Ultrasound in medicine & biology
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Ultrasound (US) interstitial syndrome is a sonographic lung pattern characterized by the presence of acoustic artifacts (B-lines and white lung). The purpose of this study was to demonstrate how interstitial syndrome is determined by acoustic interactions in lungs of variable density and in healthy organs deflated to a nonphysiologic level of density. ⋯ Artifacts (B-lines and white lung) appear in the normal rabbit lung through air-dependent increases in density. As in pathologic conditions, US interstitial syndrome can be reproduced in histologically normal lungs that are deflated to a critical level (>0.45 g/mL) of density, which is not achievable under physiologic conditions.
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Ultrasound Med Biol · Jul 2012
A method of evaluating the lower limit of cerebral autoregulation and its correlation with blood pressure by transcranial Doppler in rats.
The aim of present study was to validate the assessment of lower limit of cerebral autoregulation (LLCA) as derived from mean artery blood pressure (MABP) and cerebral zero flow pressure (ZFP) by means of transcranial Doppler (TCD) and to determine the accurate relationship between LLCA and MABP in stroke-prone renovascular hypertensive rats (RHRSP). We studied two groups of rats: RHRSP and normal controls. Blood flow velocity of middle cerebral artery was monitored by TCD and arterial blood pressure was recorded in right femoral artery to compute the ZFP. ⋯ The increase of LLCA was positively correlated with MABP, following an "S" curve, demonstrating that the change of LLCA was more obvious in the middle range of MABP in RHRSP (R(2) = 0.8848, p < 0.05). In conclusion, TCD is a valid and noninvasive method for determination of LLCA compared with the classic method in rats. Our data demonstrated that the change of LLCA may be correlated with MABP, following an "S" curve relationship.