Electronic apparatus for medical use, medical apparatus; apparatus for assisting, supporting or substituting patient/subject ventilation, apparatus for supporting nasal ventilation, apparatus for supporting nasal and oral ventilation, apparatus for assisting, modulating or maintaining effective patient/subject respiratory function, patient/subject monitoring, analysing, and/or recording apparatus including digital apparatus; apparatus for investigating, monitoring, analysing, diagnosing and/or recording sleep, sleep related and resiratory disorders, resiratory function and respiration including portable monitoring apparatus, apparatus for investigating, monitoring, analysing, diagnosing and/or recording electrophysiological variables including variables relating to the nervous system, neurology, cardiology and physiology; apparatus for sleep staging; filters including low pass, high pass and notch filters being part of apparatus for monitoring patient variables; interface apparatus and sensors for monitoring patient variables including EEG (electroencephalogram), EOG (electroculogram), EMG (electromyogram), SaSO2 (oxygen saturation), CO2 (carbon dioxide), nasal air flow, patient/subject movement including leg movement, thoracic and abdominal respiratory movement, heart rate, body temperature including rectal temperature, blood pressure, pH level, oesophageal pressure, snoring noises, CPAP (continuous positive air pressure), mask pressure, CPAP mask air flow, CPAP titration; radiology imaging apparatus including remote imaging and transmitting apparatus; computer hardware and software especially for assisting, modulating, and/or maintaining effective patient/subject respiratory function; apparatus for monitoring and/or displaying graphical and/or other data when used for medical purposes; parts and accessories thereof and therefor