Modeling liver electrical conductivity during hypertonic injection

Abstract

Metastases in the liver frequently grow as scattered tumor nodules that neither can be removed by surgical resection nor focally ablated. Previously, we have proposed a novel technique based on irreversible electroporation that may be able to simultaneously treat all nodules in the liver while sparing healthy tissue. The proposed technique requires increasing the electrical conductivity of healthy liver by injecting a hypersaline solution through the portal vein. Aiming to assess the capability of increasing the global conductivity of the liver by means of hypersaline fluids, here, it is presented a mathematical model that estimates the NaCl distribution within the liver and the resulting conductivity change. The model fuses well-established compartmental pharmacokinetic models of the organ with saline injection models used for resuscitation treatments, and it considers changes in sinusoidal blood viscosity because of the hypertonicity of the solution. Here, it is also described a pilot experimental study in pigs in which different volumes of NaCl 20% (from 100 to 200 mL) were injected through the portal vein at different flow rates (from 53 to 171 mL/minute). The in vivo conductivity results fit those obtained by the model, both quantitatively and qualitatively, being able to predict the maximum conductivity with a 14.6% average relative error. The maximum conductivity value was 0.44 second/m, which corresponds to increasing 4 times the mean basal conductivity (0.11 second/m). The results suggest that the presented model is well suited for predicting on liver conductivity changes during hypertonic saline injection.

Focused transhepatic electroporation mediated by hypersaline infusion through the portal vein in rat model. Preliminary results on differential conductivity

“…found 0.12 S/m and 0.27 S/m for normal and tumoural liver tissue, respectively. 24 Although little data is available in the literature on increasing conductivity by administering HI through the portal vein, in our previous study on pigs, with the same HI protocol, similar peak conductivity results were obtained (range 0.21-0.37 S/m) 17 , which further supports the consistency of the present data despite the small sample size. Finally, our actual TW (175±115.2 sec) appears to be enough to implement a conventional IRE protocol.…”

“…The results also show that this infusion could be safe when it is correctly compensated as we previously demonstrated in the pilot study on pigs. 17 …”

“…This model was further validated with an in vivo pilot safety study on pigs, which demonstrated that this infusion could increase the mean basal conductivity by up to 4 times. 17 Interestingly, the tumour nodules lack of sinusoids means they are only supplied with blood from the hepatic artery. 18 , 19 , 20 In fact, this characteristic is currently used for identifying tumours by injecting contrast agents with CT or MRI.…”

Avoiding neuromuscular stimulation in liver irreversible electroporation using radiofrequency electric fields

“…The conductivity of the ionic solutions increased by about 2% for each increase of 1 °C in temperature. Therefore, an additional term was included in both conductivity expressions (3) and (4) (Castellví et al 2017).…”