Laparoscopic vs Open Distal Pancreatectomy: Technical Evaluation from Dalin Tzu Chi Experience

( Wen Yao Yin ) 대한간학회 2017 춘·추계 학술대회 (KASL) Vol.2017 No.1

Aims: This study emphasized on the postoperative complications following resection solely on normal pancreatic tissue by laparoscopic technique or open method. Methods: We collected a total of 47 cases of cases who underwent distal pancreatectomy. The prospective group: 9 cases of laparoscopic distal pancreatectomy(LDP) and 13 cases of open distal pancreatectomy who were operated in recent 3 consecutive years, were compared with the other retrospective group of 25 cases operated before laparoscopic era. The postoperative mortality and morbidity were compared and statistically evaluated. Results: The overall complication between laparoscopic and open group was quite similar (6/9, 66.6% vs 14/38,,32.4%, p=0.142). However severe complications occurred higher in patients with open method in both groups (8/13 61.5% vs 3/9 33.3%, p=0.387) though no significant difference probably due to small number of cases. In contrast, patients in retrospective group (all open) showed surprisingly low severe complication (3/25, 12%). If we look at the severe complications in three subgroups (two laparoscopic and open in prospective group and one retrospective open group), a significant difference with p value 0.002 only between the two open groups (prospective open 69.2% vs retrospective open 3/25 12%, p=0.001). Regarding the transaction site, no difference seen between neck and tail but taken together with closure method, closure with TA (mostly at neck) was much better than GIA. Severe complication for LDP was lower than open group for soft pancreas with good p value (3/9 33.3% vs 8/11 72.7% p -0.07). Conclusions: Closure technique with TA55 resected at neck is a reliable technique. LDP was associated with early recovery with less overall complications. Fistula rate was comparable but less severe in LDP. Double Clamping technique (developed by our team) with slowly flattening method may be helpful for favorable outcome

Thorough Pre-Transplant Evaluation and Appropriate Case Selection Is the Mainstay for Better Survival in Recipients with Malignancy

( Wen Yao Yin ) 대한간학회 2017 춘·추계 학술대회 (KASL) Vol.2017 No.1

Aims: Death from cardiovascular disease and infection are decreasing proper screening, prophylaxis, aggressive risk factor management, and interventional therapies. Cancer, on the other hand, is poorly screened both in recipient and donor to prevent post-transplant malignancy. Methods: We review the cases of liver and kidney transplant patients taken care in Dalin Tzu Chi General hospital in the past twelve years. We reviewed the issues on cancer before transplant, any cancer transmission from the donor, cancer after transplantation, outcomes of transplant recipients with cancer, and the role of screening and therapy in reducing the impact of cancer in transplant recipients. Results: There were 40 liver transplant and 46 kidney transplant patients with a total of 86 cases in this study. Sixteen cases (19.28 %) were associated with malignancy.A total of 16 cases (19.28%) died in this study. Among the kidney transplant patients, a total of 5 cases had malignancy: one renal cell carcinoma (RCC), three Transitional cell carcinoma (TCC) and one colon cancer. Two TCC cases were de novo malignancy.A case of TCC died of recurrence Among the liver transplant patients, 5 cases of living donor liver transplant (LDLT) and 4 cases of deceased donor liver transplant (DDLT) patients were associated with malignancy. No recurrence after follow up of 6 months to 8 years except a patient with an occult cecal cancer died one year after LDLT. Four cases of malignancy in DDLT: two HCC, one prostate cancer, and one nasopharyngeal cancer were noted. Both of the HCC patients died 3 months after DDLT and about 3 years after transplantation respectively. Conclusions: No significant difference in survival between cancer and non-cancer patients. We considered thorough preoperative screening is fundamental to prevent poor prognosis.

Cadaveric Study of Pancreatic Duct Leak after Distal Pancreatectomy with Laparoscopic Stapler Based on Critical Findings in Clinical Study at Dalin Tzu Chi General Hospital

( Bradley Yin ),( Chun Ming Chang ),( Wen Yao Yin ) 대한간학회 2017 춘·추계 학술대회 (KASL) Vol.2017 No.1

Aims: Our clinical study showed that transection site (body) and staple sizes (>2.5mm) were key factors contributing to the occurrence of postoperative pancreatic fistua( POPF). If we can create a neck (thin pancreas) on the body of the pancreas by slowly compressing before cutting using another clamp (double clamping) to allow optimal situation for 2.5mm staples, then the occurrence of POPF and leakage can be significantly reduced. Such a study is the first study in literature done on a well preserved cadaver Methods: Three adult cadavers were used, with each pancreas exposed for convenience but with equipment of laparoscopy to showcase assure that the technique can be done laparoscopically. Each pancreas was cut at multiple sites: one cut at each neck and tail, and three cuts each on the body of the pancreas. Each cut different staple size ( 2.5 mm and 3.8 mm) and the clamping method (single or double). The leakage was checked by three steps: gross observation, probing with catheter, and methylene blue. Results: Cuts performed with 2.5 mm staple and/or double clamping showed no leakage on both neck and body region. Cuts with both 3.8mm staple and single clamping technique show leakage on body region but no leakage at the neck and tail. Conclusions: The result had supported the hypothesis of double clamping method and smaller staple can reduce the chance of leakage and therefore reduce the chance of fistula after the operation.

Accurate Voltage Parameter Estimation for Grid Synchronization in Single-Phase Power Systems

Dai, Zhiyong,Lin, Hui,Tian, Yanjun,Yao, Wenli,Yin, Hang The Korean Institute of Power Electronics 2016 JOURNAL OF POWER ELECTRONICS Vol.16 No.3

This paper presents an adaptive observer-based approach to estimate voltage parameters, including frequency, amplitude, and phase angle, for single-phase power systems. In contrast to most existing estimation methods of grid voltage parameters, in this study, grid voltage is treated as a dynamic system related to an unknown grid frequency. Based on adaptive observer theory, a full-order adaptive observer is proposed to estimate voltage parameters. A Lyapunov function-based argument is employed to ensure that the proposed estimation method of voltage parameters has zero steady-state error, even when frequency varies or phase angle jumps significantly. Meanwhile, a reduced-order adaptive observer is designed as the simplified version of the proposed full-order observer. Compared with the frequency-adaptive virtual flux estimation, the proposed adaptive observers exhibit better dynamic response to track the actual grid voltage frequency, amplitude, and phase angle. Simulations and experiments have been conducted to validate the effectiveness of the proposed observers.

Accurate Voltage Parameter Estimation for Grid Synchronization in Single-Phase Power Systems

Zhiyong Dai,Hui Lin,Yanjun Tian,Wenli Yao,Hang Yin 전력전자학회 2016 JOURNAL OF POWER ELECTRONICS Vol.16 No.3

This paper presents an adaptive observer-based approach to estimate voltage parameters, including frequency, amplitude, and phase angle, for single-phase power systems. In contrast to most existing estimation methods of grid voltage parameters, in this study, grid voltage is treated as a dynamic system related to an unknown grid frequency. Based on adaptive observer theory, a full-order adaptive observer is proposed to estimate voltage parameters. A Lyapunov function-based argument is employed to ensure that the proposed estimation method of voltage parameters has zero steady-state error, even when frequency varies or phase angle jumps significantly. Meanwhile, a reduced-order adaptive observer is designed as the simplified version of the proposed full-order observer. Compared with the frequency-adaptive virtual flux estimation, the proposed adaptive observers exhibit better dynamic response to track the actual grid voltage frequency, amplitude, and phase angle. Simulations and experiments have been conducted to validate the effectiveness of the proposed observers.