The first sentence means that had the nurse-patient ratios been equal (at whatever point in the past the writer is talking about), then the number of surgical deaths in hospital would have been lower, at that time.
The second sentence suggests that if the ratio were to be equal now or in the future, then the number of deaths would be lower, at the relevant time. I would say it's more likely to be read as meaning the future.
If talking about the present, I would perhaps say "Matching nurse-patient ratios would result in there being fewer surgical deaths in hospitals". This could still refer to the future, but I think I would assume it referred to the present if I read it.
If the sentence read "If the nurse-patient ratios match, there will be fewer deaths...." then it could only mean the future.
Student or Learner