Effects of 14 Days Head-down Tilt Bed Rest on Autonomic Response
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چکیده
Cardiovascular responses to orthostatic stress induced by tilt maneuver were measured in seven subjects, before and after a 14 days head-down tilt bed rest (HDTBR). The response of the autonomic nervous system was evaluated through the analysis of the heart rate (HRV) and arterial blood pressure (ABP) variability. Spectral components, entropy indices and the Lempel Ziv Complexity were measured on the HRV and ABP variability signals. After HDTBR, a significant increase of the HF component in the diastolic arterial pressure was reported (rest: 81 ± 55 mmHg; tilt 313 ± 179 mmHg), accompanied by a significant decrease of the LZC (rest: 0.72± 0.07; tilt: 0.63±0.08). On the contrary, a significant decrease of the HF component in the RR series was obtained (rest: 174 ± 57 ms; tilt: 76 ± 28 ms), accompanied by a significant increase of LZC (rest: 0.64 ± 0.10; tilt: 0.77 ± 0.05). The results obtained suggested that different compensatory mechanisms act on the complexity of heart rate and pressure in the response to cardiovascular deconditioning.
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تاریخ انتشار 2010