A non-transitory computer readable medium having stored thereon instructions that, when executed by a computing device, cause to be performed a method of assisting and monitoring an operator as the operator manually prepares a liquid pharmaceutical composition to be administered to a patient using a medical instrument, the method being performed by a digital assistant appliance and comprising:
- storing in a memory device, for each active principle of the liquid pharmaceutical composition, one or more first sample images of vials that can contain said active principle, and/or one or more second sample images of syringes that can be used for transferring to transfer the active principle from said vials to the medical instrument;
- acquiring, through an artificial viewing system, an image of a vial positioned on a scale of the appliance by the operator and/or an image of a syringe positioned on the scale by the operator;
- comparing said acquired vial image with each of said first sample images to determine whether the vial positioned on the scale by the operator is incorrect;
- and/or
- comparing said acquired syringe image with each of said second sample images to determine whether the syringe positioned on the scale by the operator is incorrect;
- and
- providing a warning to the operator, through a user-interface system, when the vial positioned on said scale is incorrect and/or the syringe positioned on said scale is incorrect.