Diabetes Insipidus Case Study (60 min)

Mrs. Ford is a 32 year old female who was admitted to the neuro ICU two days ago after a fall, which caused a large epidural hematoma over the left parietal lobe. She was intubated due to a low level of consciousness to protect her airway. An External Ventricular Drain (EVD) was placed to monitor her ICP. She also has an orogastric tube, and a Foley catheter in place

Mrs. Ford’s vital signs are as follows:
BP 124/68 MAP 86

HR 84 Temp 98.9
RR 16 (ventilated)
ICP 12

She is not on any sedation. You determine her GCS is 6, she withdraws to pain, but does not open her eyes. Her pupils are equal and reactive bilaterally, 4mm. For this hour she has put out 120 ml of urine that is clear and yellow. She is receiving normal saline at 75 mL/hour as well as tube feeds at 40 mL/hour. Her EVD is open at 15 cmH2O and draining a clear pink fluid, 6 ml this hour.

faq lesson=”true” blooms=”Application” question=”Calculate her cerebral perfusion pressure.”]

• CPP = MAP – ICP
• 86 – 12 = 74 mmHg [/faq]

Hourly urine output for Mrs. Ford For the last 3 hours were 180 mL, 240 mL, and 440 mL. The urine is clear and barely pale yellow. Her blood pressure is 108/56, HR is 104. Her ICP is 15.

Lab Values:
Na+ 155 mg/dL
Serum osmo 310 mOsm/kg
Urine SG 1.005

The provider orders the following:

Free water flush via OG Tube – 200 mL q4h

Change IVF to D5W at 125 mL/hr

Desmopressin (DDAVP) 2 mcg IV push q 12h

Daily weight

q4h Sodium and Serum Osmolality levels

You set the tube feeding pump to administer the free water and change the IV fluids while waiting for the DDAVP from the pharmacy

After 2 days of treatment, misses Fords urine output and urine specific gravity return to Baseline. However, she continues to have a GCS between 4 + 6, and now her left pupil is 8mm and fixed. The nurse notes her respiratory rate is erratic, her ICP is 18, and her heart rate is dropping.