A ventilator system including an oxygen delivery cylinder, an air delivery unit, connecting tubes, and a digital display unit. The system further includes a Y connector configured to mix air and oxygen, to form a gas and pass said gas towards an outlet of the system. A water manometer that is configured to monitor a pressure of the gas in the system and blow off the excess pressure of the gas. A solenoid valve that is configured to adjust an end respiratory pressure obtained from a breathing device connected to the outlet of the system. The pressure of the gas being instantly delivered to the breathing device is measured by water manometer from a dead space near the outlet, thereby enabling a dual monitoring of the gas pressure being delivered to the breathing device.