Hemodynamic response to the upright posture

The authors' objective was to review previous studies of immediate (first 30 seconds) and stabilized (30 seconds to 20 minutes) hemodynamic responses of healthy adults to the head-up posture, with particular reference to alteration of such responses in the elderly and the usefulness of such data in the diagnosis of orthostatic hypotension. The immediate response in healthy young adults is characterized by a prompt rise in heart rate, which peaks at about 8 to 15 seconds and then tapers; the arterial pressure and total vascular resistance decrease sharply at 5 to 10 seconds, followed by a rapid rebound and overshoot. Over the first 30 seconds there is a steady parallel decline of thoracic blood volume and stroke volume; there is also an initial surge of cardiac output followed by a steady decrease. During the stabilized response (30 seconds to 20 minutes), the hemodynamic variables are relatively steady, showing average increases in heart rate of about 15 to 30%, in diastolic pressure of 10 to 15%, and in total vascular resistance of 30 to 40%; during the 5th to 20th minutes there are also decreases in thoracic blood volume averaging about 25 to 30%, in cardiac output 15 to 30%, and in pulse pressure about 5 to 10%. It is evident that in normal human subjects, assumption of the upright posture results in profound hemodynamic changes, most of them occurring during the first 30 seconds. In elderly subjects (aged 60-69 years), there are, in the upright posture, lesser increments of heart rate and diastolic pressure, but no significant differences from younger age groups in the response of thoracic blood volume, cardiac output or total vascular resistance. However, beginning at about age 75, there is an increasing incidence of orthostatic hypotension, which averages about 14 to 20% at age 75 and older. The tendency toward orthostatic hypotension in the elderly is due (1) to the structural and functional changes in the circulation itself, (2) to a decline in autonomic function, and (3) to a probable functional deficiency of the skeletal muscle pump. The authors believe that closer hemodynamic monitoring of orthostatic hypotension patients would considerably increase our understanding and aid in the diagnosis of this condition.
CiteULike    Complore    Connotea    Del.icio.us    Digg    Reddit    Technorati    Twitter    What's this?

This article has been cited by other articles:

				A. Fedorowski, L. Stavenow, B. Hedblad, G. Berglund, P. M. Nilsson, and O. Melander Orthostatic hypotension predicts all-cause mortality and coronary events in middle-aged individuals (The Malmo Preventive Project) Eur. Heart J., August 20, 2009; (2009) ehp329v1. [Abstract] [Full Text] [PDF]

				P. Gandia, S. Saivin, A. P. Le-Traon, A. Guell, and G. Houin Influence of simulated weightlessness on the intramuscular and oral pharmacokinetics of promethazine in 12 human volunteers. J. Clin. Pharmacol., September 1, 2006; 46(9): 1008 - 1016. [Abstract] [Full Text] [PDF]

				K. M. Rose, M. L. Eigenbrodt, R. L. Biga, D. J. Couper, K. C. Light, A. R. Sharrett, and G. Heiss Orthostatic Hypotension Predicts Mortality in Middle-Aged Adults: The Atherosclerosis Risk in Communities (ARIC) Study Circulation, August 15, 2006; 114(7): 630 - 636. [Abstract] [Full Text] [PDF]

				S. B. Harrap, J. S. Cui, Z. Y. H. Wong, and J. L. Hopper Familial and Genomic Analyses of Postural Changes in Systolic and Diastolic Blood Pressure Hypertension, March 1, 2004; 43(3): 586 - 591. [Abstract] [Full Text] [PDF]

				P. Gandia, M.-P. Bareille, S. Saivin, A. P. Le-Traon, M. Lavit, A. Guell, and G. Houin Influence of Simulated Weightlessness on the Oral Pharmacokinetics of Acetaminophen as a Gastric Emptying Probe in Man: A Plasma and a Saliva Study J. Clin. Pharmacol., November 1, 2003; 43(11): 1235 - 1243. [Abstract] [Full Text] [PDF]

				D. S. Goldstein, S. Pechnik, C. Holmes, B. Eldadah, and Y. Sharabi Association Between Supine Hypertension and Orthostatic Hypotension in Autonomic Failure Hypertension, August 1, 2003; 42(2): 136 - 142. [Abstract] [Full Text] [PDF]

				J. S. Pankow, K. M. Rose, A. Oberman, S. C. Hunt, L. D. Atwood, L. Djousse, M. A. Province, and D. C. Rao Possible Locus on Chromosome 18q Influencing Postural Systolic Blood Pressure Changes Hypertension, October 1, 2000; 36(4): 471 - 476. [Abstract] [Full Text] [PDF]

				F. Saborowski, G. Krahe-Fritsch, M. Krakau, K. Wallbrueck, and M. Schaldach The effects of orthostasis on the ventricular-evoked response Europace, January 1, 2000; 2(4): 333 - 338. [Abstract] [PDF]

				B Panayiotou, J Reid, M Fotherby, and P Crome Orthostatic haemodynamic responses in acute stroke Postgrad. Med. J., April 1, 1999; 75(882): 213 - 218. [Abstract] [Full Text]

				S. McGee, W. B. Abernethy III, and D. L. Simel Is This Patient Hypovolemic? JAMA, March 17, 1999; 281(11): 1022 - 1029. [Abstract] [Full Text] [PDF]

				A. S. M. Shamsuzzaman, Y. Sugiyama, A. Kamiya, Q. Fu, and T. Mano Head-up suspension in humans: effects on sympathetic vasomotor activity and cardiovascular responses J Appl Physiol, May 1, 1998; 84(5): 1513 - 1519. [Abstract] [Full Text] [PDF]

				J. E. Naschitz, D. Hardoff, I. Bystritzki, D. Yeshurun, L. Gaitini, A. Tamir, and M. Jaffe The Role of the Capnography Head-up Tilt Test in the Diagnosis of Syncope in Children and Adolescents Pediatrics, February 1, 1998; 101 (2): e6 - e6. [Abstract] [Full Text] [PDF]