Correspondence
Central Venous Pressure in Space
N Engl J Med 1993; 328:1853-1854June 24, 1993
- Article
To the Editor:
When a person enters zero gravity, a large amount of fluid (1 to 2 liters) shifts toward the head. The response to this shift includes the principal cardiovascular effects of spaceflight -- e.g., hypovolemia, dehydration, and postflight orthostatic intolerance1. On earth, a similar headward shift of fluid increases central venous pressure2; in space, however, peripheral antecubital venous pressure does not increase3,4. It is not known whether such peripheral measurements reflect central venous pressure. Only direct, continuous measurements recorded during a change from earth's gravity (1 g) to zero gravity can resolve these controversies. In June 1991, we directly measured central venous pressure in an astronaut on a space shuttle during the National Aeronautics and Space Administration's Spacelab Life Sciences 1 flight. We hypothesized that the pressure would increase as a result of the headward fluid shift.
To measure the expected small changes in pressure, a special device for continuous ambulatory measurement of central venous pressure was designed5. Owing to research constraints, only one crew member of the shuttle could be studied. A 4-French catheter was inserted through an arm vein the night before the planned launch. Before the launch, the crew member was strapped into the horizontally positioned orbiter seat; he remained supine, with his legs up, for four hours. Central venous pressure was measured continuously from suit-up until nine hours into the flight. Eight hours after launch, cardiac volume was measured with both two-dimensional and three-dimensional echocardiography; the heart rate and blood pressure (indirect measurement) were also recorded.
The central venous pressure rose from 5 to 6 cm of water while the crew member was seated to 10 to 12 cm of water while he was in the launch position in the shuttle orbiter (Figure 1Figure 1
Central Venous Pressure in an Astronaut before and during Spaceflight.). It increased further during launching, to approximately 15 to 17 cm of water, owing to anterior-posterior gravitational loading, in which the chest is subjected to three times the force of earth gravity. Once in zero gravity, however, the central venous pressure dropped to 0 to -3 cm of water within 60 seconds. It remained within 1 to 2 cm of 0 until the catheter was removed. The left ventricular internal end-diastolic dimension increased during flight from 4.6 (its preflight value in the supine position) to 5.2 cm; the left ventricular end-diastolic volume, from 141 to 167 ml; the stroke volume, from 68 to 89 ml; and the cardiac output, from 5.2 to 6.0 liters per minute.The central venous pressure decreased in space. This finding refutes the hypothesis that central venous pressure increases as a result of the headward fluid shift induced by zero gravity. Despite the fall in central venous pressure, the heart size increased. Thus, spaceflight produced unique hemodynamic changes in the astronaut studied that were not predicted by ground-based models. In space, gravity no longer exerts any pressure within tissues. This could alter compliance throughout the cardiovascular system, so that the same blood volume is contained at a lower pressure.
5 ReferencesJay C. Buckey, M.D.
University of Texas Southwestern Medical Center, Dallas, TX 75235F. Andrew Gaffney, M.D.
Vanderbilt University, Nashville, TN 37232Lynda D. Lane, M.S., R.N.
University of Texas Southwestern Medical Center, Dallas, TX 75235Benjamin D. Levine, M.D.
Presbyterian Hospital of Dallas, Dallas, TX 75231Donald E. Watenpaugh, M.A., M.S.
NASA-Ames Research Center, Moffett Field, CA 94035C. Gunnar Blomqvist, M.D.
University of Texas Southwestern Medical Center, Dallas, TX 752351
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2
Nixon JV ,Murray RG ,Bryant C , et al. Early cardiovascular adaptation to simulated zero gravity. J Appl Physiol 1979;46:541-548
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Medline
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Donald E. Watenpaugh, Alan R. Hargens. 2011. The Cardiovascular System in Microgravity. .
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Andr?? Diedrich, Sachin Y. Paranjape, David Robertson. (2007) Plasma and Blood Volume in Space. The American Journal of the Medical Sciences 334:1, 80-85
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Lowan H. Stewart, Donald Trunkey, G. Steve Rebagliati. (2007) Emergency medicine in space. The Journal of Emergency Medicine 32:1, 45-54
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Frank Beckers, Bart Verheyden, Andr
E. Aubert. 2006. Space Physiology. .
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G. Kim Prisk. (2005) The Lung in Space. Clinics in Chest Medicine 26:3, 415-438
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David S Martin, Donna A South, Kathleen M Garcia, Philippe Arbeille. (2003) Ultrasound in space. Ultrasound in Medicine & Biology 29:1, 1-12
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Catherine C.Y Pang. (2001) Autonomic control of the venous system in health and disease: effects of drugs. Pharmacology & Therapeutics 90:2-3, 179-230
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Laurence Somody, Sophie Fagette, Jean Frutoso, Claude Gharib, Guillemette Gauquelin. (1998) Recording heart rate and blood pressure in rats during parabolic flight. Life Sciences 63:10, 851-857
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Joan Vernikos. (1996) Human physiology in space. BioEssays 18:12, 1029-1037
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RUPERT GERZER, MARTINA HEER, CHRISTIAN DRUMMER. (1996) Body fluid metabolism at actual and simulated microgravity. Medicine & Science in Sports & Exercise 28:10, 32-35
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VICTOR A. CONVERTINO. (1996) Clinical aspects of the control of plasma volume at microgravity and during return to one gravity. Medicine & Science in Sports & Exercise 28:10, 45-52
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MARY ANNE BASSETT FREY. (1996) Space research activities during missions of the past. Medicine & Science in Sports & Exercise 28:10, 3-8
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GUNNAR C. BLOMQVIST. (1996) Regulation of the systemic circulation at microgravity and during readaptation to 1G. Medicine & Science in Sports & Exercise 28:10, 9-13
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CHARLES M. TIPTON. (1996) Animal models and their importance to human physiological responses in microgravity. Medicine & Science in Sports & Exercise 28:10, 94-100
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ALAN R. HARGENS, DONALD E. WATENPAUGH. (1996) Cardiovascular adaptation to spaceflight. Medicine & Science in Sports & Exercise 28:8, 977-982
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CHARLES M. TIPTON, JOHN E. GREENLEAF, CATHERINE G. R. JACKSON. (1996) Neuroendocrine and immune system responses with spaceflights. Medicine & Science in Sports & Exercise 28:8, 988-998
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John W. Hines. (1996) Medical and surgical applications of space biosensor technology. Acta Astronautica 38:4-8, 261-267
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(1993) More on Central Venous Pressure in Space. New England Journal of Medicine 329:24, 1822-1822
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