NONHYPOTENSIVE HYPOVOLEMIA REDUCES ASCENDING AORTIC DIMENSIONS IN HUMANS

被引:139
作者
TAYLOR, JA
HALLIWILL, JR
BROWN, TE
HAYANO, J
ECKBERG, DL
机构
[1] MCGUIRE DEPT VET AFFAIRS MED CTR, DEPT PHYSIOL, RICHMOND, VA USA
[2] KRUG LIFE SCI, HOUSTON, TX 77058 USA
[3] NAGOYA CITY UNIV, SCH MED, DEPT INTERNAL MED 3, NAGOYA, AICHI 467, JAPAN
[4] VIRGINIA COMMONWEALTH UNIV MED COLL VIRGINIA, RICHMOND, VA USA
来源
JOURNAL OF PHYSIOLOGY-LONDON | 1995年 / 483卷 / 01期
关键词
D O I
10.1113/jphysiol.1995.sp020585
中图分类号
Q189 [神经科学];
学科分类号
071006 ;
摘要
1. The notion that small, 'non-hypotensive' reductions of effective blood volume alter neither arterial pressure nor arterial baroreceptor activity is pervasive in the experimental literature. Mie tested two hypotheses: (a) that minute arterial pressure and cardiac autonomic outflow changes during hypovolaemia induced by lower body suction in humans are masked by alterations in breathing, and (b) that evidence for arterial baroreflex engagement might be obtained from measurements of thoracic aorta dimensions. 2. In two studies, responses to graded lower body suction at 0 (control), 5, 10, 15, 20 and 40 mmHg were examined in twelve and ten healthy young men, respectively. In the first, arterial pressure (photoplethysmograph), R-R interval, and respiratory sinus arrhythmia amplitude (complex demodulation) were measured during uncontrolled and controlled breathing (constant breathing frequency and tidal volume). In the second, cross-sectional areas of the ascending thoracic aorta were calculated from nuclear magnetic resonance images. 3. Lower body suction with controlled breathing resulted in an increased arterial pulse pressure at mild levels (5-20 mmHg; ANOVA, P < 0.05) and a decreased arterial pulse pressure at moderate levels (40 mmHg; ANOVA, P < 0.05). Both R-R intervals and respiratory sinus arrhythmia were negatively related to lower body suction level, whether group averages (general linear regression, r > 0.92) or individual subjects (orthogonal polynomials, 12 of 12 subjects) were assessed. 4. Aortic pulse area decreased progressively and significantly during mild lower body suction, with 47 % of the total decline occurring by 5 mmHg. 5. These results suggest that small reductions of effective blood volume reduce aortic baroreceptive areas and trigger haemodynamic adjustments which are so efficient that alterations in arterial pressure escape detection by conventional means.
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收藏
页码:289 / 298
页数:10
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