Most Catholics know that when someone is ill and unable to attend Mass that they may receive Eucharist. When they are in danger of death and it is likely to be their last time it is also called the Viaticum. This is usually in the form of the Precious Body.
What is not generally realized is that in cases of special need, for example for a person who cannot swallow, it is permitted for them to receive the Precious Blood. This requires special preparation on the part of the consecrating priest, because it is generally not allowed to retain the Precious Blood, and then only for a very short time. Unlike in the case of the consecrated Host there is not an equivalent to the pyx for transporting the Precious Blood. In most cases only a few drops are really necessary. Except in the case of Celiac disease, most who can't receive the Body of the Lord will only be able to take as much Precious Blood as can be absorbed in the mouth, since they cannot swallow.
If you know someone in this situation discuss the option with their priest. Many believe that there is no option that will allow them to receive the Lord if they are unable to swallow the Host.