DI AND SIADH

1. DI AND SIADH Pat Hock RN PICU Nurse Educator Lucile Packard Children’s Hospital

2. DI and SIADH Disturbances of Water Balance • 60% to 80% of the human body is composed of water. • Water content varies with age, gender, skeletal muscle mass and fat content. • Osmolality is one of several factors regulating fluid balance between the intracellular and extracellular fluid compartments.

3. ADH: AntiDiuretic Hormone • Formed in the supraoptic and paraventricular nuclei of the hypothalamus. • Transported to the posterior lobe of the Pituitary Gland and stored. • ADH is released: in response to an increase in intravascular osmotic pressure, hypovolemia, decrease in pulse pressure. And in response to fear, pain, anxiety.

6. Function of ADH • ADH increases the permeability of the renal distal tubule and collecting ducts to water. • Less free water is excreted in urine • Urine volume is decreased • Concentration of urine is increased

7. Diabetes Insipidus • DI is a clinical condition due to a deficit of ADH or due to the kidney’s resistance to the effects of ADH. • DI may be central (neurogenic) or nephrogenic. • DI may be a transient or a permanent condition.

8. Etiologies of DI • CNS disorders that damage or create pressure in the area of the hypothalamus, pituitary stalk, or posterior pituitary gland • Head Injuries • CNS infections • Intraventricular Hemorrhage • Neurosurgical Procedures: common postoperatively with resection of craniopharyngiomas, pituitary gland tumors, or suprasellar tumors. • Associated with certain drugs: Ethanol, phenytoin, halothane, opiate antagonists, lithium

10. Signs and Symptoms of DI • POLYURIA- first sign • Low Urine osmolality (less than 100-200 mOsm/L) • Urine specific gravity <1.010 • Hypernatremia (serum sodium greater than 145 mEq/L) • Serum hyperosmolar (greater than 300 mOsm/L) • Thirst, polydipsia • Irritability or mental status changes • Dehydration • Shock

11. Clinical Management of DI • Goal is to prevent circulatory failure and hyperosmolar encephalopathy. • Replace volume deficit and ongoing losses • Replace ADH • Close monitoring of serum and urine lytes/osmolality

12. Fluid Replacement • Correct Hypernatremia slowly • Bolus with NS if hypotensive • Volume deficit replaced over 24 to 48 hours • Replace ongoing urine losses

13. Vasopressin • Available IV, subcutaneous, and intranasal forms • DDAVP given intranasally • Pitressin IV • Therapeutic effect: increase in specific gravity and decrease in urine output within 1 hour of dose.

14. Nursing Management • Close monitoring of intake and output • Frequent hemodynamic monitoring • Frequent Neuro assessments • Serial labs: urine specific gravity and osmolality, Serum sodium and osmolality

15. Complications • Cardiac collapse • Shock • Cerebral Edema • Herniation • Death • Electrolyte imbalances • Water intoxication and fluid overload

16. Syndrome of Inappropriate AntiDiuretic Hormone • SIADH is a clinical condition involving and excess of ADH secretion. • The patient is hyponatremic with a low serum osmolality, which normally would inhibit ADH secretion.

17. Etiology of SIADH • Head Trauma • Cerebral Tumors • Meningitis • Cerebral Hemorrhage • Pulmonary Diseases • Chronically ill or malnourished children • Spinal surgery • BMT or Stem Cell Transplants • Medications • Positive pressure ventilation

18. Signs and Symptoms of SIADH • Low urine output in absence of hypovolemia • Hyponatremia (serum sodium<135mEq/L) • Low Serum osmolality (<285 mOsm/L) • High urine specific gravity (>1.020) • Nausea and vomiting • Mental status changes

19. Clinical Management • Normalize serum sodium over 24 to 48 hours • Normalize serum osmolality • Correct excess extravascular fluid volume • Prevent neurological sequelae • Restrict fluids • 3% NaCl • Loop diuretics

20. Nursing Management • Close monitoring of intake and output • Maintain fluid Restriction • Frequent Hemodynamic monitoring • Frequent Neuro assessments • Serial labs: serum electrolytes, serum osmolality, specific gravity

21. Complications • Seizures • Cerebral edema • Cerebral hemorrhage • Pulmonary edema • Muscle cramps or weakness

22. Triphasic response post Neurosurgery • Transient DI 12-48 hours postop • SIADH after transient DI phase lasting up to 10 days postop • Permanent DI

23. Case Scenario #1 A 3 month old is admitted to the PICU for shock with a 2 day history of fever and irritability. Blood and CSF cultures are positive for Streptococcus pneumoniae. He has had decreasing urine output over the last 24 hours (< 0.5 ml/kg/hr)

24. ? Assessment ? Labs might be ordered

25. Labs Serum Na 126 mEq/L se osmo 260mOsmo/L Cl 98 mEq/L Bun 4mg/dl K 3.7 mEq/L Cr 0.4 mg/dl CO2 25mEq/L glucose 129 mg/dl Urine sp gr 1.025

26. ? Abnormal findings ? Etiology ? Treatment

27. Abnormalities • Hyponatremia • Oliguria • Concentrated urine • Low serum osmolality

28. SIADH Treatment: Fluid Restriction

29. Case Study #2 A 5 year old (15kg) boy is admitted to the PICU with a history of MVA 2 days ago. He sustained an isolated head injury with an intraventricular hemorrhage and multiple cerebral contusions. Three hours ago he had an episode of severe intracranial hypertension (ICP 90mmHg, MAP 50 mmHg) requiring volume and an epi drip for hypotension. Over the last 2 hours his uo has increased to 130-150 ml/hr (~8ml/kg/hr.)

30. ? Assessment ? Labs might be ordered

31. Labs Serum: Na 155mEq/L BUN 13 mg/dl Cl 114 mEq/L Cr 0.6 mg/dl K 4.2 mEq/L glu 86 mg/dl CO2 22 mEq/L se osmo 320 mOsmo/L Urine sp gr 1.005

32. ?Abnormal Findings ? Etiology ? Treatment

33. Abnormalities • Hypernatremia • Polyuria • Dilute urine • High serum osmolality

34. DI Treatment: Acute: Vasopressin infusion Chronic: DDAVP Monitor for Hyponatremia

35. References • Curley, Critical Care Nursing of Infants andChildren. Saunders • Hazinski. Manuel of Pediatric Critical Care. Mosby • Kliegman. Nelson’s Textbook of Pediatrics. Saunders • Slota. AACN’s Core Curriculum forPediatric Critical Care. Saunders