Figure 3.

Low-cost pneumotachograph. (A,B) Diagrams of resistors for the pneumotachographs. (B,C) Photograph of the manually drilled resistor. (C,D) Diagram of resistor and (one side) standard PVC tube piece to assemble the pneumotach. (E) Photograph of the assembled pneumotachograph. (F) Example of the flow signals during pressure-controlled mechanical ventilation simultaneously measured by a reference pneumotachograph (red) and by the pneumotachograph constructed and calibrated by the low-cost procedures (black). (G) Volume measured during different magnitudes of pressure-control and volume-control mechanical ventilation of a patient model. Volume was simultaneously measured with the low-cost and the reference pneumotachograph (open circles). Each set of four bars corresponds to the volumes measured by the low-cost pneumotachograph using independent calibrations. Reprinted with permission from Ref. [61]. Creative Commons CC-BY license.