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Detection of changes in lung tissue properties with multiple-indicator dilution.
D L Roerig1, S H Audi, J H Linehan
1Department of Anesthesiology and Pharmacology/Toxicology, Medical College of Wisconsin, Milwaukee 53226, USA.
Journal of Applied Physiology (Bethesda, Md. : 1985)
|June 16, 1999
Summary
This study shows that multiple-indicator dilution can detect lung injury by analyzing indicator outflow patterns. These unique patterns help identify specific changes in lung tissue properties caused by inflammation or fluid.
Area of Science:
- Pulmonary physiology
- Pharmacokinetics
- Medical diagnostics
Background:
- Lung injury models are crucial for understanding respiratory diseases.
- The multiple-indicator dilution method offers a way to assess tissue properties non-invasively.
- Identifying specific tissue changes in lung injury remains a challenge.
Purpose of the Study:
- To evaluate the utility of multiple-indicator dilution for detecting and identifying lung tissue abnormalities.
- To determine if different lung injury models produce unique indicator outflow patterns.
- To explore the potential of specific indicators to reflect changes in lung tissue composition.
Main Methods:
- Isolated perfused rabbit lungs were used to model lung injury.
- Four indicators ([14C]diazepam, 3HOH, [14C]phenylethylamine, vascular reference) were injected into the pulmonary artery.
- Lung injury was induced by granulomatous inflammation (complete Freund's adjuvant - CFA) or intratracheal fluid instillation.
- Pulmonary venous outflow concentration-time curves were analyzed using mathematical models.
Main Results:
- Both CFA-induced inflammation and fluid instillation altered lung tissue composition and indicator outflow patterns.
- Each experimental condition produced a unique pattern in the concentration-time curves.
- Mathematical modeling yielded distinct parameter vectors for each condition, confirming detectability of changes.
- A notable finding was a CFA-induced change in diazepam disposition, suggesting increased peripheral-type benzodiazepine receptors.
Conclusions:
- The multiple-indicator dilution method, using a carefully selected group of indicators, can effectively detect and identify lung tissue property changes.
- Unique indicator outflow patterns can differentiate between various lung injury models.
- This technique holds promise for diagnosing and characterizing lung injuries based on specific tissue alterations.
