Physiological responses of aged men to head-up tilt during heat exposure

Shiraki, Keizō; Sagawa, Sueko; Yousef, Mohamed; Konda, Nobuhide; Miki, Kenju

doi:10.1152/jappl.1987.63.2.576

Cited by 22 publications

(19 citation statements)

References 12 publications

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“…A blunted HR response and a smaller increase in peripheral resistance are well documented in the elderly (29)(30)(31)33). In the present study, the magnitude of tachycardia during head-up tilt in elderly subjects was attenuated compared with young subjects.…”

Section: Discussionsupporting

confidence: 55%

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Initial drop of blood pressure during head-up tilt in patients with cerebrovascular accidents

Enishi

Tajima

Akimoto

et al. 2004

Environ Health Prev Med

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Objective: To investigate cardiovascular responses to orthostatic stress in patients with cerebrovascular accidents (CVA).Methods: Twelve male patients with CVA, 11 healthy elderly and 12 healthy young males participated in the present study. The CVA patients had suffered stroke with hemiplegia at least 11 months prior to the study, their medical conditions were stable, and no subjects were taking medications affecting the cardiovascular system. Heart rate (HR) was determined using RR intervals from the ECG. Stroke volume (SV) was estimated by an impedance method, and cardiac output (CO) was calculated by multiplying SV by HR. Blood pressure (BP) was determined by the auscultatory method. SV, HR, CO and BP were measured every 2 min before and during 7 min of 60-degree head-up tilt (HUT).Results: SV decreased and HR increased immediately after starting HUT in all groups. CO in healthy elderly and young subjects immediately decreased during HUT also, and the decrease was sustained throughout the head-up period. However, CO in CVA patients remained constant throughout the experiment. HUT immediately decreased SBP in all groups and the magnitude of initial SBP reduction in CVA patients was greater than that in the other groups.Conclusions: We identified an initial reduction of BP during HUT in CVA patients and the recovery of BP by 3 min of head-up tilt. We emphasize that adjustment to orthostatic stress in CVA patients should be practiced by HUT, as our findings showed that CVA patients maintained physiological orthostatic tolerance except for the initial fall in BP.

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Section: Discussionsupporting

confidence: 55%

“…Numerous studies have compared cardiovascular responses to orthostatic stress in elderly and young subjects (28)(29)(30)(31)(32)(33). A blunted HR response and a smaller increase in peripheral resistance are well documented in the elderly (29)(30)(31)33).…”

Section: Discussionmentioning

confidence: 99%

Initial drop of blood pressure during head-up tilt in patients with cerebrovascular accidents

Enishi

Tajima

Akimoto

et al. 2004

Environ Health Prev Med

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“…It should be noted that sustaining an equivalent esophageal temperature and mean T sk between younger and older participants is inherently difficult. For example, a previous study (Shiraki et al 1987) found maintaining mean T sk between older and younger males resulted in older participants having a significant higher esophageal temperature. Thus, whilst acknowledging the possibility that small differences in T sk may influence MAP (Wilson et al 2002), we preferentially maintained esophageal temperature above mean skin temperature.…”

Section: Limitationsmentioning

confidence: 94%

Compression leggings modestly affect cardiovascular but not cerebrovascular responses to heat and orthostatic stress in young and older adults

Lucas

Ainslie

Morrison

et al. 2011

AGE

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We tested the hypothesis that wearing commercially available compression leggings would attenuate postural reductions in mean arterial blood pressure (MAP) and cerebral perfusion during heat stress, particularly in older adults. Six older (70 years±4) and six younger (29 years±4) males were heated (esophageal temperature raised 0.5°C) in a water-perfused suit whilst wearing compression or control leggings (>1 week apart, randomized order). Blood flow velocity in the middle cerebral artery (MCAv), blood pressure (photoplethysmography), total peripheral resistance (TPR; ModelFlow) and the partial pressure of end-tidal carbon dioxide were measured continuously before and during 3-min standing in each thermal state. When supine, compression leggings did not change any cardiorespiratory variables in either age group or thermal condition (P>0.05). Upon standing, wearing compression leggings delayed (~15%; P=0.044) the maximal drop (nadir) in MAP irrespective of age or thermal condition. During the last minute of standing, wearing compression leggings in normothermia increased TPR (+16%) in older participants but dropped TPR (−8%) in younger participants (P=0.004 compression×age group). When standing and heated, wearing compression leggings lowered TPR in older and younger participants (~43%; P<0.01) without changing MAP or MCAv (P>0.05). In older adults, when standing, compression leggings maintained MAP by elevating TPR. In contrast, under combined heat and orthostatic stress, wearing compression leggings dropped TPR in both older and younger adults, though MAP and MCAv were maintained.

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“…Numerous studies have compared cardiovascular responses to orthostatic stress (hypovolemic stress, i.e., lower body negative pressure: LBNP) in older and young subjects [3,[6][7][8][9]. A blunted heart rate (HR) response and a smaller increase in peripheral resistance are well documented [3,6,9] in the old.…”

Section: Introductionmentioning

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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Physiological responses of aged men to head-up tilt during heat exposure

Cited by 22 publications

References 12 publications

Initial drop of blood pressure during head-up tilt in patients with cerebrovascular accidents

Initial drop of blood pressure during head-up tilt in patients with cerebrovascular accidents

Compression leggings modestly affect cardiovascular but not cerebrovascular responses to heat and orthostatic stress in young and older adults

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

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