This paper suggests a method to assess the extent to which ultra-short Heart Rate Variability (HRV) features (less than 5 min) can be considered as valid surrogates of short HRV features (nominally 5 ...min). Short term HRV analysis has been widely investigated for mental stress assessment, whereas the validity of ultra-short HRV features remains unclear. Therefore, this study proposes a method to explore the extent to which HRV excerpts can be shortened without losing their ability to automatically detect mental stress.
ECGs were acquired from 42 healthy subjects during a university examination and resting condition. 23 features were extracted from HRV excerpts of different lengths (i.e., 30 s, 1 min, 2 min, 3 min, and 5 min). Significant differences between rest and stress phases were investigated using non-parametric statistical tests at different time-scales. Features extracted from each ultra-short length were compared with the standard short HRV features, assumed as the benchmark, via Spearman's rank correlation analysis and Bland-Altman plots during rest and stress phases. Using data-driven machine learning approaches, a model aiming to detect mental stress was trained, validated and tested using short HRV features, and assessed on the ultra-short HRV features.
Six out of 23 ultra-short HRV features (MeanNN, StdNN, MeanHR, StdHR, HF, and SD2) displayed consistency across all of the excerpt lengths (i.e., from 5 to 1 min) and 3 out of those 6 ultra-short HRV features (MeanNN, StdHR, and HF) achieved good performance (accuracy above 88%) when employed in a well-dimensioned automatic classifier.
This study concluded that 6 ultra-short HRV features are valid surrogates of short HRV features for mental stress investigation.
The aim of this paper is to describe the design and the preliminary validation of a platform developed to collect and automatically analyze biomedical signals for risk assessment of vascular events ...and falls in hypertensive patients. This m-health platform, based on cloud computing, was designed to be flexible, extensible, and transparent, and to provide proactive remote monitoring via data-mining functionalities. A retrospective study was conducted to train and test the platform. The developed system was able to predict a future vascular event within the next 12 months with an accuracy rate of 84 % and to identify fallers with an accuracy rate of 72 %. In an ongoing prospective trial, almost all the recruited patients accepted favorably the system with a limited rate of inadherences causing data losses (<20 %). The developed platform supported clinical decision by processing tele-monitored data and providing quick and accurate risk assessment of vascular events and falls.
Standing from a bed or chair may cause a significant lowering of blood pressure (ΔBP), which may have severe consequences such as, for example, falls in older subjects. The goal of this study was to ...develop a mathematical model to predict the ΔBP due to standing in healthy subjects, based on their Heart Rate Variability, recorded in the 5 minutes before standing.
Heart Rate Variability was extracted from an electrocardiogram, recorded from 10 healthy subjects during the 5 minutes before standing. The blood pressure value was measured before and after rising. A mathematical model aiming to predict ΔBP based on Heart Rate Variability measurements was developed using a robust multi-linear regression and was validated with the leave-one-subject-out cross-validation technique.
The model predicted correctly the ΔBP in 80% of experiments, with an error below the measurement error of sphygmomanometer digital devices (± 4.5 mmHg), a false negative rate of 7.5% and a false positive rate of 10%. The magnitude of the ΔBP was associated with a depressed and less chaotic Heart Rate Variability pattern.
The present study showes that blood pressure lowering due to standing can be predicted by monitoring the Heart Rate Variability in the 5 minutes before standing.
Introduction
In inguinal hernia repair, many complications are due to mesh fixation technique. Therefore, new types of atraumatic methods of fixation have been proposed. In this article, we present ...the results of a prospective multicentric parallel randomized controlled trial aiming to compare two mesh fixation techniques: fibrin sealant (QUIXIL
®
, Omrix Biopharmaceuticals S.A., Belgium) and Lichtenstein technique.
Method
Adult patients with primary uncomplicated inguinal hernia were randomized in two groups: fibrin sealant group (FSG) and Lichtenstein group (LTG). The two groups underwent a follow-up of 15 months. Operative time is the primary outcome. Intraoperative and postoperative outcomes were analyzed. Moreover, a differential cost analysis was performed. Patients and evaluators (with exception of the surgeon who treated the patient) were blinded.
Results
A total of 102 patients, 50 in FSG and 52 in LTG, were enrolled from January 2009 to June 2010, and two patients were lost to follow-up at the twelfth month. No significant differences in baseline and clinical characteristics were observed in the two groups. Operative time was longer in LTG (median/ interquartile range: 35 min/30–42.5 min vs. 31 min/28–35 min; effect size: 0.65/95 % CI 0.50–0.91;
p
< 0.05). No differences in intraoperative complications were observed. No significant differences were observed in early complication rate (RR = 0.62;
p
> 0.05). Numbness rate was lower in the FSG at 1 week (RR = 0.43;
p
< 0.01) and at 1 month (RR = 0.17;
p
< 0.05). No significant differences were observed after 6 months. Postoperative pain was lower in the FSG at 1 week (0/0–1 vs. 1/0–2;
p
< 0.05) and at 1 month (0/0–0 vs. 0/0–1;
p
< 0.05). Pain disappeared in all patients after 6 months. Analgesic assumption rate was lower in the FSG (RR = 0.42;
p
< 0.05). Twenty per cent of FSG and 9.62 % of LTG patients were discharged within 12 h; 78 % of FSG and 90.38 % of LTG patients were discharged within 24 h. The only one recurrence we observed was in FSG group. About costs, although fibrin sealant needed for one mesh fixation is about 10 times more costly than the needed sutures, the total costs of the two procedures did not change significantly. This was mainly due to reduction in operative time.
Conclusions
The use of fibrin sealant determined a significant reduction in short-term numbness rate and postoperative pain. There was no relevant difference in total costs per patient between the two procedures.
Artemisia annua L. (Qinghao) is a promising and potent antimalarial herbal drug. This activity has been ascribed to its component artemisinin, a sesquiterpene lactone that is very effective against ...drug-resistant
Plasmodium species with a low toxicity. Our studies indicate that several flavonoids of
A. annua can promote and enhance the reaction of artemisinin with hemin. These data are in good agreement with previous investigations on the in vitro potentiation of antimalarial activity of artemisinin by such flavonoids.
As a consequence, in view of a possible use of the phytocomplex rather than pure artemisinin, an HPLC/DAD/MS method is proposed for the simultaneous detection and quantification of both flavonoids and artemisinin. Different extracts, obtained from two different herbal drugs, a commercial sample and a selected cultivar, were analyzed in order to determine which solvents provide the best yields of both artemisinin and flavonoids. Qualitative and quantitative results obtained using an HPLC method are described, which will be useful for developing highly effective herbal drug preparations.
•Mental stress significantly reduced variability and chaotic behaviour of HRV.•Stress causes sympathetic activation and parasympathetic withdrawal.•Pooled HRV power ratio changed significantly while ...did not in individual studies.•Studies investigating HRV non-linear measures and mental stress are required.•The method proposed to meta-analyze HRV features can be adopted for other studies investigating HRV.
Mental stress reduces performances, on the work place and in daily life, and is one of the first causes of cognitive dysfunctions, cardiovascular disorders and depression. This study systematically reviewed existing literature investigating, in healthy subjects, the associations between acute mental stress and short term Heart Rate Variability (HRV) measures in time, frequency and non-linear domain. The goal of this study was to provide reliable information about the trends and the pivot values of HRV measures during mental stress. A systematic review and meta-analysis of the evidence was conducted, performing an exhaustive research of electronic repositories and linear researching references of papers responding to the inclusion criteria. After removing duplicates and not pertinent papers, journal papers describing well-designed studies that analyzed rigorously HRV were included if analyzed the same population of healthy subjects at rest and during mental stress. 12 papers were shortlisted, enrolling overall 758 volunteers and investigating 22 different HRV measures, 9 of which reported by at least 2 studies and therefore meta-analyzed in this review. Four measures in time and non-linear domains, associated with a normal degree of HRV variations resulted significantly depressed during stress. The power of HRV fluctuations at high frequencies was significantly depressed during stress, while the ratio between low and high frequency resulted significantly increased, suggesting a sympathetic activation and a parasympathetic withdrawal during acute mental stress. Finally, among the 15 non-linear measures extracted, only 2 were reported by at least 2 studies, therefore pooled, and only one resulted significantly depressed, suggesting a reduced chaotic behaviour during mental stress. HRV resulted significantly depressed during mental stress, showing a reduced variability and less chaotic behaviour. The pooled frequency domain measures demonstrated a significant autonomic balance shift during acute mental stress towards the sympathetic activation and the parasympathetic withdrawal. Pivot values for the pooled mean differences of HRV measures are provided. Further studies investigating HRV non-linear measures during mental stress are still required. However, the method proposed to transform and then meta-analyze the HRV measures can be applied to other fields where HRV proved to be clinically significant.
This study aims to develop an automatic classifier for risk assessment in patients suffering from congestive heart failure (CHF). The proposed classifier separates lower risk patients from higher ...risk ones, using standard long-term heart rate variability (HRV) measures. Patients are labeled as lower or higher risk according to the New York Heart Association classification (NYHA). A retrospective analysis on two public Holter databases was performed, analyzing the data of 12 patients suffering from mild CHF (NYHA I and II), labeled as lower risk, and 32 suffering from severe CHF (NYHA III and IV), labeled as higher risk. Only patients with a fraction of total heartbeats intervals (RR) classified as normal-to-normal (NN) intervals (NN/RR) higher than 80% were selected as eligible in order to have a satisfactory signal quality. Classification and regression tree (CART) was employed to develop the classifiers. A total of 30 higher risk and 11 lower risk patients were included in the analysis. The proposed classification trees achieved a sensitivity and a specificity rate of 93.3% and 63.6%, respectively, in identifying higher risk patients. Finally, the rules obtained by CART are comprehensible and consistent with the consensus showed by previous studies that depressed HRV is a useful tool for risk assessment in patients suffering from CHF.
Objetivo: Descrever os resultados de uma série de pacientes com Trombocitopenia Imune (PTI) tratados com azatioprina. Materiais e métodos: Estudo observacional retrospectivo através da análise dos ...prontuários digitais de pacientes adultos atendidos no Hospital de Transplantes Euryclides de Jesus Zerbini-Hospital Brigadeiro. Critérios de inclusão: 1) pacientes adultos com diagnóstico de PTI; 2) histórico de tratamento com azatioprina como terapia de segunda linha (ou linha posterior). Pacientes com falta de informações suficientes sobre o tratamento no prontuário digital foram excluídos do estudo. A resposta foi definida como contagem de plaquetas sustentada ≥30.000/mm3 (remissão:≥ 100.000/mm3 e resposta parcial: 30.000 - 100.000/mm3). Resultados/Discussão: Entre dezembro de 2015 e julho de 2023, 19 pacientes utilizaram azatioprina. A mediana de idade no início do tratamento foi de 36 anos (variação:16-82) e 84% eram do sexo feminino. Distribuição dos pacientes quanto ao número de tratamentos anteriores: 6 pacientes-1 linha prévia, 4 pacientes-2 linhas prévias, 5 pacientes-3 linhas prévias, 4 pacientes- 4 ou mais linhas prévias. Todos receberam azatioprina após um ano do diagnóstico de PTI (fase crônica), com mediana de tempo para início da droga desde o diagnóstico de 20 meses (variação:3-332). Um paciente (5%) era esplenectomizado. A maioria recebeu tratamento associado por algum período(63% com corticoide e 10% com outras drogas). Ao todo, 10 pacientes (53%) obtiveram alguma resposta - 1 (5%) obteve resposta completa e 9 (47%) obtiveram resposta parcial. Dos pacientes que obtiveram resposta parcial, 3 pacientes (15%) perderam resposta. A mediana de tempo para resposta foi de 4 semanas (variação:2-16). A dose utilizada para obtenção de resposta foi 50 mg para 1 paciente (5%), 100 mg para 5 pacientes (26%) e 150 mg para 4 pacientes (21%). A maioria necessitou mudança na dose durante o período de tratamento.A mediana de tempo de duração da resposta foi de 8 meses (variação:2-58). A mediana de tempo de duração do tratamento foi de 4 meses (variação:1-33). Em relação aos eventos adversos, 6 pacientes (32%) apresentaram sangramento (2 pacientes- grau 2 do escore de sangramento para PTI), 5 pacientes (26%) apresentaram sintomas gastrointestinais, 2 pacientes (10%) apresentaram infecção, 2 pacientes (10%) apresentaram toxicidade hematológica e 1 paciente (5%) apresentou alteração hepática. Não houve nenhum óbito durante uso da medicação. Três pacientes (15%) descontinuaram o uso por eventos adversos. A mediana de seguimento foi de 12 meses (variação: 2-74). Um paciente perdeu o seguimento. Conclusão: Os dados de mundo real sobre uso de uma droga de baixo custo e fácil acesso para tratamento de PTI refratária, com possibilidade de bons desfechos clínicos, têm papel importante no serviço público de saúde brasileiro. Neste cenário clínico, obtivemos taxa de resposta semelhante às relatadas em estudos prévios com efeitos colaterais manejáveis.
Mental stress may cause cognitive dysfunctions, cardiovascular disorders and depression. Mental stress detection via short-term Heart Rate Variability (HRV) analysis has been widely explored in the ...last years, while ultra-short term (less than 5 minutes) HRV has been not. This study aims to detect mental stress using linear and non-linear HRV features extracted from 3 minutes ECG excerpts recorded from 42 university students, during oral examination (stress) and at rest after a vacation. HRV features were then extracted and analyzed according to the literature using validated software tools. Statistical and data mining analysis were then performed on the extracted HRV features. The best performing machine learning method was the C4.5 tree algorithm, which discriminated between stress and rest with sensitivity, specificity and accuracy rate of 78%, 80% and 79% respectively.
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