Fluids, Electrolytes, Acid-Base Disorders, and Nutrition Support

Patient Case

Questions 8 and 9 pertain to the following case.

A 60-year-old woman (weight 80 kg) was admitted to the hospital after 1 week of severe diarrhea. She presents

with clinical evidence of dehydration (hypotension, tachycardia, decreased urine output) and is weak. Her serum

laboratory values are as follows: Na 145 mEq/L, K 3.0 mEq/L, Cl 118 mEq/L, total CO2 18 mEq/L, BUN 29

mg/dL, SCr 0.9 mg/dL, glucose 122 mg/dL, calcium 9.1 mg/dL, phosphorus 3.7 mg/dL, magnesium 1.4 mg/L,

albumin 3.9 g/dL, and lactate 1.6 mmol/L. Her ABG is pH 7.29, Po2 93 mm Hg, Pco2 34 mm Hg, HCO3 17 mEq/L,

and base excess -5 mEq/L. She has a 30 pack/year smoking history.

Which best describes the patient’s type of acid-base disorder?

Which is the most appropriate initial fluid therapy for this patient?

Assessment (to help guide treatment) based on urinary chloride

Saline responsive (urinary chloride less than 10 mEq/L)

Excessive gastric fluid losses

ii.

Diuretic therapy (especially loop diuretics)

iii.

Dehydration (contraction alkalosis)

iv.

Hypokalemia

(Over-) Correction of chronic hypercapnia

Saline resistant (urinary chloride greater than 20 mEq/L)

Excessive mineralocorticoid activity (e.g., hydrocortisone, fludrocortisone, licorice)

ii.

Excessive alkali intake

iii.

Profound potassium depletion (serum potassium less than 3 mEq/L)

iv.

Massive blood transfusion

Respiratory compensation (highly variable and may not be possible for ventilator-dependent

patients)

Treat underlying cause (if possible).

Decreased intravascular volume: Give intravenous 0.9% sodium chloride, Plasmalyte/Normosol,

or Lactated Ringer’s infusion (with potassium chloride, if necessary).

Increased intravascular volume: Acetazolamide 250–500 mg orally or intravenously once to four

Med 1999;27:1257-61; Acta Anaesthesiol Scand 1983;27:252-4).

Hydrochloric acid therapy if alkalosis is refractory or initial pH greater than 7.6

Hydrochloric acid should be given by central venous administration, and the solution must

be in a glass bottle.