重复暴露于+Gz过程中的血压、血管阻力和+Gz耐力。

Blood pressure, vascular resistance, and +Gz tolerance during repeated +Gz exposures.

作者信息

Stevenson Alec T, Scott Jonathan P R, Chiesa Scott, Sin Debbie, Coates Gabriella, Bagshaw Michael, Harridge Stephen

出版信息

Aviat Space Environ Med. 2014 May;85(5):536-42. doi: 10.3357/asem.3816.2014.

DOI:10.3357/asem.3816.2014

PMID:24834568

Abstract

BACKGROUND

Cardiovascular reflexes that regulate blood pressure (BP) adapt during repeated exposure to +Gz acceleration separated by short (< 20 s) breaks, but whether this effect is preserved with longer intervals remains unknown.

METHODS

There were 17 subjects who completed 5 repeated gradual onset (0.1 G x s(-1)) runs (GOR1-5) to 60 degrees peripheral light loss (PLL) on a human centrifuge, separated by 2 min. Heart rate (HR) and BP were measured before and during each GOR and noninvasive estimation of cardiac output (CO) was used to calculate total peripheral resistance (TPR).

RESULTS

Mean resting (+/- SE) systolic BP (138 +/- 4 vs. 128 +/- 3 mmHg) and TPR (13.9 +/- 1.2 vs. 12.7 +/- 1.0 mmHg x L(-1) x min(-1)) were elevated after GOR1 and remained elevated thereafter. Compared with that before GOR1, resting HR was decreased (5-6 bpm) before GOR2-5. Resting CO decreased from 8.3 +/- 0.6 L x min(-1) before GOR1 to a nadir of 7.2 +/- 0.5 L x min(-1) before GOR4 and GOR5. The change in HR under increased +Gz decreased from +39 +/- 3 bpm during GOR1 to +31 +/- 3 bpm during GOR4 and GOR5, but the decrease in eye level BP under +Gz was unaffected. RGT did not change across the five GORs.

CONCLUSIONS

Increased resting BP and TPR following a single +Gz exposure suggest alterations in the cardiovascular system expected to confer improved tolerance during subsequent exposures. However, these changes were insufficient to improve +Gz tolerance measured during repeated GORs separated by 2 min.

摘要

背景

在短时间（<20秒）间隔的重复 +Gz 加速度暴露过程中，调节血压（BP）的心血管反射会发生适应性变化，但间隔时间更长时这种效应是否仍然存在尚不清楚。

方法

17名受试者在人体离心机上完成了5次重复的逐渐增加（0.1 G x s(-1)）运行（GOR1 - 5），直至外周光损失（PLL）达到60度，每次运行间隔2分钟。在每次GOR之前和期间测量心率（HR）和血压，并使用心输出量（CO）的无创估计值来计算总外周阻力（TPR）。

结果

GOR1后平均静息（±SE）收缩压（138 ± 4 vs. 128 ± 3 mmHg）和TPR（13.9 ± 1.2 vs. 12.7 ± 1.0 mmHg x L(-1) x min(-1)）升高，此后一直保持升高。与GOR1之前相比，GOR2 - 5之前静息HR降低（5 - 6次/分钟）。静息CO从GOR1之前的8.3 ± 0.6 L x min(-1)降至GOR4和GOR5之前的最低点7.2 ± 0.5 L x min(-1)。+Gz增加时HR的变化从GOR1期间的 +39 ± 3次/分钟降至GOR4和GOR5期间的 +31 ± 3次/分钟，但 +Gz下眼水平血压的降低不受影响。在五次GOR中RGT没有变化。