1) unexplained reduction in vital capacity;
2) CO2 retention while awake or during sleep, specifically in the absence of severe airflow obstruction;
3) shortness of breath;
4) orthopnoea (shortness of breath while supine), or dyspnoea during bathing or swimming;
5) short sentences during speech;
6) tachypnoea;
7) paradoxical movement of the abdominal or thoracic wall;
8) problems with cough (and recurrent infections); and
9) generalised muscle weakness.