Minchat Shlomo, Vol. 2, 86:4

In relation to the obligation to pay the costs of saving the life of a sick person who is in danger of dying: From the straightforward reading of Sanhedrin 73a , we see that one is obligated to do everything to save him, and if not, one transgresses the negative commandment: “Do not stand idly by the blood of your neighbor.” (According to my humble opinion, it’s clear that the sick person is obligated afterwards to repay the expenses.) And if we say that the commandment is directed at action, and therefore one is not under an obligation to spend all his money, nevertheless 10 or 20% of his property surely is required. It is more logical that this prohibition is far more stringent and that he is obligated to spend all his property. But regretfully, we encounter this all of the time and nobody does it. I heard that the Gaon Israel Salanter was very uncertain about this issue. As to what to do in our case: it looks to me certain that in a case such as this, where one sees his friend drowning in the river and there is no one to save him, he has to spend all his resources to save him. But when the matter is publicly known to everyone, there are those who rely on the lenient opinion, and one is not obligated to give more than his fair share. But in any event, this doesn’t make sense to me, because how can he absolve himself from such a stringent negative commandment simply because others are not concerned with it and violate it? This matter requires great study. [AJWS translation]