Ultra-short term HRV features as surrogates of short term HRV: a case study on mental stress detection in real life.

BACKGROUND: 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. METHODS: 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. RESULTS: 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. CONCLUSION: This study concluded that 6 ultra-short HRV features are valid surrogates of short HRV features for mental stress investigation.

Heart rate variability in individuals with thoracic spinal cord injury.

STUDY DESIGN: Cross-sectional study. OBJECTIVES: The main goal of our study was to explore the differences in heart rate variability (HRV) while sitting between able-bodied (AB) participants and paraplegic (P) individuals. SETTING: The study was conducted in the Physical Therapy department and the Physical Education and Sports department of the University of Valencia and Vall d'Hebrón Hospital. METHODS: To record the HRV, a 1000-Hz Suunto Oy t6 heart rate monitor was used. The data were analyzed in the temporal and frequency domains, and nonlinear analysis was performed as well. RESULTS: We found significant differences between P and AB participants in SDNN: t(76)=2.81, P<0.01; root mean squared of the difference of successive RR intervals: t(76)=2.35, P<0.05; very low frequency: t(76)=2.97, P<0.01; low frequency: t(41.06)=2.33, P<0.05; total power of the spectrum: t(45.74)=2.57, P<0.05; SD1: t(76)=2.35, P<0.05; SD2: t(76)=2.82, P<0.01. Furthermore, there is a reduced variability in the P participants who adopted a sedentary lifestyle as could be observed in detrended fluctuation1 t(40)=-2.10; P<0.05. CONCLUSION: Although individuals in the P group were more active in sports than the AB group, they had an altered HRV when compared with AB individuals. It could be important to develop more intense sports programs to improve cardiac vagal tone, which in turn produces a decrease in work and oxygen consumption of the heart.

Is CT angiography of the pulmonary arteries indicated in patients with high clinical probability of pulmonary embolism? / ¿Está indicada la angiografía por tomografía computarizada de las arterias pulmonares en pacientes con alta probabilidad clínica de tromboembolia pulmonar?

When a diagnostic test confirms clinical suspicion, the indicated treatment can be administered. A problem arises when the diagnostic test does not confirm the initially suspected diagnosis; when the suspicion is grounded in clinically validated predictive rules and is high, the problem is even worse. This situation arises in up to 40% of patients with high suspicion for acute pulmonary embolism, raising the question of whether CT angiography of the pulmonary arteries should be done systematically. This paper reviews the literature about this issue and lays out the best evidence about the relevant recommendations for patients with high clinical suspicion of acute pulmonary embolism and negative findings on CT angiography. It also explains the probabilistic concepts derived from Bayes' theorem that can be useful for ascertaining the most appropriate approach in these patients.

An analysis of and intervention in the sexual transmission of disease.

Sexually transmitted diseases are a serious threat to the public health. Indeed, when an individual seeks medical treatment for a sexually transmitted disease, health authorities frequently attempt to identify, procure, and treat that individual's sexual contact(s). We conducted a comparative analysis of three alternative approaches to tracing the sexual partners of individuals diagnosed as having a sexually transmitted disease. The first approach involved counseling individuals (n = 27) infected with either gonorrhea or nongonococcal urethritis and exhorting them to procure their sexual partners for treatment. In addition to counseling, the second and third approaches involved distributing "occasion cards" for patients to use when informing sexual contacts of the need for treatment. Moreover, in the second approach, the counselor (a nurse or physician) informed infected patients (n = 19) that they and their partners could waive the $3 clinic fee contingent upon the partners seeking treatment within 1 week. In the third approach, the counselor asked infected persons (n = 19) to accept a follow-up telephone contact if their sexual partners failed to seek treatment within 1 week. The third approach was most effective. Ninety percent of the partners identified through this approach sought treatment, versus only about 60% of the partners in the other two conditions. The third approach was also the least expensive, costing about $2.95 to procure each partner for treatment.

Compensatory hyperplasia with increasing loss of renal mass.

When a rat with two kidneys is cross-circulated with an anephric rat, compensatory renal hypertrophy occurs as indicated by an increased ratio of RNA to DNA within 6 hours and an increased ratio of kidney weight to body weight within 12 hours. Removal of three kidneys between the rats further increases residual renal mass and RNA/DNA after 24 and 48 hours of cross-circulation as compared with results of removing two kidneys. Trinephrectomy triples the mitotic index and doubles the proliferative index. Increasing the magnitude of renal loss causes appreciable hyperplasia as well as increasing the magnitude of compensatory renal hypertrophy.

Ileo biliar recurrente. Presentacion de un caso. / Recurrent biliary ileus.Report of a case

Se presenta un caso poco frecuente en una paciente de 58 anos de edad que acude el cuerpo de Guardia sin antecedentes previos de ningun tipo, por presentar vomitos incoercibles y dolor abdominal; hallazgo incidental operatorio en intestino delgado en un calculo biliar procedente de una fistula bilioenterica, y presencia transoperatoria de un gran calculo en vesicula biliar. Se presenta, igualmente, un segundo cuadro oclusivo: Localizacion radiologica del sitio de la obstruccion alta por el calculo; reintervencion; evolucion de la paciente y complicaciones. No conocemos otro caso similar descrito en nuestro pais ni en la literatura revisada, que presente un gran calculo vesicular en su totalidad, que logra su autoseccion y ofrece dos ileos biliares en tiempo menor de 20 dias en una paciente. Hacemos revision de la literatura