Hardware: The flow-sensor assembly consists of a differential pressure sensor that measures the pressure drop across a flow channel and a second sensor that measures the pressure in the sensor relative to atmosphere. Signals from these sensors are processed by a Raspberry Pi (RPi) based interface box connected via an RJ-45 jack.
The RPi in the interface box converts the raw signals to flow and pressure readings, which are logged and made available to a remote monitoring station over a network. The RPi scans flow and pressure information and sets off alarms when patients experience difficulties. An LCD displays basic information and a rotary encoder is used to set alarm thresholds. Colored LEDs and a piezoelectric buzzer announce alarms.
A networked remote monitoring station displays more detailed information from up to 20 interface boxes. In addition to alarm status, the system also displays respiratory rate, tidal volume, positive end-expiratory pressure (PEEP), peak inspiratory pressure (PIP), and the ratio of inspiratory time to expiratory time (I:E). The system has a touch screen interface with multiple views to either show all patients simultaneously or to show details of a single patient.