Today, people who present respiratory insufficiency distress and who do not respond to non-invasive treatments require mechanical ventilation. This was increased in the COVID 19 pandemic, where governments and companies increased production, research of mechanical fans. One of the main steps for the development of a medical device is its simulation. This article shows the necessary procedure to mathematically model the waves of volume, flow and pressure in the pressure-controlled continuous mandatory ventilation mode (PC-CMV) and the volume-controlled continuous mandatory ventilation mode. For its development, input parameters such as Compliance, resistance, respiratory rate, inspiratory time, expiratory time, pause time, PEEP, PIP and tidal volume were taken into account for simulation in the Matlab software and obtaining ventilation parameters in the mode PC-CMV and VC-CMV.