Development of an Automatic Detection of Pressure Distortion and Alarm System of Endotracheal Tube Md. Nasfikur R. Khan, M M Tanzirul Iqbal, Sarmila Yesmin, A K Ehsanul Haque Mashuk, Faisal Bin Shahin, M Abdur Razzak Department of Electrical and Electronic Engineering, Independent University, Bangladesh Plot-16, Block-B, Bashundhara, Dhaka-1212, Bangladesh E-mail: mnrkhan@iub.edu.bd Abstract – Endotracheal tube (ETT) is a widely used lifesaving tool in case of moderate to severe medical predicaments. It enables an alternative means of mechanical ventilation for tranced or comatose patients. The gadget also helps in ventilation in case of giving general anaesthesia during major surgical procedures. Along the symbiotic use of the system comes the delicate maintenance and adequate monitoring of the instrument. One of the important features of the system is the air-filled cuffs or simply the air balloons that are availed to sustain the optimal intrinsic conditions of the pharmacological actions desired for the patient. The mechanism is to prevent aspiration of secretion of nasal mucosa. Because these secretions can cause aspiration pneumonia which is a life-threatening complication of these morbid patients. However, this requires periodic monitoring of pressure levels and facile adjustments to avoid aspiration, which might be even fatal. The subtlety of the course of action is often overlooked and negligence gives rise to unsought fatality in some patients. To reverse the course of this mishap, we came about our vocational modification to the conventional endotracheal tubes and air cuffs. The embodiment of automation ensures the inviolability as well as omission of professional lapse. The automatic apparatus facilitates the automatic detection of the pressure distortion and alarms the designated healthcare expert as a forewarning and hence the patient is bypassed any associated threat. Keywords: Endotracheal tube, air cuffs, pressure sensor, alarm system, PVC tube, microcontroller, Bluetooth module, Arduino. I. INTRODUCTION During 1893, the use of a cuffed Endotracheal Tube (ETT) was first explained by Esienmenger, and the intracuff pressure monitoring system using pilot balloon was also introduced during that time [1]. Franz Kuhn, a well-known anaesthesiologist, showed the use of metal tubes, and preferred the oral route over tracheostomy which made orotracheal anaesthesia popular in the early 1900s [2]. He was the first to discover the importance of the ETT as a path to remove pulmonary secretions. In 1913, Jackson and Janeway published their experiences using laryngoscopy, paving the way for development and claiming of flexible rubber tubes [3]. They used Insufflation anaesthesia technique, where gas was blown into lungs through a small tube and exhaled gas flowed around outside of the tube. In 1920, an improved laryngoscope was introduced, making the endotracheal technique more accepted [4]. Row Botham and Magill (1926) designed larger rubber tubes that allowed gas to follow bidirectional manner through the tube [5]. The early tubes were made from commercial rubber hose, whose diameters are varying from 3/8 to 3/16th of an inch. Now, the simplest Endotracheal Tube is considered to be made from the transparent polyvinyl chloride (PVC) with a tubing length of about 30cm long. This ETT is an improvement comparing to the early day’s rubber and metal ETTs. These PVC EET tubes are in flammable and easy to make curvature shape comparing to those metal and rubber ETTs. Due to curvature shape, these ETTs are easy to insert. The Anatomical curvature of the endotracheal tube guides the path of the airway and the head should be held in the neutral position. According to ISO5356-1 standard [2], a curvature of approximately 140mm radius (+/- 20mm) is needed to be designed with some exceptions, where the size of connectors for airway equipment are determined by the size of the body. According to this standard, the connectors’ internal diameters should be 15mm and 22mm, respectively. In order to avoid ventilation, all airway equipment should be connectable to each other. For adults, air-filled cuff is the key feature of the ETT. Once filled with air, the cuff seals the lungs against the liquid secretions sloshing around in the upper airway. This problem has been solved using pilot balloon which can be pressurized below the cuff and ventilated with a carefully controlled gas mixture. This method seals the trachea thereby preventing to escape the positive pressure from the lower airway. This will also seal the upper airway by blocking material above the glottis to enter into the trachea. However, pilot balloon is a small sack of air to guide to the integrity of anyone’s cuff. It is connected to the cuff with a narrow lumen, which is not very strong, and can be overtaken easily. There is also a spring- powered one-way valve used in the pilot balloon which can break in the process of frequent use. The size of the pilot balloon is another concern of fixing this problem. Suction port enables the aspiration of secretions which is collected above the tube cuff. Those secretions which consist of an infected mixture of saliva and nasal mucus, stewing in the steamy environment of the plugged larynx. The disadvantage of suctioning above the cuff is mucosal damage because the sucker applies about 100mmHg pressure to the tracheal wall. This sort of pressure known as "low wall suction" can still strip mucosa off the walls of the trachea. So, there is a risk associated with continuous rather than intermittent subglottic suction [6]. 2018 IEEE-EMBS Conference on Biomedical Engineering and Sciences (IECBES) 978-1-5386-2471-5 ©2018 IEEE 476