Intraluminal pressure of the small intestine of the unanesthetized dog

Effects of cyanoacrylate on leakage pressures of cooled canine cadaveric jejunal enterotomies

OBJECTIVE

To compare the intraluminal initial and maximal pressures of enterotomies closed using three different techniques (single-layer appositional continuous closure; closure with cyanoacrylate; a single-layer appositional closure augmented with cyanoacrylate) in a cooled canine cadaveric jejunal model and to report the initial leak location in all samples.

STUDY DESIGN

Experimental, ex-vivo study.

SAMPLE POPULATION

Grossly normal chilled small intestine segments from three canine cadavers.

METHODS

A total of 45 chilled jejunal segments (n = 15 segments/group) were assigned to a handsewn group (HSE), a cyanoacrylate only group (CE) and a handsewn and cyanoacrylate group (HS + CE). A 2 cm antimesenteric enterotomy was performed and closure with one of the above techniques. Initial leakage pressures (ILP), maximal intraluminal pressures (MIP) and initial leakage location were recorded by a single observer.

RESULTS

Handsewn enterotomies leaked at higher ILP when augmented with cyanoacrylate (83.3 ± 4.6 mmHg, p < .001) compared to both the HSE group (43.8 ± 5.3 mmHg) and the CE group (18.6 ± 3.5 mmHg). Those sealed with cyanoacrylate only leaked at a lower MIP compared with the other groups (p < .001). Maximal intraluminal pressures did not differ between handsewn enterotomies, whether augmented or not (p = .19).

CONCLUSION

Reinforcement of a sutured enterotomy closure with cyanoacrylate was easy to perform and resulted in significantly increased initial leak pressures in cadaveric jejunum.

CLINICAL SIGNIFICANCE

The increased leakage pressures achieved by reinforcing enterotomies with cyanoacrylate could consequently reduce the incidence of postoperative intestinal leakage following an enterotomy and may result in reduced patient morbidity or mortality.

Gastrointestinal thickness, duration, and leak pressure of five intestinal anastomosis techniques in cats

OBJECTIVE

To compare time to construct completion and resistance to leakage for five intestinal anastomosis techniques in cats and to report normal feline gastrointestinal thickness.

STUDY DESIGN

Experimental study.

SAMPLE POPULATION

Grossly normal intestinal segments (n = 120) from 10 fresh cat cadavers.

METHODS

A total of 8 cm segments of fresh feline cadaveric intestine were collected, and mural thickness was recorded. Segments were randomly allocated between a control group (n = 20 segments) and five treatment groups (20 segments/group with 2 segments/construct = 10 constructs per group): (1) hand-sewn anastomosis - simple interrupted (HSA-SI), (2) hand-sewn anastomosis - simple continuous (HSA-SC), (3) functional end-to-end stapled anastomosis (FEESA), (4) functional end-to-end stapled anastomosis with oversew (FEESA-O), (5) skin stapled anastomosis (SS). Time to construct completion, leakage location, initial leak pressure (ILP), and maximum intraluminal pressure (MIP) were compared.

RESULTS

Mean mural thickness ± SD (mm) for the stomach, duodenum, jejunum, and ileum were 1.66 ± 0.28, 2.05 ± 0.18, 2.28 ± 0.30, and 2.11 ± 0.39, respectively. ILPs (mean ± SD) for HSA-SI (165 ± 122 mmHg), HSA-SC (149 ± 83), FEESA-O (63 ± 25, FEESA (84 ± 59), SS (77 ± 56), and control segments (>500) were compared. There was no statistically significant difference in ILP (p > .08) or MIP (p > .084) between any treatment groups. Nonoversewn FEESAs were 2.4 times faster to perform compared to oversewn FEESA and SS groups, and 4.7 times faster than HSA (p < .001).

CONCLUSION

All anastomosis techniques provide resistance to leakage that is supraphysiological to that of the normal maximum intraluminal pressure. HSA take longer to complete than stapled anastomoses.

CLINICAL SIGNIFICANCE

All anastomotic techniques may be appropriate in cats. Hand-sewn anastomoses result in a longer surgical time.

Influence of barbed suture oversew of the transverse staple line during functional end-to-end stapled anastomosis in a canine jejunal enterectomy model

Objective

To evaluate the influence of barbed suture oversew of the transverse staple line during functional end‐to‐end stapled anastomosis (FEESA) in dogs.

Study design

Randomized, experimental, ex vivo.

Animals or sample population

Grossly normal jejunal segments from 14 adult canine cadavers.

Methods

Ninety‐eight jejunal segments (n = 14/FEESA group, n = 14 controls) were harvested and randomly assigned to a control group, FEESA + monofilament suture oversew, FEESA + unidirectional barbed suture oversew or FEESA + bidirectional barbed suture oversew. Oversew techniques were performed using a Cushing suture pattern. Initial (ILP) and maximum leakage pressure (MLP), repair time (s), and location of observed leakage were recorded.

Results

No differences were detected in ILP (p = .439) or MLP (p = .644) respectively between experimental groups. Repairs times using barbed suture were ~ 18% faster (~25 s faster; p < .001) compared to monofilament suture. There was no difference between barbed suture types (p = .697). Mean ILP (p < .001) and MLP (p < .0001) were 6.6x and 5.1x greater respectively in the control group. Leakage location occurred predominately at the crotch of the FEESA in all groups.

Conclusion

FEESAs closed with a transverse staple line oversew using barbed suture, regardless of barb orientation, were completed faster and resulted in similar resistance to anastomotic leakage compared to monofilament suture.

Clinical significance

Oversewing the transverse staple line following FEESA using barbed suture offers similar resistance to anastomotic leakage, and may be associated with decreased surgical times in dogs compared to monofilament suture. Further studies are necessary to determine the benefits of barbed suture use in both open and laparoscopic gastrointestinal surgical applications following FEESA in dogs.

Ex vivo comparison of different thoracoabdominal stapler sizes for typhlectomy in canine cadavers

OBJECTIVE

To determine the influence of staple size on leakage pressure of typhlectomy sites in canine cadavers.

STUDY DESIGN

Randomized, experimental cadaveric study.

ANIMALS

Twenty-four fresh canine cadavers.

METHODS

Ileocecocolic segments were exteriorized following right paracostal laparotomy after euthanasia. Cecal base length and wall thickness were measured. Each cecum was randomly assigned to 1 of 3 groups (TA 30 V3 2.5 mm, TA 60 3.5 mm, and TA 60 4.8 mm). The cecal base was stapled and the cecum was removed. A 10 cm segment including the stapled cecal excision site was tested for initial leak pressure.

RESULTS

The mean ± standard deviation body weights across the groups were 18.7 ± 6.1 kg, 16.2 ± 7.5 kg, and 14.2 ± 5.5 kg for the TA 30 V3 2.5 mm, TA 60 3.5 mm, and TA 60 4.8 mm groups, respectively (P = .48). There were no differences for mean cecal base length or wall thickness. Mean initial leak pressure (ILP) across groups was 182 ± 111 mmHg (TA 30 V3 2.5 mm), 112 ± 57 mmHg (TA 60 3.5 mm), and 77 ± 60 mmHg (TA 60 4.8 mm) (P = .78).

CONCLUSION

Each stapler size that was evaluated resulted in a mean ILP in excess of typical intraluminal pressures under normal circumstances. There were no differences among groups.

CLINICAL SIGNIFICANCE

The results of this cadaveric study support the use of any of the stapler sizes evaluated in similarly sized dogs. A prospective study is needed to be able to correlate stapler size and clinical outcome.

Influence of crotch suture augmentation on leakage pressure and leakage location during functional end-to-end stapled anastomoses in dogs

OBJECTIVE

To determine the influence of anastomotic crotch suture augmentation on leakage pressures and leakage location following intestinal functional end-to-end stapled anastomosis (FEESA) in dogs.

STUDY DESIGN

Ex vivo, randomized, experimental.

SAMPLE POPULATION

Chilled jejunal segments from 3 adult dogs.

METHODS

Jejunal specimens were tested within 24 hours of collection. A FEESA was performed and randomly assigned to 1 of 4 treatment groups (n = 12/group): (1) no crotch suture (NCS); (2) simple interrupted crotch suture (SICS); (3) two simple interrupted crotch sutures (TCS) placed laterally on opposing jejunal limbs; (4) simple continuous crotch suture (SCCS) augmentation. Crotch sutures were performed using 3-0 USP polydioxanone. Initial (ILP) and maximal (MLP) leakage pressures (Mean ± SD mm Hg) and leakage location were recorded and compared between groups.

RESULTS

Initial leakage pressure was greater after placement of TCS (37.8 ± 6.4, P < .039) and SCCS (47.6 ± 11.0, P < .002) than NCS (27.1 ± 2.5) and SICS (33.0 ± 6.0). Maximal leakage pressure was greater in specimens including SICS, TCS, and SCCS than those without crotch suture augmentation (P < .043). Leakage occurred at the anastomotic crotch in 8/12 NCS, 6/12 SICS, 11/12 TCS, and 12/12 SCCS constructs (P < .001).

CONCLUSION

Augmentation of FEESA with TCS and SCCS increased ILP and decreased the occurrence of leakage from the anastomotic crotch, while all methods of anastomotic crotch augmentation increased MLP.

CLINICAL SIGNIFICANCE

Augmenting the FEESA with crotch suture(s) improved the resistance of the jejunal anastomosis to leakage in normal cadaveric segments. Placing 2 crotch sutures or use of a simple continuous pattern for anastomotic augmentation appeared to be superior to the placement of a single suture.

Analysis of Intestinal Movements with Spatiotemporal Maps: Beyond Anatomy and Physiology

Over 150 years ago, methods for quantitative analysis of gastrointestinal motor patterns first appeared. Graphic representations of physiological variables were recorded with the kymograph after the mid-1800s. Changes in force or length of intestinal muscles could be quantified, however most recordings were limited to a single point along the digestive tract.In parallel, photography and cinematography with X-Rays visualised changes in intestinal shape, but were hard to quantify. More recently, the ability to record physiological events at many sites along the gut in combination with computer processing allowed construction of spatiotemporal maps. These included diameter maps (DMaps), constructed from video recordings of intestinal movements and pressure maps (PMaps), constructed using data from high-resolution manometry catheters. Combining different kinds of spatiotemporal maps revealed additional details about gut wall status, including compliance, which relates forces to changes in length. Plotting compliance values along the intestine enabled combined DPMaps to be constructed, which can distinguish active contractions and relaxations from passive changes. From combinations of spatiotemporal maps, it is possible to deduce the role of enteric circuits and pacemaker cells in the generation of complex motor patterns. Development and application of spatiotemporal methods to normal and abnormal motor patterns in animals and humans is ongoing, with further technical improvements arising from their combination with impedance manometry, magnetic resonance imaging, electrophysiology, and ultrasonography.

Volume of saline (0.9% NaCl) solution required to reach maximum peristaltic pressure in cadaveric intact jejunal specimens from dogs of various sizes

OBJECTIVE

To compare the volume of saline (0.9% NaCl) solution required to reach a maximum intraluminal peristaltic pressure of 25 mm Hg in dogs of various sizes.

SAMPLES

25 grossly normal jejunal segments from 6 canine cadavers < 20 kg (small dogs) and 25 segments from 5 cadavers ≥ 20 kg (large dogs).

PROCEDURES

Jejunal specimens were obtained within 1.5 hours after euthanasia. Harvested tissue was transected into 12-cm-long segments, mesentery was trimmed, and each segment was measured from the antimesenteric to mesenteric serosal edges. A 10-cm segment was isolated with Doyen forceps, securing a pressure sleeve within the lumen. Intraluminal saline was infused, and the volume was recorded when a pressure of > 25 mm Hg was achieved. Data were analyzed only from specimens in which the pressure remained between 24 and 26 mm Hg for > 5 seconds.

RESULTS

Mean ± SD intestinal measurement for large dogs (17.82 ± 1.44 mm) was greater than that for small dogs (12.38 ± 1.38 mm) as was the volume of saline solution infused (17.56 ± 7.17 mL vs 3.28 ± 1.41 mL, respectively). The volume infused increased by 1.31 mL (95% CI, 1.08 to 1.18) for every 1-mm increase in intestinal measurement and by 1.06 mL (95% CI, 1.052 to 1.068) for every 1-kg increase in body weight.

CONCLUSIONS AND CLINICAL RELEVANCE

The volume of saline solution used for intestinal leak testing should be determined on the basis of patient intestinal measurement or body weight. In vivo studies are necessary to establish the optimal volume for intestinal leak testing.

In vivo models to evaluate ingestible devices: Present status and current trends

Evaluation of orally ingestible devices is critical to optimize their performance early in development. Using animals as a pre-clinical tool can provide useful information on functionality, yet it is important to recognize that animal gastrointestinal physiology, pathophysiology and anatomy can differ to that in humans and that the most suitable species needs to be selected to inform the evaluation. There has been a move towards in vitro and in silico models rather than animal models in line with the 3Rs (Replacement, Reduction and Refinement) as well as the better control and reproducibility associated with these systems. However, there are still instances where animal models provide the greatest understanding. This paper provides an overview of key aspects of human gastrointestinal anatomy and physiology and compares parameters to those reported in animal species. The value of each species can be determined based upon the parameter of interest from the ingested device when considering the use of pre-clinical animal testing.

Influence of preconstructed effector loop location using a barbed unidirectional suture on leakage pressures following canine enterotomy closure

OBJECTIVE

To evaluate the influence of preconstructed effector loop location using a barbed unidirectional suture on leakage pressures following canine enterotomy closure.

STUDY DESIGN

Randomized, experimental, cadaveric.

ANIMALS OR SAMPLE POPULATION

Grossly normal jejunal segments from three canine cadavers.

METHODS

Jejunal segments were harvested and randomly assigned based upon effector loop location from the beginning of the incisional line. Groups (n = 12/group) included 0 mm, 5 mm, 10 mm, 15 mm, and intact controls (n = 6/group), repaired using a 3-0 unidirectional barbed suture in a simple continuous pattern. Initial leakage pressure (ILP), maximum intraluminal pressure (MIP), repair time, and leakage location were recorded.

RESULTS

Mean ILP for 0 mm group (24.42 ± 8.43 mmHg) was lower (p ≤ .001) compared to all experimental groups with ILP ~40% lower. There was no difference in MIP among experimental groups (p = .239). Repair time increased (p < .0001) as the distance of the effector loop increased ≥5 mm from the beginning of the incisional line. Leakage location differed among groups (p < .001) with leakage in the 0 mm group from the incisional line (75%), compared to leakage from predominantly from the suture holes in other groups, respectively.

CONCLUSION

Effector loop location influenced ILP and leakage location. Effector loops placed at the beginning of the incisional line (0 mm) decreased ILP compared to loops placed at 5, 10, and 15 mm.

CLINICAL SIGNIFICANCE

Effector loop location using a unidirectional barbed suture should be placed ≥5 mm from beginning of the incisional line for enterotomy closure. Further in vivo studies are necessary to determine the clinical significance of these findings.

Intraoperative surgeon probe inspection compared to leak testing for detecting gaps in canine jejunal continuous anastomoses: A cadaveric study

OBJECTIVE

To compare the detection of gaps in jejunal continuous anastomoses by probing (PT) versus leak testing (LT).

STUDY DESIGN

Experimental study.

ANIMALS

Normal jejunal segments (n = 24) from two fresh canine cadavers.

METHODS

Intestinal segments were randomly selected by four volunteers who created six simple continuous anastomoses: two constructs using standard technique with 2-3 mm suture spacing (ST, 8 total), and four constructs with one 4-mm gap (IG, 16 total). All 24 anastomoses were examined with PT (1 volunteer) prior to LT (3 volunteers). LT was performed within a maximal peristaltic pressure range (34-54 cmH₂ O). The presence and location of anastomotic leaks (L_A ) detected with LT were compared with gaps detected with PT.

RESULTS

Nineteen out of twenty-four (79.2%) samples had at least one probe drop, and four out of twenty-three (17.4%) samples leaked. LT results from one sample were excluded due to iatrogenic suture failure. PT was 100% sensitive (95% CI: 51.01, 100%) with a 100% negative predictive value (95% CI: 56.55, 100%) at detecting gaps compared with LT. The location of all L_A was accurately identified with PT and confirmed during LT.

CONCLUSION

PT was highly sensitive at detecting gaps compared with LT. All L_A were accurately detected by PT. None of the segments negative during PT leaked.

CLINICAL SIGNIFICANCE

The diagnostic value of PT appears adequate to recognize gaps in cadaveric small intestinal anastomoses. PT offers surgeons an alternative to detect suture gaps that may contribute to postoperative dehiscence of intestinal anastomoses.

Translating the seminal findings of Carl Lüderitz: A description in English of his extraordinary studies of gastrointestinal motility accompanied by a historical view of peristalsis

BACKGROUND

Carl Lüderitz provided the first comprehensive description of peristalsis in vivo in his publication from 1889 before Bayliss and Starling described the peristaltic reflex in isolated intestinal segments ex vivo 10 years later. At that time, the peristaltic reflex, responsible for progression of intestinal content, was referred to as the Lüderitz-Bayliss-Starling reflex. This shows that his peers around 1900 were very well aware of the significant impact of Lüderitz´s papers.

PURPOSE

A major intention in this review is to bring the significant contributions by Dr. Carl Lüderitz (1854-1930) to the attention of our colleagues working in the field of Gastroenterology, in particular those interested in Neurogastroenterology and Gastrointestinal Motility. Until 1891, Carl Lüderitz published five more papers on the sensory and motor components of peristalsis including one seminal paper on stimulus-evoked muscle responses in the stomach in vivo. For most of his life, Carl Lüderitz was a practicing physician and doctor for the poor in Berlin. He spent a rather short time in academia, mostly during his studies in Jena under supervision of his cousin, the famous internist Hermann Nothnagel, and later in Berlin, where he volunteered for short periods at various university institutes but without any formal appointment. This paper is to honor Carl Lüderitz. We divided it into four chapters: a short biography, a summary and evaluation of his contributions, a translation of his seminal paper on peristalsis, and finally a historical view on peristalsis.

Ex vivo comparison of leak testing of canine jejunal enterotomies: Saline infusion versus air insufflation

OBJECTIVE

To compare the ability to detect leakage of enterotomy closures by intraluminal injection of saline or air.

STUDY DESIGN

Ex vivo study.

ANIMALS

Grossly normal jejunal segments (n = 60) from five fresh canine cadavers.

METHODS

Eight-centimeter jejunal segments were randomly assigned to two control (saline control [n = 5], air control [5]) and two treatment groups (injection of saline [n = 25] or air [25] after enterotomies were closed in a simple continuous pattern using 4-0 glycomer 631). Initial leak pressure (ILP, mean ± SD), maximum intraluminal pressure (MIP), and leakage location were compared. For all air insufflation constructs, the volume of air insufflated at the time of initial leakage was recorded.

RESULTS

The ILPs of control segments did not differ whether injected with saline (405.71 ± 56.97 mmHg) or air (376.84 ± 42.54, p = 1.00). Enterotomy closures leaked at lower pressures when injected with air (ILP: 68.52 ± 6.56) compared to saline (87.76 ± 5.20, p = .03). Similar results were obtained when comparing MIPs. A moderate association (r = .51) was identified between volume of air infused and ILPs. The strength of the association improved when stratified by cadaver. The location of leakage-most commonly suture tracks-was identified for all air constructs and for 14 of 25 saline constructs.

CONCLUSION

Enterotomy closures leaked at lower pressures after intraluminal injection of air compared to saline.

CLINICAL SIGNIFICANCE

Intraoperative leak testing of small intestinal enterotomy closures may be rendered more sensitive and precise by the use of air instead of saline as the infusate.

Evaluation of intraoperative leak testing of small intestinal anastomoses performed by hand-sewn and stapled techniques in dogs: 131 cases (2008-2019)

OBJECTIVE

To compare the rate of postoperative dehiscence on the basis of intraoperative anastomotic leak test results (ie, positive or negative for leakage or testing not performed) between dogs that underwent hand-sewn anastomosis (HSA) or functional end-to-end stapled anastomosis (FEESA) of the small intestine.

ANIMALS

131 client-owned dogs that underwent 144 small intestinal anastomoses (94 FEESA and 50 HSA).

PROCEDURES

Medical records were searched to identify dogs that had undergone a small intestinal anastomosis (HSA or FEESA) from January 2008 through October 2019. Data were collected regarding signalment, indication for surgery, location of the anastomosis, surgical technique, the presence of preoperative septic peritonitis, performance of intraoperative leak testing, development of postoperative dehiscence, and duration of follow-up.

RESULTS

Intraoperative leak testing was performed during 62 of 144 (43.1%) small intestinal anastomoses, which included 26 of 94 (27.7%) FEESAs and 36 of 50 (72.0%) HSAs. Thirteen of 144 (9.0%) anastomoses underwent dehiscence after surgery (median, 4 days; range, 2 to 17 days), with subsequent septic peritonitis, including 10 of 94 (10.6%) FEESAs and 3 of 50 (6.0%) HSAs. The incidence of postoperative dehiscence was not significantly different between FEESAs and HSAs; between anastomoses that underwent intraoperative leak testing and those that did not, regardless of anastomotic technique; or between anastomoses with positive and negative leak test results. Hand-sewn anastomoses were significantly more likely to undergo leak testing than FEESAs. Preoperative septic peritonitis, use of omental or serosal reinforcement, preoperative serum albumin concentration, and surgical indication were not significantly different between anastomotic techniques.

CONCLUSIONS AND CLINICAL RELEVANCE

Performance of intraoperative anastomotic leak testing, regardless of the anastomotic technique, was not associated with a reduction in the incidence of postoperative anastomotic dehiscence.

Swine Small Intestine Sealing Performed by Different Vessel Sealing Devices: Ex-Vivo Test

This study aimed to evaluate the sealing quality of swine small intestine using different laparoscopic radiofrequency vessel sealing devices (two 5 mm: RFVS-1 and -2; one 10 mm: RFVS-3) and a harmonic scalpel (HS) compared to golden standard closure technique. The study was divided into two arms. In study arm 1: n = 50 swine intestinal loops (10 per group) were transected with each instrument and the loops in which the devices provided complete sealing, at the gross inspection, were tested for maximum burst pressure (BP) and histological evaluation and compared to an automatic linear stapler. After the BP tests, the devices that achieved significantly lower BP values were excluded from the second arm. The RFVS-1 and -3 provided statistically significant results and were used in study arm 2, to obtain full-thickness biopsies along the antimesenteric border of the loop and were compared with hand-sewn intestinal closure (n = 30; 10 per group). The biopsies were histologically evaluated for thermal injury and diagnostic features, and intestinal loops tested for BP. RFVS-3 achieved comparable results (69.78 ± 4.23 mmHg, interquartile range (IQR) 5.8) to stapler closing technique (71.09 ± 4.22 mmHg, IQR 4.38; p > 0.05), while the RFVS-1 resulted in significantly (p < 0.05) lower BP (45.28 ± 15.23 mmHg, IQR 24.95) but over the physiological range, conversely to RFVS-2 (20.16 ± 7.19 mmHg, IQR 12.02) and HS (not measurable). RFVS-3 resulted not significantly different (p > 0.05) (45.09 ± 8.75 mmHg, IQR 10.48) than Suture (35.71 ± 17.51 mmHg, IQR 23.77); RFVS-1 resulted significantly lower values (23.96 ± 10.63 mmHg, IQR 9.62; p < 0.05). All biopsies were judged diagnostic. Data confirmed that RFVS-1 and -3 devices provided suitable intestinal sealing, with BP pressures over the physiological range. Conversely, the HS and RFVS-2 should not be considered for intestinal sealing. RFVS devices could be employed to obtain small intestine stump closure or full-thickness biopsies. However, further studies should be performed in live animals to assess the role of the healing process.

Comparison of a simple continuous versus simple interrupted suture pattern for the repair of a large, open duodenal defect with a jejunal serosal patch in a canine cadaveric model

OBJECTIVE

To determine whether jejunal serosal patches could securely seal large, open defects in duodenal segments harvested from canine cadavers and to compare intraluminal pressures at which leakage first occurred and maximal intraluminal pressures for repaired duodenal segments between 2 suture patterns.

SAMPLE

Duodenal and jejunal segments from 9 canine cadavers.

PROCEDURES

20 constructs were created through repair of large, open duodenal defects with circumferential suturing of an intact jejunal segment (jejunal serosal patch). Constructs were randomly assigned to have the serosal patch anastomosed to the duodenal segment by a simple continuous or simple interrupted suture pattern. The pressure at which the first leakage was observed and the maximum pressure obtained during testing were recorded and compared between suture patterns.

RESULTS

Initial leakage pressure was significantly higher with the simple interrupted pattern (mean ± SD, 68.89 ± 5.62 mm Hg), compared with the simple continuous pattern (59.8 ± 20.03 mm Hg). Maximum intraluminal pressures did not significantly differ between the simple interrupted (91 ± 8.27 mm Hg) and simple continuous patterns (90.7 ± 16.91 mm Hg). All constructs, regardless of suture pattern, withstood supraphysiologic pressures.

CONCLUSIONS AND CLINICAL RELEVANCE

Jejunal serosal patches adequately sealed large, open duodenal defects and prevented leakage in these constructs. Constructs with simple continuous or simple interrupted suture patterns withstood physiologic and supraphysiologic intraluminal pressures, although constructs with a simple interrupted suture pattern initially leaked at higher pressures. (Am J Vet Res 2020;81:985-991).

Comparison of intestinal leak pressure between cadaveric canine and commercial synthetic intestinal tissue that did and did not undergo enterotomy

OBJECTIVE

To compare initial leak pressure (ILP) between cadaveric canine and synthetic small intestinal segments that did and did not undergo enterotomy.

SAMPLE

Eight 8-cm grossly normal jejunal segments from 1 canine cadaver and eight 8-cm synthetic small intestinal segments.

PROCEDURES

Intestinal segments were randomly assigned to undergo enterotomy (6 cadaveric and 6 synthetic segments) or serve as untreated controls (2 cadaveric and 2 synthetic segments). For segments designated for enterotomy, a 2-cm full-thickness incision was created along the antimesenteric border. The incision was closed in a single layer with 4-0 suture in a simple continuous pattern. Leak testing was performed with intestinal segments occluded at both ends and infused with dilute dye solution (999 mL/h) until the solution was observed leaking from the suture line or serosal tearing occurred. Intraluminal pressure was continuously monitored. The ILP at construct failure was compared between cadaveric and synthetic control segments and between cadaveric and synthetic enterotomy segments.

RESULTS

Mean ± SD ILP did not differ significantly between cadaveric (345.11 ± 2.15 mm Hg) and synthetic (329.04 ± 24.69 mm Hg) control segments but was significantly greater for cadaveric enterotomy segments (60.77 ± 15.81 mm Hg), compared with synthetic enterotomy segments (15.03 ± 6.41 mm Hg).

CONCLUSIONS AND CLINICAL RELEVANCE

Leak testing should not be used to assess the accuracy or security of enterotomy suture lines in synthetic intestinal tissue. Synthetic intestinal tissue is best used for students to gain confidence and proficiency in performing enterotomies before performing the procedure on live animals.

Gastrointestinal thickness, duration, and leak pressure of six intestinal anastomoses in dogs

OBJECTIVE

To compare leak pressures and construct completion time of six intestinal anastomoses and report normal canine gastrointestinal thickness.

STUDY DESIGN

Experimental study.

ANIMALS

Grossly normal jejunal segments (n = 140) from 10 fresh canine cadavers.

METHODS

Gastrointestinal thickness was recorded. Eight-centimeter cooled canine cadaveric jejunal segments were randomly assigned to a control group (20 segments) and six treatment groups (20 segments/group [10 constructs/group]): (1) handsewn anastomosis (HSA), (2) functional end-to-end stapled anastomosis (FEESA)-blue thoracoabdominal (TA; FEESA-TAB), (3) FEESA-green TA (FEESA-TAG), (4) FEESA TA-gastrointestinal anastomosis (GIA), (5) FEESA with suture oversew (FEESA-O), and (6) skin staples (SS). Construct assembly time, initial leak pressure (ILP), maximum intraluminal pressure (MIP), and leakage location were compared.

RESULTS

Initial leak pressures (mean ± SD) for control (308.38 ± 115.91 mm Hg), HSA (41.96 ± 15.97), FEESA-TAB (31.71 ± 15.71), FEESA-TAG (27.24 ± 14.11), FEESA-GIA (25.62 ± 11.22), FEESA-O (31.01 ± 17.38), and SS (44.42 ± 28.88) groups were compared. No difference in ILP (P > .24) or MIP (P > .17) was detected between treatment groups. Sutured anastomoses took up to 10 times longer to complete (P = .0025). The stomach, duodenum, jejunum, and ileum mural thicknesses (mean ± SD) were 3.99 ± 0.44 mm, 2.34 ± 0.16, 2.49 ± 0.28, and 2.30 ± 0.31, respectively.

CONCLUSION

The ILP of all anastomoses exceeded maximum intraluminal peristaltic pressures. Stapled anastomoses were faster to complete.

CLINICAL SIGNIFICANCE

All anastomoses may be considered when performing an intestinal resection and anastomosis, with stapled anastomoses resulting in a shorter surgical time. Canine intestinal thickness may warrant use of a larger staple size.

Effect of presurgical storage conditions on leakage pressures of enterotomy sites closed with unidirectional barbed suture material in fresh, chilled, and frozen-thawed cadaveric canine jejunal specimens

OBJECTIVE

To evaluate the effect of presurgical storage conditions on leakage pressures of enterotomy sites closed with unidirectional barbed suture material in fresh, chilled, and frozen-thawed cadaveric canine jejunal specimens.

SAMPLE

36 grossly normal jejunal segments obtained from 4 dog cadavers.

PROCEDURES

9 jejunal segments were harvested immediately from each euthanized dog and randomly assigned to be tested within 4 hours after collection (fresh segments), stored at 4°C for 24 hours before testing (chilled segments), or stored at -20°C for 7 days and thawed at 21°C for 6 hours before testing (frozen-thawed segments). For leakage pressure testing, a 3-cm-long antimesenteric enterotomy was performed and repaired with 3-0 unidirectional barbed suture material in a simple continuous pattern in each segment. Time to complete the enterotomy, initial leakage pressure, maximum intraluminal pressure, and leakage location were recorded for each segment.

RESULTS

Mean ± SD initial leakage pressure for fresh, chilled, and frozen-thawed segments was 52.8 ± 14.9 mm Hg, 51.8 ± 11.9 mm Hg, and 33.3 ± 7.7 mm Hg, respectively. Frozen-thawed segments had significantly lower mean initial leakage pressure, compared with findings for fresh or chilled segments. Time to complete the enterotomy, maximum intraluminal pressure, and leakage location did not differ among groups.

CONCLUSIONS AND CLINICAL RELEVANCE

Leak pressure testing of cadaveric jejunal segments that are fresh or chilled at 4°C for 24 hours is recommended for enterotomy studies involving barbed suture material in dogs. Freezing and thawing of cadaveric jejunal tissues prior to investigative use is not recommended because leak pressure data may be falsely low.

Influence of oversewing the transverse staple line during functional end-to-end stapled intestinal anastomoses in dogs

OBJECTIVE

To determine the effect of oversewing the transverse staple line after functional end-to-end stapled intestinal anastomoses (FEESA) on canine jejunal leakage pressures.

STUDY DESIGN

Experimental, ex vivo, randomized study.

SAMPLE POPULATION

Jejunal segments from three adult canine cadavers.

METHODS

Jejunal segments were harvested within 2 hours of euthanasia and anastomosed (24 jejunal segments per group, consisting of two segments per construct with n = 12/ group). Constructs were then randomly assigned to receive FEESA alone, FEESA + Cushing oversew, or FEESA + simple-continuous oversew of the transverse staple line with 3-0 polydioxanone. Results for initial leakage pressure (ILP) and maximal leakage pressure (MLP) and initial leakage location (LL) were compared between groups.

RESULTS

Mean ILP was 1.8-fold higher for FEESA + Cushing oversew (62.4 ± 7.8 mm Hg) compared with FEESA alone and FEESA + simple-continuous oversew (P < .001). Mean MLP were higher for both oversewn techniques compared with FEESA alone (P < .001). Oversewing the transverse staple line with either pattern increased mean MLP by 1.4-fold compared with FEESA alone. Leakage occurred at the level of the transverse staple line in nonoversewn constructs (P < .001).

CONCLUSION

Oversewing the transverse staple line after FEESA increased MLP and decreased the occurrence of leakage at this location. Oversewing with a Cushing pattern increased ILP compared with oversew with a simple-continuous pattern.

CLINICAL SIGNIFICANCE

Our results provide evidence to support oversewing the transverse staple line after FEESA. Doing so may reduce the occurrence of postoperative dehiscence. These findings warrant additional focused investigation in vivo through a prospective randomized clinical trial.

The Pathophysiology of Small Intestinal Foreign Body Obstruction and Intraoperative Assessment of Tissue Viability in Dogs: A Review

Small intestinal foreign body obstructions occur commonly in dogs, accounting for 80% of all canine intestinal obstructions. Such obstructions induce local aberrations in secretion, absorption, and intestinal motility that can precipitate devastating systemic consequences, including a systemic inflammatory response, sepsis, and multiorgan dysfunction. Radiographic diagnosis is poorly sensitive relative to ultrasonography for diagnosing the presence of obstructive foreign material. Emergent surgical intervention is indicated for dogs with obstructive foreign material due to an inability to assess the degree of compromise of the intestinal wall that may precipitate intestinal perforation and to mitigate progression of life-threatening electrolyte and acid-base imbalances secondary to sequestration and emesis. Intraoperatively, an enterotomy or resection and anastomosis may be required to remove the obstructive material. A number of subjective and objective techniques for assessing the viability of intestinal tissue have been described due to the poor accuracy associated with surgeon assessment of color, peristalsis, pulsation, bleeding, and mural thickness alone. Such techniques have the potential to alter the surgeon's decision-making regarding performance of an enterotomy or resection and anastomosis, potentially reducing morbidity associated with intestinal surgery.

Ex vivo comparison of leakage pressures and leakage location with a novel technique for creation of functional side-to-side canine small intestinal anastomoses

OBJECTIVE

To determine the ability of functional side-to-side small intestinal anastomoses (FSS-SIA) created with an electrothermal bipolar vessel sealing (EBVS) device to resist leakage.

STUDY DESIGN

Experimental, ex vivo.

SAMPLE POPULATION

Jejunal segments (n = 130) from 10 healthy canine cadavers.

METHODS

Four types of anastomoses were created (two segments/construct and 15 constructs/group): EBVS (group A), EBVS + transverse stapling (group B), stapled (group C), and EBVS + suture augmentation (group D). Initial leakage pressure (ILP), initial leakage location (ILL), and maximal intraluminal pressure were compared between groups, and five group A constructs were analyzed histologically.

RESULTS

Initial leakage pressure was greater in group D than in groups A, B, and C (P < .011). There was a difference in ILL among groups (P = .003). Leakage occurred at the side-to-side intestinal anastomosis fusion line in 13 of 15 (87%) constructs for groups A and B and in nine of 15 (60%) constructs for group D. Maximal intraluminal pressure was greater in group C than in groups A, B, and D (P < .004). Histological examination was consistent with collagenous fusion without cavitation defects.

CONCLUSION

Functional side-to-side small intestinal anastomosis was consistently achieved with an EBVS device. Augmentation of EBVS anastomoses with simple interrupted sutures along the anastomotic fusion line increased ILP compared with stapled anastomoses.

CLINICAL SIGNIFICANCE

Despite the success and feasibility of creating an FSS-SIA with an EBVS device, additional in vivo studies are required to determine the effectiveness of intestinal fusion prior to clinical implementation.

Influence of closure technique on leakage pressures in an ex vivo canine typhlectomy model

OBJECTIVE

To determine the influence of three closure techniques on leakage pressures of canine typhlectomies.

STUDY DESIGN

Experimental, ex vivo.

SAMPLE POPULATION

Grossly normal cecal segments from 24 adult canine cadavers.

METHODS

Typhlectomies were assigned to one of three closure techniques: simple continuous closure with a Parker-Kerr pattern with 4-0 polydioxanone (group 1), closure with a 60-mm gastrointestinal stapler loaded with a 3.8-mm staple cartridge (group 2), and placement of a Cushing suture to augment the stapled closure (group 3). The median (range) of initial leakage pressure (ILP) and maximum leakage pressure (MLP) was compared between groups along with leakage location.

RESULTS

Typhlectomies in group 3 leaked at higher ILP (310 mm Hg; 188-310) than those in groups 1 (43 mm Hg; 31-80) and 2 (109.5 mm Hg; 68-173; P < .0001). Maximum leakage pressure were greater in group 3 than in other groups (P < .0001). Leakage was detected in 20 of 24 (83%) typhlectomies, located at the incisional line in 13 of 24 (54%) specimens and from suture holes in seven of 24 (29%) specimens.

CONCLUSION

Placement of a Cushing suture pattern to augment stapled incisions improved the ability of typhlectomies to sustain pressure compared with sutured or stapled cadaveric specimens alone.

CLINICAL SIGNIFICANCE

These results provide evidence to support placement of a Cushing suture pattern to augment the staple line for typhlectomies in dogs, although in vivo studies are required to determine the clinical significance of these findings.

Initial leak pressures of four anastomosis techniques in cooled cadaveric canine jejunum

OBJECTIVE

To compare the effectiveness of four different intestinal anastomosis techniques at preventing leakage after enterectomy.

STUDY DESIGN

Experimental study.

SAMPLE POPULATION

Grossly normal jejunal segments (N = 70) from three fresh canine cadavers.

METHODS

Eight-centimeter cooled canine cadaveric jejunal segments were randomly assigned to a control group (six segments) and four treatment groups (16 segments each [two segments/anastomotic construct]): (1) handsewn anastomosis (HSA), (2) barbed suture anastomosis (B-HSA), (3) stapled functional end-to-end anastomosis (SFEEA), and (4) stapled functional end-to-end anastomosis with an oversew (SFEEA-O). Control segments and anastomotic constructs were infused intraluminally to the point of leakage. Initial leak pressures were recorded and compared.

RESULTS

Initial leak pressures (median + range) for jejunal control segments, HSA, B-HSA, SFEEA, and SFEEA-O were 331.88 mmHg (range, 315.34-346.64), 35.17 (20.29-56.24), 24.99 (6.08-38.64), 28.77 (18.80-85.09), and 35.92 (12.05-80.71), respectively. No difference was detected between leak pressures of anastomosed segments (P = .35), all of which were more variable and lower than those of intact segments.

CONCLUSION

No difference in initial leak pressures was detected between the four anastomosis techniques tested in cooled canine cadaveric jejunum.

CLINICAL SIGNIFICANCE

All four anastomosis techniques evaluated in this study may be suitable in dogs.

Ex vivo comparison of the effect of storage temperature on canine intestinal leakage pressures

OBJECTIVE

To determine the effect of storage temperature on cadaveric small intestinal leakage pressures after enterotomy.

STUDY DESIGN

Experimental ex vivo study.

ANIMALS

Grossly normal jejunal segments from four canine cadavers.

METHODS

Thirty-six jejunal segments (n = 12 segments/group) were harvested immediately after euthanasia and assigned to a fresh group (tested within 4 hours), chilled group (stored for 24 hours at 4°C before testing), or freeze-thaw group (frozen at -20°C for 7 days and thawed at 21°C for 6 hours before testing). A 2-cm antimesenteric enterotomy was performed and repaired with 4-0 monofilament suture in a simple-continuous pattern. Initial leakage pressure (ILP), maximal intraluminal pressure (MIP), and leakage location were recorded, with testing performed at room temperature.

RESULTS

Mean ± SD ILP for fresh, chilled, and frozen-thawed specimens was 52.9 ± 8.4, 51.8 ± 11.9 and 29.8 ± 4.4 mm Hg, respectively. There was a difference in ILP among groups (P < .003), with freeze-thaw samples demonstrating lower ILP compared with other groups. There was no difference in MIP between groups (P = .186) There was a difference in leakage location among groups (P = .004), with the majority of chilled and freeze-thaw samples leaking at the suture holes compared with the incisional line in fresh samples.

CONCLUSION

Freezing and subsequent thawing prior to specimen testing reduced ILP compared with use of fresh and chilled specimens but did not affect MIP among experimental groups.

CLINICAL SIGNIFICANCE

Cadaveric canine intestinal specimens tested immediately after collection or after chilling for 24 hours should be recommended for ex vivo burst pressure assessment in dogs. Additional studies to evaluate loss in testing viability of chilled intestinal specimens are warranted to help govern experimental methodologies.

A Comparison of Ex Vivo Leak Pressures for Four Enterotomy Closures in a Canine Model

Initial and maximum intraluminal leak pressures of four enterotomy closures were compared. Closure patterns included a modified Gambee, simple interrupted, simple continuous, and skin staple closure. Forty-eight 3-cm enterotomy constructs were created from jejunal segments harvested from 12 dogs. Twelve each were randomly assigned to the four closure methods. Time of closure, as well as initial and maximum leak pressures, were measured and compared. The modified Gambee closure was the slowest closure to perform, with skin staple closure being the fastest. All suture patterns tested had higher mean initial leak pressures than reported physiologic intestinal pressures during peristalsis, although the skin staple closures resulted in leakage below normal physiologic pressure in several samples. The modified Gambee closure was able to sustain a significantly higher initial leak pressure than skin staple closures. The modified Gambee suture pattern had the greatest maximum leak pressure of all enterotomy closure patterns tested. Use of the modified Gambee suture pattern should be considered in enterotomy closure, although in vivo studies are required to determine if these differences are clinically significant.

Controlled temperature tissue fusion: argon laser welding of canine intestine in vitro

BACKGROUND AND OBJECTIVE

Thermal denaturation of proteins is recognized as a rate process governed by the local temperature-time response and is believed to be the principal mechanism for photothermal tissue welding. Since rate processes are exponential with temperature, feedback control of tissue surface temperature is hypothesized to create a quasi-constant rate of denaturation that will enhance the tissue welding process.

STUDY DESIGN, MATERIALS AND METHODS

Controlled temperature tissue welding of severed edges of fresh canine jejunum was performed in vitro by remote sensing of tissue surface temperature with an infrared sensor. A hardware controlled temperature feedback system opened and closed a shutter located in the beam path of an argon ion laser to provide constant temperature welding.

RESULTS

Strong tissue fusion was not possible at or below a surface temperature of 70 degrees C, but was accomplished at 80 degrees, 90 degrees, and 95 degrees, and 100 degrees C. Fusion was achieved with thermal coagulation of the collagenous submucosa and mucosal tissues. The bursting strength of welds created at 90 degrees C and 95 degrees C were significantly stronger than those performed at 80 degrees C.

CONCLUSION

Laser-assisted intestinal anastomoses created in vitro are optimally strong at 90-95 degrees C feedback control temperatures.

Enterotomy fusion with laser energy: preliminary results in rabbit ileum

The utility of enterotomy closure with the argon and CO2 lasers was examined in New Zealand white rabbit ileum. Thermal properties of 10 argon (0.5 W power for 30 s, energy fluence 230 J/cm2) and 10 CO2 (1.0 W power for 30 s, energy fluence 2700 J/cm2) laser-fused enterotomies were determined during acute fusion experiments using an AGA 782 digital thermographic camera. Healing of the fusions created by the two lasers was subsequently assessed in an additional group of 28 rabbits by comparing three 1.0-cm longitudinal ileal enterotomies, with each rabbit having both types of laser-welded closures and a sutured control. Thermal measurements made from the 10 closures with each laser revealed that the CO2 fusions generated significantly higher temperatures (max. 198 degrees C, mean 106 +/- 37 degrees C, n = 100) than argon (max. 85.2 degrees C, mean 60.5 + 8.1 degrees C, n = 100) p less than 0.001. In the healing studies, four rabbits died from weld failures (one argon and one CO2 disruption, two rabbits with both welds disrupted). Two additional rabbits died at 1 day and one at 10 days for undetermined reasons. The remainder of the animals were sacrificed at 1 (n = 11), 2 (n = 2) and 4 (n = 9) weeks postoperatively. Sutured closures exhibited more granulation tissue and adhesions surrounding the wounds than did welded closures and seven microabscesses were noted adjacent to sutured repairs. One of the CO2 repairs had an abscess at 4 weeks and none of the argon laser fusions had evidence of disruption or abscess.(ABSTRACT TRUNCATED AT 250 WORDS)

Laser-assisted intestinal anastomosis

Laser-assisted tissue fusion has been investigated as a new technology to enhance the healing of soft tissues. Laser fusion of intestinal anastomoses shows promise as a method to obtain primary healing while eliminating a foreign-body reaction associated with the sutures. This paper reviews the experimental data that are available regarding laser-assisted intestinal anastomoses and summarizes our experience using the CO2, Nd:YAG, and argon lasers to form fusions in small bowel.

Closure of rabbit ileum enterotomies with the argon and CO2 lasers: bursting pressures and histology

In this study, we examined short-term strength and histology of experimental argon and CO2 laser-welded and control-sutured enterotomies in a rabbit model. Longitudinal 1.0-cm enterotomies were closed with the argon laser at 0.5 (n = 10) or 1.0 (n = 10) W power and a spot diameter of 2.8 mm resulting in energy fluences of 230 and 450 J/cm2, respectively. Similar enterotomies were closed using the CO2 laser at 0.5 (n = 10) or 1.0 (n = 10) W power and a spot diameter of 1.2 mm, resulting in energy fluences of 1,360 and 2,730 J/cm2. In all closures, continuous wave laser was delivered for 30 seconds. Using a pressure-monitored infusion system with normal saline, the pressure required to burst each weld as well as sutured controls (n = 10) was recorded approximately 1 minute following fusion. Mean bursting pressures for the argon laser at 0.5 W and 1.0 W were 34.1 +/- 19.4 mm Hg (mean +/- SD) and 17.3 +/- 8.3 mm Hg, respectively, and for the CO2 laser were 23.5 +/- 12.0 mm Hg and 31.8 +/- 15.6 mm Hg, respectively. Sutured controls leaked at 45.2 +/- 12.0 mm Hg. With the exception of argon-laser welds at an energy fluence of 450 J/cm2, which were less than sutured repairs, the bursting pressures for welded closures were not significantly different from the sutured controls (Student's t distribution, P less than .05). Histologic examination of both types of welds demonstrated a fibrin and red blood cell coagulum bridging the anastomosis, with some evidence of mild thermal injury at the mucosa.(ABSTRACT TRUNCATED AT 250 WORDS)

Bursting pressures of CO2 laser-welded rabbit ileum

In this study, the short-term bond strength of laser-welded New Zealand white rabbit ileum was examined. Forty-eight longitudinally oriented 0.5-cm transmural, scalpel incisions were reanastomosed solely through the use of the CO2 continuous wave laser at low energy levels. Random power levels of 250, 500, 750, or 1,000 mW were delivered to weld sites by either continuous application for 30 seconds or a pulsating application (ie, 0.5 seconds on, 0.5 seconds off) for 60 seconds. This provided 53.6, 107.1, 160.7, and 214.3 J/cm2, respectively. With the aid of a plexiglass clamp and pressure monitored infusion system, each type of weld was tested six times to determine the intraluminal hydrostatic pressure required to burst the welded seam 1 minute after completing the weld. For the welds made with 107.1, 160.7, and 214.3 J/cm2 in both lasing modes, the mean bursting pressure was 40.7 mmHg (SD +/- 24.9) with no statistically significant difference in weld strengths at these energy densities. There was also no difference between continuous and pulsating delivery methods. However, the energy density of 53.6 J/cm2 in either method produced a mean bursting pressure significantly lower than those produced by the higher energy densities tested and below the estimated basal ileal intraluminal pressure of approximately 9 mmHg. Since 107.1 J/cm2 energy density caused the minimal gross tissue changes while producing an equally strong bond and since continuous is faster than pulsating, 500 mW of continuous delivery was considered the optimal setting for the CO2 laser welding of rabbit ileum.

[Effect of pH on the motility of isolated jejunal loops in dogs]

Thirty-Vella jejunal loops are perfused at a constant rate with solutions of variable pH (1.55-11.25). Net loop absorption and motility of the oral segment do not significantly vary between pH values of 2.2 to 10.0. At a more acid pH, there exists a strong increase in the amplitude of pressure waves accompanied by a decrease in their frequence.

Characteristics of intraluminal pressure sensing balloons of different materials

The physical properties of the balloons made of some polymeric substances were studied. The polyurethanes provided high frequency characteristics but air-leaking disqualified except ECD-651 which was most satisfactory: low permeability and ease of fabrication. Saran was proper but troublesome in making the balloon. Polypropylene and polyethylene, available in film, required heat sealing, which resulted in deformity and low frequency characteristics.