摘要
目的探讨二氧化碳反应过程中脑血流自动调节功能的变化规律,及建立自动调节下限临床测定的新方法。方法同步监测大脑中动脉血流、桡动脉血压和呼气终末呼出气体二氧化碳分压(ETco2),用临界关闭压(CCP)法测定脑血流自动调节下限(LLCA),观察正常健康志愿者79名正常呼吸和屏气、过度通气时的LLCA,并与正常呼吸测定结果比较。结果正常呼吸时LLCA为58mmHg±10mmHg(1mmHg=0.133kPa),屏气时明显上升至69mmHg±15mmHg(P<0.05),过度通气明显下降至44mmHg±11mmHg(P<0.05)。与正常呼吸相比,屏气和过度通气时LLCA测定差异的95%CI分别为2.70mmHg和2.18mmHg。屏气和过度通气LLCA变化率均与CCP的变化率呈负相关(r=-0.6105、-0.5551,均P<0.05),且过度通气LLCA变化率和ETco2的变化率呈“S”型曲线关系。同时,平均血流速度变化率与LLCA变化率呈正相关(r=0.5841、0.7739,均P<0.05),并呈现“S”型曲线关系。结论利用CCP可精确、无创地测定人类脑血流自动调节下限。CO2反应过程中脑血流自动调节功能相应的升高或降低,其机理和脑血管张力的改变密切相关。
Objective To investigate the shifts of cerebral autoregulation following end-tidal CO_2, and set up a new clinical way to evaluate the lower limit of cerebral autoregulation.Methods The cerebral blood flow spectrum of middle cerebral artery, radial blood pressure and end-tidal CO_2 (ETco_2) were simultaneously monitored amoung 70 healthy volunteers,38 males and 41 females,aged 21-77. The Lower limit of cerebral autoregulation (LLCA) was determined by critical closing pressure (CCP). We observed the shifts of LLCA of healthy subjects respectively between normocapnia and hyper- and hypocapnia. Results The LLCA of healthy subjects was 58 mm Hg± 10 mm Hg at normocapnia,increased at hypercapnia and decreased at hypocapnia significantly (69 mm Hg±15 mm Hg and 44 mm Hg±11 mm Hg, P<0.05). The 95% CI of difference were 2.70 mmHg between hyper- and normocapnia and 2.18 mm Hg between hypo- and normocapnia. The shifting rates of LLCA correlated inversely to the rates of CCP at both hyper- and hypocapnia (r=-0.610 5、-0.555 1,both P<0.05), and the relation between LLCA′s and CCP′s shifts displayed an “S” pattern curve at hypocapnia. The rate of mean velocity changing in middle cerebral artery was significantly correlative to the LLCA shifts′ rate (r=0.584 1, P<0.05), and showing an “S” pattern curve.Conclusion The lower limit of cerebral autoregulation can be determined by CCP exactly. The cerebral autoregulation can shift up or down following ETco_2, and its physiological basis is closely correlated with the cerebrovascular tone.
出处
《中华医学杂志》
CAS
CSCD
北大核心
2005年第22期1542-1546,共5页
National Medical Journal of China
基金
广州医学院博士启动基金资助项目(03Q01)
