Initial Curve Research Articles

Non-Uniform B-Spline Curve Interpolation Method for Feature Points Selection under Curvature Adaptive Condition

<p indent=0mm>Aiming at the massive discrete tool position data generated in the computer numerically controlled programming stage, a non-uniform B-spline curve interpolation method based on curvature adaptive selecting feature point is proposed under the condition of satisfying the preset interpolation accuracy. Firstly, the curvature of each discrete data point is calculated by the method of forming an approximate arc from three adjacent points, and the feature data points such as the segment point of the curvature segment and the maximum point of curvature are used as the initial interpolation data points to construct and generate the initial non-uniform B-spline interpolation curve. Secondly, the interpolation error calculation model is established and used to calculate the interpolation errors between all the data points not participating in the interpolation and the non-uniform B-spline interpolation curve, and the new feature points that are beyond the preset interpolation error in the curve segments are added to generate a new non-uniform B-spline interpolation curve. Repeat the above processes until all data points that are not on the non-uniform B-spline interpolation curve can meet the interpolation accuracy condition. The simulation calculation results of the actual tool position data show that the method can better retain the characteristics of the original data curve in terms of shape and accuracy even when a large amount of the original tool position data is removed, and it has advantages of fewer iteration calculations and larger removing the data points. The method will have high application value to the spline computer numerically controlled programming of massive discrete tool position data.

An optimization approach of rotor contour for variable reluctance resolver

An effective approach for optimizing the rotor contour for variable reluctance (VR) resolver is presented. Using this approach, the procedure for optimizing the rotor is divided into two parts: the establishment of initial shape curve, and then computation for the optimization. In order to simplify the process of the former, a shape function is constructed. And the latter is carried out by Taguchi optimization method and finite element method (FEM). An example of a 3–10 VR resolver is used to present the procedure of the optimization, and the testing results confirmed the effectivity of the approach.

Automatic Recognition Method of Letter Images in English Self-Learning Based on Partial Differential Equation Method

According to the current situation of knowledge popularization, students simply rely on the knowledge learned in the classroom that is far from adapting to the development of modern society; so, every student needs to have the consciousness and ability of independent learning. The research of the English self-help learning system based on partial differential equation method comes into being with information network technology as the foundation for survival and development. The existing partial differential equation recognition models based on average curvature motion are all edge-based and need to use the external force defined by the image gradient to attract the zero level set (evolution curve) to move to the target edge and finally stay on the target edge. Therefore, it is difficult to obtain ideal results when extracting fuzzy or discrete boundaries (perceptual boundaries), and it is very sensitive to the selection of initial contour and noise. To solve this problem, this paper proposes a new recognition model of partial differential equations based on mean curvature motion. This overcomes some defects of existing edge models because it is region-based and does not require image gradient as a condition to stop evolution. The proposed model can avoid manual initial curve selection and allow stopping conditions to be set in the algorithm. In addition, in the numerical solution of partial differential equations, the existing model uses upwind difference scheme, and the semi-implicit additive operator separation method is adopted in this paper. Some other layers are added, and some hyperparameters are adjusted when the convolutional neural networks of inception PDEs are constructed by stacking the structure of inception PDEs. In the contrast experiment with the prototype, the software and hardware environment are the same, and the input is exactly the same. For the handwritten English alphabet data set, the variant structure can obtain more than 90% of the training accuracy and verification accuracy, which is better than the experimental accuracy of the prototype. In addition, because the inception PDE structure contains fewer parameters than the prototype, it is more computationally efficient and takes less training time per batch than the prototype.

CML-451: Outcomes of Allogeneic Stem Cell Transplant in Chronic Myeloid Leukemia Blast Phase: A Single Center Experience from South India

Context: Blast phase (BP) remains a significant challenge in the treatment of chronic myeloid leukemia (CML). Currently, allogeneic stem cell transplant (AlloSCT) remains the best chance of cure for BP, with 3-year survival ranging from 35–40%. Outcomes of AlloSCT are better when performed in the second chronic phase. Objective: There is limited contemporary data of AlloSCT in CML-BP from resource-limited settings. We hereby present our experience of AlloSCT in patients with CML-BP Design: Retrospective study of CML-BP patients who underwent AlloSCT between October 2017 to July 2019. Median follow-up was 24 months. Setting: Tertiary institution with developing transplant unit. Patients or Other Participants: Seven CML-BP (WHO criteria) patients underwent AlloSCT at our center after reverting to chronic phase. Interventions: All patients received myeloablative conditioning and stem cells harvested from peripheral blood. Main Outcomes Measures: Leukemia-free survival (LFS) was defined as the time from the AlloSCT to relapse or death due to any cause. Overall survival (OS) was the time from AlloSCT to death due to any cause. Results: The median age was 40 years (range, 9–52), and the male-to-female ratio was 5:2. Four patients had de novo BP; the subtype of BP was lymphoid in three, myeloid in three, and mixed phenotypic (B/myeloid) in one. The median time from the diagnosis to ASCT was 6 (3–12) months. The median CD34+ dose was 7.6 (range, 6.6–8.9) x106 cells/kg. Peri-transplant toxicities within the first 100 days included febrile neutropenia with septic shock in three, cytomegalovirus (CMV) reactivation in three, ≥ grade 3 mucositis in two patients, secondary graft failure (SGF) in one, and poor graft function (PGF) in one. In both patients who had a haploidentical donor transplant, one had SGF and one had PGF. Day 100 transplant-related mortality (TRM) was observed in two patients, disseminated infections being the cause of death for both. Post-AlloSCT, all living patients received dasatinib maintenance starting at a median of 50 (47–60) days. On the last follow-up on April 30, 2021, two-year PFS and OS were 43% and 57%, respectively. Conclusions: AlloSCT can result in promising survival for carefully selected patients of CML-BP, especially with a matched sibling donor. The adverse outcome for both the haplo-transplant patients underscores the need for careful donor selection and reflects the initial learning curve. None of the authors have any relevant conflicts of interest to declare.

Brace treatment for scoliosis secondary to chiari malformation type 1 or syringomyelia without neurosurgical intervention: A matched comparison with idiopathic scoliosis.

To evaluate the effectiveness of brace treatment in patients with Chiari malformation type 1 (CM-1) or syringomyelia associated scoliosis without neurosurgical intervention. This was a retrospective case-control study. 34 CM-1 or syringomyelia (CMS) patients who received brace treatment without neurosurgical intervention were recruited. Another 68 matched patients with idiopathic scoliosis who received bracing served as the control group. The matching criteria included gender, age (± 1years), Risser sign (± 1 grade), initial curve magnitude (± 5°), curve patterns and follow-up time (± 6months). Patients who encountered curve progression and scoliosis surgery were compared between different groups. Until the last visit, 16 (47%) patients in CMS group and 18 (26%) patients in IS group occurred curve progression; 9 (26%) patients and 15 (22%) patients underwent scoliosis surgery, respectively. Compared to idiopathic scoliosis, patients with CMS-associated scoliosis had a significantly higher rate of curve progression (P = 0.038). However, no significant difference was observed between two groups regarding to the rate of surgery (P = 0.867). Patients with combined CM-1 and syringomyelia had a higher rate of surgery than patients with isolated CM-1 or syringomyelia (P = 0.049). The double major curve pattern was identified as the risk factor for curve progression. Brace treatment is effective for CMS-associated scoliosis without neurosurgical intervention. Compared to idiopathic scoliosis, brace can provide similar prevention for scoliosis surgery in CMS patients, but slight or moderate curve progression may occur. Specifically, patients with combined CM-1 and syringomyelia should be followed closely with a higher expectation of curve progression.

42. Do no harm: a retrospective analysis of the initial risk of complications in robotic spine surgery

<h3>BACKGROUND CONTEXT</h3> Incorporation of open and MIS robotic techniques in spine surgery has been growing over the past decade, resulting in altered surgical techniques and the need for newly developed skills. With the initial learning curve involved in using this new technology, the upfront risk of complications and poor outcomes during the learning process has been understudied in the literature. <h3>PURPOSE</h3> To evaluate the initial risk of complications with the incorporation of robotic assisted spine surgery. <h3>STUDY DESIGN/SETTING</h3> Retrospective review of a national patient database between 2007-2016. <h3>PATIENT SAMPLE</h3> A total of 3,759,824 elective spine surgery patients. <h3>OUTCOME MEASURES</h3> Comorbidity burden, perioperative complication rates, year-to-year complications, mechanical complications. <h3>METHODS</h3> Inclusion criteria: elective spine surgery procedures from 2007-2016 as defined by ICD-9-CM and ICD-10-CM codes. Exclusion criteria: emergency, trauma or nonelective surgery. Descriptive statistics assessed demographic information. Rates of open and MIS robot-assisted procedures were assessed, as well as trends in postoperative complications and length of stay. Logistic regressions were performed to see if robotic use was independently predictive of a postoperative complication. <h3>RESULTS</h3> The study included 3,759,824 elective spine surgery patients. Overall, 4,185 patients underwent robotic spine surgery (0.1%). There was a significant increase from in robotic surgery cases from 2010 to 2016 with 11 patients in 2010 to 1,535 patients in 2016 (p<0.001). During this time, 93% of robotic spine cases were open compared to 7% MIS (p<0.001). Relative to nonrobotic patients, robotic-spine patients presented with higher rates of anemia, rheumatoid arthritis, uncomplicated diabetes, hypertension, hypothyroidism, fluid and electrolyte disorders (all p<0.001). Overall, robotic-spine patients had higher overall perioperative complication rates, including cardiac, urinary and anemia (all p<0.001). Postoperatively, year-to-year overall complications in robotic surgery patients increased from 25% in 2011 to 29.6% in 2016 (p <0.001), with a high of 31.8% in 2015. Robotic-open cases compared to robotic-MIS cases were shown to have significantly higher overall complications (28.2 vs 13.6%, p<0.001), including complications associated with anemia and mechanical complications (both p<0.001). <h3>CONCLUSIONS</h3> The rise of robotic assisted spine surgery has yielded a concurrent rise in perioperative complications as surgeons adjust to this new technology. Until the learning curve lessens for incorporation of robotic techniques in spine surgery, providers should weigh MIS or open robotic procedures with an eye towards perioperative complications. <h3>FDA DEVICE/DRUG STATUS</h3> This abstract does not discuss or include any applicable devices or drugs.

Performing Multiple Posterior Spinal Fusions in 1 Day: A Comparison of Perioperative Outcomes Between Morning and Afternoon Cases.

High-volume centers for idiopathic scoliosis (IS) have difficulty in scheduling posterior spinal fusions (PSFs) due to operating room availability, particularly during school vacation. A solution is for 1 surgeon to perform 2 PSF cases back-to-back. This study aims to compare morning and afternoon PSF cases performed by the same surgeon for perioperative outcomes. A retrospective review of PSF cases for IS that occurred on the same day as another PSF by the same surgeon between January 2013 and December 2019 was conducted. Perioperative outcomes included surgical time, estimated blood loss, length of stay, and inpatient opioid consumption normalized by the patient's weight. Postoperative outcomes included complications, revision rate, curve correction, and patient-reported outcomes using the Scoliosis Research Society-30. A total of 95 patients (87% female), mean age 15.6 years, were analyzed, with 48 morning cases and 47 afternoon cases. The median follow-up was 1.9 years (range: 0.3 to 6.1 y). Tests for equivalency determined equivalence in median anesthesia and mean surgical duration (P=0.05). The groups had similar initial curve correction (P=0.43) and rate of complications at 90 days postoperative (2 in each group for a total of 4 complications). No significant differences were seen between Scoliosis Research Society-30 scores at 6 months or in those who have reached 2 years postoperative. Little literature exists on the safety of a surgeon performing 2 PSF cases in 1 day, particularly in regard to pain outcomes, 30- and 90-day complication rates, and quality of life measures. This study indicates that few differences in safety, pain, and quality of life outcomes may appear between morning and afternoon PSF cases. Level II.

Predictive Factors for Outcomes of Overcorrection Nighttime Bracing in Adolescent Idiopathic Scoliosis: A Systematic Review.

Predictive clinical and radiological factors can potentially identify adolescent idiopathic scoliosis (AIS) most likely to benefit from overcorrection nighttime bracing. These factors can provide helpful information in clinical decision making. However, the relationship between these factors and outcomes of overcorrection nighttime bracing is unclear. This systematic review determined the predictive factors for identifying outcomes of overcorrection nighttime bracing in AIS. A systematic search was conducted on PubMed, MEDLINE, Scopus, and Embase from January 1986 to January 2021. Studies on AIS patients, aged 10–18 years, with a Risser sign of 0–2 and an initial Cobb angle of 20°–45°, who were treated with overcorrection nighttime bracing and for whom at least one predictive factor of treatment outcome (failure and/or success) was assessed were included. Two blinded reviewers independently evaluated the studies using a quality assessment tool. To determine predictive factors, the level of evidence was rated through best-evidence synthesis. A total of nine studies met the inclusion criteria. A Providence brace was used in six of the included studies, while a Charleston bending brace was used in three. Findings from two high-quality studies provided strong evidence of the association between curve flexibility and brace treatment success. In terms of the Risser sign, this evidence was obtained from three high-quality studies. Moderate evidence indicated a positive association between premenarchal status and nighttime bracing failure. Inconclusive evidence indicated that poor brace compliance is associated with treatment failure. Conflicting evidence of treatment failure was indicated for initial curve magnitude, curve type, in-brace correction, age, Risser sign, curve apex, and sex. These findings show that greater curve flexibility and a higher Risser sign are associated with overcorrection nighttime bracing success.

Imageless robotic handpiece-assisted total knee arthroplasty: a learning curve analysis of surgical time and alignment accuracy

IntroductionRobotic-assisted surgery techniques are increasing in total knee arthroplasty (TKA). One crucial point is the prolonged time of surgery. The primary objective of this study was to determine the learning curve necessary to minimize the time of surgery. The secondary objective was to evaluate the accuracy of the implant alignment when using an imageless robotic system for TKA.Materials and methodsIn a case–control study, the first 70 consecutive robotic-assisted TKA procedures performed by a single senior surgeon were analyzed with regard to surgery time and implant alignment by comparing the intraoperative plan with the postoperative alignment. The evaluation of the learning curve with respect to surgery time was conducted using cumulative summation (CUSUM) analysis. The joint line height was measured with a new technique. Surgery time and joint line reconstruction were compared to 70 consecutive conventional TKA procedures.ResultsThe learning curve for robotic TKA was completed after 11 cases. The learning curve did not influence the accuracy of joint line obliquity, joint line height, or limb alignment. The intraoperative plan designed for the robotic system was precisely implemented. The mean skin-to-skin time in the robotic group after the learning curve was completed did not differ from that in the manual group. A significant positive correlation was observed between the preoperative hip–knee–ankle angle and the postoperative distalization of the joint line in the robotic-assisted TKA group.ConclusionAfter completing the initial learning curve of 11 cases, the surgery time required to perform imageless robotic handpiece-assisted TKA was similar to that for the conventional technique. However, no learning curve was observed for the implant positioning when using the imageless robotic system. The implementation of the intraoperative plan was accurate up to < 2°. The precision of the system allows the implementation of different joint balancing approaches between valgus and varus morphotypes.

A novel state of health estimation method for lithium-ion battery based on partial incremental capacity and Support vector regression

State of Health (SOH) is critical for lithium-ion batteries as it ensures the safety of batteries’ health condition and provides a basis for retirement of the batteries. In order to provide an accurate estimation of the SOH, a novel hybrid estimation method based on the partial incremental capacity and Support vector regression (SVR) is proposed in this paper. Firstly, the Savitzky-Golay method is applied to smooth the initial incremental capacity curves under the period of constant current charge. Then the key health features are extracted from the partial incremental curve theoretically and selected through correlation analysis methods. Finally, an SVR model is constructed to estimate the SOH. Several battery datasets under different cycling test conditions are used to validate the effectiveness of the proposed method. The result shows that the proposed method can provide a reliable and accurate estimation for SOH.

Extraction of Cerebral Hemorrhage on CT Images Using Level Set Algorithm and Otsu Threshold

Extraction of cerebral hemorrhage on CT images has always been the focus of several research hotspots and is still challenging as it does not show clear boundary. In this paper, a novel segmentation framework is presented for extracting the cerebral hemorrhage in brain CT images with weak boundary. Firstly, we utilize the Otsu threshold algorithm to get the coarse outline approximate to the target boundary as the initial curve of level set algorithm. Then, the active contour model is employed using both edge information and global Gaussian distribution fitting energy of images to modify energy function of level set. The proposed approach is applied on real images which from Quzhou People’s Hospital. Compared to manual delineation, the proposed technique shows a higher JS value than the existing methods and requires less interaction which is listed in the literature.

In vivo deformation of anatomically pre-bent rods in thoracic adolescent idiopathic scoliosis

Some surgical strategies can maintain or restore thoracic kyphosis (TK); however, next-generation surgical schemes for adolescent idiopathic scoliosis (AIS) should consider anatomical corrections. A four-dimensional correction could be actively achieved by curving the rod. Thus, anatomically designed rods have been developed as notch-free, pre-bent rods for easier anatomical reconstruction. This study aimed to compare the initial curve corrections obtained using notch-free rods and manually bent, notched rods for the anatomical reconstruction of thoracic AIS. Two consecutive series of 60 patients who underwent anatomical posterior correction for main thoracic AIS curves were prospectively followed up. After multilevel facetectomy, except for the lowest instrumented segment, either notch-free or notched rods were used. Patient demographic data, radiographic measurements, and sagittal rod angles were analyzed within 1 week after surgery. Patients with notch-free rods had significantly higher postoperative TK than patients with notched rods (P < .001), but both groups achieved three-dimensional spinal corrections and significantly increased postoperative rates of patients with T6–T8 TK apex (P = .006 for notch-free rods and P = .008 for notched rods). The rod deformation angle at the concave side was significantly lower in the notch-free rods than in the notched rods (P < .001). The notch-free, pre-bent rod can maintain its curvature, leading to better correction or maintenance of TK after anatomical spinal correction surgery than the conventional notched rod. These results suggest the potential benefits of anatomically designed notch-free, pre-bent rods over conventional, manually bent rods.

METHOD FOR OPTIMIZING OF MOBILE ROBOT TRAJECTORY IN REPELLER SOURCES FIELD

The article discusses the procedure for correcting the trajectory of a robotic platform (RTP) on a plane in order to reduce the probability of its defeat/detection in the field of a finite number of repeller sources. Each of these sources is described by a mathematical model of some factor of counteraction to the RTP. This procedure is based, on the one hand, on the concept of a characteristic probability function of a system of repeller sources, which allows us to assess the degree of influence of these sources on the moving RTP. From this concept follows the probability of its successful completion used here as a criterion for optimizing the target trajectory. On the other hand, this procedure is based on solving local optimization problems that allow you to correct individual sections of the initial trajectory, taking into account the location of specific repeller sources with specified parameters in their vicinity. Each of these sources is characterized by the potential, frequency of impact, radius of action, and parameters of the field decay. The trajectory is adjusted iteratively and takes into account the target value of the probability of passing. The main restriction on the variation of the original trajectory is the maximum allowable deviation of the changed trajectory from the original one. If there is no such restriction, then the task may lose its meaning, because then you can select an area that covers all obstacles and sources, and bypass it around the perimeter. Therefore, we search for a local extremum that corresponds to an acceptable curve in the sense of the specified restriction. The iterative procedure proposed in this paper allows us to search for the corresponding local maxima of the probability of RTP passage in the field of several randomly located and oriented sources, in some neighborhood of the initial trajectory. First, the problem of trajectory optimization is set and solved under the condition of movement in the field of single source with the scope in the form of a circular sector, then the result is extended to the case of several similar sources. The main problem of the study is the choice of the General form of the functional at each point of the initial curve, as well as its adjustment coefficients. It is shown that the selection of these coefficients is an adaptive procedure, the input variables of which are characteristic geometric values describing the current trajectory in the source field. Standard median smoothing procedures are used to eliminate oscillations that occur as a result of the locality of the proposed procedure. The simulation results show the high efficiency of the proposed procedure for correcting the previously planned trajectory.

Learning Curve for Left Bundle Branch Area Pacing – the Experience of a Romanian Academic Center

Abstract Introduction There is an increasing interest in the past decade for more physiological pacing strategies due to detrimental long-term right ventricular pacing. His bundle pacing is the most physiological one, but it has some drawbacks, mainly an increased pacing threshold. Left bundle branch area pacing (LBBAP) emerged in the recent years as the next step in conduction system pacing. We present our initial experience and learning curve with this latter procedure. Material and methods During January 2019 and February 2021, 20 patients with pacing indications that failed initial permanent His bundle pacing underwent successful LBBAP. Results The mean age was 65.9 ± 12.7 years. The indications for cardiac pacing were AV block in 14 patients (70%) and cardiac resynchronization therapy in 6 patients (30%). At baseline, normal QRS complex was noted in 9 patients, a left bundle branch block pattern in 10 patients and a right bundle branch block in one patient. A total of 18 dual-chamber and one single chamber pacemakers were implanted and a cardiac resynchronization therapy defibrillator (CRT-D) device. The acute pacing threshold was 0.56±0.2 V at 0.4ms, the sensing threshold was 10.3±3.9 mV and the impedance was 684.9±112.2 Ω. The overall QRS duration decreased after LBBAP from 128.5 ± 27ms to 103.6 ± 17.4ms (p= 0.001). In patients with baseline wide QRS complex there was a highly significant decrease from 148.2 ± 11.6 ms to 104.7 ± 19.4 ms (p&lt;0.001). The fluoroscopy time, including the time spent for His bundle location, was 13.8 ± 8.5 minutes. The pacing thresholds remained constant after three-months (0.6 ± 0.2 V vs. 0.56 ± 0.2 V at 0.4 ms). We had two intraprocedural septal perforations without any consequences and three micro dislodgements at follow-up with pure left septal capture. Conclusion Left bundle branch area pacing is a feasible physiological pacing technique with a high success rate and the potential to overcome the limits of permanent His bundle pacing. It can be successfully performed virtually in all types of pacing indications, including cardiac resynchronization therapy as provides a rapid and synchronous activation of the left ventricle.

What happens to the unfused upper thoracic curve after posterior spinal fusion for adolescent idiopathic scoliosis?

Spontaneous lumbar curve correction after selective thoracic fusion in surgery for adolescent idiopathic scoliosis (AIS) is well described. However, only a few articles have described the course of the uninstrumented upper thoracic (UT) curve after fusion, and the majority involve a hybrid construct. In this study, the authors sought to determine the outcomes and associated factors of uninstrumented UT curves in patients with AIS. The authors retrospectively reviewed a prospectively collected multicenter AIS registry for all consecutive patients with Lenke type 1-4 curves with a 2-year minimum follow-up. UT curves were considered uninstrumented if the upper instrumented vertebra (UIV) did not extend above 1 level from the lower end vertebra of the UT curve. The authors defined progression as > 5°, and divided patients into two cohorts: those with improvement in the UT curve (IMP) and those without improvement in the UT curve (NO IMP). Radiographic, demographic, and Scoliosis Research Society (SRS)-22 survey outcome measures were compared using univariate analysis, and significant factors were compared using a multivariate regression model. The study included 450 patients (370 females and 80 males). The UT curve self-corrected in 86% of patients (n = 385), there was no change in 14% (n = 65), and no patients worsened. Preoperatively, patients were similar with respect to Lenke classification (p = 0.44), age (p = 0.31), sex (p = 0.85), and Risser score (p = 0.14). The UT curves in the IMP group self-corrected from 24.7° ± 6.5° to 12.6° ± 5.9°, whereas in the NO IMP group UT curves remained the same, from 20.3° ± 5.8° to 18.5° ± 5.7°. In a multivariate analysis, preoperative main thoracic (MT) curve size (p = 0.004) and MT curve correction (p = 0.001) remained significant predictors of UT curve improvement. Greater correction of the MT curve and larger initial MT curve size were associated with greater likelihood of UT curve improvement. Spontaneous UT curve correction occurred in the majority (86%) of unfused UT curves after MT curve correction in Lenke 1-4 curve types. The magnitude of preoperative MT curve size and postoperative MT curve correction were independent predictors of spontaneous UT curve correction.

87 Profitability and medical resource optimization of minimally invasive hysterectomy approach

The objective of this study was to assess the profitability of minimally invasive hysterectomy approach within a hospital system with a mature robotics program. Financial data for all hysterectomies were collected between January 2018 through December 2019. All cost data were collected in real time. Hysterectomies were grouped based upon the approach used, defined as either simple robotic, simple laparoscopic or simple vaginal procedures. Robotic and laparoscopic hysterectomy were then compared to vaginal hysterectomy using a two-sided, independent measures t-test with a P value < 0.05 considered statistically significant. There were 859 robotic, 128 laparoscopic and 155 vaginal hysterectomies that were analyzed. Vaginal hysterectomy was associated with the shortest operative time, followed by robotic and laparoscopic approach. Vaginal hysterectomy was associated with a significantly lower direct cost when compared to robotic approach and a similar direct cost to laparoscopic approach. Robotic approach was associated with largest profit per minutes and profit margin. The studied hospital system functions as a mature robotics program where all surgeons operate well beyond the initial learning curve in robotics. With an optimized robotics program, vaginal hysterectomy remains superior in regard to operative time and direct cost. However, robotic approach is more profitable. This unique evaluation of profits allows for greater resource optimization within the healthcare system.

Catheter ablation with ethanol infusion in the vein of marshall for persistent atrial fibrillation: safety and procedure duration

Abstract Funding Acknowledgements Type of funding sources: None. Background Ethanol Infusion in the Vein of Marshall (EIVOM) has been recently introduced as an efficient technique that helps achieving mitral isthmus block during ablation procedures for persistent atrial fibrillation (PAF) or peri-mitral atrial flutter. Purpose We have evaluated the safety of EIVOM and the duration required to perform this procedure. Methods We performed EIVOM in 121 patients for PAF (mean age of 65 years (range 40-83, 73% men; Mean EF 50%. The main steps of the EIVOM were as follows: the procedure commenced with catheterization of the coronary sinus, followed by the subsequent introduction of an angiography catheter that allowed for iodine contrast injection and vein of Marshall (VOM) localization, 1.5-2.5 mm angioplasty balloon over 0.014" guidewire placement and finally the ethanol injection up to 10 ml. Results No major complications were observed during the ablation procedure or before hospital discharge. In 62 patients in whom procedure duration data was available the mean EIVOM procedure time was 41 min (range from 13 to 105 min). After the first 20 procedures, where the learning curve for the operators has to be taken into consideration, a reduction in the time required to achieve EIVOM was consistently noted, with an average of less than 30 min. and for the last 20 procedures less than 20 min. Factors which increase the time required for successful EIVOM include: difficulty in visualizing the ostium of the VOM, a VOM ostium located proximally, difficulty in advancing the angioplasty wire into the VOM and balloon displacement and repositioning. Conclusions Ethanol infusion in the Vein of Marshall is a safe and efficient technique that can be performed in an acceptable amount of time after an initial learning curve. Abstract Figure. Image 1 VOM

Predictive factors for early discharge (≤24 hours) and re-admission following robotic-assisted laparoscopic pyeloplasty in children.

Minimally invasive pyeloplasty (MIP) for correction of ureteropelvic junction obstruction in children has significantly improved the postoperative management of these patients. In this study, we sought to examine the factors associated with early discharge (≤24 hours) in children who underwent robotic-assisted laparoscopic pyeloplasty (RALP). We performed a retrospective chart review of all children who underwent RALP from 2012-2018 in our center. Descriptive statistics and a non-adjusted risk analysis were performed to evaluate the factors associated with early discharge (≤24h), re-admission, and complications within the first 30 days after the procedure. Eighty-nine patients out of 124 total pyeloplasties (72%) stayed ≤24 hours post-surgery. Of the variables analyzed, later cases were statistically associated with length of stay (LOS); the first 55 patients had a lower probability of being hospitalized for ≤24 hours (odds ratio [OR] 0.24, 95% confidence interval [CI] 0.09-0.64, p=0.004). RALP for children is associated with a high rate of early recovery, short hospital stay, and low re-admission and complication rates. Although not statistically significant, patients with shorter operative room time also had a shorter LOS. An increased LOS was observed in the initial patients of our series, and this is most likely explained by the initial learning curve of the team for the procedure itself and the more conservative postoperative management.

Studies of thermoluminescence kinetic parameters of polymer pencil lead graphite under photon exposures

This study analysed thermoluminescence (TL) glow curves of the polymer pencil lead graphite (PPLG) due to its potential applications in radiation dosimetry. The TL glow curves provide information on the physical parameters of the defects participating in luminescence process. The glow curves for different diameters PPLG samples were obtained with varying temperature from 50 to 300 °C, at a fixed heating rate of 10 °Cs−1. A number of methods (initial rise, peak shape and curve fitting) were used to fit the TL glow peaks of the PPLG samples obtained under photon dose of 200 Gy. From the fitted TL signals, the trap parameters such as the order of kinetics, the activation energy, the frequency factor, etc. for the individual peaks were numerically determined. The lifetimes of TL process were calculated assuming the first-order kinetics. The results are compared among the different methods adopted in this study. Implications about the possible results in glow curve deconvolution are discussed.

Analysis of factors associated with unintended initial dissection of the posterior plane during small incision lenticule extraction.

BackgroundTo investigate potential risk factors for unintended initial dissection of the posterior plane in the initial learning curve of small incision lenticule extraction (SMILE).MethodsData were derived from consecutive 263 eyes of 136 patients who underwent SMILE at the beginning of the surgeon’s learning curve. Probabilities of unintended initial dissection of the posterior plane in left and right eyes were analyzed. Preoperative sphere, cylinder, spherical equivalent (SE), J0, J45, lenticular diameter, lenticular thickness, corneal thickness, and axial length were assessed between eyes in which posterior plane dissection was unintended and those in which it was not.ResultsUnintended initial dissection of the posterior plane occurred in 29 eyes, corresponding to an incidence rate of 11.03%. The probability of difficulty in plane dissection in the left eye was significantly higher than that in the right eye (P=0.003). Significant differences were found in sphere (T =2.8, P=0.006), SE (T =2.37, P=0.019), J0 (T =2.05, P=0.043) and axial length (T =−2.79, P=0.006) between eyes with and without unintended initial dissection of the posterior plane.ConclusionsIn the present study, difficulty in plane dissection during SMILE was encountered significantly more often in left eyes for a right-hand doctor, and in eyes with low SE or high J0 values. Special attention should be paid to prevent unintended initial dissection of the posterior plane in such situations.