As a medical practitioner specialising in civilian aero-medical evacuation, I am called upon to move ventilator dependent patients, and I have used several types of transport ventilators (Oxylog, Logic, Bear, pneuPac and TransPac), but I have finally chosen to use the latter two exclusively. The requirements for a transport ventilator in the civilian aero-medical evacuation environment are: portability (volume small, weight low, shape compact) self-contained power supply (not needing access to Ring Main Voltage or compressed gas circuit) extreme reliability (mechanically and/or electrically simple as no back-up available) ruggedness (resists knocks, blows, being dropped) no broadcast effects on avionics ability to withstand explosive decompression The pac series of ventilators are modular, with simple but reliable mechanical linkages. They are light, can be slung over the shoulder in the customised carry-case (which takes a D cylinder as compressed gas source) and can provide settings to safely volume-cycle ventilate a wide range of patients. They allow over-pressure venting above pre-set values (unlike some rivals) and they produce accurately metered gas volumes. They withstand considerable abuse, with no evidence of the controls freezing or altered calibration. They are tolerant of cabin pressure altitudes up to 10,000 feet (in my experience, which does not include loss of cabin altitude, yet) and are electrically neutral to cabin avionics. I have ventilated patients on long haul trips, for example from upper Egypt to Ireland ( 14 hours) and from Lagos, Nigeria to London, England (10 hours). They have worked in ambient temperatures of 46 C and in 100% humidity. I find the peripherals, such as connectors, hoses, non-return valves to be well chosen and safe, and accessories such as the Venturi-driven aspirator effective. I cite the above from personal experience over the last four years, mainly with the TransPac ventilator.