Portable medical support system with ancillary viewing mode and method of operation thereof

A medical ventilator, comprising:

• a first user interface having a touch-sensitive display having a display area;
• and
• at least one controller which:
• determines whether a second user interface having a touch-sensitive display is coupled to the medical ventilator,
• enables the first user interface when it is determined that the second user interface is not coupled to the medical ventilator, and
• enables the second user interface when it is determined that the second user interface is coupled to the medical ventilator,
• senses when the medical ventilator switches from an external power source to an internal power source and in response, disables the second user interface if the second user interface is enabled and enables the first user interface if the first user interface is disabled.