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Plasma volume expansion with oral fluids in hypohydrated men at rest and during exercise.
Aviat Space Environ Med. 1998 Sep; 69(9):837-44.AS

Abstract

BACKGROUND

The purpose for this study was to evaluate various carbohydrate (CHO)-electrolyte fluid formulations for consumption by astronauts to maintain or restore their plasma volume (PV) and total body water (TBW) during and after extravehicular activity (exercise experiment, EE) and for a few hours before reentry and immediately after landing (rest experiment RE).

HYPOTHESIS

That fluid formulation electrolyte content would be more important than osmotic (Osm) content for increasing or maintaining PV during the RE and EE.

METHODS

In the RE, 5 healthy men (23-44 yr), previously dehydrated for 24 h, drank 6 fluid formulations (Water, 19.6 Na, 157 Na, 19.6 Na + glucose, and the prepared drinks Performances and Power)--one each at weekly intervals, and then sat for 70 min. In the EE, four healthy 24-h dehydrated men (30-46 yr) exercised for 70 min supine on a cycle ergometer (load = 71 +/- 1% peak VO2).

RESULTS

Rest: Subjects who consumed formulations with total Osm concentrations nearer the normal range (157 Na - 270 mOsm x kg(-1), Performance with 19.6 mEq x L(-1) Na - 380 mOsm, and to some extent Power with 23.5 mEq x L(-1) Na - 390 mOsm) had the greater increases in PV; intake of drink 157 Na, with the largest Na content, induced the greatest hypervolemia of 7.6% (p < 0.05). The various additional ions, in addition to 19.6 Na, probably contributed to the 4.6% (p < 0.05) hypervolemia with Performance. Water was not effective. Exercise: Stabilization of PV between 15-70 min was not related to drink total CHO, Na or Osm content. Performance and 157 Na were no more effective than 19.6 Na or 19.6 Na + glu for PV stabilization. Water was the least effective. Regulatory mechanisms controlling PV during exercise appear to be independent of oral fluid formulation Osm-electrolyte content.

CONCLUSIONS

Drink cation (sodium) content is more important that its total osmotic content for increasing plasma volume at rest. Fluid formulations with greater hypervolemic action in resting subjects may not be as effective during exercise; therefore different formulations for use during exercise appear to be necessary.

Authors+Show Affiliations

Life Science Division, NASA, Ames Research Center, Moffett Field, CA 94035-1000, USA.No affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info available

Pub Type(s)

Clinical Trial
Comparative Study
Journal Article
Randomized Controlled Trial
Research Support, U.S. Gov't, Non-P.H.S.

Language

eng

PubMed ID

9737753

Citation

Greenleaf, J E., et al. "Plasma Volume Expansion With Oral Fluids in Hypohydrated Men at Rest and During Exercise." Aviation, Space, and Environmental Medicine, vol. 69, no. 9, 1998, pp. 837-44.
Greenleaf JE, Jackson CG, Geelen G, et al. Plasma volume expansion with oral fluids in hypohydrated men at rest and during exercise. Aviat Space Environ Med. 1998;69(9):837-44.
Greenleaf, J. E., Jackson, C. G., Geelen, G., Keil, L. C., Hinghofer-Szalkay, H., & Whittam, J. H. (1998). Plasma volume expansion with oral fluids in hypohydrated men at rest and during exercise. Aviation, Space, and Environmental Medicine, 69(9), 837-44.
Greenleaf JE, et al. Plasma Volume Expansion With Oral Fluids in Hypohydrated Men at Rest and During Exercise. Aviat Space Environ Med. 1998;69(9):837-44. PubMed PMID: 9737753.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Plasma volume expansion with oral fluids in hypohydrated men at rest and during exercise. AU - Greenleaf,J E, AU - Jackson,C G, AU - Geelen,G, AU - Keil,L C, AU - Hinghofer-Szalkay,H, AU - Whittam,J H, PY - 1998/9/16/pubmed PY - 1998/9/16/medline PY - 1998/9/16/entrez KW - NASA Center ARC KW - NASA Discipline Regulatory Physiology SP - 837 EP - 44 JF - Aviation, space, and environmental medicine JO - Aviat Space Environ Med VL - 69 IS - 9 N2 - BACKGROUND: The purpose for this study was to evaluate various carbohydrate (CHO)-electrolyte fluid formulations for consumption by astronauts to maintain or restore their plasma volume (PV) and total body water (TBW) during and after extravehicular activity (exercise experiment, EE) and for a few hours before reentry and immediately after landing (rest experiment RE). HYPOTHESIS: That fluid formulation electrolyte content would be more important than osmotic (Osm) content for increasing or maintaining PV during the RE and EE. METHODS: In the RE, 5 healthy men (23-44 yr), previously dehydrated for 24 h, drank 6 fluid formulations (Water, 19.6 Na, 157 Na, 19.6 Na + glucose, and the prepared drinks Performances and Power)--one each at weekly intervals, and then sat for 70 min. In the EE, four healthy 24-h dehydrated men (30-46 yr) exercised for 70 min supine on a cycle ergometer (load = 71 +/- 1% peak VO2). RESULTS: Rest: Subjects who consumed formulations with total Osm concentrations nearer the normal range (157 Na - 270 mOsm x kg(-1), Performance with 19.6 mEq x L(-1) Na - 380 mOsm, and to some extent Power with 23.5 mEq x L(-1) Na - 390 mOsm) had the greater increases in PV; intake of drink 157 Na, with the largest Na content, induced the greatest hypervolemia of 7.6% (p < 0.05). The various additional ions, in addition to 19.6 Na, probably contributed to the 4.6% (p < 0.05) hypervolemia with Performance. Water was not effective. Exercise: Stabilization of PV between 15-70 min was not related to drink total CHO, Na or Osm content. Performance and 157 Na were no more effective than 19.6 Na or 19.6 Na + glu for PV stabilization. Water was the least effective. Regulatory mechanisms controlling PV during exercise appear to be independent of oral fluid formulation Osm-electrolyte content. CONCLUSIONS: Drink cation (sodium) content is more important that its total osmotic content for increasing plasma volume at rest. Fluid formulations with greater hypervolemic action in resting subjects may not be as effective during exercise; therefore different formulations for use during exercise appear to be necessary. SN - 0095-6562 UR - https://www.unboundmedicine.com/medline/citation/9737753/Plasma_volume_expansion_with_oral_fluids_in_hypohydrated_men_at_rest_and_during_exercise_ L2 - https://medlineplus.gov/dehydration.html DB - PRIME DP - Unbound Medicine ER -