FLUIDS ELECTROLYTES BALANCE

Dr Krunal Karade

BASIC PHYSIOLOGY : BODY WATER1)The human body consists of about 50-

70% liquids & 30-50% solids by weight. The liquid portion varies with age , sex & fat content (as fat contain very little water) .

2)In adult male TBW: 60% In adult female: 50% In neonates: 80% In TBW Thin > than obese individuals.

TOTAL BODY WATER:Body wt% Total body

water%

Total 60 100intracellular 40 67(2/3)extracellular 20 33(1/3)a) Plasma 5 8b) Interstitial 15 25

NORMAL WATER BALANCE:Oral (or IV)fluid intake & urine output are

important measurable parameters of body fluid balance.

To determine daily fluid requirement of body we should know insensible fluid input & loss:

SO HIGHER AMOUNT OF WATER IS LOST DURING EXERCISE ,ABNORMAL SWEATING, PYREXIA, BURN & SURGERY.IN NORMAL PERSON DAILY INSENSIBLE LOSS IS 700 ML ,SO DAILY FLUID REQUIREMENT = U.O. +700 ML.

FLUID AND ELECTROLYTE TRANSPORT PASSIVE

TRANSPORT SYSTEMSDiffusionFiltrationOsmosis

ACTIVE TRANSPORT SYSTEMPumpingRequires

energy expenditure

FLUID TYPES Isotonic

Hypotonic

Hypertonic

ISOTONIC SOLUTION No fluid shift because solutions are

equally concentrated Normal saline (NS)solution (0.9% NaCl)

HYPOTONIC SOLUTION Lower solute concentration Fluid shifts from hypotonic solution into

the more concentrated solution to create a balance (cells swell)

Half-normal saline solution (0.45% NaCl)

HYPERTONIC SOLUTION Higher solute concentration

Fluid is drawn into the hypertonic

solution to create a balance (cells

shrink)

5% dextrose in normal saline (DNS)

REGULATORY MECHANISMS OF FLUID Baroreceptor reflex

Volume receptors

Renin-angiotensin-aldosterone

mechanism

Antidiuretic hormone (ADH)

BARORECEPTOR REFLEX Respond to a fall in arterial blood

pressure Located in the atrial walls, vena cava,

aortic arch and carotid sinus Constricts afferent arterioles of the

kidney resulting in retention of fluid

VOLUME RECEPTORS Respond to fluid excess in the atria and

great vessels Stimulation of these receptors creates a

strong renal response that increases urine output

RENIN-ANGIOTENSIN-ALDOSTERONE Renin

Enzyme secreted by kidneys when arterial pressure or volume drops

Interacts with angiotensinogen to form angiotensin I (vasoconstrictor)

RENIN-ANGIOTENSIN-ALDOSTERONE Angiotensin

Angiotensin I is converted in lungs to angiotensin II using ACE (angiotensin converting enzyme)

Produces vasoconstriction to elevate blood pressure

Stimulates adrenal cortex to secrete aldosterone

RENIN-ANGIOTENSIN-ALDOSTERONE Aldosterone

Mineralocorticoid that controls Na+ and K+ blood levels

Increases Cl- and HCO3- concentrations and fluid volume

ALDOSTERONE NEGATIVE FEEDBACK MECHANISM When ECF & Na+ levels drop secretion

of ACTH by the anterior pituitary release of aldosterone by the adrenal cortex fluid and Na+ retention

ANTIDIURETIC HORMONE Also called vasopressin Released by posterior pituitary when

there is a need to restore intravascular fluid volume

Release is triggered by osmoreceptors in the thirst center of the hypothalamus

Fluid volume excess decreased ADH Fluid volume deficit increased ADH

FLUID IMBALANCES Dehydration Hypovolemia Hypervolemia

DEHYDRATION Loss of body fluids increased

concentration of solutes in the blood and a rise in serum Na+ levels

Fluid shifts out of cells into the blood to restore balance

Cells shrink from fluid loss and can no longer function properly

CLIENTS AT RISK Confused Comatose Bedridden Infants Elderly Enterally fed

WHAT DO YOU SEE? Irritability Confusion Dizziness Weakness Extreme thirst urine output

Fever Dry skin/mucous

membranes Sunken eyes Poor skin turgor Tachycardia

WHAT DO WE DO? Fluid Replacement - oral or IV over 48

hrs. Monitor symptoms and vital signs Maintain I&O Maintain IV access Daily weights Skin and mouth care

HYPOVOLEMIA Isotonic fluid

loss from the extracellular space

Can progress to hypovolemic shock

Caused by:Excessive fluid loss (hemorrhage)

Decreased fluid intake

Third space fluid shifting

WHAT DO YOU SEE? Mental status

deterioration Thirst Tachycardia Delayed

capillary refill

postural hypotension

Urine output < 30 ml/hr

Cool, pale extremities

Weight loss

WHAT DO WE DO? Fluid

replacement Albumin

replacement Blood

transfusions for hemorrhage

Dopamine to maintain BP

MAST trousers for severe shock

Assess for fluid overload with treatment

HYPERVOLEMIA Excess fluid in the extracellular

compartment as a result of fluid or sodium retention, excessive intake, or renal failure

Occurs when compensatory mechanisms fail to restore fluid balance

Leads to CHF and pulmonary edema

WHAT DO YOU SEE? Tachypnea Dyspnea Crackles Rapid, bounding

pulse Hypertension

Increased CVP, pulmonary artery pressure and pulmonary artery wedge pressure

Increased JVP Acute weight

gain Edema

EDEMA Fluid is forced into tissues by the

hydrostatic pressure First seen in dependent areas Anasarca - severe generalized edema Pitting edema Pulmonary edema

WHAT DO WE DO? Fluid and Na+

restriction Diuretics Monitor vital

signs Hourly I&O Breath sounds

Monitor ABGs and labs

Maintain IV access

Skin & mouth care

Daily weights

DISTRIBUTION OF ELECTROLYTES:

ELECTROLYTE IMBALANCES Hyponatremia/ hypernatremia

Hypokalemia/ Hyperkalemia Hypocalcemia/ Hypercalcemia

Hypophosphatemia/

Hyperphosphatemia

Hypochloremia/ Hyperchloremia

SODIUM

Major extracellular cation

Attracts fluid and helps preserve fluid

volume

Combines with chloride and bicarbonate

to help regulate acid-base balance

Normal range of serum sodium 135 -

145 mEq/L

SODIUM AND WATER If sodium intake suddenly increases,

extracellular fluid concentration also rises

Increased serum Na+ increases thirst and the release of ADH, which triggers kidneys to retain water

Aldosterone also has a function in water and sodium conservation when serum Na+ levels are low

SODIUM-POTASSIUM PUMP Sodium (abundant

outside cells) tries to get into cells

Potassium (abundant inside cells) tries to get out of cells

Sodium-potassium pump maintains normal concentrations

Pump uses ATP, magnesium and an enzyme to maintain sodium-potassium concentrations

Pump prevents cell swelling and creates an electrical charge allowing neuromuscular impulse transmission

HYPONATREMIA Serum Na+ level < 135 mEq/L Several types

DilutionalDepletionalHypovolemicHypervolemic Isovolemic

TYPES OF HYPONATREMIA Dilutional - results from Na+ loss, water

gain Depletional - insufficient Na+ intake Hypovolemic - Na+ loss is greater than

water loss; can be renal (diuretic use) or non-renal (vomiting)

Hypervolemic - water gain is greater than Na+ gain; edema occurs

Isovolumic - normal Na+ level, too much fluid

WHAT DO YOU SEE? Primarily neurologic symptoms

Headache, N/V, muscle twitching, altered mental status, stupor, seizures, coma

Hypovolemia - poor skin turgor, tachycardia, decreased BP, orthostatic hypotension

Hypervolemia - edema, hypertension, weight gain, bounding tachycardia

WHAT DO WE DO? MILD CASE

Restrict fluid intake for hyper/isovolemic hyponatremia

IV fluids and/or increased po Na+ intake for hypovolemic hyponatremia

SEVERE CASE Infuse hypertonic

NaCl solution (3% or 5% NaCl)

Furosemide to remove excess fluid

Monitor client in ICU

HYPERNATREMIA Excess Na+ relative to body water Occurs less often than hyponatremia Thirst is the body’s main defense When hypernatremia occurs, fluid shifts

outside the cells May be caused by water deficit or over-

ingestion of Na+ Also may result from diabetes insipidus

WHAT DO YOU SEE? Think S-A-L-T

Skin flushedAgitationLow grade feverThirst

Signs of hypovolemia

WHAT DO WE DO? Correct underlying disorder Gradual fluid replacement Monitor for cerebral edema (headache,

loss of coordination , weakness, and decreasing levels of consciousness including disorientation, loss of memory, hallucinations, psychotic behavior, and coma)

Monitor serum Na+ level

POTASSIUM Major intracellular cation Untreated changes in K+ levels can lead

to serious neuromuscular and cardiac problems

Normal K+ levels = 3.5 - 5 mEq/L

BALANCING POTASSIUM Most K+ ingested is excreted by the

kidneys Three other influential factors in K+

balance :Na+/K+ pumpRenal regulationpH level

SODIUM/POTASSIUM PUMP Uses ATP to pump potassium into cells Pumps sodium out of cells Creates a balance

RENAL REGULATION Increased K+ levels increased K+ loss in

urine Aldosterone secretion causes Na+

reabsorption and K+ excretion pH: Potassium ions and hydrogen ions

exchange freely across cell membranes In Acidosis hyperkalemia (K+ moves out

of cells) In Alkalosis hypokalemia (K+ moves

into cells)

HYPOKALEMIA Serum K+ < 3.5 mEq/L Can be caused by GI losses, diarrhea,

insufficient intake, non-K+ sparing diuretics (thiazide, furosemide)

WHAT DO YOU SEE? Think S-U-C-T-I-O-N

Skeletal muscle weaknessU wave (ECG changes)Constipation, ileusToxicity of digitalis glycosides Irregular, weak pulseOrthostatic hypotensionNumbness (paresthesias)

WHAT DO WE DO? Increase dietary K+ Oral KCl supplements IV K+ replacement Change to K+-sparing diuretic Monitor ECG changes

IV K+ REPLACEMENT Mix well when adding to an IV solution

bag Concentrations should not exceed 40-60

mEq/L Rates usually 10-20 mEq/hr NEVER GIVE IV PUSH POTASSIUM

HYPERKALEMIA Serum K+ > 5 mEq/L

Less common than hypokalemia Caused by altered kidney function,

increased intake (salt substitutes), blood transfusions, meds (K+-sparing diuretics), cell death (trauma)

WHAT DO YOU SEE? Irritability Paresthesia Muscle weakness (especially legs) ECG changes Irregular pulse Hypotension Nausea, abdominal cramps, diarrhea

WHAT DO WE DO? MildWhat Do We Do?

Loop diuretics (Lasix)Dietary restriction

ModerateKayexalate

Emergency10% calcium gluconate for cardiac effectsSodium bicarbonate for acidosis

CALCIUM 99% in bones, 1% in serum and soft

tissue (measured by serum Ca++) Works with phosphorus to form bones

and teeth Role in cell membrane permeability Affects cardiac muscle contraction Participates in blood clotting

CALCIUM REGULATION Affected by body stores of Ca++ and by

dietary intake & Vitamin D intake Parathyroid hormone draws Ca++ from

bones increasing low serum levels (Parathyroid pulls)

With high Ca++ levels, calcitonin is released by the thyroid to inhibit calcium loss from bone (Calcitonin keeps)

HYPOCALCEMIA Serum calcium < 8.9 mg/dl Ionized calcium level < 4.5 mg/Dl Caused by inadequate intake,

malabsorption, pancreatitis, thyroid or parathyroid surgery, loop diuretics, low magnesium levels

WHAT DO YOU SEE? Neuromuscular

Anxiety, confusion, irritability, muscle twitching, paresthesias (mouth, fingers, toes), tetany

Fractures Diarrhea ECG changes

WHAT DO WE DO? Oral or IV calcium replacement

Calcium gluconate for postop thyroid or

parathyroid client

Cardiac monitoring

HYPERCALCEMIA Serum calcium > 10.1 mg/dl Ionized calcium > 5.1 mg/dl Two major causes

CancerHyperparathyroidism

WHAT DO YOU SEE? Fatigue, confusion, lethargy, coma Muscle weakness, hyporeflexia Bradycardia cardiac arrest Anorexia, nausea/vomiting, decreased

bowel sounds, constipation Polyuria, renal calculi, renal failure

WHAT DO WE DO? If asymptomatic, treat underlying cause Hydrate the patient to encourage

diuresis Loop diuretics Corticosteroids

BASIC PRINCIPLES OF FLUID THERAPY : Advantage: 1)Accurate ,controlled & predictable way

of administration. 2)Immediate response due to direct

infusion in intravascular compartment. 3)Prompt correction of serious fluid &

electrolyte disturbances.

INDICATION:1) Conditions when oral intake is not possible

e.g. coma , anesthesia ,surgery.2) Severe vomiting & diarrhoea.3) Moderate to severe dehydration & shock4) Hypoglycemia where 25% dextrose is life

saving.5) As a vehicle for various I.V. medication e.g.

antibiotics , chemotherapeutic agents , insulin, vasopressor agents.

6) Total parenteral nutrition.7) Treatment of critical problems:

shock ,anaphylaxis ,cardiac arrest & forced diuresis in drug overdose ,poisoning.

CONTRAINDICATION:1) I.V. fluid should be avoided if patient is

able to take oral fluid.2) Preferable to avoid I.V. fluid in patient

with congestive heart failure or volume overload.

COMPLICATIONS: 1)Local- Heamatoma , infiltration &

infusion phlebitis. 2)Systemic- circulation overload with

cardiac problem , rigors ,air embolism & septicaemia.

3)Others- fluid contamination, fungus in I.V. fluids, mixing of incompatible drugs ,improper technique of infusion , iv set or iv catheter related problems.

CLASSIFICATION OF I.V. FLUIDS: 3 GROUPS 1)Maintenance fluids: Its replaces fluid lost from

lungs ,skin ,urine & faeces. These losses are poor in salt so this maintenance fluid should be hypotonic to plasma .e.g. 5% dextrose ,dextrose with 0.45%NaCL solution.

2)Replacement Fluids: formulated to correct body fluid deficit caused by losses such as gastric drainage, vomiting ,diarrhoea ,fistula drains , intestinal oedema, oozing from trauma, infection, burns,ect. E.g. Riger’s lactate, Isotonic saline, DNS , isolyte-M,P &G.

3)Special fluids: Special fluids are used for the special indications such as hypoglycemia , hypokalemia & metabolic acidosis.e.g 25% dextrose , inj dextrose ,inj potassium chloride & inj sodium bicarbonates.

DEXTROSE SALINE (DNS): 5% DEXTROSE WITH 0.9% NACL Indication:1) correction of salt depletion

& hypovolemia with supply of energy. 2)Correction of vomiting or nasogastric

aspiration induced alkalosis & hypochloremia along with supply of calories.

3)fluid compatible with blood transfusion.

Contraindications: 1)Anasarca 2) Hypovolemic shock.

RINGER’S LACTATE: Indication: 1) correction of severe

hypovolemia rapidly. 2)for replacing fluid in postoperative patients,

burns ,fractures ,peritoneal irrigation ect. 3)Diarrhoea induced hypovolemia. 4) In diabetic ketoacidosis 5)For maintaining normal ECF fluid &

electrolyte balance during & after surgery. Contraindication: in liver disease ,in severe

CHF ,Rl & blood product in one IV line is contraindicated , calium In RL binds with certain drugs (amphotericin ,ampicillin).

NORMAL SALINE(NS): NACL 0.9% Indication:1)water & salt depletion as in

diarrhoea , vomitting ,excessive diuresis.

2)Treatment of hypovolemic shock. 3)Irrigation of washing of body fluids. 4)As a vehicle for certain drugs & can be

given safely with blood. Contraindications:Avoid in hypertensive

or preeclampsia ,CHF ,renal disease & cirrhosis. Dehydration with severe hypokalemia.

5% DEXTROSE:Indication:1)Fluid to provide adequate

calories to body.2)For pre & post operative fluid

replacement.3)For I.V. administration of various drugs4) For treatment of ketosis in

starvation ,diarrhoea ,vomiting & high grade fever.

Contraindication: Cerebral oedema , Neurosurgical procedures, stroke.

ISOLYTE-P Indication: 1)Used as maintenance fluid

in infants & children to provide daily water & electrolytes.

2)Excessive water loss or inability to concentrate urine.(DI)

Contraindication: Renal failure, Hypovolemic shock.

FLUID REQUIREMENT IN SURGICAL PATIENT: Patients awaiting surgery need to be kept fasting

for a few hours prior to & after the surgery hence fluid loss during this period needs to be replaced.

Replacement as follows: 1)Fluid requirement during starvation- 2ml/kg/h

of fasting ,replaced over 2-3 hrs. 2)Maintenance requirement- 2ml/kg/hr of

surgery. 3)Third space losses-a)minimal dissection-4ml/kg/hrb) Moderate dissection-6ml/kg/hrc) Large amount of dissection- 8ml/kg/hr of

surgery

IF HAEMATOCRIT FALL BELOW <25%-BLOOD LOSS IS REPLACED BY BLOOD TRANFUSION.IF HAEMATOCRIT >25%- BLOOD LOSS IS REPLACED WITH EQUAL AMOUNT OF COLLOID [ PLASMA EXPANDER (DRAW FLUID INTO THE BLOODSTREAM)ALBUMINPLASMA PROTEINDEXTRAN] OR 3 TIMES THE VOL WITH CRYSTALLOID.A PATIENT UNDERGOING SURGERY SHOULD RECEIVE =FLUID DEFICIT DUE TO STARVATION+MAINTENANCE FLUIDS+3RD SPACE LOSSES+ REPLACEMENT OF BLOOD LOSS.ADEQUACY OF FLUID REPLACEMENT CHECKED WITH HAEMODYNAMIC STABILITY & U.O. & IN MAJOR SURGERY BY CENTRAL VENOUS PRESSURE MONITORING.

WHAT TO GIVE: Starvation losses: replaced by an

infusion of 5% dextrose. Maintenance & 3rd space losses : By RL.