Fluid & Electrolytes

By

M.H.Farjoo M.D. , Ph.D.Shahid Beheshti University of Medical Science

M.H.Farjoo

Fluid & Electrolytes

Water Principles of Electrolyte Therapy Sodium

Hypernatremia Hyponatremia

Potassium Hyperkalemia Hypokalemia

Calcium Hypercalcemia Hypocalcemia

Drug Pictures

M.H.Farjoo

Water

Total body water: 60% of body weight Intracellular water: 40% of body weight Extracellular water (interstitial water + plasma

water): 20% of body weight Interstitial water: 15 % of body weight Plasma water: 5 % of body weight Blood volume: 9 % of body weight (blood volume =

plasma water + red blood cell volume)

M.H.Farjoo

Water (Cont’d)

Since water diffuses readily in all body, the osmolality (total solute concentration) in all body is the same: 290 mosm/kg water

In ECF sodium salts are main regulators of osmalality but in ICF potassium salts are major determinants.

Osmolality is controlled by: Water intake Water excretion

Cat drinking water

Causes of Hypovolemia

M.H.Farjoo

Principles of Electrolyte Therapy

Electrolytes are ionized molecules. If concentration of electrolytes become too

high (hyper-) or too low (hypo-), an electrolyte imbalance results.

Other anions: Plasma proteins, organic acids, sulphates Not routinely measured Constitute the "anion gap"

M.H.Farjoo

Principles of Electrolyte Therapy (Cont’d)

Determine maintenance requirements Calculate existing deficits of volume or

composition: The magnitude of volume deficits present. The pathogenesis and treatment of sodium

abnormality. Assessment of potassium requirements. Management of any coexisting acid-base

imbalance

M.H.Farjoo

Principles of Electrolyte Therapy (Cont’d)

For most problems, half of the calculated deficits should be replaced in a 24 hour period.

Reassess the patient clinical status after 24 hour and decide accordingly.

Fluid or electrolyte abnormality should take as long to correct as it took to develop.

M.H.Farjoo

Principles of Electrolyte Therapy (Cont’d)

It is difficult to recognize some electrolyte status merely according to serum values.

If a deficiency develops slowly, the organism can maintain the serum concentrations at the expense of the remaining stores.

Treatment of electrolyte disorders depends on the underlying cause of the problem.

M.H.Farjoo

Sodium

Normal sodium range: 135 - 145 meq/L Is the major component of ECF Sodium helps the kidneys to regulate the

amount of water the body retains or excretes. Generally, water and sodium disturbances

occur simultaneously. Sodium facilitates neuromuscular functioning. Sodium levels indicate overall fluid balance.

M.H.Farjoo

Hypernatremia

Hypernatremia is defined as a plasma Na+ > 145 mmol/L.

Represents chiefly loss of water Hypernatremia can be caused by inadequate

water intake or excessive fluid loss.

M.H.Farjoo

Hypernatremia (Cont’d)

Severe hypernatremia has a mortality rate of 40-60%.

Death is due to cerebrovascular damage and hemorrhage resulting from dehydration and shrinkage of the brain cells.

The major symptoms of hypernatremia are neurologic.

M.H.Farjoo

Hypernatremia Manifestations Thirst Orthostatic hypotension Dry mouth and mucous membranes Dark, concentrated urine Loss of elasticity in the skin Irritability Fatigue Lethargy Heavy, labored breathing Muscle twitching and/or seizures Coma

Approach to Hypernatremia

M.H.Farjoo

Hypernatremia Treatment

Rapid correction of hypernatremia is potentially dangerous.

A sudden decrease in osmolality causes a rapid shift of water into cells that have undergone osmotic adaptation.

This results in swollen brain cells and increases the risk of seizures or permanent neurologic damage.

M.H.Farjoo

Hypernatremia Treatment (Cont’d)

the water deficit should be corrected slowly over at least 48 to 72 h.

The quantity of water required to correct the deficit can be calculated from the following equation:

body water total140

140ionconcentrat sodium plasmadeficitwater

M.H.Farjoo

Hyponatremia

A plasma Na+ concentration < 135 mmol/L. It is one of the most common electrolyte

disorders.

Causes of Hyponatremia

hyponatremia

M.H.Farjoo

Hyponatremia Manifestations

Nausea, abdominal cramping, and/or vomiting Edema (swelling) Muscle weakness and/or tremor Paralysis Headache Disorientation Slowed breathing Seizures Coma

Approach to Hyponatremia

M.H.Farjoo

Hyponatremia Treatment

IV fluids are used only when it is necessary and then using isotonic saline.

Only when severe hyponatremia produces mental obtundation and seizure, the patient should be treated with hypertonic solutions.

Rapid correction of hyponatremia can cause permanent brain damage due to osmotic demyelination syndrome.

M.H.Farjoo

Potassium

Potassium range is: 3.5-5.5 mEq/L The serum Potassium concentration is

determined by: The pH of ECF The size of intracellular Potassium pool

Any potassium excess or deficit should be assessed in the light of blood pH.

M.H.Farjoo

Potassium (Cont’d)

98% of total body potassium is located intracellularly

Plasma potassium levels may not reflect total body potassium levels!

M.H.Farjoo

Hyperkalemia

Hyperkalemia, defined as a plasma K+ concentration > 5.0 mmol/L.

Chronic hyperkalemia is virtually always associated with decreased renal K+ excretion

Hyperkalemia may be caused by any cellular damage.

Causes of Hyperkalemia

M.H.Farjoo

Hyperkalemia (Cont’d)

ECG changes are the most helpful indicators of the severity of the problem:

In mild cases: peaking of the T wave, ST segment depression and widening of the QRS complex

In severe fatal cases (K concentration > 7.5 mmol/L): QRS widening is so severe that resembles sine wave which means:

imminent cardiac arrest

M.H.Farjoo

Hyperkalemia Manifestations

Weakness Nausea and vomiting Colicky abdominal pain Irregular heartbeat (arrhythmia) Diarrhea Muscle pain

Approach to Hyperkalemia

RTA: renal tubular acidosisTTKG: transtubular K concentration gradient.

M.H.Farjoo

Hyperkalemia Treatment

IV injection of 100 ml of 50% dextrose solution containing 20 units of regular insulin

IV injection of NaHCO3 (if pH imbalance present) Infusion of calcium gluconate to antagonize cardiac

depressant effects of potassium without changing its serum concentration.

Administration (orally or enema) of “Kayexalate” Hemodialysis

M.H.Farjoo

Hypokalemia

Hypokalemia, defined as a plasma K+ concentration < 3.5 mmol/L

In the absence of alkalosis renal wasting is usually the cause: Urine potassium excretion of >30 meq/24 h and

serum potassium <3.5 meq/L means renal wasting. If urine potassium excretion is <30 meq/24 h the

kidneys or working properly and total body potassium is low.

Causes of Hypokalemia

M.H.Farjoo

Hypokalemia Manifestations

Weakness (decreased muscle contractility) Paralysis (in muscles of respiration can cause

death) Increased urination Irregular heartbeat (arrhythmia) Orthostatic hypotension Muscle pain Tetany

Approach to Hypokalemia

TTKG: transtubularK concentration gradientRTA: renal tubular acidosis.

M.H.Farjoo

Hypokalemia Treatment

Alkalosis (if present) should be corrected. If the patient can eat, potassium should be

given orally otherwise intravenously. In iv fluids potassium is usually given as

chloride salts which helps to correct alkalosis (if present)

M.H.Farjoo

Calcium

Calcium range is: 8.8-10.4 mg/dl Almost half of the serum calcium is bound to

plasma proteins (albumin), 10% is complexed to plasma anions and 40% is free or ionized.

The ionized fraction is responsible for the biologic effects.

Acidosis increases and alkalosis decreases ionized calcium concentration

M.H.Farjoo

Hypercalcemia Manifestations

Fatigue Constipation Anorexia & depression Muscle pain Nausea and vomiting Polyuria (in long standing cases) Irregular heartbeat (arrhythmia) Coma & death (in severe cases)

Causes of Hypercalcemia

M.H.Farjoo

Hypercalcemia Treatment

Mild hypercalcemia (< 12 mg/dl) can be managed by hydration.

Serum ca2+ concentrations > 12 mg/dl is a medical emergency!!

In severe cases (ca2+ > 14.5 mg/dl) IV isotonic saline is given to expand plasma valium and renal excretion of calcium.

Furosemide and iv sodium sulfate can also increase renal excretion of calcium.

In case of renal failure hemodialysis may be required.

Approach to Hypercalcemia

FHH, familial hypocalciuric hypercalcemia; MEN, multiple endocrine neoplasia;PTH, parathyroid hormone; PTHrP, parathyroid hormone related peptide.

M.H.Farjoo

Hypocalcemia Manifestations

Increase in DTR (deep tendon reflex) Carpopedal spasm Muscle & abdominal cramps Tetany and/or convulsions Mood changes (depression, irritability) Dry skin & brittle nails Prolonged QT interval Facial twitching (chvostek sign)

Causes of Hypocalcemia

M.H.Farjoo

Hypocalcemia Treatment

Check the whole blood pH and correct any alkalosis

For mild chronic cases: oral calcium, vitamin D, and aluminum hydroxide gels to bind dietary phosphate.

For severe cases: intravenous calcium gluconate.

dextrose 20%

dextrose normal saline

KCl tab

NaCl serum 0.9% for irrigation

NaCl serum 0.9% in 1000 CC normal saline

NaCl serum 0.9% normal saline

NaCl serum 0.45% in 1000 CC

NaCl serum 0.45%

ringer 500 ml

ringer 1000 ml

SummaryIn English

Thank youAny question?