The ENUF method-Ewald summation based on nonuniform fast Fourier transform: Implementation, parallelization, and application.

Computer simulations of model systems are widely used to explore striking phenomena in promising applications spanning from physics, chemistry, biology, to materials science and engineering. The long range electrostatic interactions between charged particles constitute a prominent factor in determining structures and states of model systems. How to efficiently calculate electrostatic interactions in simulation systems subjected to partial or full periodic boundary conditions has been a grand challenging task. In the past decades, a large variety of computational schemes has been proposed, among which the Ewald summation method is the most reliable route to accurately deal with electrostatic interactions between charged particles in simulation systems. In addition, extensive efforts have been done to improve computational efficiencies of the Ewald summation based methods. Representative examples are approaches based on cutoffs, reaction fields, multi-poles, multi-grids, and particle-mesh schemes. We sketched an ENUF method, an abbreviation for the Ewald summation method based on the nonuniform fast Fourier transform technique, and have implemented this method in particle-based simulation packages to calculate electrostatic energies and forces at micro- and mesoscopic levels. Extensive computational studies of conformational properties of polyelectrolytes, dendrimer-membrane complexes, and ionic fluids demonstrated that the ENUF method and its derivatives conserve both energy and momentum to floating point accuracy, and exhibit a computational complexity of O N log N with optimal physical parameters. These ENUF based methods are attractive alternatives in molecular simulations where high accuracy and efficiency of simulation methods are needed to accelerate calculations of electrostatic interactions at extended spatiotemporal scales.

Anesthetic Fluid Management of Patients With Hyponatremia Undergoing Living Donor Liver Transplantation.

OBJECTIVE: The objective of this study is to evaluate the changes in serum sodium levels in adult recipients with and without hyponatremia undergoing living donor liver transplantation (LDLT) without using hypertonic solution. METHODS: Patients were divided into 2 groups according to serum sodium level higher (GI) or lower (GII) than 130 mEq/L. The changes of serum sodium levels during an LDLT procedure and total sodium loads were compared between groups by using the Mann-Whitney U test, while the changes in the same group were paired by using the Student t test. A P value <.005 was considered significant. RESULTS: The total sodium load for GI (n = 438) and GII (n = 28) were 2737 ± 2159 mEq and 4017 ± 2830 mEq, respectively. Although GI received a significantly lower sodium load than GII, the serum sodium levels during the procedure were always within a normal range and higher than GII at all the measured time points; however, the changes of serum sodium level in GI from one point to the next measured point in the same group were unremarkable, while that of GII increased significantly between the 2 measured time points during the procedure. The mean total increase of serum sodium in GII was 5.57 ± 4.9 mEq/L in 14 hours of the LDLT procedure. None of the patients developed central pontine myelinosis (CPM) postoperatively. CONCLUSION: Patients with hyponatremia can be managed safely without using a hypertonic solution during liver transplantation. The mean increase of serum sodium of GII was of 5.57 ± 4.9 mEq/L, which was still within the acceptable and safe level. No postoperative CPM was observed in our GII patients.

Acute Kidney Injury in Adult Living Donor Liver Transplantation Performed with Different Methods of Inferior Vena Cava Clamping Maneuvers.

OBJECTIVE: The aim of this retrospective study is to evaluate and compare the incidence of acute kidney injury (AKI), defined as increase serum creatinine (SCr) of 0.3 mg/dl or increase in SCr to ≥1.5 times from baseline within 48 hour, in adult living donor liver transplantation patients performed with total cross clamp vs side clamp of the inferior vena cava (IVC). METHODS AND PATIENTS: Sixty adult living donor liver transplantation (LDLT) patients were divided into 2 groups: 30 patients in total IVC clamping (G1) and 30 in IVC side clamping (G2) during the anhepatic phase. Patients' characteristic, hemodynamic changes in percentage (%) as a result of different methods of IVC clamping, urine output during anhepatic phase were compared by using the Student t test, and the incidence of AKI were compared by using the χ2 test between groups. P value <.05 was regarded as significant. RESULTS: The negative impact of the 2 different ways of IVC clamping was significantly more severe in G1 compared to G2; consequently, the urine output of G1 was significantly less than G2. Although there was significantly more urine output of G2 during the anhepatic phase, the incidence of the postoperative AKI between groups was similar. CONCLUSION: The side clamp of the IVC had a significantly less negative impact on the hemodynamic parameters and provided sufficient urine output during the anhepatic phase (2.24 ± 3.17 vs 0.39 ± 0.33 mL/kg/h) compared to the total clamp of the IVC. But this favorable data did not protect the patient suffering from postoperative AKI in LDLT.

Comparison of Glucose Loads and Blood Glucose Changes in Patients With and Without Diabetes Mellitus Undergoing Living Donor Liver Transplantation.

BACKGROUND AND PURPOSE: The purpose of this study was to identify the quantitative amount of glucose load, which maintained the blood glucose levels between 100 and 180 mg/dL in patients with and without diabetes mellitus (DM) undergoing living donor liver transplantation (LDLT). METHODS AND PATIENTS: The anesthesia records of 477 adult LDLT patients were reviewed retrospectively. The total amount of glucose loads and the changes in blood glucose between groups were compared by using Mann-Whitney U test. One-year patient survival between groups was compared with Pearson's χ2 test. A P value of <.05 was considered statistically significant. RESULTS: Eighty patients diagnosed with DM, who were all type II except one, were placed in group 1 (G1); and 397 patients without DM were placed in group 2 (G2). Table 1 shows that G1 received significantly less glucose loads in comparison to G2, but all the measured blood glucose levels, except in the reperfusion phase, were significantly higher in G1 than in G2. Both groups received glucose loads of 0.342 ± 0.191 and 0.774 ± 0.191 mg/kg/min for G1 and G2, respectively. No difference in 1-year survival between groups was observed. CONCLUSION: Patients with DM required significantly lower glucose loads compared to patients without DM.

Effect and Outcome of Intraoperative Fluid Restriction in Living Liver Donor Hepatectomy.

BACKGROUND The purpose of this study was to evaluate the effect and outcome of intraoperative fluid restriction in living liver donor hepatectomy, regarding changes in intraoperative CVP levels, blood loss, and postoperative renal function. MATERIAL AND METHODS The charts of 167 patients were reviewed and analyzed retrospectively. Intraoperative central venous pressure levels, blood loss, fluids infused, and urine output per hour, before and after the liver allograft procurement, were calculated. Perioperative renal functions were also analyzed. RESULTS Fluid infused before and after liver allograft procurement was 3.21±1.5 and 9.0±3.9 mL/Kg/h and urine output was 1.5±0.7 and 1.8±1.4 mL/Kg/h, respectively. Intraoperative estimated blood loss was 91.3±78.9 mL. No patients required blood transfusion. Their preoperative and postoperative hemoglobin were 12.3±2.7 and 11.7±1.7 g/dL. CVP levels decreased gradually from 10.4±3.0 to a low of 8.1±1.9 mmHg at the time of transection of the liver parenchyma. Renal functions were not significantly affected based on the determination of BUN and creatinine levels. CONCLUSIONS The methods used to lower CVP are moderate and slow, with 2 main goals achieved: minimal blood loss (91.3±78.9 ml) and no blood transfusion. Furthermore, it did not have any negative effect on renal function.

Clinical Beneficial Effects of Using Crystalloid only in Recipients of Living Donor Liver Transplantation.

OBJECTIVE: Liver transplantation (LT) is a major surgery associated with intraoperative massive fluid shift, which is usually replaced by crystalloid, 5% albumin (colloid) and blood products. We studied 15 patients from 477 consecutive recipients of adult living donor liver transplantation. Each patient received crystalloid only during LT. Whether LT provides any clinical benefit is not clear and must be determined. METHODS AND PATIENTS: The anesthesia records of 477 adult LDLT were reviewed retrospectively. The patients were divided into three groups according to the fluids received. Group I (GI) had received blood products, 5% albumin and crystalloid, group II (GII) received 5% albumin and crystalloid, and group III (GIII) received crystalloid only. The characteristic intraoperative variable and postoperative acute rejection and survival rate were compared amongst groups by using One Way ANOVA post hoc with Bonferroni and by Ficher's Exact test and Chi-square χ² test. RESULTS AND CONCLUSIONS: GIII had less intraoperative ascites and blood loss; they also had more stable hemodynamics. Furthermore, they could be extubated significantly earlier than GI, and the one- and three-year survival rates were excellent, with 100% in GIII, while that of GI and GII were 94.1%, 90.5% and 98.6%, 94.5%, respectively.

Carbon dots with high fluorescence quantum yield: the fluorescence originates from organic fluorophores.

In this contribution, we have shown that the organic fluorophores, 5-oxo-3,5-dihydro-2H-thiazolo [3,2-a] pyridine-3,7-dicarboxylic acid (TPDCA) and 5-oxo-3,5-dihydro-2H-thiazolo [3,2-a] pyridine-7-carboxylic acid (TPCA), are the main ingredients and fluorescence origins of N,S-CDs via systematic analyses. It inspires us to deeply analyze and understand the fluorescence origins of carbon dots with high fluorescence quantum yields, which will expand their applications.

Accelerating electrostatic interaction calculations with graphical processing units based on new developments of Ewald method using non-uniform fast Fourier transform.

We present new algorithms to improve the performance of ENUF method (F. Hedman, A. Laaksonen, Chem. Phys. Lett. 425, 2006, 142) which is essentially Ewald summation using Non-Uniform FFT (NFFT) technique. A NearDistance algorithm is developed to extensively reduce the neighbor list size in real-space computation. In reciprocal-space computation, a new algorithm is developed for NFFT for the evaluations of electrostatic interaction energies and forces. Both real-space and reciprocal-space computations are further accelerated by using graphical processing units (GPU) with CUDA technology. Especially, the use of CUNFFT (NFFT based on CUDA) very much reduces the reciprocal-space computation. In order to reach the best performance of this method, we propose a procedure for the selection of optimal parameters with controlled accuracies. With the choice of suitable parameters, we show that our method is a good alternative to the standard Ewald method with the same computational precision but a dramatically higher computational efficiency.

Impact of Early Release of the IVC Clamp from Different IVC Clamping Maneuvers on Changes in Hemodynamic Parameters in Living Donor Liver Transplantation.

BACKGROUND The aim of this study was to evaluate the impact of different methods of inferior vena cava (IVC) clamping and release of the cross clamp on hemodynamic parameters of recipients during living donor liver transplantation. MATERIAL AND METHODS Ninety-six adult living donor liver transplantation patients were divided into 3 groups according to cross-clamp of the IVC for all the hepatic vein and portal vein reconstruction (G1), cross-clamp of the IVC only for hepatic vein reconstruction (G2), and side-clamp of the IVC for hepatic vein reconstruction (G3). In G2 and G2, the reconstructed hepatic vein was clamped instead of the IVC for portal vein reconstruction. The hemodynamic parameters among groups were compared by 1-way ANOVA and the complications in each group were compared using the Kruskal-Wallis test. RESULTS Changes in percentage of MAP and CO in G3 were significantly less than that of G1 and G2 for hepatic vein reconstruction. Hemodynamic parameters of G2 and G3 normalized to pre-clamped values during portal vein reconstruction, while the hemodynamics of G1 remained unstable. CONCLUSIONS Hemodynamic changes were less pronounced in LT with side-clamp of the inferior cava vein versus total cross-clamp. Early release of the IVC clamp minimized the hemodynamic changes. There were no differences in terms of outcome (morbidity and mortality).

Living donor liver transplantation with body-weight more or less than 10 kilograms.

AIM: To compare the outcomes of pediatric patients weighing less than or more than 10 kg who underwent liver transplantation. METHODS: Data for 196 pediatric patients who underwent living donor liver transplantation between June 1994 and February 2011 were reviewed retrospectively. The information for each patient was anonymized and de-identified before analysis. The data included information regarding the pre-transplant conditions, intraoperative fluid replacement and outcomes for each patient. The 196 patients were divided into two groups: those with body weights of less than 10 kg were included in group 1 (G1; n = 101), while those with body weights of more than 10 kg were included in group 2 (G2; n = 95). For each group, the patients' ages, body weights, heights, pediatric end stage liver disease scores, anesthesia times, and warm and cold ischemic times were analyzed. In addition, between-group comparisons were also made. Mann-Whitney U tests were used to compare all the variables except for complications and survival rates, which were analyzed using χ(2) tests and Kaplan-Meier tests, respectively. RESULTS: The general medical conditions of the G1 patients were worse than those of the G2 patients, as shown by the higher pediatric end stage liver disease scores and poorer Z-scores. In addition, the pre-operative Hb and serum albumin levels were all lower for the G1 patients than for the G2 patients. The G1 patients also had significantly more intraoperative blood loss than the G2 patients. In addition, the intraoperative fluid requirements for the G1 patients, including leukocyte poor red blood cell transfusions, 5% albumin infusions and crystalloid infusions, were significantly higher than those for the G2 patients. The risk of intraoperative portal vein thrombosis was higher for the patients in G1 than for those in G2. However, the one-year survival rates (95.9% and 96.8% for G1 and G2, respectively) and three-year survival rates (94.9% and 94.6% for G1 and G2, respectively) for both groups were similar. CONCLUSION: Patients weighing less than 10 kg typically have poorer conditions, but their survival rates are comparable to those of children weighing more than 10 kg.

The effectiveness of prophylactic attachment of adhesive defibrillation pads in adult living donor liver transplantation.

BACKGROUND: The aim of current study is to present the effectiveness of prophylactic attachment of adhesive defibrillation electrode pads in adult living donor liver transplantation. MATERIAL AND METHODS: We divided 487 adult living donor liver transplantation patients into 2 Eras according to the history of without (Era 1) and with (Era 2) pre-attachment of adhesive defibrillation pads. The incidences of intraoperative cardiac events requiring cardioversion or defibrillation, its management, and outcome between Era 1 and 2 were compared. RESULTS: Two cases out of 124 patients (1.6%) in Era 1 had cardiac arrest. The closed chest cardiac massage in 1 cardiac arrest in Era 1 required trans-diaphragmatic open-chest cardiac massage followed by internal cardiac defibrillation due to difficulty in performing external defibrillation. Both patients of Era 1 had in-hospital mortality. Four patients of Era 2 (n=363) received electrical treatment (1.01%); 2 had paroxysmal tachycardia requiring cardio-version and the other 2 had ventricular fibrillation requiring closed-chest cardiac massage and external defibrillation. All 4 patients in Era 2 regained sinus rhythm after electrical treatment, tolerated the subsequent operation well, and had 100% survival to date. CONCLUSIONS: Our results show that prophylactic attachment of adhesive defibrillation pads allows the immediate performance of cardioversion, conventional closed-chest CPR, and defibrillation if indicated without any delay and without interference with the sterility of the operation field. Our preliminary result is clear and encouraging.

Review of anesthesia in liver transplantation.

Liver transplantation (LT) is a well-accepted treatment modality of many end-stage liver diseases. The main issue in LT is the shortage of deceased donors to accommodate the needs of patients waiting for such transplants. Live donors have tremendously increased the pool of available liver grafts, especially in countries where deceased donors are not common. The main ethical concern of this procedure is the safety of healthy donors, who undergo a major abdominal surgery not for their own health, but to help cure others. The first part of the review concentrates on live donor selection, preanesthetic evaluation, and intraoperative anesthetic care for living liver donors. The second part reviews patient evaluation, intraoperative anesthesia monitoring, and fluid management of the recipient. This review provides up-to-date information to help improve the quality of anesthesia, and contribute to the success of LT and increase the long-term survival of the recipients.

Acquired hyponatremia in pediatric living donor liver transplantation.

BACKGROUND: The aim of this study was to evaluate the incidence of acquired hyponatremia (AH) in our pediatric living donor liver transplantation (LDLT) patients, and to identify the potential predictive risk factors of the causes of AH. MATERIAL/METHODS: The 189 pediatric LDLT patients were divided into 2 groups: serum sodium level at the end of the surgery lower than 130 mEq/L in GI (n=16) and higher than 130 mEq/L in GII (n=173). Patients' data were analyzed by Mann-Whitney U test, univariate analysis, and multiple binary logistic regression model. The Hosmer-Lemeshow goodness-of-fit test was used to evaluate the logistic model formulated. P value <0.05 was regarded as statistically significant. RESULTS: In the multiple binary logistic regression model, the hypotonic solution administration rate (ml/kg/h) was the only independent predictor of AH with a p<0.017. Receiver operating curve (ROC) analysis indicated that giving more than 3.5 ml/kg/h hypotonic solution infusion may cause AH. Preoperative hyponatremia did not increase the incidence of acquired hyponatremia. CONCLUSIONS: Increasing the administration of hypotonic solution by 1 ml/kg/h in pediatric LDLT would increase the risk of developing AH by 1.272 times. The critical administration rate of hypotonic solution was 3.5 ml/kg/h.

Predictive factors for pediatric patients requiring massive blood transfusion during living donor liver transplantation.

BACKGROUND: The aim of this study was to identify the preoperative risk factors that may predict the requirement of massive blood transfusion during pediatric living donor liver transplantation. MATERIAL AND METHODS: The anesthesia charts of pediatric patients undergoing living donor liver transplantation were reviewed retrospectively. Patients were grouped into 2 categories based on the amount of intraoperative blood transfusion. Group I (GI) consists of patients who received massive blood transfusion and Group II (GII) consists of patients who did not receive massive blood transfusion. The patients' characteristics and preoperative data were compared between groups with the Mann-Whitney U test. Predictive risk factors for massive blood transfusion were analyzed by binary regression. A p value of <0.05 was regarded as significant. Data are given as mean ±SD. RESULTS: A total of 198 pediatric patients were included in this study. Thirteen (6.5%) of the 198 pediatric patients undergoing living donor liver transplantation met the criteria of massive blood transfusion. The mean estimated blood volume of GI and GII was 724±322 and 1097±830 ml, respectively. The mean quantity of blood products given were 1018±591 and 187±220 ml for GI and GII, respectively. RBC was given to 67% of the patients, FFP was given to 18%, and only 1% received platelet transfusion. The patients who required massive blood transfusion were younger in age and had smaller body size, with prolonged INR (international normalized ratio) observed. INR, a measure of blood clotting time, was the only predictive factor that can impact intraoperative massive blood loss and subsequent blood transfusion. Each prolongation of 0.1 unit of INR elevates by 1.083-fold the risk of massive blood transfusion (95% C.I.=1.030-1.139, P=0.002). CONCLUSIONS: Preoperative INR was the only predictive risk factor for massive blood transfusion during pediatric living donor liver transplantation. Increasing the ratio of FFP transfusion in patients with prolonged INR before or during pediatric LDLT is recommended.

Intraoperative blood and fluid administration differences in primary liver transplantation versus liver retransplantation.

OBJECTIVES: Liver retransplantation (Re-LT) is the effective therapy for irreversible liver graft failure after primary liver transplantation (LT). The challenges faced by the operative team in the Re-LT setting have been seldom elucidated. Our aim is to analyze the differences in fluid management in primary LT and Re-LT during the surgical procedure. METHODS: The anesthesia charts of 16 patients who underwent both primary LT and Re-LT at our center in the space from October 1995 to May 2009 were analyzed. Group 1 (GI) consisted of patients who underwent primary LT, whereas patients in Group 2 (GII) were patients in GI but underwent Re-LT. GI was further divided into two subgroups depending on whether they had previous abdominal surgery before primary LT (GIB) or not (GIA). Wilcoxon signed-ranks test was used to compare GI and GII, and GIA and GIB. A p value less than 0.05 was regarded as significant. Data were given as mean ± standard deviation. RESULTS: Blood loss was significantly increased from 48.9 ± 106 mL/kg in GI to 251.5 ± 242 mL/kg in GII. Consequently more blood products, crystalloids, sodium bicarbonate, calcium chloride, and neosynephrine were required to support the hemodynamics in GII. In GI, GIB tended to bleed more and required more blood transfusions than GIA. CONCLUSION: More bleeding is expected in Re-LT than primary LT. Additional anesthetic personnel, more intravenous lines, and blood and blood products should be readily available to deal with the emergent fluid and hemodynamic resuscitations in anesthesia for Re-LT.

Evaluation of risk factors for postoperative prolonged intubation in premature infants after cryotherapy for retinopathy of prematurity.

OBJECTIVE: Premature infants are more prone to cardiorespiratory complications after surgery than term infants. Risk factors for postoperative apnea include post-conception age, gestational age, postnatal age, birth weight, history of respiratory distress syndrome, bronchopulmonary dysplasia, anemia, necrotizing enterocolitis, use of opioids or nondepolarizing muscle relaxants, aminophylline use, history of apnea, body weight at operation, and pre-existing disease. The aim of this study was to identify the most important factors associated with postoperative extubation and respiratory outcomes among premature infants undergoing cryotherapy for retinopathy of prematurity (ROP). METHODS: We retrospectively analyzed the clinical records of 62 premature infants, with mean +/- standard deviation gestational age of 26.4 +/- 2.3 weeks, birth weight of 914.8 +/- 208.5 g, postconception age of 37.0 +/- 2.8 weeks, and body weight at the time of operation of 1970.0 +/- 446.8 g, who underwent cryotherapy for ROP. RESULTS: Only 17 infants were successfully extubated within 2 hours after operation. The most predictive factor for successful or unsuccessful extubation was body weight at the time of operation. CONCLUSION: Body weight at the time of operation was the most important factor associated with postoperative ventilatory support among premature infants under-going cryotherapy for ROP.

Hereditary angioedema: a family study.

Hereditary angioedema (HAE) is a rare, life-threatening, autosomal dominant disease characterized by recurrent episodes of angioedema, and caused by a deficiency of the plasma protein C1-esterase inhibitor (C1-INH). Clinical manifestation of HAE may first develop during childhood but typically presents around puberty with nonpruritic and non-pitting edema of the subcutaneous and mucosal tissues. Up to now, there has been no published report of HAE case in Taiwan. We reported a 33 year-old female patient who had recurrent painful swelling of face and hands since 27 years of age. She first suffered from sudden onset of painful swelling of the eyelids and lips in August 1998 when she was pregnant for the first time. Subsequently, similar episodes recurred for a few times. Her blood test disclosed that her C3 and C4 were 125 mg/dl and 6 mg/dl, respectively. Her uncle died of laryngeal edema at the age of 30 years. Her father and elder brother also had the similar history of recurrent facial and hand swelling. The C4 levels of her elder brother were 6 mg/dl and 13.3 mg/dl on two separate occasions. The C1-INH antigen serum level and functional assay of the index patient and ten other family members were studied. A total of seven members of the family were confirmed to have type 1 HAE as evidenced by the low C4 and low C1-INH antigenic level and functional activity. Two of the seven cases were asymptomatic up to the date of our report.