a1_Non-invasive methods of determination of baroreflex sensitivity (BRS, ms/mmHg) are based on beat-to-beat systolic blood pressure and inter-beat interval recording. Sequential methods and spectral methods at spontaneous breathing include transient superposition of breathing and 0.1 Hz rhythms. Previously, a cross-spectral method of analysis was used, at constant breathing rate using a metronome set at 0.33 Hz, enabling separate determination of BRS at 0.1 Hz (BRS0.1Hz) and respiratory rhythms (BRS0.33Hz). The aim of the present study was to evaluate the role of breathing in the spectral method of BRS determination with respect to age and hypertension. Such information would be important in evaluation of BRS at pathological conditions associated with extremely low BRS levels. Blood pressure was recorded by Finapres (5 minutes, controlled breathing at 0.33 Hz) in 118 healthy young subjects (YS: mean age 21.0±1.3 years), 26 hypertensive patients (HT: mean age 48.6±10.3 years) with 26 age-matched controls (CHT: mean age 46.3±8.6 years). A comparison of BRS0.1Hz and BRS0.33Hz was made. Statistically significant correlations were found between BRS0.1Hz and BRS0.33Hz in all groups: YS: r=0.52, p<0.01, HT: r=0.47, p<0.05, and CHT: r=0.70, p<0.01. The regression equations indicated the existence of a breathing-dependent component unrelated to BRS (YS: BRS0.33Hz=2.63+1.14*BRS0.1Hz; HT: BRS0.33Hz=3.19+0.91*BRS0.1Hz; and CHT: BRS0.33Hz=1.88+ +1.01*BRS0.1Hz; differences between the slopes and the slope of identity line were insignificant). The ratios of BRS0.1Hz to BRS0.33Hz were significantly lower than 1 (p<0.01) in all groups (YS: 0.876±0.419, HT: 0.628±0.278, and CHT: 0.782±0.260). Thus, BRS evaluated at the breathing rate overestimates the real baroreflex sensitivity. This is more pronounced at low values of BRS, which is more important in patients with pathologic low BRS., a2_For diagnostic purposes we recommend the evaluation of BRS at the frequency of 0.1 Hz using metronome-controlled breathing at a frequency that is substantially higher than 0.1 Hz and is not a multiple of 0.1 Hz to eliminate respiratory baroreflexnon- related influence and resonance effect on heart rate fluctuations., P. Bothová ... [et al.]., and Obsahuje bibliografii a bibliografické odkazy
To determine the relationship between hyperventilation and recovery of blood pH during recovery from a heavy exercise, short-term intense exercise (STIE) tests were performed after human subjects ingested 0.3 g · kg-1 body mass of either NaHCO3 (Alk) or CaCO3 (Pla). Ventilation (V.E) - CO2 output (V.co2) slopes during recovery following STIE were significantly lower in Alk than in Pla, indicating that hyperventilation is attenuated under the alkalotic condition. However, this reduction of the slope was the result of unchanged V.E and a small increase in V.co 2.A significant correlation between V.E and blood pH was found during recovery in both conditions. While there was no difference between the V.E - pH slopes in the two conditions, V.E at the same pH was higher in Alk than in Pla. Furthermore, the values of pH during recovery in both conditions increased toward the preexercise levels of each condition. Thus, although V.E - V.co 2 slope was decreased under the alkalotic condition, this could not be explained by the ventilatory depression attributed to increase in blood pH. We speculate that hy perventilation after the end of STIE is determined by the V.E - pH relationship that was set before STIE or the intensity of the exercise performed., T. Yunoki ... [et al.]., and Obsahuje seznam literatury
Inactive forearm muscle oxygenation has been reported to begin decreasing from the respiratory compensation point (RCP) during ramp leg cycling. From the RCP, hyperventilation occurs with a decrease in arterial CO2 pressure (PaCO2). The aim of this study was to determine which of these two factors, hyperventilation or decrease in PaCO2, is related to a decrease in inactive biceps brachii muscle oxygenation during leg cycling. Each subject (n = 7) performed a 6-min two-step leg cycling. The exercise intensity in the first step (3 min) was halfway between the ventilatory threshold and RCP (170±21 watts), while that in the second step (3 min) was halfway between the RCP and peak oxygen uptake (240±28 watts). The amount of hyperventilation and PaCO2 were calculated from gas parameters. The average cross correlation function in seven subjects between inactive muscle oxygenation and amount of hyperventilation showed a negative peak at the time shift of zero (r = -0.72, p<0.001), while that between inactive muscle oxygenation and calculated PaCO2 showed no peak near the time shift of zero. Thus, we concluded that decrease in oxygenation in inactive arm muscle is closely coupled with increase in the amount of hyperventilation., H. Ogata, T. Arimitsu, R. Matsuura, T. Yunoki, M. Horiuchi, T. Yano., and Obsahuje bibliografii a bibliografické odkazy
The cardiovascular system is described by parameters including blood flow, blood distribution, blood pressure, heart rate and pulse wave velocity. Dynamic changes and mutual interactions of these parameters are important for understanding the physiological mechanisms in the cardiovascular system. The main objective of this study is to introduce a new technique based on parallel continuous bioimpedance measurements on different parts of the body along with continuous blood pressure, ECG and heart sound measurement during deep and spontaneous breathing to describe interactions of cardiovascular parameters. Our analysis of 30 healthy young adults shows surprisingly strong deep-breathing linkage of blood distribution in the legs, arms, neck and thorax. We also show that pulse wave velocity is affected by deep breathing differently in the abdominal aorta and extremities. Spontaneous breathing does not induce significant changes in cardiovascular parameters., P. Langer, P. Jurák, V. Vondra, J. Halámek, M. Mešťaník, I. Tonhajzerová, I. Viščor, L. Soukup, M. Matejkova, E. Závodná, P. Leinveber., and Obsahuje bibliografii