Critical Care Medicine-Hematologic and Oncologic Disorders>>>>>Solid Tumors
Question 1#

A 67-year-old man with past medical history of hypertension, diabetes mellitus, smoking, and recent diagnosis of small cell lung cancer is admitted to the ICU presents with complaints of nausea, vomiting, weakness, and altered mental status. On examination he is somnolent but opens his eyes to voice. He is not oriented to person or place. He appears well hydrated and his vital signs are within normal limits. His basic metabolic panel is notable for:

The patient has a seizure as you are examining him. After ensuring adequate oxygenation and ventilation the most appropriate next treatment is ?

A. Fluid Restriction
B. Intravenous furosemide
C. Intravenous 3% NS
D. Tolvaptan

Correct Answer is C

Comment:

Correct Answer: C

The patient presents with hyponatremia (serum Na <135 mEq/L) most likely secondary to syndrome of inappropriate antidiuretic hormone (SIADH) resulting from his lung cancer. Patients with hyponatremia and severe neurological symptoms (seizures, coma, inability communicate) should be treated with hypertonic saline. Left untreated, severe hyponatremia can lead to potentially lethal cerebral edema.

The SIADH is characterized by euvolemic hyponatremia, low serum osmolality (<280 mOsm/kg), and increased urine osmolality. Hyponatremia is secondary to antidiuretic hormone–induced retention of ingested water. Common causes of SIADH include malignancies (highest among patients with small-cell lung cancer), infections (pneumonia, meningitis, AIDS), medications, hormone deficiencies (hypothyroidism, adrenal insufficiency), neurological injuries (subarachnoid hemorrhage), and surgery.

Treatment of hyponatremia depends on the severity of the symptoms and the rapidity with which they develop. In asymptomatic patients, treatment of the underlying cause can correct hyponatremia. Fluid restriction is the mainstay of therapy in patients with SIADH without any neurological symptoms. Patients with neurological symptoms, and those with resistant hyponatremia, should be treated with intravenous hypertonic saline. 

References:

  1. Sterns RH, Hix JK, Silver SM. Management of hyponatremia in the ICU. Chest. 2013;144:672-679.
  2. Gross P. Clinical management of SIADH. Ther Adv Endocrinol Metab. 2012;3:61-73.