title: Development of a diagnostic sensor for measuring blood cell concentrations during haemoconcentration.
abstract: BACKGROUND
  HemoSep®is a commercial ultrafiltration and haemoconcentration device for the concentration of residual bypass blood following surgery. This technology is capable of reducing blood loss in cardiac and other types of "clean site" procedures, including paediatric surgery. Clinical feedback suggested that the device would be enhanced by including a sensor technology capable of discerning the concentration level of the processed blood product. We sought to develop a novel sensor that can, using light absorption, give an accurate estimate of packed cell volume (PCV).
  
  
  METHODS
  A sensor-housing unit was 3D printed and the factors influencing the sensor's effectiveness - supply voltage, sensitivity and emitter intensity - were optimised. We developed a smart system, using comparator circuitry capable of visually informing the user when adequate PCV levels (⩾35%) are attained by HemoSep®blood processing, which ultimately indicates that the blood is ready for autotransfusion.
  
  
  RESULTS
  Our data demonstrated that the device was capable of identifying blood concentration at and beyond the 35% PCV level. The device was found to be 100% accurate at identifying concentration levels of 35% from a starting level of 20%.
  
  
  CONCLUSIONS
  The sensory capability was integrated into HemoSep's®current device and is designed to enhance the user's clinical experience and to optimise the benefits of HemoSep®therapy. The present study focused on laboratory studies using bovine blood. Further studies are now planned in the clinical setting to confirm the efficacy of the device.
authors: Department of Biomedical Engineering, University of Strathclyde, Glasgow, UK.
authors: Craig A
authors: CA
authors: Robertson
authors: Department of Biomedical Engineering, University of Strathclyde, Glasgow, UK.
authors: Terence
authors: T
authors: Gourlay
mesh_terms: D000818:Animals; D015374:Biosensing Techniques / Q000295:instrumentation / Q000379:methods*; D001773:Blood Cells / Q000166:cytology; D016063:Blood Loss, Surgical / Q000517:prevention & control; D002315:Cardiopulmonary Bypass / Q000379:methods; D002417:Cattle; D002469:Cell Separation / Q000379:methods; D004867:Equipment Design; D006400:Hematocrit / Q000295:instrumentation / Q000379:methods*; D006801:Humans; D066330:Printing, Three-Dimensional; D014462:Ultrafiltration / Q000379:methods*
keywords: autotransfusion; haematocrit; haemoconcentration; light sensor; packed cell volume