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  • Author: Débora Pereira da Silva x
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Abstract

Freshwater is an essential natural resource for humanity, however, its quality has been compromised as a result of natural and anthropogenic interference. The objective of the present study was to determine the Bascarán Water Quality Index (WQIB) for the Tamanduá stream in the municipality of Aparecida de Goiânia, Goiás, Brazil, and relate it to the limits established by CONAMA resolutions nº 357 [] and nº 274 [], for Class 2 freshwater bodies. The study was carried out at three sampling points proximate to urban parks, with samples collected in both the dry and the rainy seasons with the measurement of flow. The physical, chemical and biological parameters were analyzed as recommended in Standard Methods []. Parametric descriptive statistics were used for data analysis. The WQIB results classified the water as acceptable (24%), normal (48%), improper (20%) and unpleasant (8%), with turbidity, DO and total coliforms responsible for decreased WQIB in the rainy season. The parameters pH, apparent color and DO do not conform with CONAMA resolution nº 357 [] while water resources for bathing were classified as excellent according to CONAMA resolution nº 274 [].

Abstract

The study of heart autonomic control (HAC) in patients with chronic kidney disease (CKD) undergoing dialysis treatment has been carried out, however, there are no studies reporting the reliability of measurements of HAC parameters involving the mentioned samples and conditions. The reliability of many HAC parameters was evaluated from patients with CKD during two sessions of hemodialysis. The successive R-R intervals were recorded during two sessions of hemodialysis from 14 CKD patients that were undergoing dialysis for at least 6 months and with no history of recurrent hypotensive events. HAC parameters were obtained with time and frequency domain analysis, as well as with nonlinear methods. The reliability was measured with the intraclass correlation coefficient (ICC). The results showed excellent reliability (ICC=0.90–0.98) for most heart rate variability (HRV) parameters, especially the parameters obtained in the time domain [square root of the mean squared differences between successive R-R intervals (RMSSD), percentage of adjacent R-R intervals that differ by more than 50 ms (pNN50), mean of the 5-min standard deviations of R-R intervals (SDNNi), and triangular index] and with non-linear methods [standard deviation of the instantaneous variability beat-to-beat (SD1), standard deviation in long-term continuous R-R intervals (SD2), detrended fluctuation analysis (DFA) α1 and α2, approximate and sample entropies, and correlation dimension (D2): ICC=0.86–0.96]. Among the parameters obtained in the frequency domain (normalized magnitude from the spectrum of low-frequency components (LFnu), normalized magnitude from the spectrum of high-frequency components (HFnu), and LF/HF ratio), the LF/HF ratio showed better reliability (ICC=0.96 vs. ICC=0.70). Measurements of HAC parameters have excellent test-retest reliability for the studied samples and conditions.