Mechanical Ventilator Milano (MVM):A Novel Mechanical Ventilator Designed for Mass Scale Production in response to the COVID-19 Pandemics

Galbiati Cristiano; Walter Bonivento; Mauro Caravati; Marco Razeti; Sandro DeCecco; Giuliana Fiorillo; Federico Gabriele; Roberto Tartaglia; Alessandro Razeto; Davide Sablone; Eugenio Scapparone; Gemma Testera; Marco Rescigno; Davide Franco; Iza Kochanek; Cary Kendziora; Stephen H. Pordes; Hanguo Wang; Andrea Ianni; Art McDonald; L. Molinari Tosatti; T. Dinon; M. Malosio; D. Minuzzo; A. Zardoni; A. Prini

The incoming oxygen flow is controlled by pneumatic valve PV1. We have verified that an orifice with diameter of 6 mm is sufficient to guarantee that a proper respiratory minute volume is delivered to the patient; Humidifier OTH1: the incoming oxygen flow is humidified before reaching the patient by entering the oxygen therapy humidifier OTH1; Vent trap VT1: vent trap VT1 is filled with a vertical column of oil, which raises the minimum vent pressure to a value of approximately 30 mbarg. The value of the minimum vent pressure can be easily adjusted in the neighborhood of 30 mbarg by varying the oil level or by adjusting the vertical position of the tube reaching below the oil surface. The vent line connects directly to the atmosphere, guaranteeing that the pressure differential delivered to the patient does not exceed the preset minimum vent pressure of VT1; Nasal or oronasal mask: from OTH1, the incoming humidified oxygen flow is delivered to the patient outfitted with a non-vented NIV mask. Breathing system: the NIV mask is connected to a breathing system, supporting the attachment of two plastic tubes of typical size 22 mm connecting respectively to pneumatic valves PV1 and PV2, and to a smaller plastic tube leading to pressure sensor PS1. The standard for connection of the breathing system is the 22 mm cone and socket combination defined in the publication "ISO 5356-1:2015 -Anaes-thetic and respiratory equipment -Conical connectors -Part 1: Cones and sockets" [16] . Oxygen line: the oxygen line from OTH1 to the patient is branched into a line connected to vent trap VT1; Expiration pneumatic valve PV2: PV2 controls the expiratory flow. As for PV1, a valve orifice with diameter of 6 mm is sufficient to guarantee the flow corresponding to the expiration of a proper respiratory minute volume; Vent trap VT2: vent trap VT2 is filled with a vertical column of liquid, which raises the minimum vent pressure to the value of 5 mbarg; Spirometer SP1: a portable digital spirometer can be connected to the vent line of vent trap VT2 to monitor the peak and average expiratory flow rate. We are also investigating the possibility to integrate the spirometer in the main control unit, shifting its installation point so that it is directly connected to the downstream port of PV2; Note on VT1 and VT2: both those liquid based vent traps act as adjustable pressure relief valves where the pressure level can be monitored. They could be replaced by mechanical pressure relief valves set at fixed values of 30 and 5 mbarg respectively. They are very compact objects available on the market, the only drawback being the pressure in the ventilation line cannot be monitored.