7. Elektrolit Dan Keseimbangan Metabolik

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Electrolyte Imbalance

Management

Syafruddin Gaus

Dept. of Anesthesiology, Intensive Care and Pain ManagementFaculty of Medicine Hasanuddin University


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Introduction

Common in critically ill & injured emergencypatients

Alter physiologic function and contribute tomorbidity & mortality

The most common electrolytedisturbance in emergency patients are:disturbance in K and Na levels


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Objectives

Review causes and clinical manifestations

of electrolyte disturbances

Outline emergent management of

electrolyte disturbances


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Principles of Electrolyte Disturbances

Management

Implies an underlying disease process.

Treat the electrolyte change, but seek the

cause.

Clinical manifestations usually not specific

to a particular electrolyte change, e.g.,

seizures, arrhythmias.


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Principles of Electrolyte Disturbances

Management

Clinical manifestations determine urgency

of treatment, not laboratory values

Speed and magnitude of correctiondependent on clinical circumstances

Frequent reassessment of electrolytes

required


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MONITORING OF FLUID &ELECTROLYTE THERAPY

Serum electrolytes do not need to be measured pre-operativelyin healthy children prior to elective surgery where IV fluids areto be given.

Serum electrolytes need to be measured pre-operatively in allchildren presenting for elective or emergency surgery who

require IV fluid to be administered prior to surgery. Serum electrolytes should be measured every 24 hours in all

children on IV fluids or more frequently if abnormal.

Children should be weighed prior to fluids being prescribedand given.

Although ideally children should be weighed daily while on IVfluids, practically this is difficult in older children, or those whohave undergone major surgery. Use of a fluid input/outputchart will help with fluid management.

Association of Pediatric Anesthetists Consensus Guideline on Perioperative FluidManagement in Children, September 2007.


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Electrolyte Disturbances

Potassium: hypo- & hyperkalemia

Sodium : hypo- & hypernatremia

Others:

Calcium : hypo- & hypercalcemia

Phosphate : hypo- & hyperphosphatemia

Magnesium : hypo- & hypermagnesemia


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Potassium (K)

The main intracellular cation.

Normal serum concentration: 3.5 - 5 mEq/L.

Concentration in cell is maintained by the

membrane sodium-potassium adenosinetriphosphate (Na+, K+-ATPase) pump.

Essential for maintenance of the electricalmembrane potential.

Alteration of K primarily effect the CV,neuromuscular, and GI systems, effect onmyocardial cells are the most prominentand severe.


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Hypokalemia

Plasma [K+] < 3.5 mEq/L (< 3.5 mmol/L)

Can occur as a result from:

1.increased K loss (renal or extrarenallosses)

2.intercompartmental shift / transcellularshift of K

3.inadequate or decreased K intake


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Disorders of Potassium Balance

HYPOKALEMIA

- Inadequate intake- GI losses: vomiting, diarrhea, continuous gastric aspiration, removal

of GI contents

- Renal losses: diuretics, steroids, renal tubular acidosis

- Bartters syndrome

Causes of hypokalemia


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The consequences of hypokalemia are

related to the effects on muscle cells:

- Abdominal distention & diminished bowel

motility

- Cardiac effect much greater concern

Clinical manifestation:


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Mosby items and derived items 2005, 2002 by Mosby, Inc.

Symptoms of hypokalemia.


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Hypokalemia

ECG may be a better measure of serious

imbalance than the serum [K]

ECG changes:

- Depressed ST segment

- Flattened T wave

- Higher U wave


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Due to delayed ventricular repolarization: T wave flattening and inversion

Prominent U wave

ST segment depression

Increased P wave amplitude

Prolongation of the PR interval


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Treatment (1)

Stop offending drugs (if possible)

Correct other electrolyte disturbances

Correct alkalosis

Treatment is aimed:

Correcting the underlying cause

Administering potassium


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Treatment (2)

K replacement

KCl should given very slowly (over 1 h):

< 0.5 mEq/kg/hr

Rapid IV administration may cause fatal

arrhythmias and cardiac arrest may

result

Ford DM. Fluid, Electrolyte, and Acid-Base Disorders and Therapy. In: Current Pediatric Diagnosis

& Treatment, 18th Ed.


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Lund GJ. Fluid and electrolyte. The Harriet Lane Handbook. 8th Ed, 2009

K+ deficit (mEq/L) =

fluid deficit (L) x proportion from ICF x K+

concentration (mEq/L) in ICF


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Monitoring

Continuous ECG monitoring is necessa-

ry (during parenteral administration of

high concentration of KCl)

Serum K levels must be monitored at

frequent interval during repletion (every

4-6 hrs during initial replacement until

correction is achieved)


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Hyperkalemia

Serum K level > 6.5 mEq/L (> 6.5 mmol/L)

Most often results from renal dysfunction

Occurs in approximately 50% of infantwhose birth weight < 1000 g and

especially common in infant with low urine

output in the first hours of life


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Disorders of Potassium Balance

HYPERKALEMIA

- Excessive intake

- Impaired excretion: renal failure, congenital adrenal hyperplasia

- Movement of potassium out of cells: catabolic states, acidosis of

any origin


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Clinical manifestation

Heart:

arrhythmias (heart block, bradycardia, dimi-

nished conduction and contraction)

ECG abnormalities (diffuse peaked T waves,

PR prolongation, QRS widening, diminished P

waves, sine waves)

Muscle: muscle weakness, paralysis, pares-thesias, and hypoactive reflexes


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ECG change:

Peaked T-wave Widening of QRS complex PR prolongation Loss of P wave Loss of R wave amplitude ST depression (occationally elevation) Sine wave Ventricular fibrillation and asystole


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Treatment (1)

Recognition & treatment of underlying diseases

Removal of offending drugs (digoxin, propanolol,phenyllephrine)

Limitation of potassium intake

Correction of acidemia or electrolyte abnorma-lities

Any serum potassium level > 6 mEq/L should beaddressed, but the urgency of treatment

depends on clinical manifestation The presence of ECG changes mandates

immediate therapy


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Treatment (2)

Several temporary measures can be taken:

- to antagonize the effect of hyperkalemia on the

myocardium: 10% calcium gluconate (0.5-1ml/kg, IV, over 5-10 min, if ECG changes persistmay be repeated after 5 min)

- to raise the blood pH and increase K influx into

cells: Na bicarbonate (1-2 mEq/kg, IV)


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Treatment (3)

- to try to increase cellular uptake of K:

* 2-agonists: albuterol or salbutamol (aerosol) 10-

20 mg

* infusion of glucose and insulin (0.5-1 g/kg glucose

and 4 g of glucose to 1 IU of insulin) over 2 h

with monitoring of the serum glucose level every

15 min

- to increase renal excretion: Furosemide (1-2 mg/kg,

IV)- to increase intestinal excretion: a potassium-binding

resin, Kayexalate (1 g/kg, by rectum or by mouth)


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Treatment (4)

Refractory hyperkalemia:If the serum [K] continues to rise and exceeds 8

mEq/L:

- Peritoneal dialysis, or hemofiltration and

hemodialysis

- Exchange blood transfusion (to avoid a high

blood K level):

* Mixture of washed red blood cells (RBCs) &

* Fresh-frozen plasma


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Monitoring

Should be monitored duringevaluation and treatment:

Repeat serum K levels (every 1-2 h)

Continuous cardiac monitoring

and serial ECG tracings


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Sodium

The main extracellular ion

Normal serum [Na] 130 150 mEq/L

More than 90% of the total amount ofsolutes in the extracellular space

Absorbed in both the small intestine and

the colon, large amount is absorbed in

the jejenum


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Sodium

Primary functions:

determinant of osmolality in the body involved in the regulation of extracellular

volume

Abnormalities in circulating Na primarily

effect neuronal and neuromuscularfunction.


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Hyponatremia

A serum Na level < 130 mEq/L Caused by retention of water relative to Na

When the serum Na concentration decrease serum osmolality decline, water moves into cells

increased water content in the brain causesthe signs and symptoms of hyponatremia:

- vomiting

- lethargy

- apnea- seizures & coma

(if serum Na concentration < 115 mEq/L)


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Disorders of Sodium Balance

HYPONATREMIA

Early:

- Perinatal asphyxia

- RDS

- Diuretics

- Nebulization associated with nasal continuous positve airway pressure

- Hypotonic fluid administered to mother during labor

Late:

- Very low birth weight infant fed human milk or standard formula- With overhydration: CHF, renal failure

- With dehydration: adrenal insufficiency, vomiting, diarrhea, peritonitis


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CNS: disorientation, decreased mentation,

irritability, seizures, lethargy, coma,

nausea and vomiting

Muscle: weakness & CNS-driven

respiratory arrest


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Treatment (1)

Treating the underlying disease

Removing offending drugs

Improving the circulating Na level


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Treatment (2)

The amount of Na needed to correct a low

serum Na level can be calculated according to

the standard formula:

Na to be given (mEq/L) = 0.6 x weight (kg) x(desired serum Na - actual serum Na)

Target serum Na concentration: 135 mEq/L.

Usually is made over several hours.


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Treatment (3)

Shock is present or impending:- Normal saline IV 10-20 ml/kg over 20-30 minute,

repeated until BP is normal

Symptomatic hyponatremia (almost always occurs onlywhen the serum Na level < 115 mEq/L):

- Hypertonic saline IV.- Initial correction: lower than normal serum Na

concentration (120-125 mEq/L).

- An abrupt or a large increase in osmolality carries the

risk of intracranial hemorrhage and CHF. Asymptomatic hyponatremia:

- Hypertonic saline is used if serum Na is < 120 mEq/L

to prevent symptoms


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Example:

A 10-kg child is lethargic and found to

have a plasma [Na+] of 110 mEq/L. How muchNaCl must be given to raise her plasma [Na+] to

130 mEq/L?


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[Na+] to be given = TBW x (130-110)

TBW is approximately 60% of body weight in

children:[Na+] to be given = 10 x 0.6 x (130-110)

= 120 mEq


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Normal saline contains 154 mEq/L, the patient

should receive 120 mEq : 154 mEq/L = 779

mL of normal saline.

This amount of saline should be given over 24hours (32.5 mL/h)


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Hypernatremia

Serum N level > 150 mEq/L (> 150

mmol/L)

Indicates intracellular volume depletionwith a loss of free water, which exceeds

Na loss


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Disorders of Sodium Balance

HYPERNATREMIA

With Dehydrat ion :

- Vomiting, diarrhea with inadequate fluid replecement

- Osmotic diuresis (hyperglycemia, mannitol)

- Radiant warmers

With Overhydrat ion:

- Excessive administration of sodium bicarbonate (NaHCO3)- Errors in administration of sodium chloride (NaCl)

Causes of hypernatremia


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CNS: altered mental, lethargy, seizures,

coma

Muscle function: muscle weakness


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Treatment (1)

Centers on correcting the underlying cause

of hypernatremia

Should not be corrected rapidly

Goal: decrease the serum Na by


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Example:

A 10-kg child is found to have a plasma

[Na+] of 160 mEq/L. What is his water

deficit?


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Greenbaum LA. Electrolyte and acid-base disorders. In: Textbook of Pediatrics. 18th Ed, 2007.

Water deficit (L)= body weight (kg) x 0.6(1-145/[current sodium])

Water deficit = 10 x 0.6 (1-145/[160])= 6 x (1 - 0.90625)

= 6 x 0.09375 = 0.5625 L

= 562.5 mL


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To replace this deficit over 48 hours, one

would give 5% Dextrose in water IV,

562.5 mL over 48 hours, or 11.8 mL/h


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TERIMAKASIH

7. Elektrolit Dan Keseimbangan Metabolik

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