Objectives: To design an improvised circuit that can be used to extend the capability of a single ventilator to ventilate two or more patients and that can be assembled from readily available parts in times of unanticipated emergency.
Design: Research and development, followed by technical analysis and evaluation.
Setting: Biomedical laboratory.
Measurements and main results: We describe two circuits that can be assembled from readily available inexpensive components to function as improvised ventilators. One circuit requires only a central mushroom valve driver and an additional source of fresh gas for each patient. The other circuit is configured as a number of secondary circuits in parallel, connected to a single ventilator. We constructed and tested the circuits using mechanical lung simulators. The secondary circuit configuration was more efficient in terms of fresh gas usage, but was more complex regarding operation and trouble-shooting.
Conclusions: These two improvised circuits can extend the capability of a standard volume-cycled ventilator to provide automatic ventilation of the lungs in times of disaster.