Effects of varying blood flow rate during peripheral veno-arterial extracorporeal membrane oxygen (V-A ECMO) on left ventricular function measured by two-dimensional strain

BackgroundWe evaluated the effects of varying blood flow rate during peripheral veno-arterial extracorporeal membrane oxygen (V-A ECMO) on left ventricular function measured by two-dimensional strain.MethodsAdult patients who were supported by peripheral V-A ECMO were recruited. Serial hemodynamic and cardiac performance parameters were measured by transthoracic echocardiogram within the first 48 h after implementation of V-A ECMO. Measurements at 100%, 120%, and 50% of target blood flow (TBF) were compared.ResultsA total of 54 patients were included and the main indications for V-A ECMO were myocardial infarction [32 (59.3%)] and myocarditis [6 (11.1%)]. With extracorporeal blood flow at 50% compared with 100% TBF, the mean arterial pressure was lower [66 ± 19 vs. 75 ± 18 mmHg, p < 0.001], stroke volume was greater [23 (12–34) vs. 15 (8–26) ml, p < 0.001], and cardiac index was higher [1.2 (0.7–1.7) vs. 0.8 (0.5–1.3) L/min/m2, p < 0.001]. Left ventricular contractile function measured by global longitudinal strain improved at 50% compared with 100% TBF [−2.8 (−7.6- −0.1) vs. −1.2 (−5.2–0) %, p < 0.001]. Similarly, left ventricular ejection fraction increased [24.4 (15.8–35.5) vs. 16.7 (10.0–28.5) %, p < 0.001] and left ventricular outflow tract velocity time integral increased [7.7 (3.8–11.4) vs. 4.8 (2.5–8.5) cm, p < 0.001]. Adding echocardiographic parameters of left ventricular systolic function to the Survival After Veno-arterial ECMO (SAVE) score had better discriminatory value in predicting eventual hospital mortality (AUROC 0.69, 95% CI 0.55–0.84, p = 0.008) and successful weaning from V-A ECMO (AUROC 0.68, 95% CI 0.53–0.83, p = 0.017).ConclusionIn the initial period of V-A ECMO support, measures of left ventricular function including left ventricular ejection fraction and global longitudinal strain were inversely related to ECMO blood flow rate. Understanding the heart-ECMO interaction is vital to interpretation of echocardiographic measures of the left ventricle while on ECMO

Sport-specific balance ability in Taekwondo practitioners

ABSTRACT Fong SSM, Cheung CKY, Ip JY, Chiu JHN, Lam KLH, Tsang WWN. Sport-specific balance ability in Taekwondo practitioners. J. Hum. Sport Exerc. Vol. 7, No. 2, pp. 520-526, 2012. Taekwondo is a combat sport emphasizing on kicking techniques and dynamic footwork. Specialized balance ability is crucial for Taekwondo practitioners. This study aimed to compare (1) the postural stability during turning, and (2) the forward lunge distance between adolescent TKD practitioners and non-practitioners. Nineteen TKD practitioners (12 males, 7 females; Mean age ± SD: 15.58 ± 1.07 years) and nineteen control participants (13 males, 6 females; Mean age ± SD: 16.21 ± 0.98 years) were recruited in the study. Balance performance was assessed by the Forward Lunge Test and Step/Quick Turn Test with the NeuroCom Balance Master system. Forward lunge distance, turn time and turn sway were measured. TKD practitioners were found to turn faster by 35.37% (p=0.004) and sway less during turning by 15.23% (p=0.034) than non-practitioners. The forward lunge distance in TKD practitioners was 5.67% shorter than that in control participants (p=0.046). This study shows that TKD practitioners might have sport-specific balance ability. The findings of this study inspire the exploration of the longitudinal training effect of TKD so as to develop the evidence base for this exercise option to improve the postural control of adolescents with balance problems

The photometric observation of the quasi-simultaneous mutual eclipse and occultation between Europa and Ganymede on 22 August 2021

Mutual events (MEs) are eclipses and occultations among planetary natural satellites. Most of the time, eclipses and occultations occur separately. However, the same satellite pair will exhibit an eclipse and an occultation quasi-simultaneously under particular orbital configurations. This kind of rare event is termed as a quasi-simultaneous mutual event (QSME). During the 2021 campaign of mutual events of jovian satellites, we observed a QSME between Europa and Ganymede. The present study aims to describe and study the event in detail. We observed the QSME with a CCD camera attached to a 300-mm telescope at the Hong Kong Space Museum Sai Kung iObservatory. We obtained the combined flux of Europa and Ganymede from aperture photometry. A geometric model was developed to explain the light curve observed. Our results are compared with theoretical predictions (O-C). We found that our simple geometric model can explain the QSME fairly accurately, and the QSME light curve is a superposition of the light curves of an eclipse and an occultation. Notably, the observed flux drops are within 2.6% of the theoretical predictions. The size of the event central time O-Cs ranges from -14.4 to 43.2 s. Both O-Cs of flux drop and timing are comparable to other studies adopting more complicated models. Given the event rarity, model simplicity and accuracy, we encourage more observations and analysis on QSMEs to improve Solar System ephemerides.Comment: 23 pages, 5 appendixes, 16 figures, 7 table

Robust estimation of bacterial cell count from optical density

Optical density (OD) is widely used to estimate the density of cells in liquid culture, but cannot be compared between instruments without a standardized calibration protocol and is challenging to relate to actual cell count. We address this with an interlaboratory study comparing three simple, low-cost, and highly accessible OD calibration protocols across 244 laboratories, applied to eight strains of constitutive GFP-expressing E. coli. Based on our results, we recommend calibrating OD to estimated cell count using serial dilution of silica microspheres, which produces highly precise calibration (95.5% of residuals <1.2-fold), is easily assessed for quality control, also assesses instrument effective linear range, and can be combined with fluorescence calibration to obtain units of Molecules of Equivalent Fluorescein (MEFL) per cell, allowing direct comparison and data fusion with flow cytometry measurements: in our study, fluorescence per cell measurements showed only a 1.07-fold mean difference between plate reader and flow cytometry data

Reducing the environmental impact of surgery on a global scale: systematic review and co-prioritization with healthcare workers in 132 countries

Abstract Background Healthcare cannot achieve net-zero carbon without addressing operating theatres. The aim of this study was to prioritize feasible interventions to reduce the environmental impact of operating theatres. Methods This study adopted a four-phase Delphi consensus co-prioritization methodology. In phase 1, a systematic review of published interventions and global consultation of perioperative healthcare professionals were used to longlist interventions. In phase 2, iterative thematic analysis consolidated comparable interventions into a shortlist. In phase 3, the shortlist was co-prioritized based on patient and clinician views on acceptability, feasibility, and safety. In phase 4, ranked lists of interventions were presented by their relevance to high-income countries and low–middle-income countries. Results In phase 1, 43 interventions were identified, which had low uptake in practice according to 3042 professionals globally. In phase 2, a shortlist of 15 intervention domains was generated. In phase 3, interventions were deemed acceptable for more than 90 per cent of patients except for reducing general anaesthesia (84 per cent) and re-sterilization of ‘single-use’ consumables (86 per cent). In phase 4, the top three shortlisted interventions for high-income countries were: introducing recycling; reducing use of anaesthetic gases; and appropriate clinical waste processing. In phase 4, the top three shortlisted interventions for low–middle-income countries were: introducing reusable surgical devices; reducing use of consumables; and reducing the use of general anaesthesia. Conclusion This is a step toward environmentally sustainable operating environments with actionable interventions applicable to both high– and low–middle–income countries

AN EXACT TEST FOR THE CHOICE OF THE COMBINATION OF FIRST DIFFERENCES AND PERCENTAGE CHANGES IN LINEAR MODELS

Econometric models are often formulated in terms of the first difference or the percentage change, both of which may be generalized by the Box-Cox difference transformation. Unfortunately, economic theory typically provides little guidance to the proper functional forms appropriate to the specification of the economic relationships. The choice of suitable functional forms thus relies heavily upon established statistical procedures. Existing procedures adopt primarily the classical likelihood approach and mainly confine to a single transformation parameter only, thus seriously limiting the use of more appropriate models. When multi-parameter transformation is allowed, these procedures would require to search over a multidimensional grid of values, rendering them extremely expensive, if not impossible, to find the optimal solution.We have derived an exact test for the parameter vector of transformation in linear models. By utilizing Taylor series approximations this reduces to a choice between two regression equations. The test statistic which has an exact F-distribution can be easily calculated from these two regression equations by least squares estimation, which algorithm is available from the very handy to the sophisticated statistical packages. It is therefore a simple and ready statistical procedure for assessing the suitable choice of the functional forms of the variables, thereby allowing more flexible and appropriate economic relations be formulated and their validity be tested.