Fluid & Electrolyte Balance

ABHITOSH DEBATA , Dept of OMFS

CONTENTS

HOMEOSTASIS TERMINOLOGIES BRIEF INTRODUCTION TO FLUID AND

ELECTROLYTES CHARACTERISTICS OF SPECIFIC

FLUIDS AND ELECTROLYTES ELECTROLYTE ABNORMALITIES CONCLUSION REFERENCES

Is defined as maintenance of static or constant conditions in the internal environment. - Guyton

HOMEOSTASIS

4

Electrolyte :

Is a substance containing free ions that behaves as an electrically conductive medium…

Osmosis :

Net movement of the solvent across the semi permeable membrane from a region of high solute potential to an area of low solute potential.

Osmotic Pressure :

Force per unit area or pressure required to prevent the passage of water through a selectively permeable membrane & into a solution of greater or equivalent concentration

Reverse Osmosis :

Solvent moving from a region of high solute conc to a region of low solute concentrate by applying pressure in excess of the osmotic pressure.

Osmolarity is defined as the number of osmoles of solute per liter (L) of solution. NaCl solution has an osmolarity of 2 osmol/L.

Osmolality is defined as the number of osmoles of solute per kilogram of solvent. It is expressed in terms of osmol/kg or Osm/kg.

Body fluids

Water constitutes an average 50% to 70% of the total body weight

Young males - 60% of total body weightOlder males – 52%

Young females – 50% of total body weightOlder females – 47%

Variation of ±15% in both group is normal

Obese have 25 to 30% less body water than lean people.

Infants - 75 to 80%

Child - 65% at one year of age

Daily loss of body water

Insensible water loss

Cannot be precisely regulated

Distribution of body fluids

Difference betwEEn ecf & icf

EXTRACELLULAR INTRACELLULAR

Main constituent – Na+ K+ , MG , sulfate , phosphate

Chief anion – CL- Hpo2 , sulfate ions

Traces of k , ca , mg ,ph,s Traces of NA+ ,CL- , no CA

15 - 20 litre in an avg adult(70kgs)

25 – 40 litre in an avg adult(70kgs)

To summarize in 70Kg male

TBW – 42 lts

ICF – 28 lts Extra vascular fluid – 10.5lts ECF – 14 lts

Intravascular fluid – 3.5lts

Blood volume = Plasma volume + RBC volume

= 8% of BW = 5.6 lt approx.

MOVEMENT OF BODY FLUIDS

- Diffusion

- Osmosis

- Active transport

Water balance

Intake Regulation

Driving force for intake .........thirst

of 10% plasma volume

↓

Dry mouth

↓

hypothalamic thirst centre ↓

Drink

Anti-diuretic hormone (vasopressin)

Inappropriate Stimuli of ADH Release

•Narcotics

•Nicotine

•Vincristine

•Carbamazepine

•Chlorpropamide

19

Input & Output of water

Sodium –Potassium Pump

Clinical Evaluation

Changes in BW…

Water loss Degree of Dehydration

4% of body wt Mild6% “ “ Moderate8% “ “ Severe

Normal urinary

output

Adult

0.5-2cc/kg/hr

Child 2cc/kg/hr

FLUID THERAPY

 0.9% NaCl (normal saline)  isotonic

 0.25% NaCl  hypotonic

 0.45% NaCl  hypotonic

 2.5% dextrose  hypotonic

 Lactated Ringer's solution  isotonic

 D5W (acts as a hypotonic solution in body)

 isotonic 

 D5 NaCl  hypertonic

 D5 in Lactated Ringer's  hypertonic

 D5 0.45% NaCl  hypertonic

   

Fluid therapy

Route……

Fluid typesCrystalloids and colloids3ml of crystalloids = 1ml of colloid (blood for intravascular replacement)

Crystalloids

1. Molecular wt <8000 daltons2.    Replaces mainly extracellular volumeE.g.

a.   Normal saline.b.    5% dextrosec.    Ringer’s lactate

3. Shorter intravascular half life 4. In trauma it stabilizes the haemodyNamics in 3 hrs

Colloids

1.   Molecular wt > 8000 daltons2.   Replace intravascular volumeE.g.

a.   Serum albumin.b.   Human plasma.c.   Synthetic plasma expanders.

i.          Gelatin solution ii.        Dextrans

3. Longer intravascular half life

4. In trauma it stabilizes the haemodyNamics in 2 hrs

IV fluids

0.9% Sodium Chloride –

iso osmolar with plasma and ECF hence Called normal saline… serves a good replacement solution for ECF volume deficient…

chloride content - higher than that of plasma infusion → too much of normal saline may produce hyperchloraemic acidosis…

IndiCation : ECF def in the presence of hyperNatremia, hypochloremia & metabolic alkylosis…

Dextrose 5% in water

It provides 50gms of dextrose / l. It is slightly hypertonic to plasma after infusion dextrose is metabolized→ water is left in the ECF… too much of 5% dextrose may Cause dilution and hypotonicity of ECF and water loading, if kidneys are not functioning normally.100ml --- dextrose 5gm

Dextrose 5% with 0.9% of saline.

Its twice as hypertonic as plasma… However within a few hours glucose is used and there is no signifiCant change in the plasma tonicity…100ml ----dextrose 5 gm, NaCl .9 gm, water

Lactated ringers solution.

This is slightly hypo osmolar compared to plasma & contains Na, K, Ca, Cl & Lactate...

Its good substitute for gastrointestiNal and other ECF fluid deficits in the absence of gross abnormalities of concentrationUsed in correcting metabolic acidosis….Should not be given in patients with liver diseases and in presence of lactic acidosis.

Ringers acetate solution.

- slightly hypo osmolar to plasma… - main use is as a replacement for ECF deficits in patients with damaged liver or lactic acidosis.. - helps in correction of mild to moderate metabolic acidosis.

0.45% sodium chloride in 5% dextrose solution

- It is used as mainteNance fluid in postoperative period. - Provides sodium for reNal adjustment of sodium concentration in the serum. - Potassium may be added to be used for mainteNance requirements in uncompliCated pt requiring only a short period of parenteral fluids.

Hypertonic saline solution

1.8 % sodium chloride

- Indicated in correction of pts with symptomatic hyponatraemia who Can not be given too much of water volume due to oliguria or anuria.

7.2-7.5 % sodium chloride

- Studies have shown that even with 50% blood loss a small volume of 7.2-7.5% NaCl restores the Cardiac output and blood pressure within one minute. - This saline is given through a peripheral vein very fast over 2 to 5 mins. And this results in rise in the plasma sodium level and plasma osmolality Causing a shift of body water in the vascular tree

Colloid solutions

Human plasma

Used for resuscitation of shock patient and for mainteNance of I.V. fluid therapy it has a composition and osmolality similar to ECF.

Human Albumin

20% purified human albumin is commercially available. Its volume expansion Capacity is 400 per cent. Rarely, aNaphylactoid reaction has been reported with albumin and may Cause post resuscitation hypotension.

The usual volume of fluid intake necessary.

The choice of IV fluid type.

Three electrolytes considered when choosing an IV solution.

In general after dentoalveolar surgery IN otherwise healthy patient requires a relatively physiologic IV solution with some calories during and after surgery, which can be provided IN combination WITH crystalloid solutions, such as 5% dextrose in a 0.45% sodium chloride solution to which 20 mEq of potassium chloride per liter MAY BE added.

ClassifiCation of Body Fluid Changes/disorders

Disorders in the fluid balance are Classified in three

general Categories.

Disturbances of

- Volume.

- Concentration.

- Composition.

Causes of ECF deficit

1. Loss of GI fluids due to:a. Vomiting.b. Diarrhea.c. Nasogastric suction.d. Fistular draiNage.

2. soft tissue injuries and infections.3. IntraabdomiNal and Intraperitoneal inflammatory processes.4. Burns.5. Insensible losses6. Sweat.

Causes of ECF excess

1. Iatrogenic

2. Secondary to reNal insufficiency

3. Cirrhosis

4. Sodium retention

5. Mineralocorticoids

6. NSAIDS

CAUSES OF VOLUME DEFICIT

• Failure to absorb or reabsorb water.

• Complete sudden cessation of intake.

• Prolonged diminished intake.

• Difficulty or inability to take orally.

• Loss from GIT via vomiting and kidneys.

•Soft tissue injuries burns.

SIGNS OF MODERATE VOLUME DEFICIT : ECF LOSSEARLY SIGNS

CNS : Sleepiness,cessation in usual activity, anorexia, thirstCVS : Orthostatic hypotension, Tachycardia, weak thready pulseGIT : progressive decrease in food consumption,

AFTER 24 HOURS

TISSUE SIGNS : Soft ,small tongue with longitudinal wrinkling, Dry mucus membrane , dry cracked lips

SIGNS OF SEVERE VOLUME DEFICIT :EARLY SIGNS

•CNS : decreased tendon reflexes, anesthesia of extremeties,•stupor, coma•CVS: hypotension, distant heart sounds, absent peripheral pulse•GIT : nausea , vomiting refusal to eat

AFTER 24 HOURS

TISSUE SIGNS: Eyeballs sunken , atonic muscles

SPECIFIC MANAGEMENT……

CAUSES OF FLUID LOSS IN SURGICAL PATIENTS

•Increased loss from lungs after anesthesia

•Fistulae

• In soft tissue injuries & infections

•Burns

•External loss of fluids

•internal redistribution of ECF in nonfunctional spaces

CLINICAL MANIFESTATION

•Skin pallor

•Cold extremities

•Weak and rapid pulse

•Hypotension

•Oliguria

•Decreased levels of consiousness

MANAGEMENT

Treat the cause

1. For burns and tissue injuries large volume of isosmolar IV fluid is administered

2. Albumin is administered for protein deficit3. IV fluid intake is maintained after major surgery to

maintain kidney perfusion 4. Pericardiocentesis if pericarditis is the cause5. Paracentesis for ascitis

Concentration changes

The serum sodium level/Conc. is used to estimate the

total body

fluid osmolality.

Even though the sodium ions are largely confined to

the

extra cellular compartment, its level/Conc. reflects total

body

osmolality.

Compositional changes

Compositional abnormalities of importance include

changes in

Acid – base balance and concentration changes of

calcium,

Potassium and magnesium.

Methods to calculate the rate of fluid infusion

• 4/2/1 Rule

•Maintenance of fluids for 24 hours : 100/50/20 rule

The Electrolyte abnormalities include –

Sodium abnormalities

Potassium abnormalities

Calcium abnormalities

Magnesium abnormalities

Na + (Sodium)

Function: Most important ion in regulating ECF volume and

thereby maintaining BPImportant in nerve and muscle function

Serum Na+

Normal daily intake: 100 mEq/lt Causes of Hyponatremia

Causes of hyponatremia with increased extracellular volume-Heart failure.-Liver failure.-Oliguric renal failure-Hypoalbuminaemia -Hyperglycemia

-Hyperlipidemia

Each 100mg/dl raise in blood glucose results in decrease in serum sodium concentration of about 1.6 to 3mEq /Lt

Clinical Signs and SymptomsSymptoms rarely develop unless serum sodium drops 120 to 125mEq/Lt

TreatmentDetermine if hyponatremia acute

Chronic

Acute serum sodium <110-115meq/lt

Symptomatic - seizures

coma

Rapid correction- Till serum sodium 120-125meq/lt

If it is asymptomatic gradual correction over 48 hrs

Hypernatremia

Clinical manifestations of hypernatremia Thirst Lethargy Neurological dysfunction due to dehydration of brain cells Decreased vascular volume

Correction of Hypernatremia

Asymptomatic: 5% dextrose in H2O

0.45% saline preferable in coma. Very large volumes of 5litres a day may be needed to be given.

Symptomatic: 1. 0.9% saline to correct volume deficit 2. Correct over a period of 48 hrs as rapid correction may lead to cerebral edema.

Potassium

Functions :

Regulates fluid, ion balance inside cell

Ph balance

Maintains cell integrity

Serum Potassium

98% located in intracellular compartment.

Normal daily intake 40-60mEq/Lt.

Over 85% is excreted in urine and stool.

Hypokalemia

Persistent reduction of serum potassium below 3.5 meq/l.Causes

•Decreased intake of k+

•Increased k+ loss: renal / non renalochronic diureticsoacid/base imbalanceo trauma and stresso increased aldosteroneo redistribution between icf and ecfoMetabolic alkalosis

Hypokalemia in surgical patients

Excessive renal secretion

Movement of potassium in cells

Prolonged administration of k- free parentaral fluids

Continued loss of k through urine

Loss of GIT secretions

Clinical manifestations •Gradual onset of drowsiness, with difficulty in rousing and slow opening of the eye

•Slow slurred speech

•Neuromuscular disorders–Weakness, flaccid paralysis, respiratory arrest, constipation

•Dysrhythmias

•Postural hypotension

•Cardiac arrest

Clinical features

BP is low and slow pulse rate

Warm and dry skin

Reddish flushed face

Increased thirst

Treatment

•Increase k+ intake, but slowly, preferably by foods

•Oral administration of potassium salt

•Potassium chloride effervescent tab 2gm 8th hrly

•In case of coma patients and severe vomiting-

• Administration of IV fluids- ISOLYTE G, ISOLYTE M

• Maintain within 7 mEq/L

• Assure adequate urine out put

HYPERKALEMIA

•Serum k+ > 5.5 meq / L

Clinical signs and symptoms- Cardiac

1. Peaked T wave

2. QRS widening.

3. St depression

4. Bradycardia

5. Ventricular fibrillation- Neuromuscular

1. Weakness

2. Paresthesia

3. Respiratory failure

Treatment:

ImmediateIf potassium levels greater than 7mEq/L1.Protect myocardium10ml of 10% calcium gluconate given over 2-3 minutes in the presence of ECG changes

In potassium level in 1hr If no response second dose can be repeated

2. Drive potassium into the cells 10 units of insulin + 5% dextrose in water I.v. administered over 5 minutes decreases serum potassium levels in 30 mins and last for several hours.

Regular check of blood glucose and potassium Repeat as necessary

3. 1.26% Sodium bicarbonate – Can be given with 5% dextrose in water.

If ECG changes still present – repeat dose 15 mins after first dose

CALCIUM

Normal serum level : 9.5 – 11 mg/dl1000 -1200 gm found in bonesDaily intake : 1- 3 gmExcretion : git,renal

HYPERCALCEMIA

Ca > 15 mg/ml

Results from:

Hyperparathyroidism Hypothyroid statesRenal diseaseExcessive intake of vitamin DMilk-alkali syndromeCertain drugsMalignant tumors – hypercalcemia of malignancy

Tumor products promote bone breakdownTumor growth in bone causing ca++ release

•EFFECTS:

– Initially GI symptoms–Nausea, abdominal cramps• Diarrhea / constipation

–Many nonspecific – vague pain–Fatigue, weakness, lethargy–Muscle cramps–Bradycardia, cardiac arrest

–Metastatic calcification– Increases formation of kidney stones and pancreatic stones

–Finally stupor & coma

Treatment

A.Measures to↑ urinary execretion of ca0.9 % nacl followed by frusemide cautiouslyHaemodialysis

B. Measures to ↓ ca reabsorptionBiphosphontes, calcitonin

C. Meassures to ↓ intestinal absorptionGlococorticosteroids, oral phosphates

Hypocalcemia

Numbness tingling sensation in the circumoral region and the tip of the fingers and toes

Convulsions in severe casesDiagnosis:

Chvostek’s signTrousseau’s sign

TreatmentIv calcium for acuteOral calcium and vitamin d for chronic cases

Acute management-

10 % ca gluconate 10 to 20 ml slow i.V. Over 10 minsIf i.V. Ca doesn’t relieve tetany, rule out hypomagnesemia

Long term management-

Rx underlying etiologyCa supplementsVitamin d supplements

MAGNESIUM

4th most common cation in ecf

2nd most common cation in icf

Serum level : 1.8 to 3 mg/l

Function: normal contractility of muscle and excitability of neuronal tissues

•Normal daily intake is 20 to 25 meq / day

•8 meq/day is absorbed and excreted in urine

Hypomagnesemia

Signs and sypmtoms: muscular tremors, hyperactive deep tendon reflexes

Magnesium deficiency

Parenteral administration of magnesium chloride or sulphate solution

Monitor heart rate, BP, respiration and ECG for signs of toxicity

Followed by 10 to 20 mEq of 50% of magnesium sulphate solution daily IM or IV

Hypermagnesemia

Hypermagnecaemia is extremely rare and is only seen in severe renal insufficiency more so when renal dialysis is carried out

Occurs when magnesium containing antacids and laxatives are used in patients with impaired renal function

Burns and massive trauma

Clinical featuresHypoactive deep tendon reflexes, shallow and slow respirations lethargy, weakness Ecg changes – increased pr interval, widened qrs complex and elevated t wave. Gradual muscular paralysis fallowed by coma---death due to cardiac or respiratory arrest

TREATMENT

Withhold administration of exogenous magnesium

Slow administration of 5 to 10 mEq of calcium chloridE.

Haemodialisis.

ACID BASE BALANCE

Metabolic acidosis 

A pH under 7.1 is an emergency, due to the risk of cardiac arrhythmias, and may warrant treatment with intravenous bicarbonate.

Bicarbonate is given at 50-100 mmol at a time under scrupulous monitoring of the arterial blood gas readings.

 Dialysis may clear both the intoxication and the acidosis.

Metabolic alkalosis

The management of metabolic alkalosis depends primarily on the underlying etiology and on the patient’s volume status.

In the case of vomiting, administer antiemetics, if possible. If continuous gastric suction is necessary, gastric acid secretion can be reduced with H2-blockers or more efficiently with proton-pump inhibitors.

In patients who are on thiazide or loop diuretics, the dose can be reduced or the drug can be stopped if appropriate. Alternatively, potassium-sparing diuretics or acetazolamide can be added.

CONSIDERATIONS FOR SURGICAL PATIENT

• PRIME GOAL

Depends on the

1.Preoperative hydration status

2.Length of npo

3.Normal maintenance needs

4.Replacement of “third space” losses (open belly, hot lights, extensive dissection of tissues)

5.Replacement of blood loss

6. Fluid shift

EFFECT OF ANESTHESIA ON FLUID BALANCE

General anesthesia produces vasodilation and some degree of myocardial contractility (usually overcome by sympathetic drive induced by the surgical stimulus)

Mechanical ventilation can increase evaporative loss if gases are not adequately humidified, which is often the case during long Operating procedures.

Other factors, including increased intrathoracic pressure brought about by mechanical ventilation, a stress response to surgical stimulus, or the prone position, may lead to increased ADH production and decreased urine output.

Monitor :

Vital signs

Urine output

Acid-base status

PREOPERATIVE CORRECTIONS

1 ) correction of hypovolemia2 ) correction of other disorders

CORRECTION OF HYPOVOLEMIA

Causes : vomiting , blood loss, nasogastric suction, fever, hyperventilation, diuretic therapy, etc

Problems : ↓ o₂ carrying capacity, ↑ed risk of tissue hypoxia & development of organ failure , risk of severe hypotension.

INTRAOPERATIVE FLUID MANAGEMENT

Roughly calculated as-

Correction of fluid deficit due to starvation + Maintenece required for period of surgery +

Loss due to tissue dissection or haemorrhage

CORRECTION OF FLUID DEFICIT

•Volume to be replaced =

duration of starvation ( hrs) * 2ml/kg body weight

•Usually corrected by –

• 5% dextrose

•Half of calculated dose in 1st hr followed by remaining half over next 2 hrs

MAINTENCE VOLUME

calculated as – duration of surgery ( hrs) *2 ml/kg body weight orrate of infusion = 2ml/kg /hr

INTRAOPERATIVE FLUID LOSS

fluid loss d/t tissue dissection & haemorrhage in different types of surgeries :

Type Fluid volume (ml/kg/hr)Least trauma nilMinimal trauma 4Moderate trauma 6Severe trauma 10

Least trauma : Hypotonic maintence fluid, dextrose , 2ml/kg/hr Minimal trauma :

Tonsillectomy, nasal septal repair,plastic surgery6 ml/kg/hr; balanced salt solution for period of surgery

Moderate traumaprocedures of extermities etc8 ml/kg/hr of ringer’s lactate or isotonic saline

Severe traumaRadical neck dissection etc12 ml/kg/hr ringer’s lactate or isotonic saline

CAUSES OF HYPOVOLEMIA IN POST OPERATIVE PATIENTS

Inadequate correction of starvation

Inadequate maintenance in intra operative period

Intra operative blood loss & fluid loss

Excessive loss due to hyperventilation, hypermetabolism & pyraxia

Lengthy operation

Environmental factors - summer

ROUTINE POST OPERATIVE IV FLUID FOR FIRST THREE DAYS

First 24 hrs – 2 liters 5% dextrose or 1.5 lit 5% dextrose + 500 isotonic saline

Second post op day - 2 liters 5% dextrose + 1lit 0.9 % saline

Third post op day – similar fluid + 40 – 60 mEq potassium/daymay require modifications depending upon clinical situations

Thank you

Thank you