Currently, the length of an inpatient stay for NIV set up is between 4.5 and 6 days. As yet it is unknown whether or not a patient can be set up onto NIV as effectively on an outpatient basis using an AE-AVAPS (Automatic Expiratory Positive Airway Pressure - Average Volume Assured Pressure Support) algorithm compared to the usual practice of inpatient titration by specialist respiratory nurses. Furthermore, the cost effectiveness of outpatient initiation vs inpatient initiation is unknown in this group of patients.