Autonomic nervous system (ANS) plays an important role in the regulation of the physiological processes of the human organism during normal and pathological conditions. Among the techniques used in its evaluation, the heart rate variability (HRV) has arising as a simple and non-invasive measure of the autonomic impulses, representing one of the most promising quantitative markers of the autonomic balance. The HRV describes the oscillations in the interval between consecutive heart beats (RR interval), as well as the oscillations between consecutive instantaneous heart rates. It is a measure that can be used to assess the ANS modulation under physiological conditions, such as wakefulness and sleep conditions, different body positions, physical training and also pathological conditions. Changes in the HRV patterns provide a sensible and advanced indicator of health involvements. Higher HRV is a signal of good adaptation and characterizes a health person with efficient autonomic mechanisms, while lower HRV is frequently an indicator of abnormal and insufficient adaptation of the autonomic nervous system, provoking poor patient's physiological function. Because of its importance as a marker that reflects the ANS activity on the sinus node and as a clinical instrument to assess and identify health involvements, this study reviews conceptual aspects of the HRV, measurement devices, filtering methods, indexes used in the HRV analyses, limitations in the use and clinical applications of the HRV.

Background: It was reported that autonomic nervous system function is altered in subjects with chronic obstructive pulmonary disease (COPD). We evaluated short- and long-term fractal exponents of heart rate variability (HRV) in COPD subjects. Patients and methods: We analyzed data from 30 volunteers, who were divided into two groups according to spirometric values: COPD (n = 15) and control (n = 15). For analysis of HRV indices, HRV was recorded beat by beat with the volunteers in the supine position for 30 minutes. We analyzed the linear indices in the time (SDNN [standard deviation of normal to normal] and RMSSD [root-mean square of differences]) and frequency domains (low frequency [LF], high frequency [HF], and LF/HF), and the short- and long-term fractal exponents were obtained by detrended fluctuation analysis. We considered P < 0.05 to be a significant difference. Results: COPD patients presented reduced levels of all linear exponents and decreased short-term fractal exponent (alpha-1: 0.899 ± 0.18 versus 1.025 ± 0.09, P = 0.026). There was no significant difference between COPD and control groups in alpha-2 and alpha-1/alpha-2 ratio. Conclusion: COPD subjects present reduced short-term fractal correlation properties of HRV, which indicates that this index can be used for risk stratification, assessment of systemic disease manifestations, and therapeutic procedures to monitor those patients.

Burnout syndrome can be defined as long-term work stress resulting from the interaction between constant emotional pressure associated with intense interpersonal involvement for long periods of time and personal characteristics. We investigated the prevalence/propensity of Burnout syndrome in clinical nurses, and the factors related to Burnout syndrome-associated such as socio-demographic characteristics, work load, social and family life, leisure activities, extra work activities, physical activities, and work-related health problems.

Decreased heart rate variability (HRV) is related to higher morbidity and mortality. In this study we evaluated the linear and nonlinear indices of the HRV in stable angina patients submitted to coronary angiography.

Introdução: A redução da variabilidade da frequência cardíaca (VFC) em pacientes com doença pulmonar obstrutiva crônica (DPOC) em repouso já foi evidenciada na literatura. Objetivo: Com intuito de inserir elementos na literatura sobre essa temática, foram avaliados índices geométricos de VFC de indivíduos com DPOC. Método: Foram analisados dados de 34 voluntários, divididos em dois grupos, de acordo com os valores espirométricos, com 17 voluntários cada: DPOC (VEF1/CVF = 47,3 ± 10,2; VEF1 = 50,8 ± 15,7) e controle (VEF1/CVF = 78,8 ± 10,8; VEF1 = 100,1 ± 14,7). Para análise dos índices de VFC, a frequência cardíaca foi captada batimento a batimento com os voluntários em decúbito dorsal por 30 minutos. Foram analisados os índices seguintes: índice triangular (RRtri), interpolação triangular dos intervalos RR (TINN) e plot de Poincaré (SD1, SD2 e relação SD1/SD2). Foi realizada também análise visual da figura formada no plot de Poincaré. Teste t de Student para dados não pareados e teste de Mann-Whitney com nível de significância de 5% foram utilizados para análise dos dados. Resultados: Foram observadas reduções estatisticamente significantes dos índices geométricos: RRtri (0,043 vs. 0,059, p = 0,018), TINN (105,88 vs. 151,47, p = 0,014), SD1 (9,76 vs. 14,55, p = 0,014) e SD2 (34,86 vs. 51,51, p = 0,010) no grupo DPOC. A relação SD1/SD2 (0,30 ± 0,11 vs. 0,28 ± 0,07; p = 0,605) não apresentou diferença significante entre os grupos. Os voluntários com DPOC apresentaram na análise visual do plot de Poincaré menor dispersão dos intervalos RR, tanto batimento a batimento como em longo prazo. Conclusão: Indivíduos com DPOC apresentaram diminuição dos índices geométricos da VFC, indicando que apresentam redução da variabilidade da frequência cardíaca. Background: It was already evidenced decreased heart rate variability (HRV) in chronic obstructive pulmonary disease (COPD) patients at rest. Objective: In order to insert new elements in the literature regarding this issue, we evaluated geometric index of HRV in COPD subjects. Method: We analyzed data from 34 volunteers, divided into two groups according to spirometric values: COPD (17 volunteers, FEV1/FVC = 47.3 ± 10.2; FEV1 = 50.8 ± 15.7) and control (17 volunteers, FEV1/FVC = 78.8 ± 10.8; FEV1 = 100.1 ± 14.7). For analysis of HRV indexes the volunteers remained in the supine position for 30 minutes. We analyzed the following indexes: triangular index (RRtri), triangular interpolation of RR intervals (TINN) and Poincaré plot (SD1, SD2 and SD1/SD2). Student t test for unpaired samples and Mann-Whitney test were used for data analysis. Results: We observed statistically significant reductions in geometric indexes in the COPD group: RRtri (0.043 ± 0.01 vs. 0.059 ± 0.02; p = 0.018), TINN (105.88 ± 51.82 vs. 151.47 ± 49.9; p = 0.014), SD1 (9.76 ± 4.66 vs. 14.55 ± 6.04; p = 0.014) and SD2 (34.86 ± 17.02 vs. 51.51 ± 18.38; p = 0.010). SD1/SD2 (0.30 ± 0.11 vs. 0.28 ± 0.07; p = 0.605) were not significantly different between groups. Patients with COPD presented a visual analysis of Poincaré plot of lower dispersion of RR intervals both beat to beat and the long term. Conclusion: Subjects with COPD present reduction of geometric indexes of HRV, indicating reduced heart rate variability.