A numerical assessment of methods to estimate aortic stiffness from arterial pulse waves

<p><strong>INTRODUCTION</strong><br> Aortic stiffness is a predictive of cardiovascular events and all-cause mortality. Consequently, several methods have been proposed to estimate aortic stiffness from the arterial pulse wave. Translation of these methods into clinical practice is hindered by a lack of evidence on the relative performance of the methods, and an incomplete understanding of the physiological factors which cause the methods to be inaccurate. Therefore, the aims of this numerical study were: (i) to compare the accuracy and precision of pulse wave-derived indices of aortic stiffness, and (ii) to identify the physiological determinants of each index.<br> <br> <strong>METHODS</strong><br> The study was performed using a database of simulated arterial pulse waves and reference values of aortic stiffness. The database was constructed by varying the cardiovascular input parameters of a 1-D model of arterial haemodynamics to simulate a population of adult subjects. The input parameters were varied to model the cardiovascular changes observed during ageing from young to old age, and to model the normal physiological variation observed across a population. Estimates of aortic stiffness were derived from the pulse waves of each virtual subject using a wide range of previously proposed methods (see Figure), including: (i) pulse wave velocities (PWVs) calculated from pulse waves measured simultaneously at central and peripheral locations; (ii) PWVs calculated from ECG-gated pulse waves obtained sequentially; and (iii) pulse wave indices calculated from blood pressure or photoplethysmogram pulse waves at superficial sites including the carotid, radial and digital arteries. Reference aortic stiffness values were obtained by calculating theoretical aortic PWVs from model input parameters.<br> <br> <strong>RESULTS</strong><br> Relative performance was assessed by comparing the correlations between reference values of aortic stiffness and estimated values produced by each method. In addition, the performance of PWV-based methods was quantified using the limits of agreement technique. Sensitivity analyses were performed to quantify the influence of each input parameter on each method. Most methods were indicative of aortic stiffness to some extent, but were also influenced by the stiffness of other arteries, and by other unrelated cardiovascular parameters. The potential clinical utility of the best performing methods was evaluated by considering their accuracy and precision, potential confounders, and ease of measurement. This informed recommendations of when more laborious, PWV-based methods should be used, and when less time-consuming pulse wave indices should be used.<br> <br> <strong>CONCLUSION</strong><br> We assessed the performance of a wide range of methods for estimating aortic stiffness using a database of arterial pulse waves simulated numerically. This resulted in recommendations of the most suitable methods for use in different clinical scenarios.</p> <p><strong>ACKNOWLEDGMENT</strong></p> <p>This work was supported by the British Heart Foundation [PG/15/104/31913] and the Wellcome EPSRC Centre for Medical Engineering at King’s College London [WT 203148/Z/16/Z]. The views expressed are those of the authors and not necessarily those of the British Heart Foundation, Wellcome Trust or EPSRC.</p

Breathing rate monitoring to detect deteriorations using wearable sensors

<p>This poster provides an overview of the work described in:</p> <p>P. H. Charlton, "Continuous respiratory rate monitoring to detect clinical deteriorations using wearable sensors," Ph.D. Thesis, King’s College London, 2017.</p

アイヌ遺骨問題に関する関係者インタビュー

北海道には先住民族であるアイヌ民族が住んでいます。独自の文化と言語を持つ彼らに対して、開拓の名のもとに同化政策を押し進められたのが約150 年前です。また、世界的に形質人類学がもてはやされた時期からは、盗掘ともとれる大々的な収集が組織的に行われました。そして、それは主に各地の大学機関によって行われ、北海道大学が一番多くアイヌの遺骨を保管していました（2019年11月に慰霊施設に集約されました）。1980 年代からアイヌ民族による遺骨返還の請求があり、ごく一部の遺骨に関しては返還できたものの、それ以降2010年代は裁判の和解による返還しか実現できていません。 多くの科学技術や研究開発が人々の幸福を望んで行われていることは間違いないと思います。しかし、その結果が研究者の意図に反して社会との軋轢を生じる場合もあります。その一例がアイヌ遺骨の収集の歴史と現在だと思います。本調査では、北海道大学が研究のために収集・保管しているアイヌの遺骨、副葬品など、過去の研究が現在にもたらした「負の側面」に注視し、ステークホルダーへのインタビューを敢行します。過去の研究がもたらした結果に、それぞれの立場で、どのように向き合っているのかを、わずかでも浮き彫りにできればと思います