|Budget Amount *help
¥5,800,000 (Direct Cost: ¥5,800,000)
Fiscal Year 2004: ¥1,200,000 (Direct Cost: ¥1,200,000)
Fiscal Year 2003: ¥4,600,000 (Direct Cost: ¥4,600,000)
1.Data Acquisition :
Arterial pressure, blood flow velocity in the middle cerebral artery(Vmca) measured with transcranial Doppler(TCD), and ECG were simultaneously recorded into PC via AD converter in 5 adult volunteers.
2.Development of new method for analyzing of dynamic cerebral autoregulation(dCAR) :
Beat by beat mean values of arterial pressure (MAP) and Vmca were calculated, aligned at each R peak of ECG, and then resampled at 0.5Hz. dCAR was analyzed with using transfer function between MAP and mean Vmca. V Coherence (coh), gain, and phase were calculated. During hypercpnia (PetCO_2>50mmHg), coh <0.07Hz was significantly increased, and normalized during normocapnia ((PetCO_2:30-40mmHg). These results indicate that an increase of coh <0.07Hz may be reliable indicator of dCAR.
3.Evaluation of dCAR on static autoregulation curve :
(1)Animal study : Regional CBF(rCBF) measured with laser Doppler, Vmca measured with TCD,ECG,and MAP were simultaneously measured in 5 adult cats. Stepwise changes of MAP(40,70,100,120,and 180mmHg) were induced by phlebotomy, transfusion, or an infusion of phenylephrine. Steady condition was maintained at each MAP for 5min, and dCAR was evaluated at each MAP. Normocapnia was maintained during study.
mean Vmca and rCBF were maintained in the range of MAP between 70-120mmHg, and significantly reduced at MAP of 40mmHg, and increased at MAP of 180mmHg(P<0.05 in both). As compared at 100mmHg, coh in <0.07Hz was significantly increased at MAP=40mmHg, and coh in all frequency was significantly increased at MAP=180mmHg (P<0.05 in both).
An increase of coh <07Hz can clearly correlate with degree of impairment of static autoregulation. Thus, bed side evaluation of dCAR is feasible and reliable.