Dynamic Cell Imaging: application to the diatom Phaeodactylum tricornutum under environmental stresses

The dynamic movement of cell organelles is an important and poorly understood component of cellular organisation and metabolism. In this work we present a non-invasive non-destructive method (Dynamic Cell Imaging, DCI) based on light scattering and interferometry to monitor dynamic events within photosynthetic cells using the diatom Phaeodactylum tricornutum as a model system. For this monitoring we acquire few seconds movies of the signals that are related to the motion of dynamic structures within the cell (denoted scatterers), followed by a statistical analysis of each pixel time series. Illuminating P.tricornutum with LEDs of different wavelengths associated to short pulsed or continuous-wave modes of illumination revealed that dynamic movements depend on chloroplast activity, in agreement with the reduction in the number of pixels with dynamic behaviour after addition of photosystemII inhibitors. We studied P. tricornutum under two environmentally relevant stresses, iron and phosphate deficiency. The major dynamic sites were located within lipid droplets and chloroplast envelope membranes. By comparing standard deviation and cumulative sum analysis of the time series, we showed that within the droplets two types of scatterer movement could be observed: random motions (Brownian type) but also anomalous movements corresponding to a drift which may relate to molecular fluxes within a cell. The method appears valuable for studying the effects of various environments on a large variety of microalgae in the laboratory as well as in natural aquatic environments.

Learning Curve from 100 Cases of Totally Thoracoscopic Mitral Valve Replacement

Background: To investigate and analyze the learning curve of totally thoracoscopic mitral valve replacement and provide a quantitative reference for cardiac surgeons to carry out the operation step by step. Methods: The clinical data were retrospectively analyzed of 100 consecutive patients with totally thoracoscopic mitral valve replacement successively performed by the same surgeon in a single center from May 2019 to June 2020. The learning curve was divided into 2 stages by using cumulative sum analysis, and relevant surgical parameters and perioperative indicators were analyzed. Results: The first stage of the learning curve is the skill acquisition stage, which includes 1 to 40 surgical procedures. The second stage is the proficiency stage, involving 41 to 100 operations. Among the surgical parameters of the patients in the 2 stages, detectable improvements were observed in operative time, cardiopulmonary bypass time, cross-clamp time, and intraoperative injury. After surgery, the amount of drainage, length of hospital stay, blood creatinine levels, and oxygenation index 24 h after surgery were also significantly different between the 2 groups (all P < .05). The age and sex distributions of the patients were balanced, and there was no statistically significant difference in terms of conversion to median sternotomy between the 2 stages (P > .05). Conclusions: Cumulative sum analysis was used to accurately analyze the learning curve of totally thoracoscopic mitral valve replacement, indicating that 40 cases are needed to master the technique.

Assessment of the learning curve of total thoracoscopic mitral valve repair using cumulative sum analysis (CUSUM)

Objective: To evaluate the learning curve and safety of total thoracoscopic mitral valve repair (MVP). Background: Total thoracoscopic MVP is characterized by minimal trauma, minimal bleeding, and short postoperative recovery time. The learning curve of any new procedure needs to be evaluated for learning and replication. However, minimally invasive mitral valve technique is a wide-ranging concept, no further analysis of the outcomes and learning curve of total thoracoscopic mitral valve repair has been performed. Methods: One hundred and fifty consecutive patients who underwent minimally invasive MVP alone without concurrent surgery were evaluated. Using Cardiopulmonary bypass (CPB) time and Aortic clamping (AC) time as evaluation variables, we visualized the learning curve for total thoracoscopic MVP using Cumulative sum analysis. We also analyzed important postoperative variables such as postoperative drainage, duration of mechanical ventilation, ICU stay and postoperative hospital stay. Results: The slope of the fitted curve was negative after 75 procedures, and the learning curve could be crossed after the completion of the 75th procedure when AC and CPB time were used as evaluation variables. And as the number of surgical cases increased, CPB, AC, postoperative drainage, duration of mechanical ventilation, ICU stay and postoperative hospital stay all showed different degrees of decrease. The incidence of postoperative adverse events is similar to conventional mitral valve repair. Conclusions: Compared to conventional MVP, total thoracoscopic MVP provides the same satisfactory surgical results and stabilization can be achieved gradually after completion of the 75th procedure.

The Learning Curve of Computer-Assisted Free Flap Jaw Reconstruction Surgery Using 3D-Printed Patient-Specific Plates: A Cumulative Sum Analysis

BackgroundComputer-assisted jaw reconstruction (CAJR) has benefits in reducing operation time and improving reconstruction accuracy, compared to conventional freehand jaw reconstruction. However, no information is available regarding learning curves in CAJR with the use of 3D-printed patient-specific surgical plates (PSSP). The purpose of this study was to assess surgical outcomes and learning curve for the first 58 consecutive CAJR using 3D-printed PSSP performed by a single surgical team in a single institution.MethodsIn a prospective study, consecutive patients who underwent free flap CAJR using 3D-printed PSSP were included. The determination of proficiency, based on the cumulative sum of surgical success (no major adjustment of 3D-printed PSSP, flap survival) passing the acceptable boundary line of cumulative sum analysis, was the primary outcome. To find out any potential factors influencing the learning curve, baseline characteristics of patients were compared before and after proficiency achievement. Secondary outcomes included inflexion points of the total operation time, blood loss, length of hospital stay, and bone graft deviation, measured by the cumulative sum analysis.ResultsFrom December 2016 to November 2020, 58 consecutive cases underwent surgery performed by a single surgical team. The overall surgical success rate was 94.8% (55/58). A three-stage learning curve of primary outcome was observed. The proficiency was achieved after 23 cases. The proportions of advanced tumor staging and concomitant surgery after obtaining proficiency were significantly higher than those before achieving proficiency (p = 0.046 and p &lt; 0.001, respectively). Mean values of operation time, intraoperative blood loss, length of hospital stay, and bone graft deviation were 532.5 ± 119.2 min, 1,006.8 ± 547.2 ml, 16.1 ± 6.3 days, and 0.9 ± 1.2 mm, respectively. Two trends of learning curve were observed in the CUSUM analyses of total operation time, length of hospital stay, and bone graft deviation, in which the first and second inflexion points occurred between 8 and 17 cases and between 43 and 46 cases, respectively.ConclusionOur results revealed a three-stage learning curve of CAJR with the use of PSSP, including initial learning, plateau, and overlearning. Based on CUSUM analysis, the surgical proficiency was achieved after 23 cases, and total operation time, length of hospital stay, and bone graft deviation stabilized after 8–17 cases.

Assessing ultrasound-guided axillary vein cannulation using a cumulative sum analysis: A single operator experience

Background: Ultrasound-guided axillary vein (AxV) cannulation has been described as an effective alternative to internal jugular vein cannulation in adult cardiac surgical patients. However, the learning curve for this technique has not yet been addressed. This study aimed to determine the number of cases required to achieve proficiency in performing AxV cannulation among novice anesthesiologists. Methods: This prospective study included the first 60 patients who underwent ultrasound-guided AxV cannulation performed by a single third-year resident who was trained in adult cardiac anesthesia. This study investigated the number of cases required to gain technical proficiency by applying cumulative sum analysis on the learning curve (LC-CUSUM) of ultrasound-guided AxV cannulation. Results: Based on the assessment of the CUSUM plots, a descending inflection point for decreasing the overall procedural time for AxV cannulation was observed after patient 29. Regarding the procedural outcomes, comparing the early-experience group with the late-experience group (29 vs 31 cases), the former group had longer operating time (1526 s vs 1120 s, p < 0.001) and identification time (110 s vs 92 s, p < 0.001) and lower first-attempt success rate (8, 27.6% vs 30, 96.8%, p < 0.001) than the latter group. Conclusions: CUSUM demonstrated that at least 29 successful cases are required to achieve an expertized manipulation in ultrasound-guided AxV cannulation for inexperienced novices. The learning curve for ultrasound-guided AxV cannulation was observed in 29 cases. After adequate training, the overall procedural time and the first-attempt success rate, and puncture-related complications for AxV cannulation improved with increased experience.

Lung ultrasound training and evaluation for proficiency among physicians in a low-resource setting

Background Lung ultrasound (LUS) is helpful for the evaluation of patients with dyspnea in the emergency department (ED). However, it remains unclear how much training and how many LUS examinations are needed for ED physicians to obtain proficiency. The objective of this study was to determine the threshold number of LUS physicians need to perform to achieve proficiency for interpreting LUS on ED patients with dyspnea. Methods A prospective study was performed at Patan Hospital in Nepal, evaluating proficiency of physicians novice to LUS. After eight hours of didactics and hands-on training, physicians independently performed and interpreted ultrasounds on patients presenting to the ED with dyspnea. An expert sonographer blinded to patient data and LUS interpretation reviewed images and provided an expert interpretation. Interobserver agreement was performed between the study physician and expert physician interpretation. Cumulative sum analysis was used to determine the number of scans required to attain an acceptable level of training. Results Nineteen physicians were included in the study, submitting 330 LUS examinations with 3288 lung zones. Eighteen physicians (95%) reached proficiency. Physicians reached proficiency for interpreting LUS accurately when compared to an expert after 4.4 (SD 2.2) LUS studies for individual zone interpretation and 4.8 (SD 2.3) studies for overall interpretation, respectively. Conclusions Following 1 day of training, the majority of physicians novice to LUS achieved proficiency with interpretation of lung ultrasound after less than five ultrasound examinations performed independently.