primary transfer:from an accident scene;

secondary transfer:between healthcare facilities (intra- or inter-hospital);

domiciliary ventilation;

improvised intensive care facilities, for example, military field hospitals, civilian contingency planning

Each application entails differences in the clinical condition of patients, operator experience, and demands

of the environment. A single device is unlikely to be ideal for all situations; therefore, a range of ventilators

are available. Three of these are considered as examples throughout this review (Table 1). Key practical

features of a portable ventilator are the gas and power supplies required and modes of ventilation supported.