Tags

Type your tag names separated by a space and hit enter

Orthostatic blood pressure control before and after spaceflight, determined by time-domain baroreflex method.
J Appl Physiol (1985) 2005; 98(5):1682-90JA

Abstract

Reduction in plasma volume is a major contributor to orthostatic tachycardia and hypotension after spaceflight. We set out to determine time- and frequency-domain baroreflex (BRS) function during preflight baseline and venous occlusion and postflight orthostatic stress, testing the hypothesis that a reduction in central blood volume could mimic the postflight orthostatic response. In five cosmonauts, we measured finger arterial pressure noninvasively in supine and upright positions. Preflight measurements were repeated using venous occlusion thigh cuffs to impede venous return and "trap" an increased blood volume in the lower extremities; postflight sessions were between 1 and 3 days after return from 10- to 11-day spaceflight. BRS was determined by spectral analysis and by PRVXBRS, a time-domain BRS computation method. Although all completed the stand tests, two of five cosmonauts had drastically reduced pulse pressures and an increase in heart rate of approximately 30 beats/min or more during standing after spaceflight. Averaged for all five subjects in standing position, high-frequency interbeat interval spectral power or transfer gain did not decrease postflight. Low-frequency gain decreased from 8.1 (SD 4.0) preflight baseline to 6.8 (SD 3.4) postflight (P = 0.033); preflight with thigh cuffs inflated, low-frequency gain was 9.4 (SD 4.3) ms/mmHg. There was a shift in time-domain-determined pulse interval-to-pressure lag, Tau, toward higher values (P < 0.001). None of the postflight results were mimicked during preflight venous occlusion. In conclusion, two of five cosmonauts showed abnormal orthostatic response 1 and 2 days after spaceflight. Overall, there were indications of increased sympathetic response to standing, even though we can expect (partial) restoration of plasma volume to have taken place. Preflight venous occlusion did not mimic the postflight orthostatic response.

Authors+Show Affiliations

Department of Physiology, Rm. M01-215, Academic Medical Center, University of Amsterdam, PO Box 22700, 1100 DE Amsterdam, The Netherlands. j.gisolf@amc.uva.nlNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info available

Pub Type(s)

Comparative Study
Journal Article
Research Support, Non-U.S. Gov't

Language

eng

PubMed ID

15649869

Citation

Gisolf, J, et al. "Orthostatic Blood Pressure Control Before and After Spaceflight, Determined By Time-domain Baroreflex Method." Journal of Applied Physiology (Bethesda, Md. : 1985), vol. 98, no. 5, 2005, pp. 1682-90.
Gisolf J, Immink RV, van Lieshout JJ, et al. Orthostatic blood pressure control before and after spaceflight, determined by time-domain baroreflex method. J Appl Physiol. 2005;98(5):1682-90.
Gisolf, J., Immink, R. V., van Lieshout, J. J., Stok, W. J., & Karemaker, J. M. (2005). Orthostatic blood pressure control before and after spaceflight, determined by time-domain baroreflex method. Journal of Applied Physiology (Bethesda, Md. : 1985), 98(5), pp. 1682-90.
Gisolf J, et al. Orthostatic Blood Pressure Control Before and After Spaceflight, Determined By Time-domain Baroreflex Method. J Appl Physiol. 2005;98(5):1682-90. PubMed PMID: 15649869.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Orthostatic blood pressure control before and after spaceflight, determined by time-domain baroreflex method. AU - Gisolf,J, AU - Immink,R V, AU - van Lieshout,J J, AU - Stok,W J, AU - Karemaker,J M, Y1 - 2005/01/13/ PY - 2005/1/15/pubmed PY - 2005/8/19/medline PY - 2005/1/15/entrez SP - 1682 EP - 90 JF - Journal of applied physiology (Bethesda, Md. : 1985) JO - J. Appl. Physiol. VL - 98 IS - 5 N2 - Reduction in plasma volume is a major contributor to orthostatic tachycardia and hypotension after spaceflight. We set out to determine time- and frequency-domain baroreflex (BRS) function during preflight baseline and venous occlusion and postflight orthostatic stress, testing the hypothesis that a reduction in central blood volume could mimic the postflight orthostatic response. In five cosmonauts, we measured finger arterial pressure noninvasively in supine and upright positions. Preflight measurements were repeated using venous occlusion thigh cuffs to impede venous return and "trap" an increased blood volume in the lower extremities; postflight sessions were between 1 and 3 days after return from 10- to 11-day spaceflight. BRS was determined by spectral analysis and by PRVXBRS, a time-domain BRS computation method. Although all completed the stand tests, two of five cosmonauts had drastically reduced pulse pressures and an increase in heart rate of approximately 30 beats/min or more during standing after spaceflight. Averaged for all five subjects in standing position, high-frequency interbeat interval spectral power or transfer gain did not decrease postflight. Low-frequency gain decreased from 8.1 (SD 4.0) preflight baseline to 6.8 (SD 3.4) postflight (P = 0.033); preflight with thigh cuffs inflated, low-frequency gain was 9.4 (SD 4.3) ms/mmHg. There was a shift in time-domain-determined pulse interval-to-pressure lag, Tau, toward higher values (P < 0.001). None of the postflight results were mimicked during preflight venous occlusion. In conclusion, two of five cosmonauts showed abnormal orthostatic response 1 and 2 days after spaceflight. Overall, there were indications of increased sympathetic response to standing, even though we can expect (partial) restoration of plasma volume to have taken place. Preflight venous occlusion did not mimic the postflight orthostatic response. SN - 8750-7587 UR - https://www.unboundmedicine.com/medline/citation/15649869/Orthostatic_blood_pressure_control_before_and_after_spaceflight_determined_by_time_domain_baroreflex_method_ L2 - http://www.physiology.org/doi/full/10.1152/japplphysiol.01219.2004?url_ver=Z39.88-2003&amp;rfr_id=ori:rid:crossref.org&amp;rfr_dat=cr_pub=pubmed DB - PRIME DP - Unbound Medicine ER -