High normal resting pCO2 is a risk factor for salt sensitivity of blood pressure (BP) in normotensive humans and has been associated with higher resting systolic BP in postmenopausal women. To date, however, no known studies have investigated the effects of regular practice of voluntary mild hypocapnic breathing on BP in hypertensive patients. The objective of the present research was to test the hypothesis that capnometric feedback training can decrease both resting pCO2 and 24-h BP in a series of mildly hypertensive postmenopausal women. A small portable end tidal CO2 (etCO2) monitor was constructed and equipped with software that determined the difference between the momentary etCO2 and a pre-programmed criterion range. The monitor enabled auditory feedback for variations in CO2 outside the criterion range. 16 mildly hypertensive postmenopausal women were individually trained to sustain small decreases in etCO2 during six weekly sessions in the clinic and daily sessions at home. 24-h BP monitoring was conducted before and after the intervention, and in 16 prehypertensive postmenopausal women in a control group who did not engage in the capnometric training. Following the intervention, all 16 capnometric training participants showed decreases in resting etCO2 (− 4.3 ± 0.4 mmHg; p < .01) while 15 showed decreases in 24-h systolic BP (− 7.6 ± 2.0 mmHg; p < .01). No significant changes in either measure was observed in the control group. In addition, nighttime (− 9.5 ± 2.6; p < .01) and daytime (− 6.7 ± 0.2 mmHg) systolic BP were both decreased following capnometric training, while no significant changes in nighttime (− 2.8 ± 2.2 mmHg; p = .11) or daytime (− 0.7 ± 1.0 mmHg; p ≤ .247) systolic BP were observed in the control group. These findings support the hypothesis that regular practice of mild hypocapnic breathing that decreases resting etCO2 reliably decreases 24-h blood pressure in hypertensive postmenopausal women. The extent to which these effects persist beyond the training period or can be observed in other hypertensive subgroups remains to be investigated.

中文翻译：

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二氧化碳反馈训练可降低绝经后高血压女性的 24 小时血压

高正常静息 pCO2 是血压正常的人血压 (BP) 盐敏感性的危险因素，并且与绝经后妇女较高的静息收缩压有关。然而，迄今为止，尚无已知的研究调查定期进行自愿轻度低碳酸血症呼吸对高血压患者血压的影响。本研究的目的是验证二氧化碳反馈训练可以降低一系列轻度绝经后妇女的静息 pCO2 和 24 小时 BP 的假设。构建了一个小型便携式潮气末二氧化碳 (etCO2) 监测器，并配备了确定瞬时 etCO2 与预编程标准范围之间差异的软件。监测器能够对标准范围之外的 CO2 变化进行听觉反馈。对 16 名轻度绝经后妇女进行了单独培训，以在诊所每周六次和在家中的每日课程中维持 etCO2 的小幅下降。在干预之前和之后进行了 24 小时血压监测，并在对照组中的 16 名未参加二氧化碳测量培训的高血压绝经后妇女中进行。干预后，所有 16 名二氧化碳监测培训参与者均显示静息 etCO2 降低（- 4.3 ± 0.4 mmHg；p < .01），而 15 名显示 24 小时收缩压降低（- 7.6 ± 2.0 mmHg；p < .01）。在对照组中没有观察到任何一项测量的显着变化。此外，夜间 (- 9.5 ± 2.6; p < .01) 和白天 (- 6.7 ± 0.2 mmHg) 收缩压在二氧化碳测定训练后均下降，而夜间 (- 2.8 ± 2.2 mmHg; p = . 11) 或白天 (- 0.7 ± 1.0 mmHg; p ≤ .247) 在对照组中观察到收缩压。这些发现支持这样的假设，即减少静息 etCO2 的轻度低碳酸呼吸的常规练习能够可靠地降低高血压绝经后妇女的 24 小时血压。这些影响在训练期后持续存在的程度或在其他高血压亚组中可以观察到的程度仍有待研究。