We have created a lung simulation to quantify lung heterogeneity from the
results of the inspired sinewave test (IST). The IST is a lung function test
that is non-invasive, non-ionising and does not require patients' cooperation.
A tidal lung simulation is developed to assess this test and also a method is
proposed to calculate lung heterogeneity from IST results. A sensitivity
analysis based on the Morris method and linear regression were applied to
verify and to validate the simulation. Additionally, simulated emphysema and
pulmonary embolism conditions were created using the simulation to assess the
ability of the IST to identify these conditions. Experimental data from five
pigs (pre-injured vs injured) were used for validation. This paper contributes
to the development of the IST. Firstly, our sensitivity analysis reveals that
the IST is highly accurate with an underestimation of about 5% of the simulated
values. Sensitivity analysis suggested that both instability in tidal volume
and extreme expiratory flow coefficients during the test cause random errors in
the IST results. Secondly, the ratios of IST results obtained at two tracer gas
oscillation frequencies can identify lung heterogeneity (ELV60/ELV180 and
Qp60/Qp180). There was dissimilarity between simulated emphysema and pulmonary
embolism (p < 0:0001). In the animal model, the control group had ELV60/ELV180
= 0.58 compared with 0.39 in injured animals (p < 0.0001)