Effects of Aging on Cardiovascular Responses to Gravity-Related Fluid Shift in Humans

Miwa, Chihiro; Sugiyama, Yoshiki; Mano, Tadaaki; Matsukawa, Tetsuya; Iwase, Satoshi; Watanabe, Takemasa; Kobayashi, Fumio

doi:10.1093/gerona/55.6.m329

Cited by 21 publications

(17 citation statements)

References 17 publications

(20 reference statements)

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“…Although the increased cardiac baroreflex delay of ϳ1.3 s in cervical SCI subjects may seem small, it represents an increased latency of ϳ70%, which is not inconsiderable. Similar increases in latency have been seen in other pathological conditions of blood pressure regulation (21)(22)(23)(24) and in the elderly (50), in whom baroreflex responses and blood pressure control are impaired (40,41). However, the cross-spectral estimates of cardiac baroreflex function may or may not be reflected in baroreflex control of sympathetic vascular regulation.…”

Section: Discussionsupporting

confidence: 60%

Clinical correlates of frequency analyses of cardiovascular control after spinal cord injury

Claydon

Krassioukov²

2008

American Journal of Physiology-Heart and Circulatory Physiology

132

129

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Claydon VE, Krassioukov AV. Clinical correlates of frequency analyses of cardiovascular control after spinal cord injury. Am J Physiol Heart Circ Physiol 294: H668 -H678, 2008. First published November 16, 2007 doi:10.1152/ajpheart.00869.2007.-Spinal cord injury (SCI) has profound effects on cardiovascular autonomic function due to injury to descending autonomic pathways, and cardiovascular diseases are the leading causes of morbidity and mortality after SCI. Evaluation of cardiovascular autonomic dysfunction after SCI and appraisal of simple noninvasive autonomic assessments that are clinically meaningful would be useful to SCI clinicians and researchers. We aimed to assess supine and upright cardiovascular autonomic function from frequency analyses of heart rate and blood pressure variability (HRV and BPV) after SCI. We studied 26 subjects with chronic cervical or thoracic SCI and 17 able-bodied controls. We continuously recorded R-R interval (RRI, by ECG) and beat-to-beat blood pressure (by Finometer) in supine and seated positions. Cardiovascular control was assessed from spectral analysis of RRI and blood pressure time series. Cardiac baroreflex control was assessed from cross-spectral analyses of low-frequency spectra. Supine and upright low-frequency HRV and BPV were reduced in cervical SCI subjects, as were total BPV and HRV. Supine high-frequency HRV was reduced in thoracic SCI subjects. Cardiac baroreflex delay was increased in cervical SCI subjects. Supine frequency domain indexes were correlated with sympathetic skin responses, orthostatic cardiovascular responses, and plasma catecholamine levels. SCI results in reduced sympathetic drive to the heart and vasculature and increased baroreflex delay in cervical SCI subjects and reduced cardiac vagal tone in thoracic SCI subjects. Frequency analyses of autonomic function are related to clinical measures of autonomic control after SCI and provide useful noninvasive clinical tools with which to assess autonomic completeness of injury following SCI. baroreceptor reflex; autonomic nervous system; spectral analysis SPINAL CORD INJURY (SCI) is associated with abnormal cardiovascular control that is related to the level and severity of injury to descending autonomic (sympathetic) pathways (10,15,35). The leading cause of morbidity and mortality in SCI individuals is cardiovascular disease (16,45). This most commonly manifests as neurogenic shock (in acute SCI) (35); supine hypotension (35); orthostatic hypotension (marked decreases in blood pressure in the upright position) (10, 11); autonomic dysreflexia (profound and life-threatening blood pressure increases following afferent stimulation below the lesion) (35); ECG abnormalities and arrhythmia (38), particularly during autonomic dysreflexia (9, 14); and abnormal cardiovascular responses to exercise (8).The severe impact of cardiovascular dysfunction on quality of life after SCI has prompted the search for simple physiological bedside assessments of autonomic function that can easily be performed in the clin...

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Section: Discussionsupporting

confidence: 60%

Clinical correlates of frequency analyses of cardiovascular control after spinal cord injury

Claydon

Krassioukov²

2008

American Journal of Physiology-Heart and Circulatory Physiology

132

129

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“…2). This finding is difficult to explain; however, Miwa et al [35] demonstrated that the arterial baroreflex gain for HR deceased with the upright position in young subjects. They suggested that young subjects showed an adaptive response of baroreflex function to the hypovolemic stress, and the decreased sensitivity may maintain a higher HR, compensating for the hypotensive effect of reduced SV during head-up tilt.…”

Section: Discussionmentioning

confidence: 97%

“…Only a few studies [34,35] addressed the age-related differences of the effect of hypovolemic stress on baroreflex sensitivity of the HR. Of interest, the graded LBNP gradually reduced the baroreflex sensitivity of the HR in the young but not in the elderly, in spite of the increased intensity of hypovolemic stress ( fig.…”

Section: Discussionmentioning

confidence: 99%

Cardiovascular Responses to Lower Body Negative Pressure in the Elderly: Role of Reduced Leg Compliance

Tsutsui¹,

Sagawa²,

Yamauchi³

et al. 2002

Gerontology

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Background: It is warranted to test the hypothesis that the orthostatic tolerance does not diminish in the aging process per se in healthy individuals. Objective: The purpose of the present study was to examine the effects of aging on cardiovascular response and baroreflex sensitivity during lower body negative pressure (LBNP) with a special reference to leg compliance. Methods: Fifteen healthy old male subjects [mean age 68.2 ± (SE) 0.8 years] and 22 young male subjects [mean age 21.4 ± (SE) 0.3 years] underwent a 21-min bout of ramped LBNP (from 0 to –60 mm Hg, 10 mm Hg each for 3 min). Heart rate (HR), blood pressure, stroke volume (SV), forearm blood flow, and leg volume were measured throughout the experimental period. The arterial baroreflex sensitivity was calculated from spontaneous changes in beat-to-beat arterial pressure and HR during LBNP. Results: The leg compliance was lower, and the orthostatic tolerance index was higher in old than in young participants. The LBNP-associated increases in leg volume and HR and the decreases in SV were lower in old subjects, suggesting that the reduction of venous return was less in magnitude in old subjects during LBNP. The baseline value of baroreflex sensitivity evaluated by the sequence analysis was smaller, and no LBNP-related change was observed in old subjects, whereas a gradual LBNP-related reduction was observed in young subjects. The slope of regression between ΔSV and change in forearm vascular resistance during LBNP was identical in both age groups. Conclusions: We conclude that: (1) aging per se does not increase the intolerance to orthostatic stress induced by LBNP; (2) a low magnitude of venous return reduction during LBNP contributes to a higher tolerance in the old because of lower leg compliance, and (3) the sensitivity of baroreflex control of the HR is attenuated in the old; however, there is no deterioration of the sensitivity of the peripheral vasoconstriction during LBNP.

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“…This response may be in part related to an impaired baroreflex function that causes inappropriate autonomic response. 23,24 Critically ill patients with a history of diabetes may be at a higher risk for hemodynamic instability. Autonomic dysfunction increases as diabetic complications worsen.…”

mentioning

confidence: 99%

Hemodynamic Instability: Is It Really a Barrier to Turning Critically Ill Patients?

Vollman¹

2012

Critical Care Nurse

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Effects of Aging on Cardiovascular Responses to Gravity-Related Fluid Shift in Humans

Cited by 21 publications

References 17 publications

Clinical correlates of frequency analyses of cardiovascular control after spinal cord injury

Clinical correlates of frequency analyses of cardiovascular control after spinal cord injury

Cardiovascular Responses to Lower Body Negative Pressure in the Elderly: Role of Reduced Leg Compliance

Hemodynamic Instability: Is It Really a Barrier to Turning Critically Ill Patients?

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