So I came into my shift (I'm new to an ICU I work nights). Pt was hypotensive recently weaned off levo. He was dry so they had him on maintenance fluids of 200ml/hr of .45% NSS. Plus boluses of LR. He was loosing a lot of fluids out of his abdomen (open belly procedure IV bag closure). The day nurse said to me he is on .45% because his Na (150) and Cl (114) were high. That seemed to make sense to me and its what the doctor ordered. I didnt think anything of it because eventually we stabilized his pressure and didn't need to restart levo. Which I thought was a success. Then during report in the AM. The day nurse says to me. Why is he on .45%!?!?! And I said oh because his his Na and Cl were high. Just a side note before this around 5AM his Na did come back to normal but his Cl was still high so I called the ICU resident to see if we still wanted to keep the fluids the same. All that was changed was the rate to 125/hr. So anyway the nurse I was giving report to said. No your wrong. You should know why he is on these fluids. He should be on D5. But she wouldn't tell me why and just said that I should know already. I asked the day nurse who had him yesterday and she said that he was suppose to be on .45% for high Cl and Na and didn't know why the other nurse suggested D5. Any logic or suggestions as to what fluids this patient really should have been on?