Abstract
Gravity, like any acceleration, causes a hydrostatic pressure gradient in fluid-filled bodily compartments. At a force of 1G, this pressure gradient amounts to 10 kPa/m. Postural changes alter the distribution of hydrostatic pressure patterns according to the body’s alignment to the acceleration field. At a certain location—referred to as hydrostatically indifferent—within any given fluid compartment, pressure remains constant during a given change of position relative to the acceleration force acting upon the body. At this specific location, there is probably little change in vessel volume, wall tension, and the balance of Starling forces after a positional manoeuvre. In terms of cardiac function, this is important because arterial and venous hydrostatic indifference locations determine postural cardiac preload and afterload changes. Baroreceptors pick up pressure signals that depend on their respective distance to hydrostatic indifference locations with any change of body position. Vascular shape, filling volume, and compliance, as well as temperature, nervous and endocrine factors, drugs, and time all influence hydrostatic indifference locations. This paper reviews the physiology of pressure gradients in the cardiovascular system that are operational in a gravitational/acceleration field, offers a broadened hydrostatic indifference concept, and discusses implications that are relevant in physiological and clinical terms.
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Badeer HS, Hicks JW (1992) Hemodynamics of vascular ‘waterfall’: is the analogy justified. Respir Physiol 87:205–217
Bjerkhoel P, Lindgren P, Lundvall J (1995) Protein loss and capillary protein permeability in dependent regions upon quiet standing. Acta Physiol Scand 154:311–320
Blomqvist CG, Stone HL (1983) Cardiovascular adjustments to gravitational stress. In: Shepherd JT, Abboud FM (eds) Handbook of physiology—the cardiovascular system 3: part II, Chap 28. American Physiological Society, Bethesda, MD, pp 1025–1063
Blumberg R (1885) Über den Einluss der Schwere auf Kreislauf und Atmung. Arch Ges Physiol 37:467
Broskey J, Sharp MK (2007) Evaluation of mechanisms of postflight orthostatic intolerance with a simple cardiovascular system model. Ann Biomed Eng 35:1800–1811
Buckner PS, Quail AW, Cottee BF, White SW (1999) Venous hydrostatic indifference point as a marker of postnatal adaptation to orthostasis in swine. J Appl Physiol 87:882–888
Cai Y, Boesen M, Stromstad M, Secher NH (2000) An electrical admittance based index of thoracic intracellular water during head-up tilt in humans. Eur J Appl Physiol 83:356–362
Caiani EG, Weinert L, Takeuchi M, Veronesi F, Sugeng L, Corsi C, Capderou A, Cerutti S, Vaida P, Lang RM (2007) Evaluation of alterations on mitral annulus velocities, strain, and strain rates due to abrupt changes in preload elicited by parabolic flight. J Appl Physiol 103:80–87
Clark JH, Hooker DR, Weed LH (1934) The hydrostatic factor in venous pressure measurements. Am J Physiol 109:166–177
Crandall CG, Wilson TE, Marving J, Vogelsang TW, Kjaer A, Hesse B, Secher NH (2008) Effects of passive heating on central blood volume and ventricular dimensions in humans. J Physiol 586:293–301
Cui J, Durand S, Levine BD, Crandall CG (2005) Effect of skin surface cooling on central venous pressure during orthostatic challenge. Amer J Physiol 289:H2429–H2433
Dawson EA, Secher NH, Dalsgaard MK, Ogoh S, Yoshiga CC, González-Alonso J, Steensberg A, Raven PB (2004) Standing up to the challenge of standing: a siphon does not support cerebral blood flow in humans. Am J Physiol 287:R911–R914
Della Rocca G, Cecconi M, Costa MG (2008) Mini invasive hemodynamic monitoring: from arterial pressure to cardiac output. Signa Vitae 3(Suppl 1):7–9
Edholm OG (1940) Effect of gravity on the blood pressure of the cat. J Physiol (Lond) 98:79–96
Ehmke H (2010) Das Kreislaufsystem. In: Rainer Klinke et al (eds) Physiologie, Chap 6. Georg Thieme. Stuttgart, New York. ISBN 978-3-13-796006-5
El-Bedawi KM, Hainsworth R (1994) Combined head-up tilt and lower body suction: a test of orthostatic tolerance. Clin Auton Res 4:41–47
Fortney SM, Schneider VS, Greenleaf JE (1996) The physiology of bed rest. In: Fregly MJ, Blatteis CM (eds) Handbook of physiology—environmental physiology 2, Chap 39. Oxford University Press, NY, pp 889–939
Gauer OH, Henry JP (1964) Negative acceleration in relation to arterial oxygen saturation, subendocardial hemorrhage and venour pressure in the forehead. Aerosp Med 35:533–545
Gauer OH, Thron HL (1965) Postural changes in the circulation. In: Handbook of physiology—circulation III, Chap 67. American Physiological Society, Bethesda, MD, pp 2409–2439
Geelen G, Laitinen T, Hartikainen J, Länsimies E, Bergström K, Niskanen L (2002) Gender influence on vasoactive hormones at rest and during a 70° head-up tilt in healthy humans. J Appl Physiol 92:1401–1408
Gelman S (2008) Venous function and central venous pressure: a physiologic story. Anesthesiology 108:735–748
Goswami N, Rössler A, Lackner HK, Schneditz D, Grasser E, Hinghofer-Szalkay H (2009) Heart rate and stroke volume response patterns to augmented orthostatic stress. Clin Auton Res 19:157–165
Grasser EK, Goswami N, Rössler A, Vrecko K, Hinghofer-Szalkay H (2009) Hemodynamic and neurohormonal responses to extreme orthostatic stress in physically fit young adults. Acta Astronautica 64:688–696
Green NDC (2006) Effects of long-duration acceleration. In: Rainford DJ, Gradwell DP (eds) Ernsting’s aviation medicine, Chap 8, 4th edn. Oxford University Press, New York. ISBN 10-0-340-81319-9
Greenway CV (1984) Neural control and autoregulatory escape. In: Shepherd AP, Granger DN (eds) Physiology of the intestinal circulation, Chap 5. Raven Press, NY, pp 61–71
Grissmer S (2010) Blutkreislauf. In: Jan C Behrends et al (eds) Physiologie, Chap 5. MLP Duale Reihe, Georg Thieme, Stutgart. ISBN 978-3-138447-9
Groothuis JT, Poelkens F, Wouters CW, Kooijman M, Hopman MTE (2008) Leg intravenous pressure during head-up tilt. J Appl Physiol 105:811–815
Grubb BP, Kanjwal Y, Karabin B, Imran N (2008) Orthostatic hypotension and autonomic failure: a concise guide to diagnosis and management. Clin Med Cardiol 2:279–291
Guyton AC, Greganti FP (1956) A physiologic reference point for measuring circulatory pressures in the dog, particularly venous pressure. Am J Physiol 185:137–141
Haase EB, Shoukas AA (1992) Blood volume changes in microcirculation of rat intestine caused by carotid sinus baroreceptor reflex. Am J Physiol 263:H1939–H1945
Hagan RD, Diaz FJ, Horvath SM (1978) Plasma volume changes with movement to supine and standing positions. J Appl Physiol 45:414–418
Han WQ, Hu WD, Dong MQ, Fu ZJ, Wen ZH, Cheng HW, Ma J, Ma RS (2009) Cerebral hemodynamics and brain functional activity during lower body negative pressure. Aviat Space Environ Med 80:698–702
Harrison MH (1985) Effects of thermal stress and exercise on blood volume in humans. Physiol Rev 65:149–209
Hermann, Blumberg, Wagner (1886) Plügers Arch 39:371 (cf. Gauer and Thron 1965)
Hill L (1895) The influence of the force of gravity on the circulation of the blood. I. J Physiol (Lond) 18:15–53
Hill L, Barnard H (1897) The influence of the force of gravity on the circulation of the blood. II. J Physiol (Lond) 21:323–352
Hinghofer-Szalkay H (1982) Tilt table and related studies. In: ESA SP-180, European Space Agency (Paris), pp 81–102
Hinghofer-Szalkay H (1986) Method of high-precision micro-sample blood and plasma mass densitometry. J Appl Physiol 60:1082–1088
Hinghofer-Szalkay H, Greenleaf JE (1987) Continuous monitoring of blood volume changes in humans. J Appl Physiol 63:1003–1007
Hinghofer-Szalkay H, Sauseng-Fellegger G, Greenleaf JE (1995) Plasma volume with alternating tilting: effect of fluid filtration. J Appl Physiol 78:1369–1373
Hinghofer-Szalkay HG, Vigas M, Sauseng-Fellegger G, König EM, Jezova D (1996) Head-up tilt and lower body suction: comparison of hormone responses in healthy men. Physiol Res 45:369–378
Hinghofer-Szalkay HG, Rössler A, Evans JM, Stenger MB, Moore FB, Knapp CF (2006) Circulatory galanin levels increase severalfold at presyncope in healthy humans. J Appl Physiol 100:844–849
Hinghofer-Szalkay HG, Goswami N, Rössler A, Grasser E, Schneditz D (2008) Reactive hyperemia in the human liver. Am J Physiol Gastrointest Liver Physiol 295:332–337
Jacob G, Ertl AC, Shannon JR, Furlan R, Robertson RM, Robertson D (1998) Effect of standing on neurohumoral responses and plasma volume in healthy subjects. J Appl Physiol 84:914–921
Jarvis SS, Pawelczyk JA (2009) Identification of the human electrical impedance indifferent point: a surrogate for the volume indifferent point. Eur J Appl Physiol 107:473–480
Jorfeldt L, Vedung T, Forsstrom E, Henriksson J (2003) Influence of leg position and environmental temperature on segmental volume expansion during venous occlusion plethysmography. Clin Sci 104:599–605
Kamegai M, Kristensen MS, Warberg J, Norsk P (1992) Carotid baroreflexes and plasma vasopressin in humans during head-up tilt. Am J Physiol 263:R318–R323
Kidd BSL, Lyons SM (1958) The distensibility of the blood vessels of the human calf determined by graded venous congestion. J Physiol (Lond) 140:122–128
Kirsch KA, Merke J, Hinghofer-Szalkay H (1980) Fluid volume distribution within superficial shell tissues along body axis during changes of body posture in man. The application of a new miniature plethysmographic method. Pflügers Arch 383:195–201
Kirsch KA, Röcker L, Gauer OH, Krause R, Leach C, Wicke HJ, Landry R (1984) Venous pressure in man during weightlessness. Science 225:218–219
Laszlo Z, Rössler A, Hinghofer-Szalkay HG (2001) Cardiovascular and humoral readjustment after different levels of head-up tilt in humans. Aviat Space Environ Med 72:193–202
Levick JR, Michel CC (1978) The effects of position and skin temperature on the capillary pressure in the fingers and toes. J Physiol Lond 274:97–109
Liebenschütz F, Henneberg U, Thron HL (1976) Central venous pressure and blood circulation in orthostatic by changes of the total blood volume in postoperative patients. Anaesthesist 25:425–430
Lozano-Nieto A, Turner AA (2001) Effects of orthostatic fluid shifts on bioelectrical impedance measurements. Biomed Instrum Technol 35:249–258
Magnaes B (1976) Body position and cerebrospinal fluid pressure. Part II: clinical studies on orthostatic pressure and the hydrostatic indifferent point. J Neurosurg 44:698–705
Matzen S, Knigge U, Schütten HJ, Warberg J, Secher NH (1990) Atrial natriuretic peptide during head-up tilt induced hypovolaemic shock in man. Acta Physiol Scand 140:161–166
Matzen S, Perko G, Groth S, Friedman DB, Secher NH (1991) Blood volume distribution during head-up tilt induced central hypovolaemia in man. Clin Physiol 11:411–422
Matzen S, Emmeluth C, Milliken MC, Secher NH (1992) Plasma endothelin-1 during central hypovolaemia in man. Clin Physiol 112:653–658
Montmerle S, Sundblad P, Linnarsson D (2005) Residual heterogeneity of intra- and interregional pulmonary perfusion in short-term microgravity. J Appl Physiol 98:2268–2277
Neto JE (2006) Great arteries contribution in orthostatic cardiovascular adaptation. Arquivos BrasilCardiol 87: No 2
Ogoh S, Yoshiga CC, Secher NH, Raven PB (2006) Carotid-cardiac baroreflex function does not influence blood pressure regulation during head-up tilt in humans. J Physiol Sci 56:227–233
Olszewski WL, Engeset A, Sokolowski J (1977) Lymph flow in the normal male leg during lying, getting up, and walking. Lymphology 10:178–183
Pang CCY (2001) Autonomic control of the venous system in health and disease. Effects of drugs. Pharmacol Ther 90:179–230
Patterson JL Jr, Warren JV (1952) Mechanisms of adjustment in the cerebral circulation upon assumption of the upright position. J Clin Invest 31:653
Perko G, Payne G, Secher NH (1993) An indifference point for electrical impedance in humans. Acta Physiol Scand 148:125–129
Perko G, Payne G, Linkis P, Jorgensen LG, Landow L, Warberg J, Secher NH (1994) Thoracic impedance and pulmonary arterial natriuretic peptide during head-up tilt induced hypovolaemic shock in humans. Acta Physiol Scand 1994:449–454
Perko G, Tilgreen R, Secher NH (1995) The venous pump does not affect the indifference point for electrical impedance in humans. Eur J Appl Physiol 72:179–182
Perko MJ, Madsen P, Perko G, Schroeder TV, Secher NH (1999) Cholinergic induced mesenteric vasorelaxation in response to head-up tilt. Acta Physiol Scand 166:279–284
Perl W (1975) Convection and permeation of albumin between plasma and interstitium. Microvasc Res 10:83–94
Petersen M (2010). Herz-Kreislauf-system. In: Michael Gekle et al (eds) Taschenlehrbuch Physiologie, Chap 6. Georg Thieme, Stutgart. ISBN 978-3-13-144981-8
Price HL, Deutsch S, Marshall BE, Stephen GW, Behar MG, Neufeld GR (1966) Hemodynamic and metabolic effects of hemorrhage in man, with particular reference to the splanchnic circulation. Circ Res 18:469–474
Prisk GK, Guy HJB, Elliott AR, West JB (1994) Inhomogeneity of pulmonary perfusion during sustained microgravity on SLS-1. J Appl Physiol 76:1730–1738
Renkin EM, Crone C (1996) Microcirculation and capillary exchange. Comprehensive human physiology: from cellular mechanisms to integration, vols 1, 2. Springer, Berlin, pp 1965–1979
Rohdin M, Petersson J, Mure M, Glenny RW, Lindahl SGE, Linnarsson D (2003) Effects of gravity on lung diffusing capacity and cardiac output in prone and supine humans. J Appl Physiol 95:3–10
Rössler A, László Z, Haditsch B, Hinghofer-Szalkay HG (1999) Effect of postural changes on adrenomedullin plasma levels in humans. Hypertension 34:1147–1151
Rowell LB (1993) Human cardiovascular control. Oxford University Press, Oxford. ISBN 0-19-507362-2
Rushmer RF (1947) A roentgenographic study of the effect of a pneumatic anti-blackout suit on the hydrostatic columns in man exposed to positive radial acceleration. Am J Physiol 151:459–468
Sander-Jensen K, Secher NH, Astrup A, Christensen NJ, Giese J, Schwartz TW, Warberg J, Bie P (1986) Hypotension induced by passive head-up tilt: endocrine and circulatory mechanisms. Am J Physiol 251:R742–R748
Scharfetter H, Brunner P, Mayer M, Brandstätter B, Hinghofer-Szalkay H (2005) Fat and hydration monitoring by abdominal bioimpedance analysis: data interpretation by hierarchical electrical modeling. IEEE Trans BME 52:975–978
Segal KR, Burastero S, Chun A, Coronel P, Pierson RN Jr, Wang J (1991) Estimation of extracellular and total body water by multiple frequency bioelectrical-impedance measurement. Am J Clin Nutr 54:6–9
Seymour RS, Hargens AR, Pedley TJ (1993) The heart works against gravity. Am J Physiol 265:R715–R720
Sjöstrand T (1953) Volume and distribution of blood and their significance in regulating the circulation. Physiol Rev 33:202–228
Sjöstrand T (1976) Regulation of blood volume. Scand J Clin Lab Invest 36:209–221
Smit AAJ, Wieling W, Fujimura J, Denq JC, Opfer-Gehrking TL, Akarriou M, Karemaker JM, Low P (2004) Use of lower abdominal compression to combat orthostatic hypotension in patients with autonomic dysfunction. Clin Auton Res 14:165–175
Smith JJ, Ebert TJ (1990) General response to orthostatic stress. In: Smith JJ (ed) Circulatory response to the upright posture. CRC Press, Boca Raton, pp 1–46
Smith EE, Guyton AC (1963) Center of arterial pressure regulation during rotation of normal and abnormal dogs. Am J Physiol 204:979
Spallone V, Uccioli L, Menzinger G (1995) Diabetic autonomic neuropathy. Diabet Metab Rev 11:227–257
Stewart JM, Medow MS, Glover JL, Montgomery LD (2006) Persistent splanchnic hyperemia during upright tilt in postural tachycardia syndrome. Am J Physiol 290:H665–H673
Stocks JM, Taylor NAS, Tipton MJ, Greenleaf JE (2004) Human physiological responses to cold exposure. Aviat Space Environ Med 75:444–457
Streeten DHP, Anderson GH (1996) Mechanisms of orthostatic hypotension and tachycardia in patients with pheochromocytoma. Am J Hypertens 9:760–769
Sundkvist G, Almér LO, Lilja B (1981) A sensitive orthostatic test in tilt table, useful in the detection of diabetic autonomic neuropathy. Acta Med Scand Suppl 656:43–45
Thompson WO, Thompson PK, Dailey ME (1928) The effect of posture upon the composition and volume of blood in man. J Clin Invest 5:573–604
Truijen J, Bungaard-Nielsen M, van Lieshout JJ (2010) A definition of normovolaemia and consequences for cardiovascular control during orthostatic and environmental stress. Eur J Appl Physiol 109:141–157
van Lieshout JJ, Wieling W, Karemaker JM, Secher NH (2003) Syncope, cerebral perfusion, and oxygenation. J Appl Physiol 94:833–848
Wagner E (1886) Fortgesetzte Untersuchungen über den Einfluss der Schwere auf den Kreislauf. Arch Ges Physiol 39:371–386
Weissler AM, McCraw BH, Warren JV (1959) Pulmonary blood volume determined by a radioactive tracer technique. J Appl Physiol 14:531–534
West JB (2010) Pulmonary physiology and pathophysiology: an integrated, case-based approach, 2nd edn. Lippincott, Williams and Wilkins, Baltimore, MD. ISBN 978-0-7817-6701-9
Westerhof BE, Gisolf J, Karemaker JM, Wesseling KH, Secher NH, van Lieshout JJ (2006) Time course analysis of baroreflex sensitivity during postural stress. Amer J Physiol 291:H2864–H2874
Wilkins RW, Bradley SE, Friedland CK (1950) The acute circulatory effects of the head-won position (negative G) in normal man, with a note on some measures designed to relieve cranial congestion in this position. J Clin Invest 29:940–949
Wissig SL, Charonig AS (1984) Capillary ultrastructure. In: Staub NC, Taylor AE (eds) Edema, Chap 6. Raven Press, NY, pp 117–142
Yndgaard S, Schifter S, Perko G, Matzen S, Secher NH (1991) Calcitonin gene-related peptide (CGRP) during head-up tilt in man. Acta Physiol Scand 143:129–130
Zweifach BW (1973) Microcirculation. Ann Rev Physiol 35:117–150
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Hinghofer-Szalkay, H. Gravity, the hydrostatic indifference concept and the cardiovascular system. Eur J Appl Physiol 111, 163–174 (2011). https://doi.org/10.1007/s00421-010-1646-9
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DOI: https://doi.org/10.1007/s00421-010-1646-9