(Greek: an, without; aisthesis, feeling)
In its strict sense the word connotes a loss of tactual sense but it has been extended to include absence of sensibility to any and all external impressions.
It may be localized or general, and may occur naturally as when caused by an injury or disease in the sensory nerve paths, or it may be produced artificially by the administration of anesthetics, as during operations.
Although fatalities are the exception, it is advisable for a Catholic patient to receive the sacraments previous to the administration of an anesthetic.
The reception of the sacraments has a psychotherapeutic value, as the patient's knowledge of having performed his religious duties makes him less susceptible to a shock which may terminate fatally.
The sacraments affect body and soul and the Blessed Sacrament particularly is regarded as medicine to both.
The Postcommunion of the Mass on 30 June, commemoration of Saint Paul, speaks of its medioinalis operatio (healing remedy).
It is wrong to use anesthetics to hasten the death of a patient.
New Catholic Dictionary