Title: Volumetric tissue reduction in upper airways by RF therapy in patients with sleep disorders
Other Titles: Gewebevolumenreduzierung der oberen Atemwege durch RF-Therapie in Patienten mit Schlafstörungen
Language: English
Authors: Dabiri Razlighi, Babak 
Qualification level: Diploma
Keywords: Radiofrequenzabtragung; Schlafstörungen; Therapie
radio frequency ablation; sleep disorders; therapy
Advisor: Kampusch, Stefan 
Assisting Advisor: Kaniusas, Eugenijus 
Issue Date: 2017
Number of Pages: 103
Qualification level: Diploma
Recently, medical interest has focused on snoring sounds as an important symptom of the sleep apnea syndrome, i.e., a temporal and repetitive cessation of effective respiration during sleep at night in patients with sleep disorder. Therefore, many efforts have been made to treat such patients with different methods. Although minimally invasive tissue ablation by high frequency current has shown satisfactory results with minimum risk factors, low cost and repeatable procedure in comparison with other methods. Perforation on mucus layer, overtreatment and less painful recovery still are major drawbacks. Nowadays, Tissue ablation with impedance or temperature control plays an important role to reduce those risks. Nevertheless, all these efforts have been made in the lower range of high frequency current (300-400 kHz) in which tissue has higher impedance and current passes mostly through the extracellular and not the intracellular space in the tissue. This thesis considered to provide an ablation and coagulation system in the radiofrequency range (4 MHz), in which biological tissue shows lower impedance and homogeneous current passage through the tissue. Tissue coagulation at this range of frequency needs lower energy application to the target tissue and reduces risk of overtreatment and unwanted scars and provides better healing recovery process with direct feedback over the process from the tissue. Hence, a 4 MHz RF ablation system was designed, which is able to be used in a closed loop control system. With sampling of the root mean square of the voltage over a calibrated variable impedance and monitoring of the control parameters in a feedback loop, the transfer function of the system was elicited. Therefore, by this approach the coagulation process benefits not only from the advantages of the higher frequency current, but also from the real-time impedance control as a feedback from the tissue. Moreover, one parameter sampling reduces the measurement fault and system hardware complexity. Result showed that the closed loop control system, controls the system by quantitative data based on boundary conditions like temperature, impedance and given energy over the coagulation process and follows the biological changes at the output stage. All results were verified with an applied calibrated variable impedance and tested in the laboratory with real biological tissue. The outlook for this approach is, utilizing a clinical based study to optimize the treatment and provide an interface between physician and system in order to prevent the risk of overtreatment and unwanted ablation on one side and characterize the best appropriate therapy for the patients based on individual specifications like body mass index, age, gender and other screening factors on the other side. Furthermore, by generalizing to other tissues, like glandular tissues, the method could be used to reduce the hypertrophic glands like tonsil instead of resecting.
Library ID: AC14465163
Organisation: E354 - Institute of Electrodynamics, Microwave and Circuit Engineering 
Publication Type: Thesis
Appears in Collections:Thesis

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