The Ambu bag, or bag-valve-mask (BVM) resuscitator, is a vital medical device used to provide positive pressure ventilation to patients who are not breathing adequately. Simulating the mechanical and fluid behavior of this device is essential for optimizing its performance, understanding airflow dynamics, and ensuring patient safety.

Using COMSOL Multiphysics, we can create a comprehensive simulation model of an Ambu bag system that captures both its mechanical deformation and the resulting airflow into the patient’s lungs.

Key Aspects of the Simulation:

• Structural Mechanics: The elastic deformation of the silicone bag is modeled using nonlinear hyperelastic material models, such as Mooney-Rivlin or Ogden, to replicate the real mechanical behavior of the squeezable chamber.

• Fluid Dynamics (CFD): The airflow generated by the compression of the bag is simulated using laminar or turbulent flow models, depending on the desired level of detail and flow conditions.

• Fluid-Structure Interaction (FSI): A fully coupled FSI simulation is used to capture the interaction between the deforming bag and the air being pushed through the valve and into the airway.

• Time-Dependent Analysis: The simulation accounts for the dynamic nature of bag compression and relaxation cycles, allowing realistic modeling of manual ventilation.

• Valve Mechanics: One-way valves are incorporated to simulate unidirectional airflow, mimicking real BVM operation and preventing backflow.

Applications and Benefits:

• Optimizing Ambu bag shape and material for efficient air delivery

• Analyzing airflow patterns to reduce dead volume and improve oxygenation

• Testing performance under various hand-compression profiles and patient conditions

• Supporting the design of advanced or automated resuscitators (e.g., emergency ventilators)

This type of simulation is particularly valuable in the context of medical device innovation, emergency care design, and pandemic preparedness, where reliable and efficient manual ventilation devices are critical.

By leveraging COMSOL’s multiphysics capabilities, engineers and researchers can deeply understand the performance of Ambu bags and develop safer, more effective respiratory support systems.