טכניון מכון טכנולוגי לישראל
הטכניון מכון טכנולוגי לישראל - בית הספר ללימודי מוסמכים  
Ph.D Thesis
Ph.D StudentPesin Jimy
SubjectClassification of Respiratory Pathologies by Quantifying
the Chest and Abdomen Dynamics
DepartmentDepartment of Biomedical Engineering
Supervisors Professor Amir Landesberg
Professor Emeritus Isak Gath


Abstract

Current techniques of monitoring lung function involve measuring the tidal volume directly or calculated by the displacement of the chest and the final output, the blood oxygen saturation and blood gases. These measurements are global in nature, do not account for asymmetric or asynchronous pathologies and cannot detect problems early enough. Respiratory function of patients in the hospital requires constant monitoring with objective measures for optimization of treatment. This allows physicians to be effective in early detection of complications. Patients who are at risk would benefit from such effective respiratory monitoring in the comfort of their own home. By implementing a higher order measurement, acceleration, it is suggested that more innate characteristics are available to assess respiratory characteristics and dynamics continuously.


The study is based on data that is acquired from experiments from rabbits and mice animal models. Pneumothorax and obstructive apnea experiments with the explicitly intended application directed towards the use in infants, regular and pre-term, rabbits represented an accurate model in terms of size, weight, respiratory, and cardiac function. For asthma, a typical mouse animal model was used. In pneumothorax, air was injected into the pleural space at a controlled and continuous rate. To induce partial obstructions, the animal’s maximum effort, based on esophageal pressure, was measured at full obstruction and then set to 50% and 25% of the maximum. In the asthmatic mouse model, methacholine was administered at increasing concentrations to observe a physiological response. In all three experiments, acceleration was monitored from the chest and abdomen in addition to vital signs. The objective was to provide an overview of a method that monitors the chest and abdominal dynamics by extracting indices in order to detect several different respiratory pathologies.


Results of experimentation revealed that the use of acceleration to monitor ventilation dynamics is not only feasible but can be more effective than current methods. In pneumothorax results demonstrate the continuous monitoring of asymmetric conditions has been achieved in all animals with 100% side identification and a diagnosis 34.1±18.8 minutes on average prior to a drop in oxygen saturation of 90%. In the apnea experiments, events of 25% maximum effort during a partial obstruction were correctly identified even though oxygen saturation was considered near perfect. Additionally, the parameters were specific enough to be able to accurately distinguish between these mild obstructions and events of high respiratory effort without obstruction. In the asthmatic model, with the use of one sensor it has been shown that it is possible to extract and analyze both the LF dynamics and HF acoustics of a small animal with higher sensitivity than the gold standard for assessing respiratory effort.


The novel technique of monitoring ventilation dynamics by placing accelerometers on the chest and abdomen was shown to be an effective way of continuous monitoring. The method is capable of providing higher sensitivity and specificity than standard methods. When relevant indices are properly chosen and combined they can be a powerful tool for identifying and classifying various pathologies.