The placement of PEG tubes is used to allow enteral nutritional support in animals with a variety of disease conditions.1–6 Complications can develop during tube placement or the postoperative period. These include aspiration of gastric contents, hemorrhage, gastrointestinal perforation, injury of intraabdominal organs, abscess formation at the site of the PEG tube, gastric paresis, necrotizing fasciitis, and gastric outlet obstruction.1,2,5,7 One of the most clinically important complications after placement is early dislodgement of a PEG tube. This can result in septic peritonitis as a result of leakage of gastrointestinal contents into the peritoneal cavity, which is a life-threatening surgical emergency. Rates of dislodgement from 5% to 12% have been reported for dogs.1,2,5,6
After a PEG tube is placed, it acts as a temporary gastropexy to maintain the gastric serosa and parietal peritoneum in apposition until adhesions develop to form a permanent gastropexy.7 The gastropexy site is under tension owing to caudolateral retraction of the gastric wall during tube placement, and the tension may be exacerbated because of the conformation of the dog (eg, deep-chested breeds).8 Adhesion formation may require 7 to 14 days, but tension can result in displacement of the gastric wall from the PEG tube before then.9 Use of additional temporary gastropexy techniques may reduce the risk that a PEG tube gastropexy will fail prior to formation of fibrous adhesions between the gastric serosa and parietal peritoneum.
Methods involving the use of T-fastener10,11 and U-stitch12,13 techniques for temporary gastropexy have been described in the veterinary and human literature. The T-fasteners were designed for endoscopic placement of low-profile gastrostomy tubes in humans and were initially evaluated in canine cadavers but without biomechanical testing.14 Biomechanical comparison of T-fasteners with other standard surgical techniques for prophylactic gastropexy in canine cadavers has been reported.10 The T-fasteners have tensile strength equivalent to that of other techniques, and the T-fastener technique can be performed more rapidly. In another study,11 T-fasteners were used to create a temporary gastropexy in dogs with experimentally induced gastric dilatation. The authors of that study11 reported that the T-fasteners could be rapidly and effectively placed in live dogs; however, strength of the gastropexy was not assessed. To our knowledge, no studies have been conducted to evaluate the biomechanical strength of T-fasteners used concurrently with PEG tubes for gastropexy in dogs.
Because T-fasteners may not be readily available at most veterinary practices and their use could be cost prohibitive, evaluation of the U-stitch technique for temporary gastropexy12,13,15,16 is also necessary. This technique involves endoscopic guidance to percutaneously place a U-shaped, simple interrupted suture pattern through the external body wall and into the gastric lumen.15 The sutures comprise standard suture material and typically are allowed to remain in place for several days after the procedure before they are removed. Use of U-stitch gastropexy can decrease separation of the stomach from the body wall in children with gastrostomy tubes.13
The objective of the study reported here was to assess percutaneous gastropexy techniques to assist in securing PEG tubes. The primary objective was to compare biomechanical strength of PEG tube gastropexy alone with that of PEG tubes placed concurrently with 2 percutaneous gastropexy techniques (ie, T-fastener and U-stitch methods) in canine cadavers. A secondary objective was to evaluate the amount of time needed to complete each technique. The addition of the T-fastener and U-stitch techniques to standard placement of a PEG tube would be expected to increase the force required for failure of a gastropexy.
Materials and Methods
Animals
Cadavers of 18 adult dogs euthanized for reasons unrelated to the present study were obtained from local animal shelters. A power analysis was performed by use of a confidence interval of 95%, power of 80%, and 20% difference in force for clinical importance; the analysis indicated a minimum of 5 cadavers/group. Size of each group was increased to 6 cadavers to reduce the risk of a type II error. All cadavers were frozen (0°C) immediately after the dogs were euthanized. Cadavers were stored frozen for 14 to 28 days. Cadavers were thawed at room temperature (approx 23°C) for 60 hours before they were used in the study. The study was approved by the University of Florida Institutional Animal Care and Use Committee.
Experimental procedures
Six cadavers were thawed at each time for use in the experiments. Of these 6 cadavers, 2 were arbitrarily assigned to each of 3 groups (PEG tube only, T-fastener, or U-stitch). Cadavers were placed in right lateral recumbency. A template was used to mark the PEG tube, T-fastener, and U-stitch insertion sites on the skin to standardize the techniques among cadavers (Figure 1). The T-fastener and U-stitch sites were 2 cm from the tube insertion site. A triangle on the template was used for the T-fastener group. The template for the U-stitch group included two 2-cm lines that were drawn perpendicular to the last rib, with the center of each line 2 cm from the PEG tube site. A PEG tubea was placed in a standard manner.8 A clamped hemostat was used as an external flange in lieu of the outer flange provided by the manufacturer to prevent slippage that may occur during biomedical testing.
Schematic depiction of the template used to standardize gastropexy performed by use of a T-fastener (n = 6) or U-stitch (6) technique in addition to placement of a PEG tube in canine cadavers positioned in right lateral recumbency. The gray center circle indicates the point where the introducer needle was inserted for placement of the PEG tube. The ends of the lines that are tangential to the large circle designate the entrance and exit points of the suture for the U-stitch technique. Each line is 2 cm long and is aligned perpendicular to the last rib and 2 cm from the PEG tube site. Each point of the triangle indicates the location for insertion of a T-fastener 2 cm from the PEG tube site.
Citation: American Journal of Veterinary Research 80, 11; 10.2460/ajvr.80.11.1020
The duration of each procedure was recorded. Insertion of the transabdominal needle into the insufflated stomach was considered the start for timing of the procedure duration. For the PEG tube only group, the end for timing of the procedure was the moment the hemostat was clamped after the PEG tube was placed.
Gastropexy was performed with T-fasteners. After a PEG tube was placed, 3 T-fasteners with absorbable sutureb were placed in a triangular pattern around the PEG tube insertion site. At each site, the needle was advanced into the gastric lumen by use of endoscopic guidance; the T-fastener with attached suture was deployed, and the needle was withdrawn from the body. The external bolster was advanced down the suture and tightened firmly to ensure the stomach wall and abdominal wall were in close apposition. The bolster was secured. The end for timing of the procedure was when the third T-fastener was secured.
Gastropexy also was performed by use of a U-stitch method. After a PEG tube was placed, 2 U-stitches with 0 polypropylene suturec swedged on a large, curved needle were placed, as described elsewhere.12 By use of endoscopic guidance, the needle was passed percutaneously into the gastric lumen at one end of the 2-cm line; the needle was rotated and then passed back out of the body wall at the opposite end of the 2-cm line. Each U-stitch was secured externally with 2 square knots. The end for timing of the procedure was when the last suture of the second square knot was cut.
Sample collection and data analysis
After the PEG tube was placed and the gastropexy completed, the stomach wall and overlying body wall with the PEG tube were harvested for tensile strength testing. Each specimen was placed on ice until biomechanical testing was performed. All biomechanical tests on a day were performed after the last specimen was harvested on that day.
Each specimen was placed in a distraction deviced for biomechanical evaluation (Figure 2). The body wall was fitted to a distraction device that compressed the tissue between 2 flat steel plates. The stomach was clasped in a jaw-style distraction device directly above the body wall. It was believed that this orientation best represented the tissues in vivo. Tension of 1 to 2 N was placed on the gastropexy site to standardize the initial load on the tissue samples. The stomach was then distracted from the body wall at a rate of 0.5 mm/s; data were recorded at 60 Hz. Each distraction was videotaped for subsequent analysis.
Photograph of a specimen of stomach and body wall harvested from a canine cadaver and fitted to a distraction device for distention testing. The stomach is clasped in a jaw-style clamp, and each side of the body wall is secured between 2 flat steel plates.
Citation: American Journal of Veterinary Research 80, 11; 10.2460/ajvr.80.11.1020
Data obtained included time to PEG tube dislodgement and maximum force at PEG tube dislodgement (PEG tube only group), time to failure of the T-fastener and maximum force at failure of the T-fastener (T-fastener group), and time to tearing of the gastric wall and maximum force at tearing of the gastric wall (U-stitch group). Force and time of failure were determined by analysis of graphed data and video evidence (both authors separately performed the determinations). Direct comparisons among groups were performed by evaluating the force at failure.
Statistical analysis
Data (body weight, sex, duration of the procedure, and force at failure) were analyzed by use of a commercial software program.e Data for body weight were normally distributed and analyzed by use of a 1-way ANOVA; values of P < 0.05 were considered significant. Data for sex, duration of a procedure, and force at failure were not normally distributed as determined by results of a Shapiro-Wilk test; thus, nonparametric analysis was performed. A Kruskal-Wallis test was used to compare results among groups; values of P < 0.05 were considered significant. When indicated, post hoc testing was performed by use of a Mann-Whitney U test and Bonferroni correction; values of P < 0.017 were considered significant.
Results
The study population consisted of 18 cadavers (6 cadavers/group). There were 10 female dogs and 8 male dogs. Mean ± SD body weight of the 18 cadavers was 21.2 ± 5.1 kg. There was no significant difference among groups regarding sex (P = 0.809) or body weight (P = 0.394).
Each PEG tube was successfully placed, and each percutaneous gastropexy was successfully completed. Minor complications included moderate amounts of food or other material within the stomach (5 cadavers of the PEG tube only group, 4 cadavers of the T-fastener group, and 1 cadaver of the U-stitch group), slow or incomplete insufflation of the stomach (1 cadaver of the T-fastener group and 3 cadavers of the U-stitch group), and difficulty passing the transabdominal needle (1 cadaver of the U-stitch group).
Force to failure differed significantly between the PEG tube only group (median, 21.9 N; range, 17.8 to 31.5 N) and T-fastener group (median, 30.8 N; range, 23.0 to 45.0 N; P = 0.016) as well as between the PEG tube only group and the U-stitch group (median, 52.8 N; range, 30.1 to 94.5 N; P = 0.006). There was no significant (P = 0.025) difference in force to failure between the T-fastener and U-stitch groups (Figure 3).
Box-and-whisker plots of maximum force at failure for canine cadavers after insertion of a PEG tube only (PO; n = 6), insertion of a PEG tube and gastropexy with a T-fastener technique (TF; 6), and insertion of a PEG tube and gastropexy with a U-stitch technique (US; 6). Boxes represent data from the 25th to 75th percentiles, the horizontal line within each box represents the median, and whiskers represent the range. One outlier for the PO group is not shown. *Median value differs significantly (P < 0.017; Mann-Whitney U test and Bonferroni correction) from the median value for the PO group.
Citation: American Journal of Veterinary Research 80, 11; 10.2460/ajvr.80.11.1020
Duration for the procedure was significantly (P = 0.004) longer for the T-fastener (median, 359 seconds; range, 323 to 517 seconds) and U-stitch (median, 508 seconds; range, 361 to 704 seconds) groups, compared with that for the PEG tube only group (median, 247 seconds; range, 179 to 321 seconds). There was no significant (P = 0.037) difference in procedure duration between the T-fastener and U-stitch groups.
Discussion
The study reported here indicated that percutaneous gastropexy by use of the U-stitch or T-fastener technique increased the amount of force needed to cause failure of the temporary gastropexy, compared with the force to failure for placement of a PEG tube alone in canine cadavers. Hence, the U-stitch or T-fastener methods may be useful for reducing early displacement of PEG tubes in clinical patients.
In the present study, we did not detect a significant difference in force to failure between the U-stitch and T-fastener gastropexy techniques. However, we believed the difference in median force between the U-stich and T-fastener groups was clinically relevant. The moment of failure for all cadavers in the U-stitch group was defined as leakage of gastric contents around the suture site as a result of tearing of the gastric wall. None of the failures in this group were initially attributable to PEG tube dislodgement or suture breakage. Tearing of the gastric wall was considered failure because the leakage of gastric contents would likely result in clinically important peritonitis. Although the cadavers in the present study were frozen immediately after the dogs were euthanized and thawed immediately before use, it is likely that freezing and thawing of the tissues may have changed tissue strength and that autolysis of the cadavers had already begun before the procedures were performed. This likely affected integrity of the gastric wall and resulted in tearing at a lower force than would be expected in live dogs.17 In 1 study,18 investigators detected a significantly lower leak pressure in porcine jejunum that was frozen-thawed, compared with results for fresh samples, which further supports this conclusion. Because the difference between the T-fastener and U-stitch groups was large in the present study, it is likely that use of the U-stitch technique in live dogs with anatomically normal gastric walls would result in a significantly greater force at failure; however, further studies would be needed to assess this supposition. Differences in integrity of the gastric wall also likely resulted in the wide range of forces for the cadavers of the U-stitch group.
An increase in the duration of anesthesia may increase the risks of adverse events, including systemic hypotension,19 and may result in additional expense to clients. The time for placement of the PEG tube alone was significantly less than the time for placement of PEG tubes in conjunction with either of the gastropexy techniques. However, the difference was unlikely to be clinically relevant because it only required an additional 2 to 4 minutes to place the T-fasteners or U-stitch. It is also unlikely that < 5 minutes of additional anesthesia time would affect patient outcomes.
In the study reported here, the U-stitch was placed by use of a simple interrupted pattern with external rather than buried knots to best standardize the technique among cadavers. In live animals, the knots preferably would be buried by tunneling the suture subcutaneously from the exit site toward the initial suture insertion site, as described elsewhere.13 Buried knots may have several advantages, including lower risks of dermal pressure necrosis and erosion by the suture, postoperative infection, and premature removal by the dog.13 In the clinical experience of one of the authors (AEG), the increased amount of time required to bury a knot when performing the U-stitch technique would likely not be clinically important. Given the location of failure in the present study and the fact that the skin and fascia have similar holding strength, burying the knot would be anticipated to yield results similar to those reported in the present study; however, further testing would be needed to validate this assumption.
The cost of additional procedures can be a limiting factor. The T-fasteners used in the present study had a hospital cost that was approximately 4 to 6 times the cost of a packet of the standard suture. Given the greater force to failure and lower expense, the U-stitch method may be the preferred technique.
One limitation for the present study was that the forces applied to the stomach and body wall likely differed from those that would be encountered in a live animal. A distraction device was used to test tensile forces, but in a live animal, the PEG tube and gastropexy sites would likely be exposed to shearing and torsional forces as well, which were not evaluated during this study because the testing device assessed only tensile forces. Another potential limitation was the learning curve associated with performing these gastropexy techniques. Before the start of this study, the investigator performing the gastropexies had not performed the U-stitch or T-fastener techniques; however, the investigator was able to easily learn the techniques. The small sample sizes precluded statistical analysis of the differences between the first and last gastropexy performed by use of each technique, but there was no clinically important difference in the duration of the gastropexy procedures.
All cadavers in the present study were selected such that they were of similar size and conformation in an effort to minimize variability among groups. Cadavers were of medium− to large-breed dogs with predominantly a barrel-chest conformation. Giant-breed dogs, deep-chested dogs, and small− or toy-breed dogs may have different biomechanical characteristics. Torsional and shear forces may be exaggerated in larger dogs or those with deeper chests, which could result in a higher rate of dislodgement as a result of added forces. Therefore, percutaneous gastropexy may be of greater use in larger dogs or those with deeper chests. However, additional cadaveric and in vivo studies would be needed to confirm this hypothesis.
The additional suture and external bolsters associated with the T-fastener technique may put animals at an increased risk for pain, pressure necrosis, erosion, or excoriation in addition to providing an additional nidus for infection,13,20,21 although these risks are thought to be minimal. Whereas percutaneous gastropexy appears to lessen the likelihood of dislodgement of the PEG tube from the stomach and abdominal wall, it will not lower the possibility of complete PEG tube removal because the tube is not incorporated into the sutures or T-fasteners. However, should displacement occur, percutaneous gastropexy may reduce the need for emergency laparotomy because clinicians may be able to place a low-profile gastrotomy tube or Foley catheter through the stoma and maintain apposition of the gastric wall to the body wall. The use of T-fasteners to create a prophylactic gastropexy has been evaluated.22 For 4 dogs in which only T-fasteners were placed, there was no evidence of gastropexy or suture present on ultrasonographic evaluation 2 weeks after the procedure, which suggested that T-fasteners may not be reliable in the long term to maintain a gastropexy; thus, the U-stitch method may be more advisable. However, investigators of that study22 did not place a PEG tube, and the wound created by placement of a PEG tube would likely be necessary for formation of a fibrous stoma.23
In the study reported here, both the T-fastener and U-stitch percutaneous gastropexy techniques increased biomechanical strength, compared with that for placement of a PEG tube alone. In the authors’ opinion, the U-stitch technique provided superior biomechanical stability with negligible increases in cost, anesthesia time, and procedural risk. However, additional studies of live animals are needed to confirm clinical efficacy with use of each technique.
Acknowledgments
Supported by an intramural grant.
The authors declare that there were no conflicts of interest.
ABBREVIATIONS
| PEG | Percutaneous endoscopic gastrostomy |
Footnotes
Mila 20Fr PEG tube, Mila International, Erlanger, Ky.
Saf-T-Pexy T-fasteners, Kimberly-Clark Health Care, Roswell, Ga.
Prolene with XLH needle, Ethicon Inc, Somerville, NJ.
MTS 858 Mini Bionix II, MTS Systems Corp, Eden Prairie, Minn.
IBM SPSS Statistics, version 25, IBM Corp, Armonk, NY.
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