Description of the input parameters
Here you can read a detailed description of the parameters to be specified for the run.
Multiple runs
When providing the model's input data, it is possible to initiate the run for multiple values of a user-selected parameter, which can be chosen from a dropdown menu.
The selectable parameters are: inhalation time; breath hold time; tidal volume; functional residual capacity; particle diameter; particle density and oral inhalation fraction.
The selection of multiple run is not mandatory; if the user wishes to provide only one value for each parameter, 'None' should be selected.
The values of the selected parameter must be listed in the corresponding row, separated by spaces.
To limit computationally intensive modeling, we restrict the number of events to 1,000,000. (This means that the product of the number of "multiple run" parameter and the "number of events" parameter cannot exceed 1,000,000.)
Multiple runs for more than 1 parameter cannot be selected at the same time; we recommend performing multiple consecutive runs.
If you would like to run the model with a higher number of events, we recommend splitting it into parts, or please let us know your special request via the provided contact email.
If an incorrect parameter is selected here, an error message will appear.
Number of events
The number of simulated particle trajectories, which determines the statistics of the result.
We propose to define at least 10,000. The maximum selected value can be 1,000,000.
Inhalation time [s]
Currently, the model can only simulate symmetrical breathing, so this parameter represents both the inhalation and exhalation times.
If the user does not wish to work with specific measurement data, we recommend selecting the appropriate value from ICRP 66 (ICRP Publication 66, 1994. Human Respiratory Tract Model for Radiological Protection, Annals of the ICRP 24, Pergamon Press, Oxford, UK.) [1].
The suggested value range is 0.5-10 seconds.
Breath hold time [s]
The breath hold time is the time interval between inhalation and exhalation.
In case of normal breathing, this value is 0 seconds.
It is significant when simulating the use of inhaled medications, with a recommended time interval of 0.5-20 seconds.
Tidal volume [cm3]
It represents the volume of air moved into or out of the lungs with each respiratory cycle during normal breathing.
If the user does not wish to work with specific measurement data, we recommend selecting the appropriate value from ICRP 66.
The suggested value range is 150-2000 cm3. This value can be even higher in case of inhalation medicines.
Functional residual capacity [cm3]
Functional Residual Capacity is the volume of air remaining in the lungs at the end of a normal, relaxed exhalation.
If the user does not wish to work with specific measurement data, we recommend selecting the appropriate value from ICRP 66.
The suggested value range is 1700-4000 cm3.
Particle diameter [micrometre]
The aerodynamic diameter of the inhaled aerosol particles, whose deposition distribution is determined using the model.
Typically, the inhalation involves polydisperse particles rather than monodisperse ones. For polydisperse particles, we recommend using the Multiple Runs parameter to define multiple particle sizes (select particle_diameter from the list). Each particle size should be entered in the text box, separated by spaces.
If the concentration/number size-distribution of the simulated particles is also available, the exact size-distribution of deposited particle sizes can be determined based on the probabilistic distributions obtained as simulation results.
The suggested value range is 10 nm-32 µm.
Particle density [g/cm3]
The density of the particles.
During the simulation, multiple density values can be specified, for which we recommend using the Multiple Runs parameter (select particle_density from the list). Each particle density value should be entered in the text box, separated by spaces.
The average environmental aerosol particle density typically ranges from 1 to 2 grams per cubic centimeter (g/cm³), depending on the composition of the particles. In case of inhalation medications this value ranges usually between 1 and 2 g/cm³.
Otherwise, we recommend using values from the scientific literature.
Oral inhalation fraction
The fraction of air going through the oral pathway in the extrathoracic region.
The value of this variable is 1 for oral breathing and 0 for nasal breathing, which can be selected from a dropdown menu.
Simultaneous nasal and oral breathing simulation is not possible.
We recommend nasal breathing up to light physical exertion. For inhaled medications, only oral breathing is used.
Recommended default parameters
Table 1. Average values for SLM input parameters
| Parameter | Recommended Value | Unit |
|---|---|---|
| Number of Events | 10,000 | - |
| Inhalation Time | 2.5 | seconds |
| Breath Hold Time | 0.0 | seconds |
| Tidal Volume | 750.0 | cm3 |
| Functional Residual Capacity | 3300.0 | cm3 |
| Particle Diameter | 0.2 | micrometre |
| Particle Density | 0.1 | g/cm3 |
| Oral Inhalation Fraction | 0.0 | - |
Table 2. Reference respiratory values [1]
| sleeping (man / woman) | sitting (man / woman) | light exercise (man / woman) | heavy exercise (man / woman) | |
|---|---|---|---|---|
| Tidal volume (cm3) | 625 / 444 | 750 / 464 | 1250 / 992 | 1923 / 1364 |
| Inhalation frequency (1/min) | 12 / 12 | 12 / 14 | 20 / 21 | 26 / 33 |
[1] Raabe, O.G., Yeh, H.C., Schum, G.M., Phalen, R.F., 1976. Tracheobronchial geometry: human, dog, rat, hamster. Lovelace Foundation Report LF-53. Lovelace Foundation, Albuquerque, NM, USA.