More than 20,000 New Zealanders are admitted to an intensive care unit (ICU) annually. ICU treatment allows acutely unwell patients with potentially reversible illnesses to survive provided they can be supported long enough to recover. However, there are limits to supportive care and when these limits are exceeded, progressive multiorgan failure develops, and patients often die. Paracetamol reduces body temperature and may prevent these limits being exceeded by reducing tissue demands associated with fever. It may also have other effects that prevent organ damage. We hypothesise that strict regular administration of intravenous paracetamol to ICU patients anticipated to require life support beyond the end of the next calendar day will increase days alive and outside ICU (ICU-free days) compared to standard care (where paracetamol is only administered when required for a specific indication). Our current study will determine whether our planned design for a 1050-patient definitive clinical trial is feasible.