Management of Hyponatremia
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Transcript of Management of Hyponatremia
Evolving Strategies for Hyponatremia
Management in the ICU
Mazen Kherallah, MD, FCCP Infectious Disease & Critical Care Medicine
Assistant Professor, University of North Dakota
Critical Care Patients at Increased Risk of
Hyponatremia*
Increased age1
Up to 30% of patients with subarachnoid hemorrhage2
Up to 30% of ICU patients3
Over 30% of AIDS patients4
Postoperative patients
– 25%-35% of pituitary surgery for tumor resection5
~30% of acute spinal cord injury6
Psychiatric inpatients: 6%-17%7
*Data not exclusive to patients with euvolemic hyponatremia.
1. Hawkins RC. Clin Chim Acta. 2003;337:169-172; 2. Mayer SA. The Neurologist. 1995;1:71-85;
3. DeVita MV et al. Clin Nephrol. 1990;34:163-166; 4. Tang WW et al. Am J Med. 1993;94:169-174;
5. Bhardwaj A. Ann Neurol. 2006;59:229-236; 6. Peruzzi WT et al. Crit Care Med. 1994;22:252-258;
7. Siegler EL et al. Arch Intern Med. 1995;155:953-957.
Mortality Related to Hyponatremia Among
Hospitalized Patients
0%
5%
10%
15%
20%
25%
Anderson1 Terzian2 Tierney3
[Na+] <130 mEq/L Normonatremia
1. Anderson RJ et al. An Intern Med. 1995,102: 164-168
2. Terzian C et al. J Gen Intern Md. 1994,9:89-91
3. Tierney WM et al. J Gen Intern Med. 1986;1: 380-385
Morbidities in Hospitalized Patients with
Symptomatic Hyponatremia
Altered
Sensorium
Seizures
Nausea &
Vomiting Gait Disturbance
& Falls Dysarthria Coma
0%
10%
20%
30%
40%
50%
60%
• Single center, retrospective over 4 years (1997-2001)
• 168 patients with serum [Na+] <115 mEq/L
• Symptoms of hyponatremic encephalopathy in 89 of 168 patient (53%)
• No documented symptoms in 79 of 168 patients (47%)
Nzenue CM et al. J Natl Med Assoc. 2003;95: 335-343
Mechanisms of Hyponatremia
↓[Na+]=𝑁𝑎
↑𝐻2𝑂 ↓[Na+]=
↓𝑁𝑎
𝐻2𝑂
Brain CT Scan: Cerebral Edema
Normal CT Scan Fatal Hyponatremia
Case I
44 year old man with schizophrenia is brought to the ED from his group home after
a witnessed tonic-clonic generalized seizure.
He was well until earlier in the day at which time he became progressively
somnolent.
His medications include haloperidol, quetiapine and citalopram.
On exam he is afebrile, BP 120/78, HR 92. He is somnolent but arousable and
following commands, is euvolemic, and there are no focal findings.
His urine output is 120 ml/hour
Serum Urine
Na 116 mEq/L Na 35 mEq/L
K 3.9 mEq/L K 15 mEq/L
Creat 0.8 mg/dL Osm 92 mOsm/kg
Osm 240 mOsm/kg
Question
What is the most likely etiology of this man’s
hyponatremia?
a) Syndrome of inappropriate antidiuresis
b) Psychogenic polydipsia
c) Pseudohyponatremia
d) Adrenal insufficiency
e) Cerebral sat wasting
The Diagnosis of Hyponatremia: Three Critical Questions
Is it real? Is water excretion
appropriate? Is ADH excretion “appropriate”?
Assessment of Hyponatremia: Three Critical Questions
Hypovolemia Appropriate ADH Secretion
Euvolemia Inappropriate ADH
Hypervolemia Maladaptive ADH Secretion
Total body water ↓
Total body Na+ ↓↓
Total body water ↑
Total body Na+ ↔
Total body water ↑↑
Total body Na+↑
U[Na+] >20 mEq/L U[Na+] <20 mEq/L U[Na+] >20 mEq/L U[Na+] >20 mEq/L U[Na+] 20 <mEq/L
Renal Losses
Diuretic excess
Mineralocorticoid
deficiency
Bicarbonaturia with
tubal acidosis and
metabolic alkalosis
Ketonuria
Osmotic diuresis
Extrarenal losses
Vomiting
Diarrhea
Third spacing of
fluids
Burns
Pancreatitis
Trauma
Glucocorticoid deficiency
Hypothyroidism
Syndrome of inappropriate
ADH secretion
Acute or chronic
renal failure
Nephrotic syndrome
Cirrhosis
Cardiac failure
1. Is it real? Plasma Osmolality Normal or High Pseudohyponatremia
Hyperglycemia
Azotemia, ETOH Intoxication
Low
2. Is water excretion appropriate? Urine Osmolality Low
(< 100 mOsm/kg) Psychogenic polydipsia
High (>100 mOsm/kg)
3. Is ADH secretion appropriate? (Volume Status)
240 mOsm/kg
92 mOsm/kg
Case II
46-year-old woman admitted to
Neurocritical Care Unit confused and
mildly lethargic secondary to subarachnoid
hemorrhage
Past medical history: hypertension, tobacco
smoker
BP 170/78 mm Hg, HR 71 bpm
0.9% saline administered at 100 mL/h
CVP 6-8 mm Hg
Mildly positive fluid balance
Remained confused and disoriented, but
lethargy gradually resolved
In the Step-Down Unit
Day 9 post-SAH
Patient transferred to step-down unit
Central venous IV catheter discontinued
IV fluid: normal saline administered at 100 mL/h through peripheral IV
Day 10 post-SAH
The patient appeared to be more confused
Serum [Na+] = 126 mEq/L
Serum Urine
Na 126 mEq/L Na 45 mEq/L
K 3.6 mEq/L K 17 mEq/L
Creat 0.7 mg/dL Osm 292 mOsm/kg
Osm 258 mOsm/kg
Question
What is the most likely etiology of this patient’s
hyponatremia?
a) SIADH
b) Psychogenic polydipsia
c) Pseudohyponatremia
d) Adrenal insufficiency
e) Cerebral sat wasting
Assessment of Hyponatremia: Three Critical Questions
Hypovolemia Appropriate ADH Secretion
Euvolemia Inappropriate ADH
Hypervolemia Maladaptive ADH Secretion
Total body water ↓
Total body Na+ ↓↓
Total body water ↑
Total body Na+ ↔
Total body water ↑↑
Total body Na+↑
U[Na+] >20 mEq/L U[Na+] <20 mEq/L U[Na+] >20 mEq/L U[Na+] >20 mEq/L U[Na+] 20 <mEq/L
Renal Losses
Diuretic excess
Mineralocorticoid
deficiency
Bicarbonaturia with
tubal acidosis and
metabolic alkalosis
Ketonuria
Osmotic diuresis
Extrarenal losses
Vomiting
Diarrhea
Third spacing of
fluids
Burns
Pancreatitis
Trauma
Glucocorticoid deficiency
Hypothyroidism
Syndrome of inappropriate
ADH secretion
Acute or chronic
renal failure
Nephrotic syndrome
Cirrhosis
Cardiac failure
1. Is it real? Plasma Osmolality Normal or High Pseudohyponatremia
Hyperglycemia
Azotemia, ETOH Intoxication
Low
2. Is water excretion appropriate? Urine Osmolality Low
(< 100 mOsm/kg) Psychogenic polydipsia
High (>100 mOsm/kg)
3. Is ADH secretion appropriate? (Volume Status)
258 mOsm/kg
292 mOsm/kg
Question
How would you treat this patient?
a) Fluid restriction (<2 L/d)
b) Salt tablets (NaCl 2 g/d)
c) Normal saline infusion
d) 3% hypertonic saline
e) IV Conivaptan
Treatment Considerations
• Often unknown
• >2 days
• Acute reduction in chronic state
• More brain adaptation with chronic
Acute or Chronic
• Mild: >129
• Moderate: 121-129
• Severe <120
Severity of Hyponatremia
• Severe Symptoms or Intracranial Pathology: seizures, impaired mental status or coma
• Moderate: confusion, lethargy,
• Mild: fatigue, nausea, dizziness, gait disturbances, forgetfulness nd muscle cramps
• Asymptomatic
Severity of Symptoms
• Treat cerebral edema
• Relieve symptoms and prevent progression of neurologic dysfunction
• Prevent osmotic demyelination syndrome
• 4-6 meq/24 hrs (<9 meq/L in any 24 hrs)
Treatment Goals
Treatment Strategies
• Treat pain, nausea, vomiting,..
• cessation of therapy with certain drugs
• glucocorticoids to patients with adrenal insufficiency
Treat Underlying Cause
• Saline to patients with true volume depletion
• Diuretics in edematous states (such as heart failure and cirrhosis)
Restoration of Euvolemia
•Fluid restriction in SIADH
Balancing the Effect of ADH
• Hypertonic saline
• Normal saline
• Salt tablets
Correction of Na and Rate of Correction
Sodium deficit= TBW (desired SNa-actual SNa)
Increase in SNa= (infusate [Na]-SNa) ÷ (TBW+1)
Treatment Options
• (NS in hypovolemia)
• Fluid restriction (<UO or <800 ml/day)
• Salt tablets
• V2 receptors antagonists
• (NS in hypovolemia)
• Hypertonic saline
• Increase Na 0.5-1 meq/hour in the first 4 hours
• 4-6 meq in 24 hours
• Hypertonic saline
• Increase Na 0.5-1 meq/hour in the first 4 hours
• 4-6 meq in 24 hours (<9 meqin any 24 hours)
• Rapid increase in Na 4-6 meq/L (in 6 hours)
• 3% saline 100 mL IV bolus
• Repeat 1-2 X at 10 minutes intervals if symptoms persist
• ≤ 9 meq/L in 24 hours Severe
Symptoms: Seizure or
coma
Moderate Symptoms: Confusion
and/or lethargy
Mild or abscent
symptoms: Na > 120 meq/L
Mild or abscent
symptoms: Na ≤120 meq/L
Treatment Course for This Patient
A 20 mg loading dose of conivaptan followed by a continuous infusion of 20 mg/d
24 hour after the start of the loading dose, the serum [Na+]
increased from 126 to 132
A second 24 hour contineous infusion given
SAH
Day
Serum [Na+]
(mEq/L)
24 Hour Fluid
Balance (L)
Conivaptan
Treatment Day
10 126 +0.2 1
11 132 -0.8 2
12 138 -1.2 3
Day 2 of Treatment
The next day serum [Na+] increased from 132 to138 mEq/L
Mental status: less confused
Conivaptan discontinued
Patient discharged to rehabilitation on SAH Day 13
Receptor-Mediated Effects of VAP
Receptor Subtype Site of Action Activation Effects
V1a Vascular smooth muscle
cells
Platelets
Lymphocytes and
monocytes
Adrenal cortex
Vasoconstriction
Platelet aggregation
Coagulation factor release
Glyconeogenesis
V1b Anterior pituitary ACTH and ß-endorphin
release
V2 Renal collecting duct
principal cells
Free water absorption
Lee CR et al. AM Heart J. 2003;143:9-18
Hyponatremia in Acute Brain Injury
Therapeutic Options
Speed Situation Pluses Minuses
Free water
restriction
Slow Hard to
regulate
NS+furosemide Sow Electrolyte
depletion
Fludrocortisone Slow Fluid overload
AVP Inhibitor Faster Asymptomatic
hyponatremia
Reliable effect Infusion site
reactions
Mannitol Fatsest Symptomatic
hyponatremia
Reduce
Edema
Can worsen
hypovolemia
Electrolyte
depletion
Hypertonic
saline
Fastest Symptomatic
hyponatremia
Reduce brain
edema
Fluid overload
Thank you