Noninvasive Monitor of Vascular Volume Fluid Shifts

Accurateintravascularvolumeassessment improves the detection of hemorrhageand hypovolemiaand facilitates decision-makingrelativeto resuscitation,surgery,and selection of higher level ofmedical care. Non-invasiveassessment techniquesare particularly important in thefield. Currentapproachesand devices do not have broad utilityand availability. Duringthe PhaseIeffort, the project team developed alow-profile phonocardiography transducerand state-of-the-art segmentation algorithm to provides insight into cardiaccycletimeintervals (CCTI’s)and, thereby, trends in intravascularvolume. In parallel, internally-funded, IRB-approved clinical studies wereconducted,acquiring non-invasive measurements on subjects in hemorrhageand hypovolemicconditionsas simulated by lower body negative pressureand hemodialysis. Changes of CCTI’s with smallamounts of hypovolemia(~2%) were demonstrated as wellas the progression to largervolumeloss with enhanced contractility. This trendingcan beimmensely useful to theclinician. Largerclinical studies will becompleted in the PhaseIIeffort including blood donorsasanother hemorrhagemodel. Datareduction from theseclinical studies will be used to identifyaset of measurement modalitiesand metrics foravolumeassessment system. Thesensingand processing hardware will beintegrated with data analysisalgorithms onto a benchtop prototypesystem.