ICIUS-2021-030 Characteristic of Paddle Squeezing Angle and AMBU Bag Air Volume in Bag Valve Mask Ventilator Cong Toai Truong 3 , Kim Hieu Huynh 3 , Van Tu Duong 1,2,3,* , Huy Hung Nguyen 3,4 , Le An Pham 5 , and Tan Tien Nguyen 1,2,3,* 1 Faculty of Mechanical Engineering, Ho Chi Minh City University of Technology (HCMUT), 268 Ly Thuong Kiet, District 10, Ho Chi Minh City, Vietnam 2 Vietnam National University Ho Chi Minh City, Linh Trung Ward, Thu Duc District, Ho Chi Minh City, Vietnam 3 National Key Laboratory of Digital Control and System Engineering (DCSELab), HCMUT, 268 Ly Thuong Kiet, District 10, Ho Chi Minh City, Vietnam 4 Faculty of Electronics and Telecommunication, Saigon University, Vietnam 5 Grant and Innovation Center (GIC), University of Medicine and Pharmacy at Ho Chi Minh City * Corresponding author: dvtu@hcmut.edu.vn, nttien@hcmut.edu.vn Abstract In the COVID-19 period, the number of deaths has increased every day around the world. The pandemic has impacted the life and economy. Especially, there is a shortage in medical including a lack of technology, facility and equipment. One of those, ventilators are the essential equipment that does not provide enough requirements for the hospital. A ventilator is an essential unit in hospitals because it seems to be the first step to protect the life of the patient getting sick. Some low-income countries aim to make a simple ventilator using locally available and low- cost materials for primary care and palliative care. One of the simple principles of ventilators is to adopt an artificial manual breath unit (AMBU) bag with paddles. Unfortunately, the squeezing angle of paddles is not proportional to the exhaust air volume from the AMBU bag. This paper analyzes the character of the squeezing angle of the paddles and the exhaust air volume of the adult AMBU bag through experiments. The result can be used to control the squeezing angle through a DC motor mounted with paddles to obtain the desired air volume. Keywords: simple ventilator, AMBU bag, Covid19, bag valve mask. 1 Introduction The coronavirus (COVID-19) pandemic is very complicating and multi-staged manner. Currently, COVID-19 has many dangerous strains and has not had the signal of decreasing around the world. Besides that, the COVID-19 patients must be treated with ventilators which have many higher functional requirements in Intensive Care Unit, but also need a simple assist ventilator in primary, palliative care, and safety transportation. Thus, the number of modern- ventilator is a big challenge for the health (Ercole et al., 2009; P Smetanin, D Stiff, A Kumar, P Kobak, R Zarychanski, N Simonsen, 2009; Stiff et al., 2011; Wiederhold and Riva, 2013), especially in developing countries (Fisher and Heymann, 2020; The Lancet, 2020; WHO, 2020). Several attempts have been made to create low-cost ventilators (Russell and Slutsky, 1999; Fang et al., 2020). In particular, there are machines operating using the grippers (Kwon et al., 2020) to deal with overloading COVID-19 cases. Medically, although some studies showed that the 2-handed mask-face technique is prone to be better than 1-handed mask-face technique (Jesudian et al., 1985; Wheatley et al., 1997; Davidovic, LaCovey and Pitetti, 2005; Joffe, Hetzel and Liew, 2010), in some emergency situations, the 1- handed technique is still applied due to the lack of AMBU compression which can be conducted by the ventilator using the grippers. Therefore, this type of ventilator is very essential which has the advantages of easy manufacturing and assembly, low cost, easy-to-find materials and control volume adjustment according to the angle of the paddles. However, the biggest difficulty when developing the BVM ventilator is that it is quite difficult to identify the mathematical model of the AMBU bag making the control process becomes complicated. To be more specific, during the development the BVM ventilator, the most important device is the AMBU bag (not only standard in ER, but also