Figure 1.
(A) Schematic of the proposed design. (B) Simplified lumped parameter model of the system. Pressures: reservoir pressure (pres), system pressure (psys), pressure at the patient connector (pconn), pressure in the distal lungs (plung). Green indicates measured and blue indicates calculated. Flow rates: qI, inhaled flow, qE, exhaled flow. The resistances represent combined influence of multiple components: RA, oxygen port connections and Valve A; RB, air port connections and Valve B; RC pneumatic pathways between the reservoir and downstream manifold; RD, all pneumatic components in the exhalation pathway; Rs, pneumatic components downstream of psys; Rett, endotracheal tube; Rlung, resistance in the lung, predominantly the upper airways; Rair, combination of Rett and Rlung, used to estimate plung.