Evidence for central venous pressure resetting during initial exposure to microgravity

Victor A. Convertino, David Ludwig, James J. Elliott, Charles E. Wade, Gary Muniz, Richard Owens

Research output: Contribution to journalArticle

9 Citations (Scopus)

Abstract

We measured central venous pressure (CVP); plasma volume (PV); urine volume rate (UVR); renal excretion of sodium (UNa); and renal clearances of creatinine, sodium, and osmolality before and after acute volume infusion to test the hypothesis that exposure to microgravity causes resetting of the CVP operating point. Six rhesus monkeys underwent two experimental conditions in a crossover counterbalance design: 1) continuous exposure to 10° head-down tilt (HDT) and 2) a control, defined as 16 h/day of 80° head-up tilt and 8 h prone. After 48 h of exposure to either test condition, a 120-min course of continuous infusion of isotonic saline (0.4 ml.kg-1·min-1 iv) was administered. Baseline CVP was lower (P = 0.011) in HDT (2.3 ± 0.3 mmHg) compared with the control (4.5 ± 1.4 mmHg) condition. After 2 h of saline infusion, CVP was elevated (P = 0.002) to a similar magnitude (P = 0.485) in HDT (ΔCVP = 2.7 ± 0.8 mmHg) and control (ΔCVP = 2.3 ± 0.8 mmHg) conditions and returned to preinfusion levels 18 h postinfusion in both treatments. PV followed the same pattern as CVP. The response relationships between CVP and UVR and between CVP and UNa shifted to the left with HDT. The restoration of CVP and PV to lower preinfusion levels after volume loading in HDT compared with control supports the notion that lower CVP during HDT may reflect a new operating point about which vascular volume is regulated. These results may explain the ineffective fluid intake procedures currently employed to treat patients and astronauts.

Original languageEnglish
JournalAmerican Journal of Physiology - Regulatory Integrative and Comparative Physiology
Volume281
Issue number6 50-6
StatePublished - Dec 1 2001
Externally publishedYes

Fingerprint

Weightlessness
Central Venous Pressure
Head-Down Tilt
Plasma Volume
Sodium
Urine
Astronauts
Macaca mulatta
Osmolar Concentration
Cross-Over Studies
Blood Vessels
Creatinine
Head

Keywords

  • Diuresis
  • Hypovolemia
  • Renal function
  • Set point

ASJC Scopus subject areas

  • Physiology
  • Physiology (medical)

Cite this

Evidence for central venous pressure resetting during initial exposure to microgravity. / Convertino, Victor A.; Ludwig, David; Elliott, James J.; Wade, Charles E.; Muniz, Gary; Owens, Richard.

In: American Journal of Physiology - Regulatory Integrative and Comparative Physiology, Vol. 281, No. 6 50-6, 01.12.2001.

Research output: Contribution to journalArticle

Convertino, Victor A. ; Ludwig, David ; Elliott, James J. ; Wade, Charles E. ; Muniz, Gary ; Owens, Richard. / Evidence for central venous pressure resetting during initial exposure to microgravity. In: American Journal of Physiology - Regulatory Integrative and Comparative Physiology. 2001 ; Vol. 281, No. 6 50-6.
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