Evolution and medicine

What I thought would've been an interesting discussion on evolution and medicine ended being a rather unconvincing argument about how certain disease gene(s) are more prevalent than expected. What I'd like to discuss more is how medicine is hindering evolution - people who normally would not have survived to reproduce now are thanks to the "miracles of medicine". I used to think that people who were "unlucky" and were involved in say, a traumatic accident, and "saved" by medicine wasn't really "cheating" evolution. But on subsequent thought, it's exactly those "unlucky" individuals that selective pressure works against. While there are always the flukes, it's very hard to distinguish between an accidental fluke and one made more likely by being "unfit" for the environment the organism found itself in. What about all the advances made in medicine, e.g. advanced neonatal technologies that is pushing back the shortest viable gestation? The nature of medicine is itself the anti-thesis of evolution through selective pressure - which brings me to the main point of this entry: Is medicine's obligation to the individual or society? As we continue to treat people, some with serious illness, and extend their longevity sufficiently long to impact fertility, we are in a sense preventing selective pressure from exerting its effects. I believe countries with socialized medicine have already faced this issue and have made conscious decisions, e.g. limiting the efforts of the healthcare industry based upon certain eligibility criteria. If the doctor's attention is patient oriented, then who's responsible for overseeing the physicians/healthcare industry to ensure that the social group as a whole benefits?