title: Outflow monitoring of a pneumatic ventricular assist device using external pressure sensors.
abstract: BACKGROUND
  In this study, a new algorithm was developed for estimating the pump outflow of a pneumatic ventricular assist device (p-VAD). The pump outflow estimation algorithm was derived from the ideal gas equation and determined the change in blood-sac volume of a p-VAD using two external pressure sensors.
  
  
  OBJECTIVE
  Based on in vitro experiments, the algorithm was revised to consider the effects of structural compliance caused by volume changes in an implanted unit, an air driveline, and the pressure difference between the sensors and the implanted unit.
  
  
  METHODS
  In animal experiments, p-VADs were connected to the left ventricles and the descending aorta of three calves (70-100 kg). Their outflows were estimated using the new algorithm and compared to the results obtained using an ultrasonic blood flow meter (UBF) (TS-410, Transonic Systems Inc., Ithaca, NY, USA).
  
  
  RESULTS
  The estimated and measured values had a Pearson's correlation coefficient of 0.864. The pressure sensors were installed at the external controller and connected to the air driveline on the same side as the external actuator, which made the sensors easy to manage.
authors: Department of Mechanical and Biomedical Engineering, College of Engineering, Kangwon National University, 192-1 Hyoja-Dong, Chuncheon-si, South Korea.
authors: Seong Min
authors: SM
authors: Kang
authors: Department of Cardiovascular and Thoracic Surgery, Soonchunhyang University Hospital, Bucheon-si, South Korea.
authors: Keun
authors: K
authors: Her
authors: Department of Mechanical and Biomedical Engineering, College of Engineering, Kangwon National University, 192-1 Hyoja-Dong, Chuncheon-si, South Korea. swchoe@kangwon.ac.kr.
authors: Seong Wook
authors: http://orcid.org/0000-0003-4045-4384
authors: SW
authors: Choi
mesh_terms: D000465:Algorithms; D000818:Animals; D001795:Blood Pressure Determination / Q000295:instrumentation*; D002417:Cattle; D006353:Heart-Assist Devices; D013318:Stroke Volume; D016277:Ventricular Function, Left