Elastic Properties of Polychloroprene Rubbers in Tension and Compression during Ageing.

Being able to predict the lifetime of elastomers is fundamental for many industrial applications. The evolution of both tensile and compression behavior of unfilled and filled neoprene rubbers was studied over time for different ageing conditions (70 °C, 80 °C and 90 °C). While Young's modulus increased with ageing, the bulk modulus remained almost constant, leading to a slight decrease in the Poisson's ratio with ageing, especially for the filled rubbers. This evolution of Poisson's ratio with ageing is often neglected in the literature where a constant value of 0.5 is almost always assumed. Moreover, the elongation at break decreased, all these phenomena having a similar activation energy (~80 kJ/mol) assuming an Arrhenius or pseudo-Arrhenius behavior. Using simple scaling arguments from rubber elasticity theory, it is possible to relate quantitatively Young's modulus and elongation at break for all ageing conditions, while an empirical relation can correlate Young's modulus and hardness shore A. This suggests the crosslink density evolution during ageing is the main factor that drives the mechanical properties. It is then possible to predict the lifetime of elastomers usually based on an elongation at break criterion with a simple hardness shore measurement.

Transumbilical single-incision laparoscopic sleeve gastrectomy.

BACKGROUND: Sleeve gastrectomy has become an established primary bariatric surgical technique. Its relatively lower complexity has made it eligible to be performed by single-incision laparoscopy (single-incision laparoscopic sleeve gastrectomy, SILSG). The aim of this paper is to present our SILSG technique and surgical outcomes and demonstrate that SILSG is a safe and feasible procedure using conventional laparoscopic instruments. METHODS: All patients who underwent SILSG since December 2012 in our institution were analyzed. The operative technique involved creation of a transumbilical incision and the introduction of a GelPoint device with four trocars. Rigid instruments were used in all patients. Gastric transection was performed 4 cm proximal to the pylorus and calibrated with a 36-Fr bougie. Hemostasis of the staple line was achieved with metallic clips. RESULTS: A total of 74 patients underwent SILSG. Their mean age and body mass index were 34.2 ± 9.2 years and 34.0 ± 3.2 kg/m(2) (range 30.0-42.7 kg/m(2)), respectively. The mean operative time was 48 ± 10 min. No reoperations or deaths occurred. One patient developed portal vein thrombosis. The mean length of hospital stay was 2.4 ± 2.0 days. The cosmetic result was satisfactory in all patients. CONCLUSIONS: SILSG is a safe and feasible procedure when performed with the technique described herein. This technique allows for the use of conventional laparoscopic instruments and reasonable operative times. The main benefit of the procedure is an excellent cosmetic result with virtually no visible scars.

Transumbilical laparoscopic Roux-en-Y gastric bypass with hand-sewn gastrojejunal anastomosis.

Single-port laparoscopic surgery has undergone significant development over the past 5 years. Single port is used in various procedures, including bariatric surgery. The aim of this paper is to describe a surgical technique for gastric bypass with a transumbilical approach (transumbilical gastric bypass-TUGB) with hand-sewn gastrojejunostomy, in selected patients who may be benefited by a better cosmetic result. The procedure begins with a transumbilical vertical incision. We use the GelPOINT single-port device and a 5-mm assistant trocar in the left flank (in the first two cases, a 2-mm subxiphoid liver retractor was used). A gastric pouch is made and calibrated with a 36-Fr bougie. The gastrojejunal anastomosis is performed by hand-sewing in two layers. A Roux-en-Y with a biliary limb of 50 cm and an alimentary limb of 120 cm is performed with a stapler. Three women were subjected to TUGB. The women were aged 28, 31, and 42 years; they had body mass indexes of 40.3, 33, and 38.2; and the operating times were 150, 200, and 150 min, respectively. The first two women underwent a Roux-en-Y gastric bypass (RYGB), and the last woman underwent a RYGB with a resection of the stomach remnant. There were no conversions to open or multitrocar techniques. No complications or deaths occurred. The three patients were satisfied with the cosmetic result. The technique described for TUGB is a feasible procedure for surgeons who have previous experience with the transumbilical approach.

Transumbilical sleeve gastrectomy with an accessory lateral port: surgical results in 237 patients and 1-year follow-up.

BACKGROUND: The transumbilical approach has recently been shown to be safe for several surgical procedures. Case series of sleeve gastrectomy (SG) with a transumbilical approach (TUSG) has been reported with various techniques. The objective of this report is to present the technique, surgical results, and 1-year follow-up results of simplified TUSG using rigid instruments. METHODS: All of the patients who had undergone SG since July 2010 were offered a transumbilical approach. The operative technique involves a transumbilical incision and the introduction of a SILS® or GelPoint® multiport and a 5-mm metallic accessory trocar laterally in the left flank. Rigid instruments were used in all patients. Gastric transection was made 4-5 cm proximal to the pylorus, calibrated with a 36-Fr bougie. Selected hemostasis to the staple line was achieved with metallic clips. RESULTS: A total of 237 patients underwent TUSG. Patient body mass index ranged from 30 to 46 kg/m(2). The mean operative time was 49.5 ± 14.9 min. Six patients presented with early complications, including hemoperitoneum in three cases, antral leak in one case, intestinal perforation in one case, and portal vein thrombosis in one case. Conversion to the multitrocar technique was required in one patient. There were no mortalities. The mean length of hospital stay was 2.2 ± 1 days. The cosmetic result was satisfactory for all of the patients. CONCLUSIONS: TUSG is a safe and feasible procedure using the described technique. The insertion of a 5-mm assistance trocar simplifies the procedure, allowing the use of rigid instruments.

Gastric leak after sleeve gastrectomy: analysis of its management.

BACKGROUND: Bariatric surgery is increasingly being performed and sleeve gastrectomy (SG) has proved to be effective and safe. Among its complications, leaks are the most serious and life threatening. METHODS: The focus of the study is nine patients who underwent a SG and developed a gastric leak after surgery. Our data were obtained from the clinical charts of the patients and through interviews with the surgeon who performed the index surgery. RESULTS: Eight patients underwent SG at outside institutions while one was operated at Clinica Alemana. Three patients developed symptoms within 5 days after surgery, while the rest were diagnosed after 10 days from the surgery. A CT scan was the method used to confirm the diagnosis in all patients. The three patients who had a leak detected during the immediate postoperative period underwent laparoscopic reoperation. Among the rest of the patients, percutaneous drainage was employed in one patient as the primary procedure while the other underwent surgical drainage. An esophageal endoluminal stent was employed in four patients. The leak closed in all patients with the healing time ranging from 21 to 240 days. CONCLUSIONS: Diagnosis of a leak after a SG required a greater index of suspicion in order to perform an early diagnosis. Sepsis control and nutritional support are the cornerstones of this treatment. Evolution is characterized by longer periods of time that are necessary in order to wait until the leak closes. Management must be tailored to each patient.

Analgesic effects of a single preoperative dose of pregabalin after laparoscopic sleeve gastrectomy.

BACKGROUND: The treatment of pain in obese patients is always a challenge. These patients have low pain thresholds, and the use of opioids can be especially harmful. Intraoperative nervous fiber section and the high temperatures of electrical scalpels probably contribute to the generation of postoperative neuropathic pain. We hypothesized that an antineuropathic pain drug like pregabalin could be helpful to optimize postoperative analgesia by reducing the requirement for opioids and their associated side effects. METHODS: Eighty adults undergoing laparoscopic sleeve gastrectomy were randomly assigned to orally receive either placebo capsules (control) or pregabalin (150 mg) 2 h before surgery. Postoperative morphine consumption during the first 24 postoperative hours was registered. Visual analog pain scores (VAS) were assessed at 1, 2, 4, 6, 8, 12, 16, and 24 h after surgery. Both the incidence of adverse reactions and patient satisfaction were also assessed. RESULTS: Over a 24-h period, the morphine consumption in the pregabalin group was 11.51 ± 7.93 mg, whereas in the control group, it was 23.07 ± 9.57 mg (p < 0.0001). VAS scores were significantly lower in the pregabalin group. Postoperative nausea and vomiting and the consumption of antiemetics were reduced in the pregabalin group. CONCLUSIONS: A single preoperative oral dose of 150 mg pregabalin is useful for reducing morphine consumption after a sleeve gastrectomy, and it guarantees effective and safe analgesia with a low incidence of adverse effects.