On the design of a compact emergency mechanical ventilator with negative expiratory exit pressure for COVID-19 patients

Abstract

The present work deals with the design of a cylinder-piston arrangement to deliver the required tidal volume (TV) of air to the patient through the respiratory tract especially in the setting of severe acute respiratory syndrome corona virus 2 (SARS CoV-2) or corona virus disease (COVID-19). The design ensures that only the desired volume of air is delivered in each breath and a negative pressure is retained at the delivery point in a separate cylinder. The frequency of piston motion is the same as that of the average human respiratory rate (RR). The effect of negative pressure on time of evacuation under the present condition has been verified. The present design provides a compact ventilator unit with a surface area of 0.8 × 0.4 m² with a minimal power requirement of 116.48 W. An RR of 16 is obtained with a volume flow rate in lit/s by using a twin cylinder arrangement with bore diameter 0.1 m and length 0.4 m. The ratio of inspiration time to expiration time is designed to be 1:2 by controlling the stroke frequency as 16 and piston speed 0.32 m/s. The present design provides promising quantitative information on the design of an automated continuous mechanical ventilator (CMV), which is different from bag mask valve (BMV) operated ventilators, and on preventing and minimising barotrauma.

Keywords:

• Ventilator
• COVID-19
• expiratory pressure
• barotrauma

Acknowledgements

The authors express their gratitude to Mr. Gijo George Netticadan, final year student, Department of Mechanical Engineering, SCMS School of Engineering and Technology (SSET), Ernakulam, India, for the graphical input. Acknowledgement is also due to the Principal and the management of SSET for their encouragement and support.

Author contributions

Conceptualisation and ideation, S.J.; data curation, V.C.; formal analysis, V.C. and S.J.; investigation, V.C.; methodology, S.J.; project administration, S.J. and R.R.; resources, S.J. and R.R.; supervision, S.J.; validation, V.C. and R.R.; visualisation, V.C.; writing – original draft, V.C. and S.J.; writing – review and editing, S.J. and R.R.

Disclosure statement

No potential conflict of interest was reported by the author(s).