Predictors of orthostatic intolerance in healthy young women.

PURPOSE Orthostatic intolerance is more prevalent in women. The purpose of this investigation was to evaluate the physiological responses of orthostatic tolerant and intolerant females to progressive lower body negative pressure (LBNP) and to identify predictors of orthostatic tolerance. METHODS Following baseline measurements, eleven healthy, moderately active women (mean age 24 ± 3 yr) underwent an orthostatic challenge involving four 12-minute stages of progressive LBNP at -15, -30, -45 and -60 mmHg. Traditional haemodynamic characteristics, as well as baroreceptor sensitivity, were analyzed across all stages. RESULTS Five women became presyncopal during the test and were classified as low tolerant (LT) while the remaining six were classified as high tolerant (HT). LBNP by group (tolerance) interactions were significantly different for stroke volume (P=0.008) and the rate of decline (slope) of stroke volume (P=0.03). During the early stages of LBNP, the LT group displayed a higher stroke volume than the HT group (76.4 ± 8.6 vs. 60.0 ± 13.3 mL/beat; P=0.02) yet by the final stage, stroke volumes were similar (22.5 ± 11.9 vs. 22.7 ± 4.5 mL/beat, P = 0.99). Baroreceptor sensitivity, heart rate variability and blood pressure variability were not significantly different between the groups. CONCLUSIONS The results of this investigation suggest that orthostatic intolerance in women can be identified during the initial stages of an LBNP challenge, as evidenced by a more rapid decline in stroke volume.

[1]  Yan Li,et al.  Blood flow pattern in the middle cerebral artery in relation to indices of arterial stiffness in the systemic circulation. , 2012, American journal of hypertension.

[2]  Michael J.A. Williams,et al.  Cardiorespiratory and cerebrovascular responses to head-up tilt II: Influence of age, training status and acute exercise , 2011, Experimental Gerontology.

[3]  Michael J.A. Williams,et al.  Cardiorespiratory and cerebrovascular responses to head-up tilt I: Influence of age and training status , 2011, Experimental Gerontology.

[4]  Y. Tzeng,et al.  Diurnal variation in time to presyncope and associated circulatory changes during a controlled orthostatic challenge. , 2010, American journal of physiology. Regulatory, integrative and comparative physiology.

[5]  S. Shibata,et al.  Menstrual Cycle Affects Renal-Adrenal and Hemodynamic Responses During Prolonged Standing in the Postural Orthostatic Tachycardia Syndrome , 2010, Hypertension.

[6]  Michael J.A. Williams,et al.  Influence of age on syncope following prolonged exercise: differential responses but similar orthostatic intolerance , 2009, The Journal of physiology.

[7]  H. Kamel,et al.  BLOOD DONORS AND BLOOD COLLECTION: Delayed adverse reactions to blood donation , 2009, Transfusion.

[8]  Michael J.A. Williams,et al.  Initial orthostatic hypotension is unrelated to orthostatic tolerance in healthy young subjects. , 2009, Journal of applied physiology.

[9]  W. Dupont,et al.  Genetic variants in the &agr;2C-adrenoceptor and G-protein contribute to ethnic differences in cardiovascular stress responses , 2008, Pharmacogenetics and genomics.

[10]  Nandu Goswami,et al.  LBNP: past protocols and technical considerations for experimental design. , 2008, Aviation, space, and environmental medicine.

[11]  D. Warburton,et al.  Diastolic ventricular interactions in endurance-trained athletes during orthostatic stress. , 2007, American journal of physiology. Heart and circulatory physiology.

[12]  Rong Zhang,et al.  Heat stress reduces cerebral blood velocity and markedly impairs orthostatic tolerance in humans. , 2006, American journal of physiology. Regulatory, integrative and comparative physiology.

[13]  Victor A Convertino,et al.  Arterial pulse pressure and its association with reduced stroke volume during progressive central hypovolemia. , 2006, The Journal of trauma.

[14]  Roger Hainsworth,et al.  Phase of the menstrual cycle does not affect orthostatic tolerance in healthy women , 2006, Clinical Autonomic Research.

[15]  K. Nazar,et al.  Hemodynamic and neuroendocrine predictors of lower body negative pressure (LBNP) intolerance in healthy young men. , 2005, Journal of physiology and pharmacology : an official journal of the Polish Physiological Society.

[16]  B. Levine,et al.  Effects of gender and hypovolemia on sympathetic neural responses to orthostatic stress. , 2005, American journal of physiology. Regulatory, integrative and comparative physiology.

[17]  W. Franke,et al.  Effects of age and fitness on tolerance to lower body negative pressure. , 2004, The journals of gerontology. Series A, Biological sciences and medical sciences.

[18]  David A Ludwig,et al.  Stroke volume and sympathetic responses to lower-body negative pressure reveal new insight into circulatory shock in humans , 2004, Autonomic Neuroscience.

[19]  P. Norsk,et al.  Heart rate and blood pressure during initial LBNP do not discriminate higher and lower orthostatic tolerant men , 2003, Clinical Autonomic Research.

[20]  V. L. Cooper,et al.  Cross-spectral analysis of cardiovascular parameters whilst supine may identify subjects with poor orthostatic tolerance. , 2003, Clinical science.

[21]  W. Franke,et al.  Training mode does not affect orthostatic tolerance in chronically exercising subjects , 2003, European Journal of Applied Physiology.

[22]  Warren D. Franke,et al.  Cardiovascular and autonomic responses to lower body negative pressure , 2003, Clinical Autonomic Research.

[23]  Patrice Abry,et al.  Orthostatic tolerance and spontaneous baroreflex sensitivity in men versus women after 7 days of head-down bed rest , 2002, Autonomic Neuroscience.

[24]  Janice V Meck,et al.  Postspaceflight orthostatic hypotension occurs mostly in women and is predicted by low vascular resistance. , 2002, Journal of applied physiology.

[25]  S. Sagawa,et al.  Hypovolemic intolerance to lower body negative pressure in female runners. , 2001, Medicine and science in sports and exercise.

[26]  R. Hainsworth,et al.  Spectral and cross-spectral autoregressive analysis of cardiovascular variables in subjects with different degrees of orthostatic tolerance , 2001, Clinical Autonomic Research.

[27]  Raffaello Furlan,et al.  The Elusive Pathophysiology of Neurally Mediated Syncope , 2000, Circulation.

[28]  V. Convertino,et al.  Vasoactive neuroendocrine responses associated with tolerance to lower body negative pressure in humans. , 2000, Clinical physiology.

[29]  B D Levine,et al.  Cardiac atrophy after bed-rest deconditioning: a nonneural mechanism for orthostatic intolerance. , 1997, Circulation.

[30]  D D White,et al.  Women have lower tolerance to lower body negative pressure than men. , 1996, Journal of applied physiology.

[31]  J B Charles,et al.  Spaceflight alters autonomic regulation of arterial pressure in humans. , 1994, Journal of applied physiology.

[32]  P. Raven,et al.  Chronic endurance exercise training: a condition of inadequate blood pressure regulation and reduced tolerance to LBNP. , 1993, Medicine and science in sports and exercise.

[33]  V A Convertino,et al.  Endurance exercise training: conditions of enhanced hemodynamic responses and tolerance to LBNP. , 1993, Medicine and science in sports and exercise.

[34]  B. Levine.  Regulation of central blood volume and cardiac filling in endurance athletes: the Frank-Starling mechanism as a determinant of orthostatic tolerance. , 1993, Medicine and science in sports and exercise.

[35]  P. Raven.  An overview of the problem: exercise training and orthostatic intolerance. , 1993, Medicine and science in sports and exercise.

[36]  A. Amery,et al.  The Inheritance of Left Ventricular Structure and Function Assessed by Imaging and Doppler Echocardiography , 1991, American heart journal.

[37]  L D Montgomery,et al.  Cardiovascular responses of men and women to lower body negative pressure. , 1977, Aviation, space, and environmental medicine.

[38]  Qi Fu,et al.  Hemodynamics of orthostatic intolerance: implications for gender differences. , 2004, American journal of physiology. Heart and circulatory physiology.

[39]  L. Lipsitz,et al.  Orthostatic hypotension. , 2002, Clinics in geriatric medicine.

[40]  L. R. Davrath,et al.  Validation of impedance cardiography during lower body negative pressure. , 1999, Aviation, space, and environmental medicine.

[41]  K. Teo,et al.  Reliability and Validity of Measures of Cardiac Output During Incremental to Maximal Aerobic Exercise , 1999, Sports medicine.

[42]  V A Convertino,et al.  Gender differences in autonomic functions associated with blood pressure regulation. , 1998, The American journal of physiology.

[43]  C. G. Blomqvist,et al.  Physical fitness and cardiovascular regulation: mechanisms of orthostatic intolerance. , 1991, Journal of applied physiology.

[44]  C. G. Blomqvist,et al.  Orthostatic hypotension. , 1986, Hypertension.