Community acquired pneumonia is a common cause of both hospital and ICU admissions. For many aspects of treatment for patients with severe pneumonia, clinicians are uncertain which is the best choice. This research programme will use an innovative design to simultaneously investigate the best of two or three options in 4 areas of practice: the size of breaths for patients receiving mechanical ventilation, the target level of oxygen in the blood, the choice of initial antibiotics, and longer treatment with an antibiotic with anti-inflammatory properties. Patients admitted to intensive care with pneumonia will be randomly allocated to one of the options in each of these four areas. Outcomes from earlier patients will be analysed as the study progresses to modify the allocation of treatment options. This system can also be quickly be modified to address questions that may arise in a future pandemic of a respiratory illness.