Ambulance CPAP: use, treatment effect and economics feasibility study

INTERVENTION: A stand‐alone randomised controlled pilot trial will be conducted. Patients with acute respiratory failure will be identified by paramedics responding to 999 ambulance call and enrolled in the study. Patients randomised to the intervention arm will receive treatment with CPAP, a form of noninvasive ventilation where oxygen is supplied to the upper airways at increased pressure through a tight‐fitting mask. The O_two CPAP unit will be used: a lightweight, single use, low flow system. Patients randomised to the control arm will receive oxygen delivered at normal atmospheric pressure via nasal cannula, an air entrainment ‘Venturi’ mask, a simple face mask, or a non‐rebreathing reservoir face mask. Patients in both trial arms will receive other standard pre‐hospital and hospital treatments. CONDITION: Acute respiratory failure (ARF) ; Respiratory ; Acute respiratory failure PRIMARY OUTCOME: The following feasibility outcomes will be reported descriptively together with their 95% confidence interval:; 1. Recruitment rate per 100,000 population per year (target 8, i.e. 120 across 1.5 million); 2. Proportion recruited in error and classified as violations or deviations (target 0% and =10%); 3. Adherence to the allocation schedule (target =90%); 4. Adherence to treatment in the CPAP arm (target =75%); 5. Retention at 30 days (target =90%); 6. Data completeness (target =90%) SECONDARY OUTCOME: Summary estimates of effectiveness outcomes will also be reported with 95% confidence intervals across the whole trial population using an as randomised analysis:; 1. Proportion surviving to 30 days; 2. Proportion undergoing endotracheal intubation by 30 days; 3. Proportion admitted to critical care at any point up to 30 days; 4. Mean and median length of hospital stay; 5. Mean EQ‐5D‐3L (measured for each participant at baseline and at the 30‐day follow‐up); 6. Key elements of health‐care resource use up to 30 days INCLUSION CRITERIA: 1. Adults aged over 18 2. Acute respiratory failure defined as respiratory distress with peripheral oxygen saturation below BTS target levels (88% for patients with COPD, 94% for other conditions), despite supplemental oxygen