The Sacrament of the Sick is available to alll Catholics upon request.  Some prefer to receive the sacrament before going to the hospital.  They simply ask for it and present themselves at the end of any parish mass, usually in the company of their family and friends. 

Others prefer to wait for times when they are in the hospital and then the sacrament is celebrated by the 'priest on call.'  Some people are shut-ins or suffering long term illnesses at home.  In this case, arrangements can be made when other family members are present to join in the celebration. 

Generally, the sacrament is offered once or twice a year or when there has been a serious change in the illness of the person in need of the Sacrament of the Sick.