The parameters of the respiratory system (RS) can be changed using sliders on the panels below the RS schema. Holding the slider grip with the mouse, it can be directed up or down, changing the parameter value. In order to adjust the values with a higher precision, the arrow keys (up and down) on the computer keyboard can be used.
The values of respiratory system parameters are expressed as percentages of the reference values. After starting the system, the reference values are those of the respiratory system parameters of the average Polish female aged about 50 years. However, the users can change this, i.e. can themselves define another set of reference values.
There are several virtual keys and buttons at the screen enabling the user to manipulate both simulation and global parameters setting, e.g. Start, Reset, Delete row (delete uninteresting simulation), Use as ref (use the present virtual patient as a reference for the others), File (makes possible to save and read simulations), ref. Default (return to the default reference), etc.
Note: the reference set of parameters does not have to correspond to a healthy subject. For example, a patient with severe obstruction may be accepted as reference, in order to observe in subsequent simulations what effects VDc changes exert on the indices and flow-volume curve. On the other hand, if we accept as reference a set, for which a parameter has extreme value (it cannot be further changed with the slider), then pressing the key Use as ref would make possible further change of that parameter value (e.g. performing the above mentioned activities, VDc can be increased several times in spite of the fact that the maximal single change with VDc slider corresponds to increase of 150%).
The user was given free choice in settings of the values of available parameters. However, for some combinations of the values the system can refuse to carry out the simulation or to complete it. In cases when the system can recognize that a person with the given combination of the values of the parameters could not survive it would provide appropriate information. In other unrealistic cases, e.g. when it is impossible to perform a simulation in time shorter than the limit set in the program, the system will provide information about simulation discontinuation due to calculation problems.
It cannot be excluded, however, that the user would manage to outwit the system and to select such a combination of parameter values that the system would not know that it could not perform the simulation. In that case it could give evidently erroneous results or even hang up.
When the user activates a slider, the assistant reminds the physiological meaning of the parameter that is connected with the slider. It also reminds connections between that parameter and others or suggests changes of some other parameters.