4 5.4
85
5.8 4.2 3.6 3.4 4.0 5.9
P3 P4 P20 P26 P30 P34
86 17
35 37 41
5.2 5.5
4.8 4.7 2.8
10.8
9.6 4.1
1.1
0.8 1.1 1.9
66.8 39.4 53.2 37.8 133.4
5.0
9.8
Rigid and hard Rigid and hard Rigid and hard Rieid and hard Rigid and hard Rigid and hard
R = Red rubber; S = silicone; L = latex; P = PVC; I = tubes implanted in the dog bile duct; U = unused tubes.
443
Achilles Apalakis Table IV: MEASUREMENTS OF THE BREAKING LOAD AND ELASTIC PROPERTIES OF THE TUBES INCUBATED FOR 30 DAYS IN HUMAN BILE Total extension of Breaking 1-crn gauge length 20% proof Load load (kg) extension (crn) (cm) load (kg) Assessment by Tube H U H U H U H U inspection of tube material 1.2 6.4 10.4 15.3 1.6 1.2 7.4 6.3 Dark and harder R L 3.9 3.9 11.3 10.9 0.5 06 2.6 3.3 Unchanged S 5.7 6.0 9.1 10.1 1.4 1.4 3.1 3.3 Unchanged P 7.0 6.3 4.8 7.5 3.3 2.4 55.1 12.1 Riaid and hard ~
R = Red rubber; L = latex; S = silicone; P = PVC; H = tubes incubated for 30 days in human bile; U = unused tubes.
term intubation. In an effort to avoid this complica- peritoneal reaction, and only in 2 dogs did poor tion, less irritant materials, such as PVC and silicone, tracts develop around them, and then only after 3 months. Similarly, they produced the least histological have been tried clinically. While biliary peritonitis following removal of red changes within the bile duct. However, all the PVC rubber or latex tubes 7-10 days after operation is an tubes were found to be hard and rigid, with marked uncommon complication, Winstone et al. (1965) loss of elasticity. The lack of tissue reaction around reported a 4 per cent incidence of biliary peritonitis them, with consequent deficient tract formation, after they had used PVC tubes. They suggested that coupled with their rapid development of rigidity the possible causes were a lessened peritoneal reaction make them unsuitable for use in biliary surgery. Both latex and silicone tubes produced about the around the tubes, owing to their inertness, and increased rigidity of the tubes which may result in trauma same degree of intraperitoneal reaction, but tract to thc bile duct or the tract during removal. For these formation around silicone tubes was slower to develop. reasons a return to latex tubes for short term drainage This agrees with the experimental findings of Nundy has been advised (Marshall et al., 1964; Sleight, 1973). et al. (1974) but contradicts thoseof Black et al. (1971) Silicone was first employed in the biliary tract of and Kolff et al. (1975). Owing to this delay in adequate dogs by Sanislow and Zuidema (1963), and in humans tract formation silicone tubes would not appear to be by Cantor (1964). Silicone does not support bacterial suitable for short term biliary drainage. There are also growth and remains unchanged by climatic variations differences reported by different authors in the degree (Brudenell, 1954), and during the past 10 years of histological reaction within the bile duct to silicone silicone tubes have become the most serious com- tubes (Sanislow and Zuidema, 1963; Black et al., 1971 ; petitors to latex tubes for long term bile duct intuba- Kolff et al., 1975), but in the present experiments no tion. However, silicone tubes have disadvantages. significant differences were noted between silicone, They are unsuitable for short term bile duct drainage latex or red rubber tubes in this respect, there being because they do not lead to the production of a wide variations in each. This response, except in satisfactory tract in a short period, with the conse- regard to red rubber, largely corresponds to the results quent risk of bile leakage after the tube has been of the mouse tissue implant experiments, where PVC removed. Also, silicone tubes may disintegrate if proved to be the most inert, and latex and silicone they are stitched through (Cantor, 1964; Black et al., evoked a slightly greater tissue reaction. By contrast, 1971), thus creating technical problems. the red rubber implants in mice produced a marked The experimental results detailed above confirmed tissue reaction. many of these clinical beliefs. All the T tubes appeared All the silicone tubes retained their physical to function well, and of 17 cholangiograms performed, properties well and showed no changes in texture, only 2 showed significant duct dilatation, and this was colour or elasticity, and are the tubes of choice when due at least in one of them to technical reasons. long term intubation is necessary, providing no Positive bile cultures were obtained in 17 out of 19 sutures are passed through them. The non-adhesive animals (90 per cent), and this conforms with the high property of silicone (Cantor, 1964; Black et al., 1971) incidence of biliary infection reported in similar was also confirmed in our study, the sludge which was experiments by Lary and Scheibe (1 952), and clinically found in all the tubes incubated in human bile being by Keighley and Graham (1971). detached easily only from the silicone tubes. Latex While red rubber tubes produced the greatest intra- tubes showed evidence of some changes in their peritoneal inflammatory reaction, and good tracts physical properties after 3 months’ implantation in the formed around all of them, within the bile ducts they dog bile duct and should probably not be used for did not cause any more reaction than latex or silicone prolonged intubation, though being less reactive than tubes, though more than PVC tubes. In the dogs red rubber tubes are probably the tube of choice for surviving for 3 months the red rubber tubes exhibited drainage periods of up to at least 3 months, as the greatest changes in their physical properties, being judged by the dog experiments. swollen and dark in colour and showing the widest range of changes in their elasticity. The red rubber Acknowledgements specimens incubated in human bile were also dark in I wish to thank Sir Rodney Smith for suggesting this colour and more rigid. PVC tubes produced the least study and for his constant encouragement and advice. 444
Material for bile duct drainage tubes Sir Theo. Crawford kindly undertook the histological examinations, and Mr Harold Taylor gave invaluable assistance with the calculations on the physical properties of the tubes. Finally, 1 wish to express my thanks to the Bernard Sunley Foundation who financed this research, and to Professor D. Slome in whose department at the Royal College of Surgeons it was carried out.
References
c. jun., HAWK J. c. jun. and RAMBO w. M. (1971) Long-term intubation of the biliary tract with siliastic catheters. Am. Surg. 37, 198-202. BRUDENELL J. M. (1954) Letter to the Editor. Lancet 1, 517. CANTOR M. 0. (1964) Silicone rubber T-tubes for common duct drainage. Am. J. Surg. 107, 666668. DEAVER J. B. (1904) Hepatic drainage. Br. Med. J . 2, 821-825. KEIGHLEY M. R. B. and GRAHAM N. G. (1971) Infective complications of choledochotomy with T-tube drainage. Br. J. Surg. 58, 764-768. KOLFF J., HOELTGE 0 . and HERMANN R. E. (1975) SilaStiC T-tube splints for biliary repair. Am. J. Surg. 129, 236-240. BLACK H.
and SCHEIBE J. R. (1952) The effect of rubber tubing on the healing of common duct anastomosis. Surgery 32, 789-795. MAINGOT R. (1974) Abdominal Operations, Vol. I, 6th ed. London, Butterworths, p. 1024. MARSHALL R. w., MORENO 0.M. and BRODIE D. A. (1964) Chronic bile duct cannulation in the dog. J. Appl. Physiol. 19, 1191-1 192. NUNDY s., BELL G. D., COWLEY D. J. and MELROSE D. 0. (1974) Are silicone rubber T-tubes better than latex rubber tubes in the common bile duct? A Rhesus monkey model. Br. J . Surg. 61, 206208. N U N N s. F. (1954) An anaesthetist’s look at Malaya. Lancet 1, 361-363. SANISLOW c. A. jun. and ZUIDEMA G. D. (1963) The use of silicone T-tubes in reconstructive biliary surgery in dogs. J. Surg. Res. 3, 497-502. SLEIGHT M. w. (1973) Polyvinyl T-tubes in biliary surgery. Br. Med. J. 3, 171. STREET A. E. (1975) Personal communication. WINSTONE N. E., GOLBY M. G . s., LAWSON L. J. and WINDSOR c. w. 0. (1965) Biliary peritonitis: a hazard of polyvinyl chloride T-tubes. Lancet 1, 843-844. LARY B. G.
445
An experimental evaluation of the types of material used for bile duct drainage tubes ACHILLES APALAKiS* SUMMARY
A comparison has been carried out of the properties of latex, silicone, red rubber and polyvinyl chloride ( P VC) T tubes draining the common bile duct in dogs. The tubes remained in the animals for 15-98 days. Bile cultures, liver function tests, cholangiograms and the histology of the common bile ducts were studied, and the changes in the physical properties of tubes implanted in the experimental animals, and of those after 1 month’s incubation in human bile, were assessed. The elasticity of the tubes was also measured and the tissue reaction around them observed. Finally, the tissue reaction following implantation in mice of tubes which had been incubated in human bile for 1 month was investigated, and compared with that when new tubes were used. Polyvinyl chloride tubes caused the least reaction in both the common bile duct and the peritoneal cavity. However, the lack of tissue tract formation around them, owing to their inertness, and their rapid development of rigidity make them unsuitable for use in biliary surgery. Red rubber tubes were found to be the most irritant. While silicone tubes proved to have desirable physical properties compared with latex tubes, they did, however, disintegrate easily with improper handling on suturing and were slow to produce a satisfactory tract, the latter fact suggesting that they would be unsuitable for short ferm biliary drainage. It appears that the latex tube is the tube of choicefor drainage periods of up to 3 months, while silicone tubes are preferable when intubation for longer periods is necessary. Red rubber tubes may be the alternative for routine short term drainage if a latex tube is not available. DRAINAGE of the common bile duct was first performed by Abbe in 1892, using a rubber catheter, and in 1904 Deaver described the T tube. The use of drainage in the biliary system, particularly for long periods, has been increasing in recent years as a result of progress in hepatobiliary surgery, and tubes of various materials have been advocated. i n clinical practice each has been shown to have advantages as well as disadvantages, and the ‘ideal’ tube remains to be found. It is the purpose of this article to describe a series of experiments undertaken to compare the properties of four of these materials: red rubber, polyvinyl chloride (PVC), latex and silicone rubbert.
Materials and methods Thirty-eight healthy dogs weighing 12-18 kg were operated on under pentobarbitone sodium anaesthesia (25mg/kg) using an aseptic technique. In all the animals a right paramedian incision was used, and 440
the common bile duct was opened longitudinally. The tube under test, sized between 6 and 12 FG according to the size of the bile duct, was inserted and the duct was closed with 4/0catgut. Ampicillin, 500 mg, was instilled into the abdominal cavity. A skin flap was raised to the right of the skin incision and the long limb of the tube was brought through a stab wound, positioned under the flap for a distance of 6-8 cm and fixed in two or three places by sutures. It was then brought to the skin surface via a separate stab wound and was connected to a bag to permit bile collection. Operative cholangiograms were obtained. After 3-4 days the tube was ligated flush with the skin, cut off and buried. In this way it was possible to observe the degree of intraperitoneal tissue reaction around it with the passage of time. This technique was used in an effort to imitate as far as possible the conditions in biliary drainage in man. Abdominal drainage was not used because of the problem of restraint of the dogs and as it was supposed that a period of 3-5 days would be adequate for a satisfactory periductal seal to be produced. When the animals were sacrificed further cholangiography was done, and specimens of the bile ducts were examined histologically. In the second part of this work portions of silicone, red rubber, latex and PVC tubes were incubated in human bile at body temperature for 30 days. The tubes were then washed with distilled water and small pieces from each type of tube were implanted into the paravertebral muscles of 4 mice, which were sacrificed after 1 month. Specimens of tissue surrounding the tubes were taken for a qualitative assessment of the resulting histological changes. A similar study of tissue reaction was performed after implantation of pieces from new tubes. Lastly, an assessment was made of the change in the elastic properties of the implanted tubes by manually comparing their stiffness with that of unused tubes. To try to confirm this subjective assessment the tube specimens were also tested mechanically using an instron tensometer. Two or three specimens of the intracholedochal portion of 20 tubes were tested after sacrifice of the animal, making a total of 50 tests. The ultimate breaking load was measured in kg, and the total elongation at rupture of a 1-cm gauge length of each tube was measured in cm. An index of elasticity, being the slope of the load/extension curve
* St George’s Hospital, London. t The latex tubes were produced by Warne Surgical Products, the silicone polymer tubes by Medical Suppliers, the polyvinyl chloride tubes by Portex and the red rubber tubes by John Bell of Croydon.
Material for bile duct drainage tubes over the initial approximately linear portion, and a proof load of 20 per cent, which it is felt would be a better measure of the change in the elastic properties of the tubes, was also calculated. The technique gave satisfactory, reproducible results with unused tubes.
Results Common bile duct drainage Thirteen dogs died, giving an overall mortality of 34.2 per cent. None of them died from biliary obstruction. The principal cause of death was, not unexpectedly, biliary peritonitis, from which 6 dogs died between the third and thirteenth postoperative days (Table I ) ; 3 with a silicone tube, 2 with PVC and 1 with a latex tube. In all cases the tube was found to be in place. Biliary peritonitis occurred primarily in the groups of dogs in which silicone and PVC had been used: 5 deaths among 22 dogs in comparison with the 1 death in the red rubber and latex groups (16 dogs). Another death was due to disintegration of a silicone tube around the silk stitch securing it. The causes of the remaining 6 deaths were considered to be irrelevant to this study. Twenty-five dogs survived until sacrificed, but in 4 the tube was not found, presumably because the animal had removed it, and in 2 dogs histological results were not obtained. Nineteen specimens were thus available for histological examination. All the tubes were well tolerated by the dogs except 2 (30P and 37s) in which a loss of weight was noticed (1 and 2 kg respectively), and in dog 37s the silicone tube was found to have slipped back into the abdominal cavity, which contained free bile. Necropsy findings Seven of the surviving dogs were sacrificed 2-3 weeks after operation, 9 at 4-6 weeks and the remaining 9 at 12-14 weeks. A skin reaction was noticed in 7 dogs; 4 with either a red rubber or latex tube, 2 with PVC and 1 with a silicone tube. A widespread peritoneal reaction was found in 2 dogs from the red rubber and latex groups. More dense and numerous adhesions were observed in animals with a red rubber tube, and the least in animals with a PVC tube. It was difficult to quantify the difference between silicone and latex tubes as both produced approximately the same intraperitoneal reaction, and well-marked tracts were observed in both groups. Five out of 6 animals with a latex tube had a good tract, while in the sixth a reasonable one was observed after 15 days. Silicone tubes produced a good (Fig. 1) and a reasonable tract after 92 and 46 days respectively, while no tract was observed after 19 days, A good tract was found in all the animals with a rubber tube. Finally, PVC tubes produced poor tracts in 2 of the 6 dogs, but only after the tubes had remained in place for 3 months. Laboratory investigations and cholangiography Bile specimens were taken from the gallbladder of 20 dogs at sacrifice, and in 18 positive cultures were obtained (90 per cent). There was no relationship between the incidence of bile infection and the histo-
Fig. 1. Good tissue tract formation around a silicone tube after 13 weeks’ implantation in a dog. Table I: OUTCOME IN 38 DOGS IN WHICH DRAINAGE OF THE COMMON BILE DUCT WAS PERFORMED Type of tube Outcome Red rubber Latex Silicone PVC Total 7 9 13 9 38 Number of dogs Number 6 6 6 7 25 surviving 3 1 4 Tube lost Histology 6 5 3 5 19 obtained in Cause of death
in 13 dogs Biliary peritonitis Tube pulled out Tube disintegrated Technical reasons Undetermined
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1
3
--
I
1
-
2 l
-
1
2
-
-
_
1
-
6
3 1 1
2
logical findings. Similarly, no relationship was found between the type of the organism and the type of the tube. The commonest bacteria were Escherichia coli and faecal streptococci. Abnormal liver function tests at sacrifice were found three times (Table ZZ), and in the case of dog S37 this was due to biliary peritonitis, as has already been mentioned. Seventeen cholangiograms were obtained at sacrifice in the 25 surviving dogs; in 4 dogs the tube had been extruded and in the remaining 4 the cholangiograms were technically unsuccessful. In 4 dogs a moderate to significant proximal bile duct dilatation was shown, without evidence of obstruction. N o relationship was found between the cholangiography findings and the liver function tests or the histological findings. Dogs with PVC tubes presented minimal cholangiographic changes (Table ZZ). Histological appearances Segments from the common bile duct in 19 surviving dogs, taken just proximal and distal to the T tube, 441
Achilles Apalakis Table I1 : LIVER FUNCTION, BILE CULTURE AND CHOLANGIOGRAPHY FINDINGS Alkaline Bilirubin phosphatase G PT (IUjl) Cholangiography Dog (mg/100 ml) ( K A units/100 ml)
0.7
9
21
Severe common bile duct dilatation
R1 I
0.7
60
65
Normal
R14 R15 R27 R33
0.5
20 21
11 10 10
Minimal dilatation
R7
0.7 0.7 0.3
21 124
25
5
5
5 8 5
5 12
Y
4
30 6
8
SI 3 S3 I s37
0.8
0.6 0.9
5 12 280
P3 P4 P20
0.1 0.2 0.0
6
5
12 10
10
P26 ~ 3 0 P34
0.4 0.3 0.7
2 2 8
19
-
Proximal dilatation Normal Slight dilatation Slight dilitation Mild dilatation Proximal dilatation and some dilatation of main ducts Minimal dilatation -
Moderate dilatation Normal Slight proximal dilatation Normal Minimal dilatation
8
-
22 4
Normal Minimal dilatation
Bile culture E. coli, Proteus, faecal streptococci E. coli, faecal streptococci N o growth Staph.vlococcirs pyogenes E. coli E. coli, faecal streptococci Pseudomonos pyocyanea, streptococci Faecal streptococci E. coli E. coli
No growth Faecal streptococci Klebsiella E. coli Klebsiellu, Proteus Klebsiella E. coli, faecal st reptococci E. coli E. coli E. coli, faecal streptococci
R = Red rubber; S = silicone; L = latex; P = PVC. Normal ranges in dogs for liver function tests are: bilirubin 0.1-1.0 mg/100 ml, alkaline phosphatase 7-35 K A units/100 ml, alanine transaminase (GPT) 25-50 lU/l (Street, 1975).
were studied histologically. PVC tubes proved to be the most inert, evoking the minimal histological changes. There were no significant differences in the histological findings with silicone, latex and red rubber tubes, which produced inflammation and fibrosis in a number of animals, and no relationship was detected between these findings, the incidence of bile infection and the results of the liver function tests. From the histological observations on the muscular tissue of mice with implanted tubes it was concluded that red rubber caused the most tissue reaction, while PVC was more inert than latex or silicone (Figs. 2-5). Elasticity findings All the PVC tubes were palpably rigid and hard while the silicone tubes appeared to be unchanged both after removal from the dogs and after incubation in human bile. Two red rubber tubes after 85 and 86 days’ implantation respectively were darkened i n colour and dilated, while all those incubated in human bile were harder and darker. Two latex tubes after 86 and 98 days’ implantation were found to be dark in colour, suggesting some change in the material. While the grips holding the tube specimens for the loading tests tended to distort them, thus affecting the elasticity measurements somewhat, the results confirmed the initial tactile assessment in most of the specimens. In the case of the PVC tubes there was a marked increase in proof stress and stiffness over those 442
of the unused materials, while for the latex and silicone tubes there was no significant change in the elastic properties. The results of the measurements on the rubber tubes varied considerably, and owing to the small number of specimens available for testing no firm conclusions could be drawn (Tables 111, I V ) .
Discussion The majority of surgeons experienced in biliary surgery recommend and practise T tube drainage of the common bile duct after exploration (Maingot, 1974), and for this purpose the red rubber tube has long been employed satisfactorily. However, where a long term intubation is required, it has become apparent that red rubber tubes have a number of undesirable properties: they gradually disintegrate, are prone to become obstructed by bile (Cantor, 1964) and may act as a local irritant, producing much tissue reaction. Furthermore, Brudenell(l954) reported that red rubber supports bacterial growth, with the consequent danger of cholangitis, while its liability to perish in hot climates has been pointed out by Nunn (1954). Latex rubber has proved to have better physical properties, and in many hospitals has replaced red rubber tubes, at least for short term drainage of the common bile duct. It has long been known that the presence within the bile duct lumen of red rubber or latex tubes may produce an irritative reaction, perhaps with stricture, especially in long
Material for bile duct drainage tubes
Fig. 2. Mouse tissue reaction to a PVC implant; there is a narrow fibrous capsule with minimal tissue reaction. ( x 75.)
Fig. 4. Mouse tissue reaction to a red rubber implant; there is a wider fibrous capsule and a wide zone of granulation tissue. ( x 75.)
Fig. 3. Mouse tissue reaction to a silicone implant showing a narrow fibrous capsule and a narrow zone of granulation tissue. ( X 75.)
Fig. 5. Mouse tissue reaction to a latex implant. This is similar to that shown with PVC and silicone, but there is as more extensive inflammatory exudate between the muscle bundles. ( x 75.)
Table Ill: MEASUREMENTS OF THE BREAKING LOAD AND ELASTIC PROPERTIES OF THE TUBES IMPLANTED IN THE DOG BlLE DUCT Total extension Breaking 20% Load (kg)/ of I-cm proof load extension gauge length load Duration (cm) 0%) (kg) (cm) Assessment by inspection of study Dog (d ) I U I U I U I U of tube Swollen and darkened 6.7 8.3 1.4 1.9 8.8 R7 91 5.1 7.0 8.9 Swollen and darkened 5.6 4.8 1.1 1.5 10.8 4.4 6.6 8.8 92 R11 2.5 Unchanged 4.1 0.7 0.7 9.4 12.3 2.9 2.9 34 R14 Unchanged 2.5 5.1 1.0 0.7 9.2 12.3 34 3.6 2.9 R15 Unchanged 8.1 7.4 0.8 1.1 5.8 8.0 21 2.6 3.6 R27 Unchanged 9.5 10.0 10.0 9.8 2.0 2.1 21 7.2 6.8 R33 7.8 8.8 9.5 10.6 10.2
13.6 10.4 11.5 14.0 10.1
0.6 0.6 0.5 0.6 0.5
0.5 0.8 0.7 0.6 0.6
2.9 2.8 2.9 2.3 2.9
3.3 3.5 2.7 2.7 3.0
Change in colour Change in colour Unchanged Unchanged Unchanged
5.8
9.0 6.4 8.4
9.6 9.6 9.1
1.2 1.3 1.5
1.3 1.4 1.4
3.6 3.5 3.0
3.3 3.1 3.3
Unchanged Unchanged Unchanged
3.0 3.1 3.2 3.2 3.2 3.2
3.7 7.0 5.8 4.1 6.9 4.6
4.6 9.1 9.3
4.0 2.5 1.8 2.0 1.8 3.6
1.5 0.9
100.0
10.2 6.3 5.0 5.0
L5 L19 L22 L24 L36
86 98 34 40 36
3.5 4.6 4.3 4.3 3.0
S13 S3 I s37
92 46 19
5.5 4.0 5.3
5.4 5.4
85
5.8 4.2 3.6 3.4 4.0 5.9
P3 P4 P20 P26 P30 P34
86 17
35 37 41
5.2 5.5
4.8 4.7 2.8
10.8
9.6 4.1
1.1
0.8 1.1 1.9
66.8 39.4 53.2 37.8 133.4
5.0
9.8
Rigid and hard Rigid and hard Rigid and hard Rieid and hard Rigid and hard Rigid and hard
R = Red rubber; S = silicone; L = latex; P = PVC; I = tubes implanted in the dog bile duct; U = unused tubes.
443
Achilles Apalakis Table IV: MEASUREMENTS OF THE BREAKING LOAD AND ELASTIC PROPERTIES OF THE TUBES INCUBATED FOR 30 DAYS IN HUMAN BILE Total extension of Breaking 1-crn gauge length 20% proof Load load (kg) extension (crn) (cm) load (kg) Assessment by Tube H U H U H U H U inspection of tube material 1.2 6.4 10.4 15.3 1.6 1.2 7.4 6.3 Dark and harder R L 3.9 3.9 11.3 10.9 0.5 06 2.6 3.3 Unchanged S 5.7 6.0 9.1 10.1 1.4 1.4 3.1 3.3 Unchanged P 7.0 6.3 4.8 7.5 3.3 2.4 55.1 12.1 Riaid and hard ~
R = Red rubber; L = latex; S = silicone; P = PVC; H = tubes incubated for 30 days in human bile; U = unused tubes.
term intubation. In an effort to avoid this complica- peritoneal reaction, and only in 2 dogs did poor tion, less irritant materials, such as PVC and silicone, tracts develop around them, and then only after 3 months. Similarly, they produced the least histological have been tried clinically. While biliary peritonitis following removal of red changes within the bile duct. However, all the PVC rubber or latex tubes 7-10 days after operation is an tubes were found to be hard and rigid, with marked uncommon complication, Winstone et al. (1965) loss of elasticity. The lack of tissue reaction around reported a 4 per cent incidence of biliary peritonitis them, with consequent deficient tract formation, after they had used PVC tubes. They suggested that coupled with their rapid development of rigidity the possible causes were a lessened peritoneal reaction make them unsuitable for use in biliary surgery. Both latex and silicone tubes produced about the around the tubes, owing to their inertness, and increased rigidity of the tubes which may result in trauma same degree of intraperitoneal reaction, but tract to thc bile duct or the tract during removal. For these formation around silicone tubes was slower to develop. reasons a return to latex tubes for short term drainage This agrees with the experimental findings of Nundy has been advised (Marshall et al., 1964; Sleight, 1973). et al. (1974) but contradicts thoseof Black et al. (1971) Silicone was first employed in the biliary tract of and Kolff et al. (1975). Owing to this delay in adequate dogs by Sanislow and Zuidema (1963), and in humans tract formation silicone tubes would not appear to be by Cantor (1964). Silicone does not support bacterial suitable for short term biliary drainage. There are also growth and remains unchanged by climatic variations differences reported by different authors in the degree (Brudenell, 1954), and during the past 10 years of histological reaction within the bile duct to silicone silicone tubes have become the most serious com- tubes (Sanislow and Zuidema, 1963; Black et al., 1971 ; petitors to latex tubes for long term bile duct intuba- Kolff et al., 1975), but in the present experiments no tion. However, silicone tubes have disadvantages. significant differences were noted between silicone, They are unsuitable for short term bile duct drainage latex or red rubber tubes in this respect, there being because they do not lead to the production of a wide variations in each. This response, except in satisfactory tract in a short period, with the conse- regard to red rubber, largely corresponds to the results quent risk of bile leakage after the tube has been of the mouse tissue implant experiments, where PVC removed. Also, silicone tubes may disintegrate if proved to be the most inert, and latex and silicone they are stitched through (Cantor, 1964; Black et al., evoked a slightly greater tissue reaction. By contrast, 1971), thus creating technical problems. the red rubber implants in mice produced a marked The experimental results detailed above confirmed tissue reaction. many of these clinical beliefs. All the T tubes appeared All the silicone tubes retained their physical to function well, and of 17 cholangiograms performed, properties well and showed no changes in texture, only 2 showed significant duct dilatation, and this was colour or elasticity, and are the tubes of choice when due at least in one of them to technical reasons. long term intubation is necessary, providing no Positive bile cultures were obtained in 17 out of 19 sutures are passed through them. The non-adhesive animals (90 per cent), and this conforms with the high property of silicone (Cantor, 1964; Black et al., 1971) incidence of biliary infection reported in similar was also confirmed in our study, the sludge which was experiments by Lary and Scheibe (1 952), and clinically found in all the tubes incubated in human bile being by Keighley and Graham (1971). detached easily only from the silicone tubes. Latex While red rubber tubes produced the greatest intra- tubes showed evidence of some changes in their peritoneal inflammatory reaction, and good tracts physical properties after 3 months’ implantation in the formed around all of them, within the bile ducts they dog bile duct and should probably not be used for did not cause any more reaction than latex or silicone prolonged intubation, though being less reactive than tubes, though more than PVC tubes. In the dogs red rubber tubes are probably the tube of choice for surviving for 3 months the red rubber tubes exhibited drainage periods of up to at least 3 months, as the greatest changes in their physical properties, being judged by the dog experiments. swollen and dark in colour and showing the widest range of changes in their elasticity. The red rubber Acknowledgements specimens incubated in human bile were also dark in I wish to thank Sir Rodney Smith for suggesting this colour and more rigid. PVC tubes produced the least study and for his constant encouragement and advice. 444
Material for bile duct drainage tubes Sir Theo. Crawford kindly undertook the histological examinations, and Mr Harold Taylor gave invaluable assistance with the calculations on the physical properties of the tubes. Finally, 1 wish to express my thanks to the Bernard Sunley Foundation who financed this research, and to Professor D. Slome in whose department at the Royal College of Surgeons it was carried out.
References
c. jun., HAWK J. c. jun. and RAMBO w. M. (1971) Long-term intubation of the biliary tract with siliastic catheters. Am. Surg. 37, 198-202. BRUDENELL J. M. (1954) Letter to the Editor. Lancet 1, 517. CANTOR M. 0. (1964) Silicone rubber T-tubes for common duct drainage. Am. J. Surg. 107, 666668. DEAVER J. B. (1904) Hepatic drainage. Br. Med. J . 2, 821-825. KEIGHLEY M. R. B. and GRAHAM N. G. (1971) Infective complications of choledochotomy with T-tube drainage. Br. J. Surg. 58, 764-768. KOLFF J., HOELTGE 0 . and HERMANN R. E. (1975) SilaStiC T-tube splints for biliary repair. Am. J. Surg. 129, 236-240. BLACK H.
and SCHEIBE J. R. (1952) The effect of rubber tubing on the healing of common duct anastomosis. Surgery 32, 789-795. MAINGOT R. (1974) Abdominal Operations, Vol. I, 6th ed. London, Butterworths, p. 1024. MARSHALL R. w., MORENO 0.M. and BRODIE D. A. (1964) Chronic bile duct cannulation in the dog. J. Appl. Physiol. 19, 1191-1 192. NUNDY s., BELL G. D., COWLEY D. J. and MELROSE D. 0. (1974) Are silicone rubber T-tubes better than latex rubber tubes in the common bile duct? A Rhesus monkey model. Br. J . Surg. 61, 206208. N U N N s. F. (1954) An anaesthetist’s look at Malaya. Lancet 1, 361-363. SANISLOW c. A. jun. and ZUIDEMA G. D. (1963) The use of silicone T-tubes in reconstructive biliary surgery in dogs. J. Surg. Res. 3, 497-502. SLEIGHT M. w. (1973) Polyvinyl T-tubes in biliary surgery. Br. Med. J. 3, 171. STREET A. E. (1975) Personal communication. WINSTONE N. E., GOLBY M. G . s., LAWSON L. J. and WINDSOR c. w. 0. (1965) Biliary peritonitis: a hazard of polyvinyl chloride T-tubes. Lancet 1, 843-844. LARY B. G.
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