6- treatment of water imbalance-2014

8/16/2019 6- Treatment of Water Imbalance-2014

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TREAMENT OFWATER IMBALANCE

Hala Kilany, MD


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TREATMENT OF WATER IMBALANCE

• Treatment of Hyponatremia –

Revisiting hyponatremia classification, pathophysiology, andsymptoms

–

Approach to hyponatremia treatment

– Systematic method of hyponatremia correction

–

Special topic: Treatment of SIADH

•

Treatment of Hypernatremia – Approach to hypernatremia treatment

– Systematic method of hypernatremia correction

–

Special topics: Treatment of NDI and CDI

Lecture Outline


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OVERVIEW

• [Na+]: 135 – 145 mEq/L

•

Osmolality = 2 x (Na+) = 2 x (135 - 145 mEq/L) –

Normal (Isotonic) 280 – 300

– Low (Hypotonic) < 280

–

High (Hypertonic) > 300

if not diabetic or no renal failure then the easiest way to calculate it is by

sodium


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REVISITINGHYPONATREMIA


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HYPONATREMIA

• Classify hyponatremia according to duration:

–

Acute: onset < 48 hours

– Chronic: onset > 48 hours or unknown onset

• 48 hrs is the time that the brain cells take to generate

osmotically active particles in response to the cellularswelling.

•

As a general rule, if the patient is completelyasymptomatic, the hyponatremia is most likely a chronic

one.

Classification

g. patient coming to

mergency room not

nowing when it started hen treat as chronic

yponatremia

evere


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HYPONATREMIA

• Water shift from the extracellular space intothe cells.

• Brain swelling occurs in the confined spaceof the skull

•

Signs will result in relation to 3 factors: – Severity of hyponatremia

– Rapidity of hyponatremia

– Risk factors

Pathophysiology


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•

In the setting of an acute drop in the serumosmolality, neuronal cell swelling occurs due to thewater shift from the extracellular space to the

intracellular space

•

Swelling of the brain cells elicits the following 2osmoregulatory responses:1. Inhibition of both arginine vasopressin secretion from

neurons in the hypothalamus and hypothalamic thirstcenter causing excess water elimination as dilute urine.

2. Immediate cellular adaptation with loss of electrolytes,and over the next few days, there is a more gradualloss of organic intracellular osmolytes.

HYPONATREMIAPathophysiology

1% drop in plasma osmolarity then ADH will stop from being

secreted


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brain swells bcz of hypoosmolar milieu

correction with saline

or hyperosmolar fluid

(both increase osmolarity here0

so correct it very slowly especially for chronic

hyponatremia


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HYPONATREMIARisk Factors of Cerebral Edema

due to hormones


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HYPONATREMIAClinical Features & Severity

not serious

so restrict water only


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Signs and symptoms of ecf depletion accordingto the degree of depletion

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TREATMENT OF HYPONATREMIA


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HYPONATREMIA

• 3 issues must be addressed: – Asymptomatic vs. symptomatic – Acute (onset < 48 hrs) vs. chronic (onset > 48 hours or

unknown)

–

Volume status

• 2 basic principles for treatment: – Raising plasma sodium at a safe rate

–

Treating the underlying cause

• Mainstay of treatment: –

Intravenous isotonic saline

– Need to discontinue diuretics

Approach

to prevent brain damage such as

hemolysis , it’s not immediate, takes

2-3 weeks to come with seizures and

coma

cz it can cause hyponatremia


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• Evaluate volume status by physical examination:

– HR and BP

•

Supine and after 1 min of standing to assess

orthostatic hypotension, defined as any of thefollowing:

– @%.&%)6% -> CE 22!# -& 2-&% -> 6=6,-/". :&%661&%

–

@%.&%)6% -> BE 22!# -& 2-&% "* 7")6,-/". :&%661&%

– ;*.&%)6% "* ![ )\%& &"6"*# A BD+HE (:2

– Skin turgor

– Lower extremity edema and sacral edema

HYPONATREMIAEvaluation of Volume Status

> patients is orthostatic and is

aving hypovolemia

hypervolemia

if decreased then hypo


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•

Raise plasma sodium at asafe rate:

– Raise Na by


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©2010 by Cleveland Clinic


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HYPONATREMIA

• Raising Na > Than 12 mEq/L elevation in the1st day

•

Overcorrection to > 140 mEq/L within the 1st 2 days

•

Hypoxic or anoxic episode prior to therapy

• Hypercatabolism or malnutrition due to burnsor chronic alcoholism

Risk Factors of Pontine Myelinolysis


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1.

Calculate Total Body Water (TBW)

2.

Decide the desired correction rate based onpt’s symptoms and onset of hyponatremia

3.

Estimate serum Na

+

change on the basis of Na

+

in the infusate

HYPONATREMIASystematic Method of Correction


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HYPONATREMIA

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Decide the desired correction rate based onpt’s symptoms and onset of hyponatremia

•

Symptomatic: – Immediate increase in serum Na+ by 8-10mEq/L in

4-6 hrs with hypertonic saline.

• Acute:

–

More rapid correction is possible, 8-10mEq/L in 4-8hrs.

• Chronic:

–

Slower rate of correction: < 10 mEq/L in the 1st

24hrs.


if patient is still symptomatic you still give hypertonic, when symptoms stop you slow down correction


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• If a patient is symptomatic due to rapid

decline in [Na+], hypertonic (3%) saline

should be considered: – A simple rule of thumb: Correction of 1 mEq/Lhr

using 3% saline by infusing the body weight as

mL/hr

– Example: a man with a body weight of 70 kg

will increase by almost 1meq/l/hr when infusedwith 3% saline at a rate of 70ml/hr


in order to correct 5 mEq in 5 hrs, then infuse 70 cc of 3% saline for 5 hrs


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Estimate serum Na+ change on the basis ofNa+ in the infusate:

!SNa+ = {[Na+ + K+]inf – SNa+} ÷ (TBW+1)

* !SNa+=change in serum sodium

* [Na+ + K+]inf = [Na+] and [K+] in 1 L of solution


+ 1 bcz you added 1 Liter of solution

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Composition of GI Fluids (mEq/L)

Source Daily Loss Na+ K+ Cl- HCO3-

Saliva 1000 30-80 20 70 30

Gastric 1000-2000 60-80 15 100 0

Panc 1000 140 5-10 60-90 40-100

Bile 1000 140 5-10 100 40

SB 2000-5000 140 20 100 25-50

LB 200-1500 75 30 30 0

Sweat 200-1000 20-70 5-10 40-60 0

o


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EXAMPLE: ONE

A 60 kg woman with a plasma [Na+]

=110 mEq/L: –

What is her total body water (TBW)?

– How high will 1 liter of NS raise the plasma Na+?

– If 40meq/l of K+ to the liter of NS are added, how

much will the plasma Na+ rise?


30 L TBW

154 mEq

so 1.4 increase so insignificant increase

2.7 mEq will be increased with each liter

ust by adding potassium, we have added to the

correction rate of this solution

(hyperosmolar)


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EXAMPLE: TWO

A 90 kg man with a plasmac [Na+

] of 110mEq/L: –

What is the TBW?

– How much 1 liter of 3% saline will raise the plasma

Na+?


54 L

530 mEq

7.6 mEq so this is the maximum

so we can’t give more than 1 Liter


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EXAMPLE: THREE

A 60 kg woman with a plasma sodium concentration of

120mEq/ L:

•

Correction of sodium deficit? – Sodium deficit = TBW x (130 – [Na+]p) = 0.5 x 60 x

(130-120) = 300mEq

– 3% NaCl contains 513 mEq sodium/L: Volume of 3% NaCl

needed = 300/513 = 585 mL

–

At 0.5 mEq/L/hr a correction of 10 mEq should be done

over 20 hours: 585 mL/20 hours = 29 mL/hour of 3% NaCl

here , the rate


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HYPONATREMIA

• SIADH is a cause of hyponatremia that cannot be

treated conventionally:

–

In hypovolemia, both Na+ and water are retained.

–

In SIADH, Na+

handling is intact•

Administered Na+ will be excreted in the urine. Some water will be

retained leading to worsening of hyponatremia

• Instead, water restriction is mainstay of therapy in SIADH

Exception to the Rule: Treatment of SIADH

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EXAMPLE: FOUR

•

85 year old male with weakness andheadache: – Serum [Na+ ] = 118meq/l

–

Plasma Osmolality = 236mosm/kg – Urine Osmolality = 450mosm/kg

– Urine Na+ = 54meq/l

– Uric acid = 3mg/dl

1. What is the cause of hyponatremia?

2. How to correct hyponatremia?

IADH

++++++

the only thing that differs

high urine sodium and high urine osmolality and low uric acid

lead to SIADH not hypovolemia

SYMPTOMATIC !

so symptomatic, hypertonic 3% saline

to correct the symptoms until symptoms

stop and then slow down to correct

it completely

we can use loop diuretics too


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TREATMENT OF HYPERNATREMIA


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HYPERNATREMIA

• General principles:

–

Rapid correction can induce cerebral edema,

seizures, permanent neurologic damage, and

death.

–

Correct slowly, not exceeding 12mEq/L per day

Approach


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HYPERNATREMIA

• Most cases of hypernatremia are due to

water deficit

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Systematic Method of Correction

bcz we have free water excretion, we have to calculate the free water deficit


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HYPERNATREMIA

• Thiazide diuretics

• Amiloride in lithium-induced NDI

–

Amiloride inhibits entry of lithium to collecting

tubules through Na+ channels

–

Increased Li+ absorption proximally

•

Low protein and low sodium diet

Treatment of Nephrogenic Diabetes Insipidus (NDI)

deplete a little bit the patient

it will block it distally and not

roximally at the level of

salt channels (sodium)


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HYPERNATREMIA

• Vasopressin by nasal insufflation or oral form

• Thiazide diuretic: Less helpful than in NDI

•

Loop diuretics should not be used

Treatment of Central Diabetes Insipidus (CDI)

bcz dilute the urine and lose

a lot of free water

6- treatment of water imbalance-2014

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