Innovative technology for elimination of microbubbles during hemodialysis treatments

Project Summary Around 400,000 patients in the US and at least 5 million world-wide, receive weekly sessions of hemodialysis (HD), the standard long-term treatment for irreversible kidney failure. Although it has revolutionized the field by increasing the longevity of patients, improvements in the technique and equipment have been stagnant for decades. Besides from still suffering from high premature mortality rate compared to the general population, HD patients carry a high burden symptomatology which requires frequent hospitalizations and significantly deteriorate the patient’s overall quality of life. It is agreed upon that a major contributor to the patients’ symptom burden arises from the HD treatment itself. The main difficulty in identifying and eliminating bio-stressors that arise from the HD treatment is that most of them appear to be minute low intensity imperfections of the procedure that only cause health problems because of the frequent and cumulative exposure time (rt600hrs/year) to which HD patients are subjected to. One of these stressors considered as an unavoidable hazard of the HD treatment is air microbubble infusion. Microbubble infusion by HD affects mostly the lungs- causing endothelial damage, atherosclerosis, pulmonary vascular remodeling, and dyspnea- but have also been found in the heart and brain of patients. There is currently no technique or technology capable of eliminating from HD the majority of microbubbles of sizes below 100 µm. SIL Technologies is proposing an acoustically expedited microbubble diffusion technology that would eliminate most, if not all, microbubbles present in the extracorporeal tubing of HD equipment. The proposed technology uses acoustic forcing to “push” microbubbles against the wall of a silicone tube which is gas permeable. The silicone tube is surrounded by degassed water. The combination of acoustic forcing and gas concentration difference (between air bubble and degassed water) provide a strong diffusion driving force, capable of working even through thick membranes (thicknesses larger than 0.5 mm). We expect to prove the feasibility of the technology by completing the following specific aims: i) An acoustic resonance chamber will be designed to maximize the acoustic force and bubble-diffusion anchoring sites by finite-element simulations. ii) The device designed in i) will be constructed and in-line installed to a fluid circuit powered by a peristaltic pump and filled with a transparent blood mimicking fluid. Pulse-Doppler microbubble counters will be placed at the entrance and exit sites of the device to collect the necessary data to determine the effectiveness of the concept. And finally, iii) the fluid circuit will be filled with real blood and the experiments carried out in ii will be repeated. A statistical analysis of the effectiveness of the device operating on blood will be determined as well as basic blood cell integrity tests to have a preliminary safety assessment of the proposed technology.