help with fluid n electrolyte case

[Phlavyah]

My book gives the following case study, my question is on #4.

I dont understand why the answer is a. D5W. I was under the understanding that even though it's an isotonic fluid and the pt Na level is normal, but, won't d%w metabolize fast and become hypotonic ? Once the pt is re-hydrated, won't the pt's serum osmolarity levels drop if given D5W?? I wanted to give the pt 0.9% NS. I know I am wrong cuz the book says so, but I don't understand why... Any help? Please?

"The patient with a history of vomiting and diarrhea from the flu presents with a rapid pulse, orthostatic hypotension, urine output of 20 mL/hr, skin turgor poor with tenting, and increased respiratory rate."

1. Which type of dehydration does this patient have? Explain your answer.

Answer: Isotonic dehydration, the most common type of fluid deficit, is

caused by loss of plasma volume. In this case, the patient lost volume by excessive vomiting and diarrhea.

2. In evaluating the patient's laboratory values, indicate whether the following values are likely to be normal, elevated, or decreased.

a. Urine specific gravity

b. Urine volume

c. Serum sodium

d. Serum hematocrit and hemoglobin

e. Blood urea nitrogen (BUN)

f. Serum osmolality

Answer: Urine specific gravity: less than 1.010

Urine volume: decreased

Serum sodium: normal

Serum hematocrit and hemoglobin: increased

Blood urea nitrogen (BUN): normal or increased

Serum osmolality: normal

3. The compensatory mechanism responsible for the patient's rapid pulse is increased:

a. circulation of angiotensin.

b. sympathetic discharge.

c. aldosterone production.

d. renal reabsorption of sodium and water.

Answer: b

4. Immediate interventions to correct this patient's fluid volume imbalance include:

a. rapid hydration with D5W.

b. administration of a loop diuretic.

c. administration of an osmotic diuretic.

d. rapid hydration with D5/0.45% NS.

Answer: a

[ckh23, BSN, RN]

I think the key to the question is "rapid infusion". Another possibility is if this patient is severely dehydrated their sodium may be extremely elevated.

However in reality, you would use 0.9%NSS to increase circulating volume and decrease the HR. Then these people are usually switched over to D5 1/2 NS for re-hydrating.

[Phlavyah]

Thanks! I thought the same but the book clearly isotonic dehydration....

I posed this case to my professor and she thinks the book is wrong and I am right!!

Let me tell ya: it felt G-O-O-D to finally (2nd year student) be right about something! lol :-)

[lovescoffee]

To me, this looks like one of those good ol' nursing school "which is the BEST answer" questions. Like you thought, and ckh23 stated, 0.9%NS is what I usually use in real-life situations to increase IVF vol. However, if you look at the answers available it appears they may be trying to get you to realize you wouldn't want to give a diuretic (b&c) because it will decrease IVF vol more. Nor would you want to give D5/0.45% NS since it's hypertonic (and continues to maintains a higher osmo vs D5W even after the dextrose is metabolized).

So from the options, the "BEST" answer would be: a. rapid hydration with D5W.

I hated this form of testing in nursing school, but once I finally grasped it I did much better. I wish you the best!

[Phlavyah]

Thank you! I took my F&E test this morning and got a 94. I was very proud of myself, being that this was my 1st test back from a summer of doing absolutely nothing...

[lovescoffee]

Congrats!!! :clpty: