A new valveless all-purpose ventilator. Description and laboratory evaluation.

A ventilator, of new design, is described which has been evaluated on a lung model and in animals. It is simple, versatile, inexpensive and easy to sterilize. A single breathing tube is used in which the respiratory gas is introduced near the patient's airway while a jet in a more distal part of the tube drives the respiratory gas into the patient's lungs. Provided the internal volume between the respiratory gas inlet and the driving jet is at least one tidal volume, the driving gas does not take part in respiratory gas exchange. During controlled ventilation only normal ventilation volumes of respiratory fresh gas are required during both normal and high frequency ventilation. It can be used for any age group with any desired respiratory gas, and is suitable for use in the operating theatre and the intensive care unit. As there are no valves in the breathing system, which is open to the atmosphere at all times, complicated systems for synchronizing the machine with spontaneous breathing are not required. PEEP, NEEP, CPAP and IMV are applied easily.