Octreotide hardens the pancreas

Soft-Tissue-Mimicking Using Hydrogels for the Development of Phantoms

With the currently available materials and technologies it is difficult to mimic the mechanical properties of soft living tissues. Additionally, another significant problem is the lack of information about the mechanical properties of these tissues. Alternatively, the use of phantoms offers a promising solution to simulate biological bodies. For this reason, to advance in the state-of-the-art a wide range of organs (e.g., liver, heart, kidney as well as brain) and hydrogels (e.g., agarose, polyvinyl alcohol –PVA–, Phytagel –PHY– and methacrylate gelatine –GelMA–) were tested regarding their mechanical properties. For that, viscoelastic behavior, hardness, as well as a non-linear elastic mechanical response were measured. It was seen that there was a significant difference among the results for the different mentioned soft tissues. Some of them appear to be more elastic than viscous as well as being softer or harder. With all this information in mind, a correlation between the mechanical properties of the organs and the different materials was performed. The next conclusions were drawn: (1) to mimic the liver, the best material is 1% wt agarose; (2) to mimic the heart, the best material is 2% wt agarose; (3) to mimic the kidney, the best material is 4% wt GelMA; and (4) to mimic the brain, the best materials are 4% wt GelMA and 1% wt agarose. Neither PVA nor PHY was selected to mimic any of the studied tissues.

Focal change of the pancreatic texture using a direct injection mixture of N-butyl cyanoacrylate and lipiodol in the pig model: a strategy for preventing pancreatic leakage during pancreatic surgery

Purpose

A soft texture of the pancreas is one of the most important predisposing factors for a pancreatic fistula. Thus, in a porcine model, we investigated a method to harden the pancreas locally by directly injecting an artificial material.

Methods

During the laparotomy, 51 samples from 17 pigs, including 13 survival models, were randomly divided into 3 groups and either received a direct injection into the pancreas of MHL (1:4 mixture of histoacryl [n-butyl cyanoacrylate] and lipiodol) (group E) or saline (group C) or only received a pinprick into the pancreas without injecting a substance (sham). We measured the change in the pancreatic hardness after the injection using a durometer and examined the histological change of the pancreas using the fibrosis grade in the survival model.

Results

The postinjection hardness of the pancreas was significantly increased in group E compared to group C and the sham group (P < 0.001). Pathologically, all cases in group E showed a severe fibrotic change, whereas the other groups demonstrated mild to no fibrosis (P < 0.001). The fibrosis in group E was localized to the area of the injection, while the surrounding areas were preserved.

Conclusion

The direct injection of MHL could induce focal hardening and fibrotic changes in the pancreas of the porcine model.

Pancreatic parenchymal injection of ethanol and octreotide to induce focal pancreatic fibrosis in rats: Strategies to eliminate postoperative pancreatic fistula

BACKGROUND

Postoperative pancreatic fistula (POPF) is more likely to occur in a soft pancreas compared to a hard pancreas in which fibrosis has progressed. There is almost no leakage at the anastomosis site or cut surface of a hard pancreas. The aim of this study was to induce localized fibrosis at the cut surface of the pancreas in a rat model.

METHODS

Thirty-six rats were divided into three groups (group S: normal saline group; group E: ethanol group; and group O: octreotide group). Each rat was directly injected with a particular compound at the duodenal lobe of the pancreatic parenchyma. Each group was divided into three subgroups according to the time of post-injection sacrifice (1, 2, or 4 weeks). The hardness, suture holding capacity (SHC), and histological fibrosis grade of each pancreas were measured.

RESULTS

The hardness, SHC, and fibrosis grade of groups E and O were increased at week 1, with greater increases in group E (all P < 0.001). In a subgroup comparison, the hardness, SHC, and fibrosis grade of group E tended to decrease gradually over time, with no regular pattern evident in group O. A comparison between the injected site (duodenal lobe) and non-injected site (splenic lobe) of the pancreas revealed increases in the three parameters of group E only in the duodenal lobe, with increases in group O at both the duodenal and splenic lobes.

CONCLUSIONS

Parenchymal injection of ethanol and octreotide increased pancreatic fibrosis. Unlike octreotide, ethanol provoked localized fibrosis that was maintained over time. It is expected that ethanol injection could eliminate POPF during pancreatic surgery.

Quantitative assessment of liver fibrosis using shore durometer

Purpose

The purpose of the present study was to investigate whether hardness of liver surface correlated with degree of liver fibrosis, and its association with posthepatectomy liver failure (PHLF).

Methods

A shore durometer was used to measure hepatic hardness in 41 patients with hepatocellular carcinoma (HCC) and in 10 patients with normal liver. We investigated how hepatic hardness correlates with various values indicating the degree of liver fibrosis, and how it correlates with PHLF.

Results

In the normal liver group, the surface shore units (SU) was 15.06 ± 2.64. In the HCC group, there was a correlation between surface SU and preoperative results indicating liver fibrosis. Among patients with PHLF after resecting over 3 segments, the surface SU of patients with grade A PHLF was 21.85 ± 5.63, and the surface SU of patients with grade C PHLF was 35.75 ± 9.26. In patients with PHLF after resecting 2 or less segments, the surface SU of patients with PHLF grade A was 20.95 ± 5.18, and the surface SU of patients with PHLF grade B was 31.60 ± 5.57. In predicting PHLF, surface SU was more effective than preoperative platelet count, spleen volume, or liver fibrosis index.

Conclusion

Hepatic hardness measured by the shore durometer was correlated with the degree of liver fibrosis. Liver surface SU was a more effective parameter for predicting PHLF, as compared to other indicators evaluated before hepatectomy. The decision to perform major hepatectomy should be reconsidered in cases with a liver surface SU of >30.

Effects of intra-arterial octreotide on pancreatic texture: a randomized controlled trial

BACKGROUND AND AIMS

Octreotide is suggested to harden the pancreas, thus facilitating the construction of a pancreatic anastomosis and lowering the risk of postoperative fistula. We tested the hypothesis that intra-arterial application of octreotide in the gastroduodenal artery during pancreatectomy may increase pancreatic hardness.

MATERIAL AND METHODS

A single-center, prospective, double-blinded, randomized controlled trial with parallel assignment was conducted. Patients planned for a pancreatoduodenectomy or a total pancreatectomy, who had a palpatory and durometer proven (<40 Shore units) soft pancreas, were assigned to receive intraoperatively either 5 mL 500µg octreotide or 5 mL 0.9% saline solution as a bolus injection in the gastroduodenal artery. Pancreatic hardness was measured before, early, and late after intervention. The investigator performing the durometer measurements and pathologist were masked to group assignment. The primary outcome was increased pancreatic hardness. Analysis was by intention to treat. This trial is registered at http://www.clinicaltrials.gov (ID NCT01400100).

RESULTS

A total of 12 patients received octreotide and 13 received saline solution. Pancreatic hardness marginally increased in the octreotide group: 0.67 ± 2.3 Shore units, whereas it decreased in the control group: -2.15 ± 2.7 Shore units. The difference was statistically significant, p = 0.029 (95% confidence interval = -4.87 to -0.77). Histology did not find any correlate for this clinically irrelevant hardening effect.

CONCLUSIONS

A single bolus application of octreotide did not deliver a clinically relevant increase in pancreatic hardness. Future studies on the hardening effect of octreotide should employ repeated or continuous preoperative administration of this drug.

A simple pancreaticojejunostomy technique for hard pancreases using only two transpancreatic sutures with buttresses: a comparison with the previous pancreaticogastrostomy and dunking methods

PURPOSE

In this study, we introduced a novel technique, the pancreaticojejunostomy (PJ), which uses only two transpancreatic sutures with buttresses (PJt), and compared the surgical outcomes with previously used methods, especially for hard pancreases.

METHODS

A total of 101 patients who underwent pancreaticoduodenectomy with hard pancreases were enrolled and divided into 3 groups according to the method of pancreaticoenteric anastomosis: 30 patients (29.7%) underwent the conventional dunking method (Du), 31 patients (30.7%) underwent pancreaticogastrostomy using transpancreatic sutures (PGt) and 40 patients (39.6%) underwent PJ using transpancreatic sutures (PJt). The surgical outcomes were compared according to the type of anastomosis to analyze the feasibility and ease of each technique.

RESULTS

The overall operative time was shorter in the PJt group (325.1 ± 63.8 minutes) than in the PGt group (367.3 ± 70.5 minutes) or the Du group (412.0 ± 38.2 minutes, P < 0.001). In terms of pancreaticoenteric anastomosis time, it was also shorter in the PJt group (10.3 ± 3.5 minutes) than in the Du group (20.7 ± 0.7 minutes) or the PGt group (16.8 ± 5.4 minutes, P = 0.005). Significant postoperative pancreatic fistula (POPF) developed in 2 cases (6.7%) in the Du group, whereas there were no POPF cases in the PGt or PJt groups (P = 0.086). Overall postoperative morbidities occurred in 31 cases (30.7%), and there were no significant differences among the 3 groups (P = 0.692).

CONCLUSION

The novel PJ technique, which uses only two transpancreatic sutures with buttresses, is a very simple, easy and secure method for hard pancreases and can be performed in a shorter amount of time compared with conventional methods.

Quantitative assessment and determinants of suture-holding capacity of human pancreas

BACKGROUND

Hard pancreas is welcome by surgeons performing resective pancreatic surgery, because it is believed to offer better suture holding capacity (SHC), thus decreasing the risk for a postoperative leak. However, neither the actual SHC of pancreatic tissue in humans nor its determinants have been studied.

METHODS

We directly measured SHC for polydioxanone 5-0 suture and tissue hardness at the pancreatic isthmus in 53 human pancreata using a dynamometer and a durometer. A histologic score based on fibrosis grade, fat content, pancreatic duct size, and signs of chronic pancreatitis was calculated for every sample. We tested the hypothesis that SHC of the pancreas was proportional to tissue hardness, and evaluated the role of different possible histomorphologic determinants of SHC.

RESULTS

Suture-holding capacity correlated perfectly with tissue hardness (r = 0.98; P < 0.001; 95% confidence interval, 0.96-0.99). The histologic score showed a stronger correlation with both parameters than any single histologic parameter. The SHC of transductal sutures was significantly higher than that of pure transparenchymal sutures. The SHC and hardness were significantly lower in patients who developed a clinically relevant pancreatic fistula postoperatively.

CONCLUSIONS

A mixture of histomorphologic features of human pancreas determines its tissue hardness and SHC. Involvement of the main pancreatic duct in the suture line appears to increase the mechanical strength of the pancreatic anastomosis.

Histomorphological features of the pancreatic remnant as independent risk factors for postoperative pancreatic fistula: a matched-pairs analysis

BACKGROUND/AIMS

Postoperative pancreatic fistula (POPF) is a major complication after resective pancreatic surgery. This study aimed to identify histomorphological features of the pancreatic remnant as independent determinants for the development of POPF.

METHODS

Twenty-five patients, 3.6% of 696 resections over a period of 5 years, who developed POPF were matched for age, gender, diagnosis, comorbidities, surgeon and procedure with 25 controls without POPF. Pancreatic duct size and index, fibrosis grade, fat content, edema, and signs of chronic and acute inflammation were measured in frozen sections of the resection margin and were then compared.

RESULTS

The POPF rate was 12.2 and 2.6% after distal pancreatectomy and pancreatoduodenectomy, respectively. The POPF group was characterized by a longer ICU and total postoperative stay, higher rate of reoperations and complications. Their pancreata were softer at palpation (88 vs. 56%). Their pancreatic duct was smaller (2.5 vs. 3.2 mm) and their pancreatic fat content higher (16 vs. 8%). High inter- and intralobular fat content, small duct size, low interlobular fibrosis grade and lack of signs of chronic pancreatitis were predictors of POPF development. A score including these parameters identified high-risk patients with a sensitivity of 92% and a specificity of 84%.

CONCLUSION

Histomorphological features of the pancreatic remnant play an independent role as risk factors for the development of POPF. A simple histological score based on the frozen sections may already intraoperatively predict the risk of POPF development.

A simple scoring system based on clinical factors related to pancreatic texture predicts postoperative pancreatic fistula preoperatively

BACKGROUND

Postoperative pancreatic fistula (POPF) is regarded as the most serious complication of pancreatic surgery. The preoperative risk stratification of patients by simple means is of interest in perioperative clinical management.

METHODS

Based on prospective data, we performed a risk factor analysis for POPF after pancreatoduodenectomy in 62 patients operated between 2006 and 2008 with special focus on clinical parameters that might serve to predict POPF. A predictive score was developed and validated in an independent second dataset of 279 patients operated between 2001 and 2010.

RESULTS

Several pre- and intraoperative factors, as well as underlying pathology, showed significant univariate correlation with rate of POPF. Multivariate analysis (binary logistic regression) disclosed soft pancreatic texture (odds ratio [OR] 10.80, 95% confidence interval [CI] 1.80-62.20) and history of weight loss (OR 0.15, 95% CI 0.04-0.66) to be the only independent preoperative clinical factors influencing POPF rate. The subjective assessment of pancreatic hardness by the surgeon correlated highly with objective assessment of pancreatic fibrosis by the pathologist (r = -0.68, P < 0.001, two-tailed Spearman's rank correlation). A simple risk score based on preoperatively available clinical parameters was able to stratify patients correctly into three risk groups and was independently validated.

CONCLUSIONS

Preoperative stratification of patients regarding risk for POPF by simple clinical parameters is feasible. Pancreatic texture, as evaluated intraoperatively by the surgeon, is the strongest single predictive factor of POPF. The findings of the study may have important implications for perioperative risk assessment and patient care, as well as for the choice of anastomotic techniques.

Assessment of pancreatic hardness-surgeon versus durometer

BACKGROUND

This study reports the first results of durometrically measured hardness of human pancreas and investigates its correlation to palpatory determined hardness, grade of pancreatic fibrosis, and preoperatively determined radiodensity.

METHODS

Fifty-two patients with pancreatic resections were prospectively recruited. Hardness of samples from pancreatic cancer, chronic pancreatitis, and normal pancreas was measured using a durometer on a 0-100 Shore units (SU) scale. Three pancreatic surgeons palpated the pancreas and reported their assessment of hardness on a subjective 0-100 "Bochum units" (BU) scale. Radiodensity and fibrosis of pancreatic tissue were used for comparison.

RESULTS

Pancreatic hardness differed significantly in normal pancreas, chronic pancreatitis, and pancreatic cancer; 30 SU, 51 SU, and 65.8 SU, respectively. Palpatory hardness of normal pancreas was 20 BU and of pancreatitis 60 BU. It correlated well to durometric readings: r(2)=0.56, P<0.00001. Fibrosis grade and radiodensity correlated neither to durometry nor to palpation. Pancreatic leak developed 4/20 (20%) patients with normal pancreas vs. 1/32 (3.1%) with chronic pancreatitis in the resection margin, P<0.05.

CONCLUSIONS

Palpatory assessment of pancreatic hardness performed by experienced surgeons correlated well to durometric measurements and remains the method of choice for intraoperative decision making. Durometry was more precise and should be considered in studies on pancreatic texture and for teaching purposes. Hardness and fibrosis grade appeared to be independent characteristics of pancreatic texture.

Selective Administration of Prophylactic Octreotide During Pancreaticoduodenectomy: A Clinical and Cost-Benefit Analysis in Low- and High-Risk Glands

BACKGROUND

The efficacy of prophylactic octreotide after pancreaticoduodenectomy has been rigorously scrutinized, yet few studies have specifically illustrated its impact in patients at high risk for pancreatic fistula. Applying a previously validated clinical classification scheme (International Study Group on Pancreatic Fistula) for postoperative pancreatic fistula severity, we examined whether prophylactic octreotide could effectuate a clinical or fiscal benefit, or both, after pancreatic resection.

STUDY DESIGN

There were 227 consecutive patients who underwent pancreaticoduodenectomy from October 2001 to January 2007. At the surgeon's discretion, prophylactic octreotide was administered intraoperatively and continued postoperatively. Clinically relevant fistulas, requiring therapeutic interventions or resulting in severe clinical sequelae, were identified, as were other complications. Through multivariate analysis, risk factors for fistula were defined as soft gland texture; small duct size; ampullary, duodenal, cystic, or islet cell pathology; and increased blood loss. Beyond a traditional review of clinical outcomes, a novel economic cost-benefit analysis of octreotide prophylaxis was performed, with concentration of impact on high-risk glands (one or more risk factors).

RESULTS

Overall, 55% of patients had at least one risk factor. Clinically relevant fistulas were present in 14.9% of all patients. High-risk glands resulted in significantly worse clinical and economic outcomes compared with low-risk glands (no risk factors present). Prophylactic octreotide in low-risk glands was neither clinically effective nor cost efficient after pancreaticoduodenectomy, contributing to $781 in overspending per patient--approximately equivalent to a 7-day postoperative course of octreotide. But in patients with high-risk glands, octreotide prophylaxis was associated with a decreased incidence (20% versus 35%) and morbidity of clinically relevant fistulas. These improved clinical outcomes were associated with reduced resource use, translating to considerable cost savings ($11,849) per high-risk patient.

CONCLUSIONS

Octreotide prophylaxis is an effective approach to mitigate the negative impact of pancreatic fistulas, but to obtain maximal clinical value and cost benefit, octreotide should be administered exclusively to patients with high-risk glands.

Mechanical behavior of intact and low-grade degenerated cartilage / Mechanische Eigenschaften von intaktem und niedriggradig geschädigtem Knorpel

Young's modulus, elastic and plastic deformation, mechanical hardness and load at failure were determined for low-grade degenerated hyaline cartilage in a porcine model. Osteochondral plugs from the medial condyle of 30 female pigs were used. Cartilage defects were classified using the International Cartilage Repair Society (ICRS) protocol. Mechanical hardness was measured using a Shore A testing device. Total stiffness and plastic deformation was evaluated in the range 50-200 N using a 5-mm indenter. The load at failure was then determined. ICRS grade I specimens showed significantly lower stiffness than grade 0 specimens. ICRS grade 0 specimen showed no significant plastic deformation within the load range 25-100 N. In degenerated cartilage, plastic deformation started at a significantly lower load (50 N). The Young's modulus at 25 N in ICRS grade 0 specimens (18.8 MPa) was significantly higher than in grade I (11.1 MPa) or grade II (10.5 MPa) specimens. Intact cartilage showed significantly higher tension at failure and mechanical Shore A hardness. Young's modulus and tension at failure showed strong correlation. Cartilage degeneration is associated with a significant loss of elasticity and mechanical stress resistance. Shore hardness measurement is an adequate method for rapid biomechanical evaluation of cartilage specimens.