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Knocking Out the Boards > Sodium > Flashcards

Sodium Flashcards

1
Q

Hypernatremia results in _____ fluid volume contraction

A

Intracellular

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2
Q

What is the appropriate response to Hypernatremia in an awake, otherwise normal patient?

A

Increased H20 intake stimulated by thirst

Excretion of minimal volume due to ADH secretion in result of osmotic stimulus

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3
Q

Causes of hypernatremia: 5

A
  1. Inadequate intake of fluids
  2. Poor intake
  3. Renal losses of hypotonic fluid
  4. Extrarenal-nonrenal loss of water
  5. Primary sodium gain
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4
Q

Lack of thirst is due to: and falls under which cause of hypernatremia?

A

damage to hypothalamus-tumors, vascular occlusion and granulomatous disease. Falls under inadequate intake of fluids. (Primary hypodipsia)

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5
Q

How do drugs and osmotic diuresis play a part in hypernatremia?

A

drug induced-diuretics can cause iso-osmotic solute diuresis

Osmotic diuresis: most common cause of H20 loss-glycosuria, mannitol

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6
Q

Diabetes insipidus-what are the two types (And how can you get them), and what does this do to sodium?

A

Central: impaired ADH secretion 2/2 destruction of the neurohypophysis. Can be idiopathic, post surgical (pituitary surgery), post traumatic (basal skull fracture, severe head injury), space occupying sellar lesions, Inflammatory (encephalitis, GBS)

Nephrogenic: End organ kidney resistance to ADH
Inherited (congenital, mutation)
Acquired-myeloma, drugs (lithium, glyburide, amphotericin B, demeclocycline), electrolytes-hypercalcemia, ADH released by the placenta

All of this can cause hypernatremia

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7
Q

What kinds of water loss can you have from the GI tract-leading to hypernatremia?

A

Osmotic diarrhea (lactulose, sorbitol, malabsorption of carbs)
Viral gastroenteritis-results in greater water loss than Na loss
Nasogastric drainage, enterocutaneous fistula

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8
Q

Primary Na+ gain is defined by: ____ . How does this happen?

A

Urine sodium greater than 800 mEq/L
This can happen via administration of hypertonic NaCl or NahCO3-, TPN, ingestion of Nacl or seawater, hypertonic enemas or dialysis

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9
Q

How much sodium does 3% NaCl contain? what about bicarb?

A

3% NaCl: 513 mEq sodium per liter

7.5% sodium bicarb in a 50 mL ampule: 44.5 mEq sodium

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10
Q

Clinical features of hypernatremia:

A

AMS, lethargy, confusion, irritability

Advanced: coma, seizures, intracranial bleeding due to rupture of cerebral veins as a result of brain shrinkage

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11
Q

What are signs of hypervolemic hypernatremia?

A 
Pleural effusion 
Ascites 
Peripheral edema 
Heart failure
Thirst or polyuria
Neuromuscular irritability-myoclonus, tremor/rigidity
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12
Q

As for dx of hypernatremia-wht are you looking for first:

Then, what do you want to measure

A

H&P
List of current meds
mental and neurologic exam
Determine if they are hypervolemic, isovolemic, or hypovolemic. Look for signs and symptoms (thirst, diarrhea, vomiting)

Then, measure urine osmolality, sodium concentration,

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13
Q

What is the normal response when plasma osmolality gets above 295?

A

secrete ADH to concentrate urine and activate thirst mechanism

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14
Q

So, with intact ADH secretion and renal function, Uosm will be _____. Will further increases in urine osmolality be seen with additional ADH administration?

A

intact-Uosm 700-800, and no more ADH will not increase urine osmolality

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15
Q

So, what are causes of hypernatremia when uosm is 700-800?

A

Unreplaced insensible losses (urine sodium should be less than 25
GI losses: urine sodium should be less than 25
Sodium overload: urine sodium greater than 100 with that f

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16
Q

Causes of hypernatremia when Uosm is less than plasma osmolality?
How to test this?

A

Consider DI
Administer ADH to distinguish between nephrogenic and central. If nephrogenic-little or no response to ADH
If central: appropriate increase in Uosm by greater than 50%

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17
Q

So, how can you treat hypernatremia with hypervolemia?

A

Diuretics and HD may be necessary to lessen symptoms

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18
Q

How do you calculate the free water deficit in liters of water? How does that differ for females?
Goal Na?
How to replace the free H20 deficit?
What do you use to replace the free water deficit?
How often do you monitor serum sodium?

A

{(plasma Na/140) - 1} x kg x 0.6 in males (0.5 in females)
Goal Na should be less than or equal to 145
Replace half of the free water deficit in first 24 hours, and remainder over 2-3 days.
Use 5% dextrose in water or 0.45% NaCl to correct the deficit
Monitor serum sodium every 1-2 hours to ensure a gradual correction.

19
Q

The rate of Na correction should not exceed:

And if it goes too fast, then what?

A

should not exceed 0.5 mEq/L per hour or 10-12 mEq/day

If too rapidly corrected, it could cause cerebral edema, seizures, and irreversible neurologic damage or death

20
Q

KIM that other reasons for hypernatremia can be mental/social such as:

A

poor access to H20, poor intake due to mental conditions, dependency on others (Nursing home)

21
Q

When taking care of a patient with hypernatremia, you want to verify what first?
Then what?
Elective vs emergent

A

Verify cause of hypernatremia by obtaining urine sodium and urine osmolality.
Then treat hypernatremia acutely-if low BP, restore BP by giving fluid replacement with 0.9% NaCL, once BP stable-address water deficit.
If case is elective-delay until Na levels are near normal. Miller recs: Na less than 150 prior to anesthesia

22
Q

Intraoperataive in a pt with hypernatremia (emergent case)
Monitors? Type of anesthetic? Meds and considerations for induction?
Plan for anesthetic?

A

Intraop: Standard ASA monitors
Arterial line (can help with frequent monitoring)
IV access: consider central line if not-then big peripheral
Regional can be considered in cases where the patient is appropriate (not mentally challenged) and can give you a better idea of mental status
Consider etomidate over propofol due to the fact that some of these hypernatremic patients are volume depleted. Consider RSI if mental status due to hypernatremia puts them at risk for aspiration.
Plan for anesthetic: short acting narcotics like remifentanil in order to lessen residual anesthesia and check out baseline mental status

23
Q

Postoperatively, what are your concerns for hyprnaremic patient:

A

ICU admission in order to have frequent monitoring of serum sodium q 1-2 hours
Investigate cause of hypernatremia-such as lack of care in facilities.

24
Q

Definition of hyponatremia: And it is commonly caused by cellular ___

A

Sodium under 135

edema with the presence of hypotonicity

25
Q

Causes of hypovolemic hyponatremia: (NON renal) 4 types

A

Nonrenal: GI losses (vomiting, diarrhea, bowel obstruction)
Integumentary losses: excessive sweating, burns
Third spacing: ascites, peritonitis
Cerebral salt wasting syndrome: (due to TBI, SAH, intracranial surgery

26
Q

So what exactly is CSW and how do you treat it? What is SIADH, and how is it treated?

A

erebral salt-wasting syndrome is characterized by the triad of hyponatremia, volume contraction, and high urine sodium concentrations (>50 mmol/L). The distinction between this syndrome and SIADH is important

27
Q

Causes of hypovolemic hyponatremia (renal)

A

Diuretics
Osmotic diuresis
hypoaldosteronism
Acute and chronic renal failure

28
Q

Euvolemic hyponatremia: what does it mean, and name some causes: (5)

A

Normal Na+ stores and total body excess of free water
Polydipsia (psychogenic, MDMA)
Administration of hypotonic fluids
Infants given too much water
Beer potomania: poor dietary protein and electrolytes consume large volumes of beer exceeding renal excretory capacity, resulting in hyponatremia

29
Q

Causes of SIADH: 4

A

Neuro: head injury, SAH, neurosurgery
Malignant tumors: pancreatic cancer
Major surgery: severe post op pain and nausea stimulate ADH secretion
Drugs-TCAs, SSRIs

30
Q

Classification of SIADH:

A

Ectopic product
Normal regulation of ADH around lower osmolality set point (cachexia, malnutrition)
Normal ADH response to hypertonicity with failure to suppress
Normal ADH secretion with increased sensitivity to its actions (rare)

31
Q

Hypervolemic hyponatremia: Name some causes: (Renal, Non-renal, electrolyte stuff, Pseudo, endocrine)

A

Total body Na+ increases, but total body water increases to a greater extent
Causes: acute/chronic renal failure
Heart failure *
Hepatic cirrhosis *
Nephrotic syndrome *
* All three of these cause a decreased effective circulating arterial volume leading to increased thirst and ADH levels
Redistributive: Water shifts from intracellular to extracellular compartments (hyperglycemia)
Pseudo: Normal plasma osmolality, aqueous phase diluted by excess protein lipids; total body water and Na+unchanged (HLD, hyperproteinemia, glycine solutions s/p TURP)
Endocrine: Adrenal insufficiency: Cortisol deficiency leads to hyper secretion of ADH
Hypothyroidism-Decreased Na due to resulting decrease in Cardiac output and GFR and increased ADH secretion in response to hemodynamic stimuli.

32
Q

Symptoms of hyponatremia: What does their severity depend on? What can happen to the brain?

A

primarily neurologic and severity is dependent on rapidity o serum Na loss
Brain can swell, or you can have cerebral edema

33
Q

numbers for asymptomatic hyponatremia:
120-125
110-120
Less than 110:

A

Over 125, or chronic over 115 (asymptomatic)
120-125: Anorexia, nausea, malaise
110-120: HA, lethargy, confusion, agitation, obtundation
Less than 110: stupor, seizures, coma

34
Q

Once hyponatremia is determined, then which lab tests do you want to get?

A

Plasma osmolality
Urine osmolality
Urine Na concentration
FeNA if you’re concerned about renal failure
TSH if you’re concerned about thyroid issues

35
Q

What is the FeNA? What do values below 1% mean? Values above 2%?

A

It is essentially a measure of how well the kidney tubules are able to perform their resorptive functions. If the FENA, is low, it indicates both that the kidneys are functionally capable of reabsorbing sodium, and also that there is a physiologic stimulus to conserve sodium (i.e. hypovolemia). If the FENA, is high, it indicates an intrinsic problem with the kidneys themselves, such as ATN, because they are unable to reabsorb sodium.

FENA of < 1% correlates with a hypovolemic, or “pre-renal” state, and one in which the kidney function will increase via volume resuscitation. Values above 2% correlate with intrinsic damage to the kidneys, such as acute tubular necrosis. The above rule is less accurate in the setting of diuretic use, FENA values near 1, or in patients with advanced stable chronic renal failure.

36
Q

Treatment of hyponatremia: isotonic, hypertonic, hypotonic:

A

isotonic tx: fix hyperlipidemia and paraproteinemia

hypertonic: correct hyperglycemia
hypotonic: (all other types) focus on raising ECF tonicity so that water will shift out of intracellular space

37
Q

What is CPM

A

Central pontine myelinosis: osmotic demyelination syndrome associated with irreversible neurologic deficits which develop 2-6 days after treatment: dysphagia, coma, quadriplegia

38
Q

How to fix hypotonic hyponatremia:

A

Correct with hypertonic saline
10 mEq/L in first 24 hours
20 mEq/L in first 48 hours

39
Q

How do you calculate the amount of sodium to be administered in hyponatremia?

A

Multiply the target change in serum sodium by patient’s TBW
TBW= kg x 0.6
To change the serum Na in first 24 hours by an equivalent of 10 mEq/L in a 70 kg male: 10 x 42= 420
(0.6 x70=42)
3% saline has Na+ concentration of 513 mEq/L, so 420/513=0.82 L which should be given in the first 24 hours

40
Q

Things to consider intraoperatively with hyponatremia:

A 
Prior to going to OR, peripheral access
central access, 
CXR to rule out pulmonary edema 
Arterial catheter for frequent monitoring 
check for ecstasy 
consider central access 
consider RSI due to lots of water drinking 
Intubated due to mental status changes.

Always consider these with hyponatremia

41
Q

Things to consider postoperatively with hyponatremia:

A

ICU admission

leave patient intubated if there were concerns about mental status

42
Q

Treatment of Central DI:

A

Desmopressin IV: 2-4 mcg 1-2 times per day
Nasal spray: 10-40 mcg (1-2 times per day)
Low Na diet (don’t have any ADH )
low dose thiazide diuretic
Carbamazepine: enhances vasopressin secretion

43
Q

Treatment of Nehrogenic DI:

A

Thiazide diuretic-reduces urine flow by inhibiting distal tubule sodium reabsorption
Vasopressin and its analogs have no role in tx of nephrogenic DI

Knocking Out the Boards (94 decks)

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