Lung simulators are widely used to test ventilators, respiratory devices, and therapies under controlled conditions. But how accurately do these devices reproduce the behavior of human lungs?

A new peer-reviewed study published in the Journal of Biomechanics examined that question by comparing four lung simulators, including the Michigan Instruments TTL®, under healthy, restrictive, and obstructive lung conditions. The research provides useful insight into what simulator accuracy means and why dynamic performance matters in ventilator testing.

What Is Dynamic Accuracy?

Lung simulator accuracy is about more than whether a device reaches a specific compliance or resistance setting. A simulator also needs to respond appropriately as airflow and other conditions change.

Dynamic accuracy describes how closely a simulator’s pressure and flow response matches the expected behavior of a lung model as conditions change. This is important when testing ventilators because respiratory devices interact with changing lung mechanics rather than a completely static load.

The study evaluated simulator responses across different flow frequencies and amplitudes, comparing their behavior against a theoretical single-compartment lung model.

How the Study Evaluated Lung Simulators

Researchers compared four commercially available simulators:

• ASL5000
• Alveo
• SmartLung 2000
• Michigan Instruments TTL®

The simulators were tested using healthy, restrictive, and obstructive lung configurations. Researchers analyzed pressure and flow responses across different frequencies and amplitudes to evaluate how closely each simulator matched the reference lung model.

This is important because lung simulators can behave differently depending on their mechanical design, resistance characteristics, and the conditions being simulated.

What the Study Found About the TTL®

The study found that the passive TTL® showed consistent behavior across the frequency range evaluated. For healthy and restrictive configurations, its response remained close to the reference model through much of the tested range.

The researchers also identified flow-amplitude dependence when the TTL® was configured to simulate obstructive conditions. This behavior was associated with its parabolic resistance characteristics.

Importantly, the study did not conclude that one simulator is universally the most accurate. Instead, the findings highlight the importance of understanding simulator-specific characteristics when designing bench tests and interpreting results.

Why Lung Condition Matters

The research demonstrates why testing a simulator under only one condition may not provide the complete picture.

Healthy, restrictive, and obstructive lungs have different mechanical characteristics. A simulator may respond differently depending on compliance, resistance, airflow, and frequency.

Michigan Instruments TTL® systems provide adjustable compliance and airway resistance, allowing users to create a range of simulated lung conditions. Their mechanical design provides a dynamic response to mechanical ventilation.

What This Means for Ventilator Testing

For engineers, researchers, and medical device manufacturers, the study reinforces an important point: the testing load matters.

A ventilator may perform differently when exposed to different lung mechanics. Using a realistic, well-characterized simulator allows teams to evaluate device performance under controlled conditions and better understand how equipment responds to changing respiratory loads.

Michigan Instruments lung simulators support ventilator testing, calibration, research, and device development. TTL® systems provide adjustable compliance and resistance, while PneuView® systems add real-time pressure, flow, and volume monitoring, along with data recording and analysis.

Accuracy Is About the Entire Testing Setup

The research shows that simulator accuracy cannot always be reduced to a single specification. Teams should consider how a simulator behaves under the specific conditions being tested.

For bench testing, that means considering the lung model, compliance and resistance settings, flow characteristics, measurement equipment, and testing protocol together.

A well-designed testing environment produces more meaningful results and helps teams understand how a ventilator or respiratory device performs under different simulated patient conditions.

Supporting More Reliable Respiratory Testing

As ventilator technology continues to evolve, realistic lung simulation remains an important part of device testing and development. Research like this provides a better understanding of the mechanical characteristics that can influence testing results.

Michigan Instruments provides lung simulation tools for teams that need realistic, repeatable respiratory mechanics. From TTL® Training Test Lungs to PneuView® systems, our solutions support ventilator testing, research, development, and respiratory education.

Contact Michigan Instruments to learn how our lung simulators can support your testing and research applications.

Research referenced: Ferencz M, Drath R, Dömer B. Dynamic accuracy of lung simulation hardware: A comparative evaluation. Journal of Biomechanics. 2026;204:113366.