Are you obligated to pay someone who saved your life?
If someone saves your life and in the process spends money do you have to pay them back?
The Gemara in Kesubos 49b seems to say yes. The Mishna there discusses the obligations a wife has to her husband. One of those obligations is to nurse their children. The gemara comments that if she is divorced we don't force her to nurse the baby (the father is obligated to suport his infant children and therefore would need to hire a wet nurse). However, the gemara says, if the baby is already attached to her (the gemara later has a machlokes what exactly the shiur of attachement is, 3 months, 50 days) then it is an issue of pikuach nefesh for her not to nurse and we force her to nurse the baby, but the father has to pay her.
The acharonim point out that we see that even though she is nursing the baby for pikuach nefesh reasons the father still needs to pay her. The same would apply in any situation of pikuach nefesh, the saved person would need to pay the saver for any monetary loss incurred.
The Rosh at the beginning of the 8th perek of Sanhedrin paskens this way, in fact, acharonim ask why he didn't bring the gemara in Kesubos as a proof. The Rosh is quoted l'halacha in the Tur in the last Siman in Choshen Mishpat.