Electrical impedance spectroscopy as a non-invasive method for evaluating perfused ex-vivo porcine kidneys
M.H. van Hoeven (TU Delft - Mechanical Engineering)
R. F. Remis – Mentor (TU Delft - Signal Processing Systems)
Marten Engelse – Graduation committee member (Leiden University Medical Center)
T.J.C. Oude Vrielink – Graduation committee member (Leiden University Medical Center)
M.J.A de Haan – Graduation committee member (Leiden University Medical Center)
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Abstract
This research addresses the following question: Is it possible to detect vascular obstructions and oedemas or monitor the decellularization process in perfused ex-vivo porcine kidneys using electrical impedance spectroscopy? Patients on the waiting list for kidney transplantation die because of a kidney shortage. A part of this problem can be solved by prolonging the period of preservation between the removal of the kidney from the body and the transplantation. However, oedemas and vascular obstructions are more likely to occur with longer perfusions. The kidney donor risk index doesn’t take this into account so a new technique needs to be established to assess the development of oedema and vascular obstruction. Another approach for increasing the supply of donor kidneys is de- and recellularization of the kidney. Electrical impedance spectroscopy shows promising results in the pancreas and this technique can probably be transferred to the kidney. EIS is a non-invasive, low cost, portable measuring technique that shows the results in real-time. A Spectra Bioimpedance and EIT Complete Kit with the 4-electrode attachment have been used at low frequencies (500 Hz) and high frequencies (70.000 Hz) for the evaluation of the porcine kidneys. Two different measurement techniques will be used, measurements through the renal artery and measurements on the kidney. These techniques are tested during the decellularization process, oedema formation, and vascular obstruction simulation to determine if impedance changes can signal these defects in the kidney. Robust changes have been made to the porcine kidneys in this regard. The sensitivity of the methods is less than expected. Only the decellularization results showed a notable change over time. The conclusion of this research is therefore: The results cannot prove a clear connection between vascular obstruction and oedema detection and electrical impedance changes. There is a probable correlation between electrical impedance and the phase of decellularization in which the kidney is in. Follow-up research is needed to substantiate this further.