Breathlessness Exertion and Morphine Sulphate

Breathlessness is an overwhelming symptom affecting tens of thousands of Australians every day. For many people, it persists even when all the underlying causes have been optimally managed (chronic breathlessness). In these circumstances, it often occurs at rest or with minimal exertion. Evidence from a number of clinical studies suggests that a small, regular dose of morphine helps to reduce safely the sensation of breathlessness. However, it is not well established which patients derive more benefit and what is the net clinical effect of this treatment (weighing benefits and harms). This is a phase III, multi-site, randomised, double-blind, placebo-controlled trial with patients with chronic obstructive pulmonary disease (COPD) and severe chronic breathlessness which will explore several important questions: * Are regular, low doses of morphine at four possible doses over 3 weeks more effective than placebo at improving breathlessness? * Does increasing the dose in people who already are experiencing some benefit provide even greater reduction in worst breathlessness? * Does the medication have any effect on daily activity and quality of life? * What are the common or serious side effects of this intervention? * Does the benefit from the medication outweigh the side effects it produces? * Are there specific characteristics of people who are more likely to receive benefit from extended release morphine? Participants will receive once daily extended release morphine (plus laxative, docusate with senna), or placebo (placebo laxative) in addition to their usual medication for up to 3 weeks at increasing doses. Participants will have a medical interview and physical examination to collect some general health information, and baseline measurements including; daily activity, symptoms, and quality of life. A small amount of blood may be required to check eligibility. Further blood samples may be taken at week 1 and 3 to enable testing on how individuals respond to op