A Tilt Table Simulation of the Push-Pull Effect

PDF

Authors
  1. Goodman, L.S.
  2. LeSage, S.
Corporate Authors
Defence and Civil Inst of Environmental Medicine, Downsview ONT (CAN)
Abstract
A simulation of the "push-pull effect" was made using a tilt table in order to examine detailed cardiovascular responses. Nine subjects were exposed to a series of six head-up tilt (HUT)-head-down tilt (HDT)-HUT randomised sequences (conducted in both standing and seated postures), under the following conditions: +70 degrees HUT for 60s, followed by transition to either 0 degrees (supine), -15 degrees HDT, or -45 degrees HDT for 7 or 15s, followed by transition to +70 degrees HUT for 60s. The rate of table rotation was 45 degrees/s. There was 2 min. supine rest between each sequence. Mean heart-level arterial blood pressure (MAP) and Heart Rate (HR) were monitored using Finapres (TRADEMARK). Stroke volume (SV) was estimated using impedance cardiography. Total Peripheral Resistance (TPR) was calculated from the SV and MAP data. Data from HDT phases were averaged over the final two s. Data for subsequent HUT were averaged over the first 15s. There were no differences in any variable for posture, HDT angle or HDT duration effects. During HDT, HR fell from 72.3 + or - 1.1 to 53.3 + or - 0.8 bpm (p < .001). Upon subsequent HUT, HR was significantly less than prior HUT (64.4 + or - 0.8 vs. 72.3 + or - 1.1; p < .001). MAP fell from 89.2 + or - 1.2 to 82.2 + or - 1.2 mmHg during HDT (p < .001), and upon HUT, did not recover (83.0 + or - 1.2 vs 89.2+1.2 mmHg; p < .001). TRUNCATED
Keywords
Push-pull effect;Tilt table;Cardiovascular regulation;Cartoid-Cardiac Baroreflex
Report Number
DCIEM-TR-1999-023 — Technical Report
Date of publication
01 Mar 1999
Number of Pages
24
DSTKIM No
99-01007
CANDIS No
510910
Format(s):
Hardcopy;Document Image stored on Optical Disk

Permanent link

Document 1 of 1

Date modified: