I came across the concept of Pidyon Nefesh in Likkutei Maran, whereby you send a letter to a Tzaddik to daven for you in a time of a crisis and then to give Tzedaka.
Is this the same concept of the gemorah in Baba Basra (119) about asking the Tzadik of the town to daven for you? Or is there something specific and unique about the process of a “pidyon nefesh”?
Furthermore is this concept of a pidyon nefesh something that is recommended that people do?
Unfortunately, I am not familiar with Likutei Maharan, however the idea of pidyon nefesh is brought a method to help a person that is sick. The basic idea is that when the person gives tzedakah, the zechus of the mitzva helps the sick person. While davening is also important, the idea of giving tzedakah has a different source. The posuk says “בחסד ואמת יכופר עון” “With kindness and truth sins are redeemed”, regarding this posuk “kindness refers to giving tzedakah, and truth refers to torah learning, therefore both of these ideas are helpful to redeem a person from a harsh heavenly decree. Another aspect of this is that when a person sins, he is in a way “captured” by the satan etc., and he has a certain jurisdiction over him, when the person “redeems himself” he is in a way releasing himself from the grip that these evil forces have over him. One form of pidyom (redemption) is to give an amount of money to tzedakah as the gematria (numerical value) of the person’s name.
Birkas Yehuda 1 pg. 325, Hashomayim Misaprim pg. 46.