SIADH, DI, Cerebral Salt Wasting - PowerPoint PPT Presentation

1 / 20
About This Presentation
Title:

SIADH, DI, Cerebral Salt Wasting

Description:

SIADH, DI, Cerebral Salt Wasting By Tracy Merrill MD Feb 24, 2003 – PowerPoint PPT presentation

Number of Views:245
Avg rating:3.0/5.0
Slides: 21
Provided by: anaesthes
Category:

less

Transcript and Presenter's Notes

Title: SIADH, DI, Cerebral Salt Wasting


1
SIADH, DI, Cerebral Salt Wasting
  • By Tracy Merrill MD
  • Feb 24, 2003

2
SIADH
  • Syndrome of Inappropriate ADH Secretion
  • Definition levels of ADH are inappropriately
    elevated compared to bodys low osmolality, and
    ADH levels are not suppressed by further
    decreases in blood osmolality.

3
SIADH causes
  • Irritation of CNS meningitis, encephalitis,
    brain tumors, brain hemorrhage, hypoxic insult,
    trauma, brain abscess, Guillain Barre,
    hydrocephalus
  • Pulmonary disorders pneumonia, asthma, positive
    end expiratory pressure ventilation, CF, TB,
    pneumothorax

4
SIADH causes continued
  • Drugs vincristine, vinblastine, opiates,
    carbamazepime, cyclophosphamide
  • Unregulated tumor production of ADH-like
    peptides oat cell lung carcinoma for example,
    Ewings sarcoma, carcinoma of duodenum, pancreas,
    thymus

5
SIADH function of ADH
  • antidiuretic hormone vasopressin
  • ADH is made in the supra-optic nuclei in the
    hypothalamus, stored in the posterior pituitary
  • Normally released into the bloodstream when
    osmo-receptors detect high plasma osmolality
  • At the kidney, attaches to receptors in the
    collecting ducts, opens up water channels
  • Water is passively reabsorbed along the kidneys
    medullary concentration gradient

6
SIADH signs and symptoms
  • Decreased/low urine output
  • Signs of hyponatremia lethargy, apathy,
    disorientation, muscle cramps, anorexia,
    agitation
  • Signs of water toxicity nausea, vomiting,
    personality changes, confused, combative
  • If Na lt 110 mEq/L, seizures, bulbar palsies,
    hypothermia, stupor, coma

7
SIADH lab values
  • Serum Na lt 135 (Na is diluted by excessive free
    water re-absorption)
  • Serum osmolality low, normal is 270
  • Urine Na is inappropriately high, gt20 mmol/L,
    actually losing Na in urine instead of retaining
    it
  • Urine osmolality is inappropriately high, can
    range b/t 300-1400 mosm/L
  • CVP is high from free water retention

8
SIADH treatment
  • Fluid restriction, ¾ maintenance
  • If symptomatic, may actually need to replace
    NaCl, can use hypertonic saline for example
    300cc/m2 of 1 ½ NS
  • Diuretics such as lasix
  • Treat underlying disorder, for example usually
    resolves after removal of lung carcinomas

9
SIADH treatment cont
  • Demeclochlorotetracycline, blocks ADH receptors
    in the renal collecting ducts
  • In severe cases, hemodialysis
  • Warning, if increase Na too fast, at risk for
    pontine myelinolysis
  • Max correction of 15mEq in 24 hours

10
DI Diabetes Insipidus
  • Definition inability to effectively conserve
    urinary water
  • Central ADH not made or not released in the
    hypothalamic-pituitary axis
  • Nephrogenic ADH is released but not detected by
    the receptors in the kidney collecting ducts,
    often a sex-linked recessive condition, also due
    to renal pathology, electrolyte disorders, drugs

11
Central DI causes
  • Head trauma
  • Brain neoplasms
  • Congenital CNS defects
  • CNS infections
  • CNS hypoxia
  • ADH secretion also decreased by certain drugs
    EtOh, demerol, MSO4, dilantin, barbiturates,
    glucocorticoids

12
DI
  • Make sure distinguish DI from conditions in which
    the presence of non-absorbable, osmotically
    active solutes in the renal tubules prevent water
    re-absorption.
  • Example glucose loss in the urine of diabetics
    will decrease the tubule- medullary concentration
    gradient and even though ADH is there, water
    wont get passively reabsorbed

13
Central DI signs/symptoms
  • Polyuria
  • Dehydration, may not be readily apparent b/c of
    hyper-osmolarity, fluid shifts from cells to
    intravascular spaces and maintains blood
    pressure, CVP
  • Weight loss is a better measure of fluid status

14
Central DI Lab values
  • Hypernatremia, Na gt150-160
  • High serum osmolality (normal 270)
  • Urine Na lt 20 mmol/L
  • Low urine osmolality (very dilute urine)

15
Central DI treatment
  • Increase po or IV free H20 consumption, use
    hypotonic saline
  • Volume replacement cc for cc
  • Vasopressin/ ADH administration (bolus or drip
    1.5-2.5 mU/kg/hr)
  • Of course, treat underlying cause

16
Cerebral Salt Wasting
  • Causes CNS damage
  • Closed head injury
  • CNS surgery
  • CNS tumors
  • CNS infections, meningitis

17
Cerebral Salt Wasting
  • Signs/symptoms
  • Polyuria
  • Wt loss
  • Dehydration/hypovolemia
  • Hypotension
  • Low CVP

18
Cerebral Salt Wasting
  • Lab values
  • Hyponatremia due to excessive renal Na loss
  • High urine Na, gt 20 mmol/L
  • Increased plasma ANP, atrial natriuretic peptide,
    b/c of low volume status
  • Inappropriately normal or low aldosterone and ADH
    levels despite high ANP

19
Cerebral Salt Wasting
  • Treatment
  • Volume for volume replacement of urine Na losses
  • When dcd from hospital, most will still need
    oral Na supplementation for a period of time

20
DI SIADH CSW
Urine Output polyuric decreased polyuric
Serum Na high low low
Urine Na low high high
Serum osm high low Can be low or normal
Urine osm low high Can be low or normal
CVP Can be normal or low high low
Write a Comment
User Comments (0)
About PowerShow.com