One of the investigators left the department, Master Degree in which this study was part of her thesis. No patients were enrolled.

The prevalence of severe dyspnoea among terminally ill patients has been reported as 70% and 90% for lung cancer and chronic obstructive pulmonary disease (COPD) patients, respectively.

Current management to dyspnoea includes opioids, psychotropic drugs, inhaled frusemide, Heliox 28 and oxygen.

Conventional oxygen supplementation is often used in these patients, but it may be inadequate, especially if they require high flows (from 30L/min to 120L/min in acute respiratory failure).

High-flow oxygen nasal cannula (HFONC) is a new technological device in high-flow oxygen system that consists of an air-oxygen blender (allowing from 21% to 100% FiO2) which generates the gas flow rate up to 55 L/min and a heated humidification system. This technology may have an important role in reducing respiratory distress in do-not-intubate patients.

Some HFONC's beneficial effects are the washout of the nasopharyngeal dead space reducing rebreathing of CO2 and improvement oxygenation through greater alveolar oxygen concentration; a better matching between patient's inspiratory demand and oxygen flow; generation of a certain level of positive pressure (PEEP) contributing to the pulmonary distending pressure and recruitment; improvement of lung and airway mucociliary clearance due to the heated and humidified oxygen; and patient's comfort because of the nasal interface allowing feeding and speech.

The investigators hypothesize that patients supported with HFONC need less opioids to decrease dyspnoea.

Inclusion Criteria:

• Consecutive patients who had end-stage lung disease (lung cancer, pulmonary fibrosis, COPD, …) - (McCabe score > 3 [<6 months life expectancy] and a Palliative Prognostic Index score ≥ 4) admitted to hospital because of acute respiratory failure and distress
• Had chosen to forego all life support and receiving only palliative care
• Severe hypoxemia (PaO2/FiO2< 250)
• At least one of the following: dyspnoea (Borg scale ≥4), signs of respiratory distress, and respiratory rate greater than 30 beats per min

Exclusion Criteria:

• Patients had to be competent (Kelly score <4)
• Refusal of treatment
• Weak cough reflex
• Agitation or non-cooperation
• Uncontrolled cardiac ischemia or arrhythmias
• Failure of more than two organs
• Use of opioids within the past 2 weeks
• Adverse reactions to opioids
• History of substance misuse
• Known contraindication for morphine (acute renal failure and recent head injury)