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Validity of the lagged normal density function as a model for pulmonary indicator dispersion
1Zentrum Physiologie und Pathophysiologie, Universität Göttingen, West Germany.
Biomedical Instrumentation & Technology
|January 1, 1990
Summary
The lagged normal density function effectively models pulmonary indicator transport, providing accurate mean transit times for calculating indicator volumes of distribution in lung research.
Area of Science:
- Physiology
- Medical Imaging
- Pharmacokinetics
Background:
- Pulmonary indicator dispersion is crucial for understanding lung function.
- Accurate modeling of indicator transport is essential for physiological studies.
- Existing models may not fully capture the complexities of lung indicator dynamics.
Purpose of the Study:
- To evaluate the efficacy of the lagged normal density function in modeling intravascular and diffusible indicator dispersion in the lungs.
- To compare the lagged normal density function model with a model-free deconvolution technique.
- To assess the utility of the lagged normal density function for determining indicator volumes of distribution.
Main Methods:
- Recorded thermal-indocyanine green dye kinetics in mongrel dogs following central venous injection.
- Employed a model-free deconvolution technique to compute reference pulmonary transport functions.
- Modeled pulmonary indicator transport using the lagged normal density function, with parameters derived via nonlinear least-squares and iterative convolution.
- Induction of pulmonary edema and postural changes were used to create varying physiological conditions.
Main Results:
- Mean transit times calculated using the lagged normal density function showed good agreement with model-free deconvolution results.
- The lagged normal density function provided a useful approximation for mean transit times.
- Model-derived transport function shapes (dispersion, skewness) were less accurately described compared to mean transit times.
Conclusions:
- The lagged normal density function is a valuable tool for modeling pulmonary indicator transport.
- This model is particularly useful for determining indicator volumes of distribution when accurate mean transit times are the primary requirement.
- While not perfectly capturing all aspects of transport function shape, its accuracy in mean transit time estimation supports its application in lung physiology research.
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