VentSim 1.5

VentSim is a comprehensive and high-fidelity mechanical ventilator simulation tool designed with physiological accuracy. Developed by Dr. Roger Stedman for iOS using the Swift programming language, it serves primarily as an educational resource for healthcare professionals involved in airway management, including critical care physicians, nurses, respiratory therapists, and anesthetists. Its core aim is to facilitate the understanding of safe and effective ventilation strategies through realistic scenario modeling.

The application employs a validated mathematical model of the human respiratory system, incorporating parameters such as volume, resistance, and compliance that are well documented within the scientific literature [link]. This model has been integrated into an interactive interface enabling users to modify various patient-specific variables, ranging from neonates to adults with complex pulmonary conditions like COPD and emphysema.

VentSim permits users to apply different ventilator settings to the respiratory model, producing pressure, volume, and flow waveforms displayed directly on the device screen. This allows for an intuitive exploration of ventilator-patient interactions under varying conditions.

Using VentSim involves several straightforward steps:

1. Initial Setup: Upon launch, the simulator view appears as the central navigation hub, providing immediate access to core functions. To configure a virtual patient, tap the ‘Patient’ button on the right side of the navigation bar, which opens the ‘Patient Settings’ panel. The controls slide in from the right, allowing you to observe ongoing changes in the simulator view.
2. Patient Parameters: Select patient type—neonatal, pediatric, or adult—and adjust weight and lung volume accordingly. Calculated lung volumes are displayed dynamically. You can choose between linear or dynamic compliance models; if linear compliance is selected, modify the compliance slider (mls/cmH2O). For dynamic compliance models, different parameters such as the time constant can be adjusted to simulate variations in airway resistance based on patient size and lung compliance.
3. Applying Ventilator Settings: Tap the ‘Ventilator’ button on the left of the navigation bar to access ‘Ventilator Settings’. Here, you can set ventilation rate (bpm) and I:E ratio via sliders. Three ventilator modes—Pressure Control, Volume Control, and Flow Control—are available, each allowing input adjustments such as inspiratory pressure, tidal volume, or inspiratory flow. Additional parameters include PEEP and end-inspiratory pause in volume control mode.
4. Monitoring Effects: Return to the main simulator view to observe how your adjustments influence respiratory parameters displayed on graphical waveforms. These visualizations offer insights into ventilator performance and patient response.

For optimal usability, especially on devices with smaller screens such as the iPhone SE, switching to landscape orientation is recommended to enhance visibility of all interface elements.

The graphical display settings can be customized by tapping the gear icon located at the top right of each graph view. This opens a panel where you can modify background and plot colors, animation speed and style (with fade mode as default), and plot styles (line or solid). Adjustments made here automatically resize and rescale graphs for best fit, updating axis labels accordingly at each respiratory cycle end.

Additional features include an ‘i’ button that provides quick access to this documentation within an embedded browser, and a menu accessed via a downward chevron icon. This menu allows toggling various views—including spirometer loop and compliance views—for deeper analysis.

Feedback regarding VentSim is welcomed at: [email protected]