Emaciated Patient & Dose by Weight

[perfectbluebuildings, BSN, RN]

Okay, I feel rather dumb that I am asking this, but just wanted to hear others' perspectives.

You have a profoundly emaciated pediatric patient- semi-normal height/length for their actual age, but extremely, profoundly underweight- truly skeletal.

Normally of course, Tylenol is dosed 15 mg/kg q4hrs, and Motrin is dosed 10 mg/kg q6hrs. My thinking is that, whatever the patient's weight is, even if it is extremely low for their age and height, you have to base your dose on that weight. But the pt's fever in this scenario is responding very little to weight-based doses of these meds (several doses spaced out over several hours).

(Setting aside the fact that the pt obviously has underlying issues causing this fever and likely needs antibiotics or other therapies.) Regarding the Tylenol and Motrin specifically, because of being so emaciated will they need a higher dose by weight of these medications since their organs are possibly closer to the same size as their same-age counterparts, even though their overall weight is not? Or is that not a factor at all? I feel like I'm being an idiot even asking this.

(If this question doesn't make a lot of sense, please ask me to clarify, too- sometimes I can think I'm being very clear but then people look at me and say "what??":confused:)

Thanks!!!

[NotReady4PrimeTime, RN]

Interesting question! I understand quite clearly what you're asking, but I don't know the answer. I don't think it's ever occurred to me. But the volume of distribution will be dependent on weight, not organ size, in the same way it's a concern with obese patients and with severely fluid-overloaded patients. Maybe ask a pharmacist.

[perfectbluebuildings, BSN, RN]

Thanks for your response!! Your explanation of the "volume of distribution being dependent on weight" helps me understand and think my instincts were correct. But I'll keep investigating and try to ask a pharmacist when I get a chance.

[morte, LPN, LVN]

If their muscle mass is less than normal, the dose may need to be less, not more.

[canoehead, BSN, RN]

If their muscle mass is less than normal, the dose may need to be less, not more.

Disagree. I think liver and kidney function tests would be the most relevant issues.

I think the pharmacist should weigh in on this one, with frequent blood levels where appropriate. Tylenol has a range you can dose, so I'd prefer to dose to effect within that range, and using the patient's weight as a starting point.

[littleneoRN]

If the body structure and vascular system is of more normal size, and the muscle and fat are depleted, this could make sense. Just like when you have a patient with significant water weight on board, you dose for their estimated dry weight because the actual weight does not reflect how their body will process medication. This is definitely a question for a pediatric pharmacist.

[perfectbluebuildings, BSN, RN]

Thanks for all the replies. Very interesting to hear your thoughts from your years of experience and expertise. And I'm still not sure of the answer overall/on a general basis, but it turned out that in this particular case, this patient's neuro system/"thermostat" not working as it should was part of the reason for the fevers. So that is probably why the temp was not coming down with Tylenol and Motrin.