Systems and techniques for estimating the severity of chronic obstructive pulmonary disease in a patient

A patient monitoring apparatus, comprising a breathing sensor, a locomotion sensor, a display device and at least one processor, said at least one processor configured to:

• receive, from the breathing sensor, a breathing signal representative of breathing activity of a patient over a time interval;
• receive, from the locomotion sensor, a locomotion signal representative of locomotive activity of the patient over the time interval;
• determine whether the received breathing signal and locomotion signal have adequate characteristics for use in generating a Chronic Obstructive Pulmonary Disease (COPD) severity estimate based on the breathing signal and locomotion signal, wherein the display device is configured to display a notification of inadequate characteristics for generating the COPD severity estimate;
• when the received breathing signal or locomotion signal are determined as inadequate, then produce an instruction notification to amend a respective error condition;
• and
• when the received breathing signal and locomotion signal are determined as adequate, then generate the COPD severity estimate in the patient based on cross-recurrence quantification analysis (cRQA) of the breathing signal and locomotion signal, wherein the display device is configured to display a visual representation of the estimate of COPD severity.