Effects of rapid saline infusion on orthostatic intolerance and autonomic tone after 20 days bed rest
Abstract
To test whether acute volume expansion can normalize orthostatic intolerance and autonomic tone after prolonged bed rest (BR), 23 men were subjected to 20 days BR. Left ventricular (LV) echocardiography was performed during the lower body negative pressure (LBNP) test before and after BR with and without preceding rapid infusion of saline (1,500 ml/30 min). Saline infusion restored heart rate, LV dimension, and stroke volume during LBNP, increased cardiac output (from 4.1 +/- 1 to 5.3 +/- 1 L/min), and normalized LBNP tolerance time (from 11 +/- 4 to 23 +/- 6 minutes). In 9 men, a Holter electrocardiogram was recorded on the day before BR, the fourth and twentieth days of BR, and the day after BR. The high-frequency component of heart rate variability during sleep gradually decreased and reached the lowest level on the day after BR (100%, 66 +/- 16%, 39 +/- 18%, 10 +/- 8%). Thus, restoring decreased blood volume is an effective countermeasure for orthostatic intolerance after BR. However, decreased vagal tone persisted, suggesting reset autonomic tone.
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Avoiding complete inactivity in POTS is important because complete bed rest can reduce blood volume.
“The avoidance of complete inactivity is important in POTS to prevent reductions in blood volume that can accompany complete bed rest (Takenaka et al., 2002).”
From Postural tachycardia syndrome and other forms of orthostatic intolerance in Ehlers-Danlos syndrome (2018) · cites this paper as Takenaka et al., 2002
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References 26 · Cited by 18
- Authors
- Takenaka, K., Suzuki, Y., Uno, K., Sato, M., Komuro, T., Haruna, Y., Kobayashi, H., Kawakubo, K., Sonoda, M., Asakawa, M., Nakahara, K., & Gunji, A.
- Affiliations
- The University of Tokyo (JP)
- Corresponding author
- Takenaka, Katsu
- Venue
- The American Journal of Cardiology
- Publisher
- Elsevier BV
- Published
- 2002-03
- Volume
- 89
- Issue
- 5
- Pages
- 557-561
- ISSN
- 0002-9149 (ISSN-L)
- OpenAlex
- W2034074970
- Cited by
- 18
- References
- 26
- Citations by year
- 2025: 2 · 2022: 3 · 2019: 2 · 2018: 1 · 2017: 2 · 2016: 1 · 2014: 1
- FWCI
- 0.32
- Type
- journal article
- Language
- en
- Open access
- closed
- Locations
- The American Journal of Cardiology (publishedVersion)
- PubMed (publishedVersion)
- Topics
- Health Sciences › Medicine › Surgery › Cardiovascular Syncope and Autonomic Disorders
- Health Sciences › Medicine › Physiology › Spaceflight effects on biology
- Health Sciences › Medicine › Cardiology and Cardiovascular Medicine › Heart Rate Variability and Autonomic Control
- Keywords
- orthostatic intolerance, autonomic tone, bed rest, saline infusion, volume expansion, lower body negative pressure, cardiac output, heart rate variability, vagal tone, blood volume, countermeasures
- MeSH terms
- Adult, Autonomic Nervous System, Bed Rest, Blood Volume, Echocardiography, Heart Rate, Hemodilution, Humans, Hypotension, Orthostatic, Lower Body Negative Pressure, Male, Sodium Chloride, Stroke Volume, Vagus Nerve, Ventricular Function, Left
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