Pediatric research
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In the healthy animal lung, high-frequency oscillatory ventilation (HFOV) achieves effective ventilation at tidal volumes (V(T)) less than or equal to dead space while generating very small pressure fluctuations in the alveolar spaces (deltaP(A)). We hypothesized that the respiratory mechanical parameters influence the magnitude of the intrapulmonary pressure fluctuations during HFOV. A computer model of the neonatal respiratory system was used to examine the independent effects of altering the compliance, nonlinear and linear resistance, and inertance of the respiratory system on V(T), and cyclic intrapulmonary pressures under homogeneous and heterogeneous conditions. ⋯ The deltaP(A)/deltaP(ao) also decreased with increasing alveolar compartment compliance, a finding that was verified in the preterm lamb lung. There was an exponential decrease in the magnitude of deltaP(A1) compared with deltaP(A2) as the ratio of the time constants of the two parallel compartments (tau(1)/tau(2)) increased in the heterogeneous computer lung model. The transmission of driving pressure amplitude to both the proximal airways and lung tissue during HFOV is dependent on lung mechanics and may be greater in the poorly compliant lung than that observed previously in experiments on healthy animals.