System Design And Experimental Research Of Lower Esophageal Sphincter Manometry In Laboratory Experiments

Lower esophageal sphincter(LES)is defined anatomically as thickened band of circular muscle at the gastroesophageal junction.Normally,it maintains a continuous contraction state and forms a high pressure band at the gastroesophageal junction,constituting a physiological anti-reflux barrier at the oesophago-gastric.When an LES dysfunction happens,it could cause the abnormal reflux of gastric contents to flow back the esophagus,leading discomfort and complications.This is the main cause of gastroesophageal reflux disease(GERD).In 2011,the prevalence rate of GERD in Asia has been reached 6%~10%.And with the change of dietary structure,the rate is increasing year by year,which causing heavy burden to society.The mainly treatments of GERD are acid suppressive therapy and surgical treatment.However,the former needs long-term medication and couldn't cure reflux disease.The latter causes large trauma,the dysphagia and vagus nerve injury.Therefore,our research group developed an implantable LES electrical stimulation system for the treatment of GERD.Before the clinical application of the LES electrical stimulation system,a large number of animal experiments need to be implemented to verify the efficacy,in which the LESP(LES pressure)is an important index to reflect the treatment effect.In clinical,LES manometry methods are mainly used with water-perfused catheter manometry and solid-state catheter manometry.But,both of them are too expensive,too heavy and too large,which is not suitable for lab experiments.Thus,a LES pressure measurement system based on balloon dilation catheter is proposed in this paper,which provides a new method with the advantages of low-cost,small size and easy to carry for animal experiments.The system consists of a balloon dilation catheter,a pressure detecting and recording module and an automatic pull-through module.The balloon can measure the sphincter pressure over the entire length and circumference of sphincter,which can be more accurate than the point pressure sensor.Firstly,this paper analyzed the epidemiology,the pathogenesis,the treatment method and current diagnosis of GERD.And then,according to the anatomical structure and movement characteristics of LES,the whole scheme of manometry system was proposed and the balloon catheter was determined.Then,based on the whole scheme of manometry system,the LES pressure measurement system was designed,which used STM32F103ZET6 as the core controlling the pressure detecting and recording module and the automatic pull-through module.The hardware of the pressure detecting and recording module consists of the STM32 minimum unit,power-supply unit,USB to serial unit and pressure sensor unit.The automatic pull-through module controls the motion of stepping motor through the key and the STM32 timer's pulse signal.The software of the system mainly realized the function of pressure sensor drive,step motor control and serial data sending based on Keil,and the pressure data display and storage based on LabVIEW.After that,the LES pressure measurement system was tested in vitro,measuring the parameters of linearity,sensitivity,repeatability,resolution,zero drift and response time.In the end,the LES pressure measurement system was applied in animal experiments.The results showed it has a good linear relationship between the proposed system and the water-perfused catheter manometry measured LESP on same five rabbits.In addition,the LES pressure measurement system was used to make sure the suitable stimulation voltage of LES stimulator was 24V~36V.Moreover,another experiments verified the long-term LES stimulation could improve the LESP.