Comparison of the Polar S810i monitor and the ECG for the analysis of heart rate variability in the time and frequency domains

The aim of the present study was to compare heart rate variability (HRV) at rest and during exercise using a temporal series obtained with the Polar S810i monitor and a signal from a LYNX® signal conditioner (BIO EMG 1000 model) with a channel configured for the acquisition of ECG signals. Fifteen healthy subjects aged 20.9 ± 1.4 years were analyzed. The subjects remained at rest for 20 min and performed exercise for another 20 min with the workload selected to achieve 60 percent of submaximal heart rate. RR series were obtained for each individual with a Polar S810i instrument and with an ECG analyzed with a biological signal conditioner. The HRV indices (rMSSD, pNN50, LFnu, HFnu, and LF/HF) were calculated after signal processing and analysis. The unpaired Student t-test and intraclass correlation coefficient were used for data analysis. No statistically significant differences were observed when comparing the values analyzed by means of the two devices for HRV at rest and during exercise. The intraclass correlation coefficient demonstrated satisfactory correlation between the values obtained by the devices at rest (pNN50 = 0.994; rMSSD = 0.995; LFnu = 0.978; HFnu = 0.978; LF/HF = 0.982) and during exercise (pNN50 = 0.869; rMSSD = 0.929; LFnu = 0.973; HFnu = 0.973; LF/HF = 0.942). The calculation of HRV values by means of temporal series obtained from the Polar S810i instrument appears to be as reliable as those obtained by processing the ECG signal captured with a signal conditioner.

Evaluación nutricional de pacientes pediátricos críticos: estudio preliminar / Nutritional evaluation of critical pediatric patients: Preliminary study

El objetivo del trabajo es evaluar el estado nutricional con respecto a hierro en un grupo de niños con diferentes patologías, al ingreso en terapia intensiva, a través de la determinación de hematocrito, concentración de hemoglobina, protoporfirinas eritrocitarias libres y analizar los niveles de fracciones séricas específicas: transferrina, proteína C reactiva y ceruloplasmina. En treinta y un pacientes (entre tres y cuarenta y ocho meses de edad) internados en la Unidad de Cuidados Intensivos Pediátricos con diferentes patologías, se determina hematocrito (Hto), la concentración de hemoglobina (g/dL) (Hb) por colorimetría, FEP por método Piomelli expresándose los resultados como FEP/Hto y FEP/Hb y transferrina, ceruloplasmina y preoteína C reactiva sérica (mg/dL) por inmunodifusión radial cuantitativa sobre placas...