Page 227 - Critical Care Notes

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■ Assess respiratory and neurological status. Hypoglycemia and decompen-
sated hyperglycemia may manifest as mental changes.
■ Provide ventilatory support as indicated.
■ Provide seizure and safety precautions.

Diabetes Insipidus (DI)
DI has been defined as the excretion of a large volume (>3L/24 hr) of dilute urine
(<300m Osm/kg) caused by a decrease in secretion of vasopressin (ADH) or
resistance of kidneys to vasopressin.
Pathophysiology
Decrease ADH → decreased ability of kidneys to reabsorb water → increase
in urine output or excessive urination (polyuria and nocturia) → excretion of
large amounts of dilute urine → hyponatremia → excessive thirst (polydip-
sia). Can also lead to dehydration and decreased cardiac output → decreased
BP → hypovolemic shock.
Types of DI include:
■ Central DI, which includes neurogenic
■ No ADH or inadequate synthesis or secretion of ADH
■ Cause can be congenital or idiopathic:
• CNS tumors
• Cerebrovascular disease, aneurysms, thrombosis, or trauma
• Infection
• Granulomas
• Pregnancy
• Brain death
■ Nephrogenic DI: rare genetic disorder
■ Secretion of ADH but no stimulation to the nephron’s collecting tubules
■ Cause can be congenital or idiopathic:
• Obstruction that hinders normal urine excretion
• Chronic tubulointerstitial disease, pyelonephritis, polycystic disease
• Medications
• Electrolyte imbalance
■ Dipsogenic DI
■ Caused by a defect or damage to the thirst mechanism in the hypothalamus
■ Results in an abnormal increase in thirst with an increased fluid intake
that suppresses ADH secretion and increases urine output
■ Gestational DI
■ Occurs only during pregnancy
ENDO