Perfusion Weighted Imaging And Nuclear Magnetic Resonance Spectroscopy Experimental Study Of Brain During Acute Hemorrhagic Shock

Purpose: The aim of this study was to investigate using perfusion weighted imagingand nuclear magnetic resonance spectroscopy whether rabbits have the timing anddegree of microcirculation changes in the brain during severe hemorrhagic shock andresuscitation in real time.Methods: Twenty New Zealand rabbit were randomized to undergo hemorrhagicshock, induced by a40%—50%blood volume bleed, and maintained MAP at30mmHg,for90min with (n=10) or without (n=10) subsequent resuscitation.Resuscitated animals received their own shed blood. The blood pressure, heart rate,temperature, respiratory rate, and arterial blood gas content were recorded duringsevere hemorrhagic shock and resuscitation in real time, and paralleled processingperfusion-weighted and spectroscopy imaging. The analysis of variance of repeateddata was made.Results: Mauchly ‘s test result is p<0.01,which means there are relations among fourthe repeatedly measured data.Using pairwise comparisons of Bonferroni andMultivariate variance analysis, mean arterial pressure （MAP）、heart rate （HR）、temperature （T）、PH、hemoglobin （Hb）、lactate （Lac）、relative cerebralblood volume(rCBV)、 relative cerebral blood flow(rCBF) were significantdifferences in the shock group and resuscitation group（p<0.05）. rCBV wassignificantly increased in shock（p <0.05）. rCBF was significant increased at90mintime points in shock（p <0.01）. MTT、TTP、T0were significantly increased at 150min time points comparing with the baseline points in shock（p <0.05）. PCr、βATP、βATP/Pi、PCr/Pi were significantly decreased in the brain of animals inshock as compared with baseline（p<0.05）. Pi was significantly increased at90minduring hemorrhagic shock （p<0.05）. PME was significantly increased at150minduring hemorrhagic shock （p<0.05）. PDE、PH were significantly decreased at150min during hemorrhagic shock. PME and Pi was significantly decreased inresuscitation group as compared with different times in shock state（p<0.05）. βATP、βATP/Pi were significantly increased in resuscitation group as compared withdifferent times in shock state. PCr/Pi was significantly decreased at150min in shockgroup as compared with resuscitation group at30、60min. However，tissuemetabolics of brain in1H spectroscopy（NAA/Cr、Cho/Cr、Lac/Cr、NAA/Cho） weren’tsignificantly different at all times in shock group and resuscitation group（p>0.05）.Conclusions: we conclude that T2*PWI and31P spectroscopy can effectivelyobserve the cerebral microcirculation and early energy metabolite changes duringacute severe hemorrhagic shock and resuscitation.