Effect of CO2 on dynamic cerebral autoregulation measurement
Effect of CO2 on dynamic cerebral autoregulation measurement
复制标题
DOI：
10.1088/0967-3334/20/3/304
复制
发表时间：
1999-08-01
影响因子：
3.2
通讯作者：
Evans, DH
中科院分区：
文献类型：
--
作者：
Panerai, RB;Deverson, ST;Evans, DH
已知动脉pCO(2)影响大脑的自动调节，但其对平均动脉血压（ABP）和平均脑血流速度（CBFV）之间的动态关系的影响尚未确定。在16例正常受试者中，采用无创法（Finapres）测量ABP，用多普勒超声估计大脑中动脉CBFV，用红外二氧化碳仪测量潮末二氧化碳（EtCO2）。在呼吸空气中含有5%二氧化碳的混合物之前、期间和之后分别进行录音。通过对CO2浓度为5.55 +/- 0.38 kPa前、6.43 +/- 0.31 kPa时和5% CO2浓度为5.43 +/- 0.26 kPa后平均ABP和CBFV的逐拍变化谱分析，计算了ABP对CBFV影响的相干函数、幅度和相位频率响应以及脉冲和阶跃响应。当CO2浓度为5%时，在0.05 Hz以下的频率范围内相干函数和幅频响应显著增加，在0.02 ~ 0.1 Hz的频率范围内相位减小。脉冲和阶跃响应表明，5% COz降低了自调节机制的效率。当EtCO2增加14.4%时，CBFV平均增加20.7%，而临界关闭压力降低25.9%，而电阻面积积的变化不显著。
Arterial pCO(2) is known to influence cerebral autoregulation but its effect on the dynamic relationship between mean arterial blood pressure (ABP) and mean cerebral blood flow velocity (CBFV), obtained from spontaneous fluctuations in ABP, has not been established. In 16 normal subjects, ABP was measured non-invasively (Finapres), CBFV was estimated with Doppler ultrasound in the middle cerebral artery, and end-tidal CO2 (EtCO2) was measured with an infrared capnograph. Recordings were made before, during and after breathing a mixture of 5% CO2 in air. The coherence function, amplitude and phase frequency responses, and impulse and step responses For the effects of ABP on CBFV were calculated by spectral analysis of beat-to-beat changes in mean ABP and CBFV before (mean CO2 5.55 +/- 0.38 kPa), during (6.43 +/- 0.31 kPa) and after 5% CO2 (5.43 +/- 0.26 kPa). During 5% CO2, the coherence function and the amplitude frequency response were significantly increased for frequencies below 0.05 Hz and the phase was reduced for the frequency range 0.02-0.1 Hz. The impulse and step responses indicated that 5% COz reduces the efficiency of the autoregulatory mechanism. A 20.7% average increase in CBFV induced by a 14.4% increase in EtCO2 was found to be mediated by a 25.9% reduction in critical closing pressure, while the change in resistance-area product was non-significant.