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Record Details

Record 13 of 88618
Computer simulation of the effect of dDAVP with saline loading on fluid balance after 24-hour head-down tilt
Author and Affiliation:
Srinivasan, R. S.(KRUG Life Sciences, Houston, TX 77058, United States)
Simanonok, K. E.
Charles, J. B.
Abstract: Fluid loading (FL) before Shuttle reentry is a countermeasure currently in use by NASA to improve the orthostatic tolerance of astronauts during reentry and postflight. The fluid load consists of water and salt tablets equivalent to 32 oz (946 ml) of isotonic saline. However, the effectiveness of this countermeasure has been observed to decrease with the duration of spaceflight. The countermeasure's effectiveness may be improved by enhancing fluid retention using analogs of vasopressin such as lypressin (LVP) and desmopressin (dDAVP). In a computer simulation study reported previously, we attempted to assess the improvement in fluid retention obtained by the use of LVP administered before FL. The present study is concerned with the use of dDAVP. In a recent 24-hour, 6 degree head-down tilt (HDT) study involving seven men, dDAVP was found to improve orthostatic tolerance as assessed by both lower body negative pressure (LBNP) and stand tests. The treatment restored Luft's cumulative stress index (cumulative product of magnitude and duration of LBNP) to nearly pre-bedrest level. The heart rate was lower and stroke volume was marginally higher at the same LBNP levels with administration of dDAVP compared to placebo. Lower heart rates were also observed with dDAVP during stand test, despite the lower level of cardiovascular stress. These improvements were seen with only a small but significant increase in plasma volume of approximately 3 percent. This paper presents a computer simulation analysis of some of the results of this HDT study.
Publication Date: May 01, 1994
Document ID:
20040089967
(Acquired Sep 07, 2004)
Subject Category: AEROSPACE MEDICINE
Document Type: Journal Article
Publication Information: Journal of gravitational physiology : a journal of the International Society for Gravitational Physiology (ISSN 1077-9248); Volume 1; 1; P106-7
Publisher Information: United States
Description: In English
Distribution Limits: Unclassified; Publicly available; Unlimited
Rights: Copyright
NASA Terms: BALANCE; BODY FLUIDS; COMPUTERIZED SIMULATION; HEAD DOWN TILT; HEMODYNAMICS; HYPOKINESIA; MODELS; PHARMACOLOGY; PHYSIOLOGICAL RESPONSES; AEROSPACE MEDICINE; BIOASTRONAUTICS; BLOOD PLASMA; BLOOD VOLUME; COUNTERMEASURES; GRAVITATIONAL PHYSIOLOGY; MALES; SODIUM CHLORIDES; WEIGHTLESSNESS
Other Descriptors: COMPUTER SIMULATION; DESMOPRESSIN/PHARMACOLOGY/THERAPEUTIC USE; HEAD-DOWN TILT/PHYSIOLOGY; HEMODYNAMIC PROCESSES/DRUG EFFECTS; MODELS, CARDIOVASCULAR; RENAL AGENTS/PHARMACOLOGY/THERAPEUTIC USE; EXTRACELLULAR SPACE/DRUG EFFECTS; FLUID THERAPY; HUMAN; MALE; PLASMA VOLUME/DRUG EFFECTS; SODIUM CHLORIDE/PHARMACOLOGY/THERAPEUTIC USE; WEIGHTLESSNESS COUNTERMEASURES; NASA CENTER JSC; NASA DISCIPLINE CARDIOPULMONARY; NASA DISCIPLINE NUMBER 14-10; NASA DISCIPLINE NUMBER 70-30; NASA PROGRAM DATA ANALYSIS; NASA PROGRAM SPACE PHYSIOLOGY AND COUNTERMEASURES; NON-NASA CENTER
Availability Source: Other Sources
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