Which patient would you see first? Nursing.?

I would vote for #1: this patient has a very high heart and respiration rate, but i think the critical thing her is the FiO2: it is generally recommended that this be kept under 60%, due to the risk of Oxygen toxicity. Patient 1 could be experiencing O2 toxicity, especially considering their high respiration rate: i'd say this is the most dangerous situation of the 4.