Giving abx in 100 ml NS instead of 50 ml

[autumn_blue]

Went to give an expensive antibiotic, accidentally grabbed a 100ml bag of NS the other day instead of a 50ml bag. Replaced it, but was thinking ... this particular patient needs more fluids, not less (kidney patient). Would it actually hurt them to run an abx at 100ml/hour over an hour vs 100ml/hr over 30 minutes and give them 50 more ml of NS? I'm thinking it would have been fine.

[JBMmom, MSN, NP]

Most likely not going to be a problem, but the bigger concern would not be the extra fluid administered, it's that the concentration of the antibiotic being administered has been changed. All antibiotics are tested for the MIC (minimal inhibitory concentration) that will be kill or inhibit growth of a bacteria. If changing the concentration in the bag were to dilute it enough that now the concentration falls below the MIC, you be administering a completely ineffective drug. It is not very often that a 1:2 dilution of the drug would put it below the MIC, but it's a remote possibility. 

[Jedrnurse, BSN, RN]

Aren't you generally restricting fluids with kidney patients, not giving extra...?

[Squidpdx, CNA, LPN]

2 minutes ago, Jedrnurse said:

Aren't you generally restricting fluids with kidney patients, not giving extra...?

Depends on the type of kidney disease, (for example, an underlying cause in AKI could be severe dehydration), and the stage of progression. In early CKD, fluid is not generally restricted.

[mmc51264, BSN, MSN, RN]

50mL vs 100mL doesn't seem like a big deal. I'm just curious if you have to mix your own abx? We don't have to, except on rare occasions where there is a product shortage and we reconstitute with 10mL. Pharmacy does the rest. 

[klone, MSN, RN]

9 hours ago, JBMmom said:

Most likely not going to be a problem, but the bigger concern would not be the extra fluid administered, it's that the concentration of the antibiotic being administered has been changed. All antibiotics are tested for the MIC (minimal inhibitory concentration) that will be kill or inhibit growth of a bacteria. If changing the concentration in the bag were to dilute it enough that now the concentration falls below the MIC, you be administering a completely ineffective drug. It is not very often that a 1:2 dilution of the drug would put it below the MIC, but it's a remote possibility. 

But if they ran the whole bag, they would still get the full dose of antibiotics. What am I missing?

[JBMmom, MSN, NP]

The concentration is based on the amount of drug in the total volume, so yes, the total drug might be the same amount, but it's a different dilution. Again, most drugs are prescribed at rates that are nowhere NEAR the MIC because of the margin of error and the drug volumes used. My answer was VERY nitpicky I realize, especially since the difference between a 50 and 100mL bag is pretty small. But if someone say, diluted in 1000mL, even if they administered the whole amount of drug, the concentration might never reach a high enough level in the body to exert it's intended effect. It was really an unnecessarily academic response on my part, I just used to work in a lab that did the MIC testing for antibiotics, so I wanted to bring awareness that overall drug concentration can matter. 

[MunoRN, RN]

4 hours ago, JBMmom said:

The concentration is based on the amount of drug in the total volume, so yes, the total drug might be the same amount, but it's a different dilution. Again, most drugs are prescribed at rates that are nowhere NEAR the MIC because of the margin of error and the drug volumes used. My answer was VERY nitpicky I realize, especially since the difference between a 50 and 100mL bag is pretty small. But if someone say, diluted in 1000mL, even if they administered the whole amount of drug, the concentration might never reach a high enough level in the body to exert it's intended effect. It was really an unnecessarily academic response on my part, I just used to work in a lab that did the MIC testing for antibiotics, so I wanted to bring awareness that overall drug concentration can matter. 

I get what you're saying, but we should probably clarify that when given systemically (IV) the concentration is the dose per 5 liters (total circulating volume in a typical adult).  So the difference between 50ml and 100ml is an extremely small change since 50ml only represents 1% of the total volume it's in.  

16 hours ago, autumn_blue said:

Went to give an expensive antibiotic, accidentally grabbed a 100ml bag of NS the other day instead of a 50ml bag. Replaced it, but was thinking ... this particular patient needs more fluids, not less (kidney patient). Would it actually hurt them to run an abx at 100ml/hour over an hour vs 100ml/hr over 30 minutes and give them 50 more ml of NS? I'm thinking it would have been fine.

The one thing I would point out is that the dose should have still been given over the appropriate time frame; whether it's 500 mg in 50ml or 500 mg in 100ml it should have been given over 30 minutes (assuming that's the appropriate time to infuse 500mg of this particular antibiotic). 

[Been there,done that, ASN, RN]

50  ml of normal saline never hurt any body. 

[JKL33]

12 hours ago, JBMmom said:

But if someone say, diluted in 1000mL, even if they administered the whole amount of drug, the concentration might never reach a high enough level in the body to exert it's intended effect.

We essentially do that all the time--the sepsis protocols where we flood people while concurrently administering all the abx.

[Guest219794]

23 hours ago, JBMmom said:

Most likely not going to be a problem, but the bigger concern would not be the extra fluid administered, it's that the concentration of the antibiotic being administered has been changed. All antibiotics are tested for the MIC (minimal inhibitory concentration) that will be kill or inhibit growth of a bacteria. If changing the concentration in the bag were to dilute it enough that now the concentration falls below the MIC, you be administering a completely ineffective drug. It is not very often that a 1:2 dilution of the drug would put it below the MIC, but it's a remote possibility. 

It is done all the time, running ABX into lines running maintenance, or bolus, or whatever.

It is the equivalent of flushing the line 5 times.

4 hours ago, Been there,done that said:

50  ml of normal saline never hurt any body. 

Well, I got splashed in the eye once, and it kinda stung.

[bluescrubs, ADN, ASN, RN]

I don't think it will make a big difference but if you would like to double check I would asked the pharmacist once you get back to work without implicating yourself if you really want to know. Another factor that's into play is this a one time abx or something that the patient is receiving over a couple of days? If they are receiving it over a couple of days I wouldn't bother calling as they are getting multiple doses.