Abstract
One strategy for assessing efficacy of a liver transplant is to monitor perfusion and oxygenation after transplantation. An implantable optical sensor is being developed to overcome inadequacies of current monitoring approaches. To facilitate sensor design while minimizing animal use, a polydimethylsiloxane (PDMS)-based liver phantom was developed to mimic the optical properties of porcine liver in the 630-1000 nm wavelength range and the anatomical geometry of liver parenchyma. Using soft lithography to construct microfluidic channels in pigmented elastomer enabled the 2D approximation of hexagonal liver lobules with 15mm sinusoidal channels, which will allow perfusion with blood-mimicking fluids to facilitate the development of the liver perfusion and oxygenation monitoring system.
Highlights
Over 6000 patients received liver transplantation each year from 2005 to 2008 [1]
Measured optical properties of the PDMS-based liver phantoms are presented in Fig. 8 in comparison to published values for porcine liver
The Fast Fourier Transform (FFT) spectrum contains a peak at 1.667 Hz, which corresponds to the pump pulse rate (100 bpm) further demonstrating the ability of the phantom to mimic the in vivo case
Summary
Over 6000 patients received liver transplantation each year from 2005 to 2008 [1]. Though many post-surgery factors may affect the health of liver grafts, vascular complications are significant contributors to graft failure [2,3]. Some surgeons use non-quantitative Doppler flowmetry to assess postoperative hepatic artery flow, but this technique is not a comprehensive solution to hepatic graft monitoring due to inability to assess microvascular perfusion and oxygenation. Time-transit Doppler flowmetry is generally not feasible for monitoring of vascular perfusion post-operatively. Neither of these techniques provide information about the oxygenation state of the blood which is critical in determining the state of the graft. A device based upon thermal diffusion (HemedexTM) has been approved for post-operative quantification of microvascular perfusion in the liver, but it does not permit direct measurement of blood flow in either the hepatic artery or portal vein nor does it assess tissue oxygenation
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