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Chapter 4 – State of the art of methods and instruments for analysis of respiratory parameters
Chapter 4
State of the art of methods and instruments
for analysis of respiratory parameters
Post-operative analysis of respiratory mechanics in mechanically ventilated patients is
useful for evaluating patient status and assessing the effect of therapy in intensive care units
(ICUs). It is important to have knowledge of two main quantities which characterize breathing
mechanical properties; total compliance, often measured under static conditions as an
indicator of lung and chest-wall elasticity and total flow resistance, which reflects properties
of both the tissue and the peripheral airways.
Several studies characterizing the main aspects of breathing mechanics have been
published in recent years. These have used different lumped-parameter models, ranging from
the simple two-element resistance-compliance linear model to more sophisticated
physiological models which include tissue viscoelasticity, the inertial effects of the airways
and branching networks, to non-linear models. However, working with non-linear models
precludes the use of many powerful concepts usually adopted in the clinical investigation of
respiratory mechanics (for example, the use of frequency-domain analysis: Bode diagrams
and input impedance).
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