Case Study 5: Drowsy - Medicine Digital Learning

Case study 5: Dolores—Drowsy

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An 85-year-old woman is brought into the ED from her assisted living apartment after she didn’t come down for breakfast. The complex has been on “infection precautions” after an outbreak of Norovirus. She had been affected but yesterday had started taking small bites of food.

She has hypertension, osteoarthritis, and chronic kidney disease. Her medications include HCTZ, irbesartan, and ibuprofen as needed. Her labs come back with a sodium of 154 mg/dL, K+ 5.2 mg/dL, BUN 30 mg/dL and Cr 1.5 mg/dL. She is drowsy. Weight 50 kg. EKG shows peaked T-waves, otherwise normal.

Question

The next step in managing this patient is:

Rationale

She has hypernatremia precipitated by a dehydrating illness (Norovirus diarrhea). Her medications would all contribute to a risk of acute kidney injury, which would then contribute to further water/sodium imbalance. Using a medical calculator (MedCalc or UTD):

Free Water Deficit =
(Total Body Water=wt kg x 0.5)* x (Na/140 -1)
60 kg x 0.5 = 30 kg x (154/140 – 1) = 30 x 0.1 = 3 L.

Replace slowly over 48–72 hours to avoid cerebral edema.

The average person needs > 1L per day of free water for resp/insensible losses-remember to add that in to correction needs. So start with LR or ½ NS and lower NA to ~147 over the first 24 hours. Her hyperkalemia may correct with rehydration. Be careful not to precipitate volume overload.

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