FLUID AND ELECTROLYTE BALANCE

Dr. SUNDEEP SHARMA (MDS 1st yr)Dept. Of Oral & MaxillofacialSurgery

BalanceMODERATOR Dr. ALOK BHATNAGAR ( READER )

CONTENTS INTRODUCTIONREGULATION OF BODY FLUIDSCOMMON DISTURBANCES IN ELECTROLYTES BALANCEACID BASE REGULATORSCAUSES OF FLUID VOLUME DEFICETSPATHOPHYSIOLOGY OF FLUID VOLUME DEFICITSPATHOPHYSIOLOGY OF FLUID VOLUME OVERLOADPRINCIPLE OF FLUID THERAPYCLASSIFICATION OF IV FLUIDSMETHODS OF DELIVERING IV FLUIDSCALCULATION FOR ROUTINE IV SETFLUID THERAPY IN SURGICAL PATIENTSCONCLUSIONREFERENCES

OVERVIEW OF NORMAL FLUIDS & ELECTROLYTES BODY FLUIDS Composed of water and dissolved substances (solute)WATER - transport & exchange of nutrients & metabolic wastesmedium for metabolic reactions within cellsconstitutes about 60% of the total body weight.

Provides structural formshock absorberProvides insulationLubricantregulating body temperature through Evaporation and Persipiration

Why women have less water than men if they are the same weight? The water content of adipose (fat) tissue is less than that of muscle, while women have more adipose tissue at the effect of feminine hormone.

Distribution of Body Solids & Fluids

BODY FLUID COMPARTMENTSRULE OF THIRDSIntracellular: 2/3 (40% TBW)Extracellular: 1/3 (20% TBW)Interstitial + Lymph: 2/3 (15% TBW)Intravascular: 1/3 (5% TBW)

Total body fluid is 60% of the body weight.

1. INTRACELLULAR fluid (ICF) 40% of the total body weight

2. EXTRACELLULAR fluid (ECF) 20% of the total body weight BODY FLUID DISTRIBUTION

EXTRACELLULAR CELL- 20% of total body weighta. Interstitial fluid- 15% of the total body weight. Located in the spaces between most of the cells of the body.b. Intravascular fluid- 5% of the total body weight. It is a plasma fluid, contained within the arteries, veins and capillaries.c. Transcellular fluid - includes urine; digestive secretions; perspiration; and CSF, pleural; synovial; intraocular, gonadal, and pericardial fluids.A trace amount of water is found in bone, cartilage, and other dense connective tissues; this water is not exchangeable with other body fluids.

What separates these different compartments?1. Cell membranes- separate interstitial fluid from intracellular fluid.

2. Capillary membranes- separate plasma from interstitial fluid

3. Epithelial membranes- separate transcellular fluid from interstitial fluid and plasma. It includes mucosa of the stomach, intestines, gallbladder, pleural, peritoneal, synovial membranes, and tubules of the kidney.

Body weight varies:Age, gender, amount of body fatBody water decreases when age over 65 about 45-50%

Note: To maintain normal fluid balance, body water intake and output should be approximately equal.

NOTE: Body fluids contain both water molecules & chemical compounds can either remain intact in solution or separate (dissociate) into discrete particles.

BODY FLUID MOVEMENTFour chemical and physiologic processes control the movement of fluid, electrolytes and other molecules across membranes between the intracellular and interstitial space and the interstitial space and plasma.

These processes are osmosis, diffusion, filtration, and active transport.

Osmolarity and Osmolality.

Osmolarity refers to the amount of solutes per liter of solution (By volume). In milliosmoles per liter (mOsm/L)Osmolality refers to the number of solutes per kilograms of water (By weight); In milliosmoles per kilograms (mOsm/kg)

Note: Osmotic activity in the body is regulated by the number of active particles (solutes) per kilogram of water, osmolality is used to describe the concentration of body fluids.

Body weight is the best way to measure body fluid- Normal Value of osmolality in ICF and ECF ranges between 275-295 mOsm/kg.

- Osmolality of ECF depends on the value of sodium (NA+) concentration.

1. OSMOSIS Movement of water across selectively semi permeable membrane from an area of lower solute concentration to an area of higher solute concentration.Osmosis continues until the solute concentration on both sides of the membrane is equal.a. Osmotic Pressure the power of a solution to draw water across membrane.Ex. Fluids in IVS & Interstitial space is essentially same except for the higher concentration albumin in plasma. This exert osmotic pressure, pulling fluid from the Interstitial space towards the IVS, to hold water inside vascular system.

Tonicity refers to the effect of the solutions osmotic pressure has on water movement across the cell membrane of cells within that solution.

A. Isotonic solution - solutions had the same concentration of solution as in plasma. Cells placed in the isotonic solution neither shrink nor swell as there is no gain or loss of water within the cell. No change in cell volume.

Types of TonicityEx. Normal saline solution (0.9% sodium chloride solution)

*

ISOTONIC SOLUTIONS0.9% Sodium Chloride Solution Ringers SolutionLactated Ringers Solution

B. Hypertonic Solution - solutions have a greater concentration of solutes than in plasma. In their presence, water is drawn out of the cell, causing them to shrink.

Ex. A 3% sodium chloride solution is hypertonic.

*HYPERTONIC SOLUTIONS3% SODIUM CHLORIDE

5% SODIUM CHLORIDE

WHOLE BLOOD

ALBUMIN

CONCENTRATED DEXTROSE (>10%)

C. Hypotonic Solution - solutions have a lower solute concentration than in plasma. When red blood cells are placed in a hypotonic solution, water moves into the cells, causing them to swell and rupture (hemolyze). Ex. 0.45% sodium chloride has a lower concentration of solute than plasma.

*5%DEXTROSE & WATER

0.45% SODIUM CHLORIDE

0.33% SODIUM CHLORIDE

HYPOTONIC SOLUTIONS

The concept of osmotic draw and tonicity are important in understanding the pathophysiologic changes that occur with fluid and electrolyte imbalances, as well as the treatment measures.

Ex. An increased sodium concentration of ECF causes water to shift from ICF to ECF compartment.

In this case administering a hypotonic intravenous solution will facilitate water movement back into the intracellular space.

2. DiffusionThe process by which solute molecules move from area of high solute concentration to an area of low solute concentration to become evenly distributed.Diffusion - The process by which solute molecules move from area of high solute concentration to an area of low solute concentration to become evenly distributed.

2.1 Types of Diffusiona. Simple diffusion occurs by the random movement of particles through a solution. (water, carbon dioxide, oxygen, and solutes move between plasma and interstitial space by simple diffusion through the capillary membrane.

b. Facilitated diffusion also called a carrier-mediated diffusion, allows large water-soluble molecules, such as glucose and amino acids, to diffuse across cell membranes.

Proteins embedded in the cell membrane function as carriers, helping large molecules cross the membrane.

The rate of diffusion is influenced by a number of factors, such as concentration of solute and the availability of carrier proteins in the cell membrane.

The effect of both simple and facilitated diffusion is to establish equal concentration of the molecules on both sides of a membrane.

3. Filtration (Hydrostatic Pressure) - The process by which water dissolved substances (solutes) move from an area of high hydrostatic pressure to an area of low hydrostatic pressure. Arterial side of the capillaryHydrostatic Pressure(arterial blood pressure)Direction of fluidAnd solute movementVenous side of the capillaryOsmotic Pressure(colloid osmotic pressure)Direction of fluidAnd solute movementCapillary BedInterstitialSpace

These usually occur across capillary membranes. Hydrostatic pressure is created by the pumping action of the heart and gravity against the capillary wall.Note: Fluid balance between the IVS and interstitial spaces is maintained in the capillary beds by a balance of filtration at the arterial end and osmotic draw at the venous end.

4. Active Transport - allows molecules to move across cell membranes and epithelial membranes against a concentration gradient.This movement requires energy (adenosine triphosphate, or ATP) and a carrier mechanism to maintain a higher concentration of a substance on the other side of the membrane than on the other.High concentration of K+ in ICF and Na+ in ECF fluids are maintained because cells activity transport K+ from interstitial fluids. (where the k+ concentration is about 150 mEq/L).

Active TransportThe sodum-potassium pump. Sodium and potassium ions are moved across the cell membranes against their concentration gradients. This active transport process is fueled by energy from adenosunetriphosphate (ATP).Interstitial fluid

Intracellular fluidNa+Na+Na+Na+Na+Na+Na+Na+Na+Na+Na+Na+Na+K+K+K+K+K+K+K+K+K+K+K+Na+

BODY FLUID REGULATIONHomeostasis requires several regulatory mechanisms and processes to maintain the balance between fluid intake and excretion. These include thirst, the kidneys, renin-angiotensin-aldosterone mechanism, anti-diuretic hormone (ADH), and atrial natri-uretic factor (ANF).These mechanisms affect the volume, distribution and composition of body fluids.

1. Thirst Mechanism

The effect after drinking.

2. Renin-Angiotensin-Aldosterone System- it works to maintain intravascular fluid balance and blood pressure.Renal Perfusion Glomerular filtration rateRenin producedAngiotensinogen converted toAngiotensin I

Angiotensin I Converted toAngiotensin IIIn the lungsSecretion ofAldosterone in theAdrenal cortex Absorption of Na+ Absorption of H2O Excretion of K+ Excretion of H+ ions

KIDNEYS - Are primary responsible for regulating fluid volume and electrolyte balance in volume and osmolality of body fluids by controlling the excretion of water and electrolytes.

- About 99% glomerular filtrate is reabsorbed, and only about 1500 ml of urine is produced over a 24-hour period.

4. ANTIDIURETIC HORMONE Regulates water excretion from the kidneys. Osmoreceptors in the hypothalamus respond to increases in serum osmolality and decreases in blood volume, stimulating ADH production and release.

2 disorders of ADH productiona. Diabetes insipidus deficiency of ADH. b. SIADH excess in ADH release.

Blood pressureBlood urineBlood osmolalityOsmo receptors inHypothalamus stimulate Posterior pituitary tosecrete ADH ADH increases distal Tubule permeability to reabsorption of H2OUrine outputBlood pressureBlood volumeBlood osmolality

5. ATRIAL NATRIURETIC FACTOR (ANF) It is a hormone released by atrial muscle cells in response to distension from fluid overload.

ANF affects several body systems: the cardio-vascular, renal, neural, gastrointestinal, and endocrine systems., but mainly the renin-agiotensin-aldosterone system.

ANF opposes the system by inhibiting renin secretion and blocking the secretion and sodium-retaining effects of aldosterone.

It promotes sodium wasting and diuresis (increase urine output) and causes vasodilation, which all help in reducing blood pressure.

DIAGNOSISA. FLUID VOLUME DEFICITDecreased Cardiac Output; Ineffective Tissue Perfusion; Risk for Injury.

B. FLUID VOLUME EXCESSRisk for Impaired Skin Integrity; Risk for Impaired Gas Exchange; Activity Intolerance

A. FLUID VOLUME DEFICIT is a decrease in intravascular, interstitial, and/or intracellular fluid in the body.Note: Third spacing (fluid shift) shift of fluid from the vascular space into an area where it is not available to support normal physiologic processes. The trapped fluid is considered a fluid loss. Assessment of fluid is maybe difficult and might not be reflected by changes in weight or intake and output records.

Phases of Third Spacing

First phase- LOSS

Immediately following surgery or trauma; 48-72 hours Increased capillary permeability Allows protein leakage in area Fluid shifts from vascular to interstitial space. Patient may become hypovolemic Decreased blood pressure Increased pulse rate Decreased urine output Increased urine specific gravity

LOSSTotal intake > total output; reflects massive leak of fluid; IMPORTANT: replace lost proteins by giving albumin or plasmanate (Plasmanate contains 5 g selected plasma proteins buffered with sodium carbonate)In managing colloid replacement, give diuretic to pull tissue fluid into vascular space for renal excretion

Goals during LOSS phasePrevent hypovolemia:Monitor blood pressure, pulse, urine outputPrecise reportingReplace fluids as soon as it is orderedMonitor potassium if diuretics usedPrevent renal failure:Monitor renal functionBlood Urea & CreatinineWeigh patient dailyQuantity of urine reflects vascular volumeQuality of urine reflects kidney function

Second phase: ReabsorptionAfter healing, fluid in tissues begin to be reabsorbed back into vascular areaRecognized by increased urine outputLimit amount of external replacementMay see weight lossWatch for circulatory overloadRale (an abnormal rattling sound heard when examining unhealthy lungs with a stethoscopeShortness of breathDistended neck veins

Causes: fluid losses, insufficient fluid intake, or failure of regulatory mechanisms, fluid shifts within the body.A)Fluid losses

Vomitingdiarrheaintestinal fistulasBurns

b. failure of regulatory mechanism kidney disorders, endocrine disorders c. excessive exercise or increased environment temperature causing excess sweating.d. hemorrhage (loss of blood)e. chronic abuse of laxatives and/or enemas drugs ex. Diuretics

CausesInadequate intake lack of fluidsInability to swallow fluids- due to oral traumaAltered thirst mechanism

Multisystem Effect of Fluid Volume Deficit (FVD)1. Mucous Membrane dry, sticky, longitudinal furrows

2. Urinary urine output (oliguria) (severe FVD) urine specific gravity

3. Musculoskeletal fatigue caused due to FVD.

4. Neurologic Altered mental status; anxiety, restlessness; diminished alertness/cognition; possible coma in cases of severe FVD.

Altered mental status is most evident to patient with water and sodium imbalance

5. Integumentary diminished skin turgor, dry pale skin and cold extremities.

6. Cardiovascular tachycardia and hypotension in cases of moderate FVDfalling systolic/diastolic pressure in Severe FVD, flat neck veins, decrease venous filling, decrease pulse volume( weak pulse), decrease capillary refill, increase hematocrit value

7. Potential complication hypovolemic shock

8. Metabolic processes body temperature (isotonic FVD), increase body temperature (dehydration), thirst, weight loss >2% mild FVD; >5% moderate FVD; >8% severe FVD.

Diagnostic Tests1. Serum electrolytes In an isotonic fluid deficit, sodium levels are within normal limits; when the loss is water only, sodium levels are high K+ are common.2. Serum osmolality Differentiates isotonic fluid loss from water loss. With water loss, osmolality is high; it may be within normal limits with an isotonic fluid loss.

3. Serum hematocrit- The hematocrit often is elevated due to loss of intravascular fluid

4. Urine specific gravity and osmolality as the kidneys conserve water, both specific gravity and osmolality of the urine

5. Central venous pressure (CVP) measures the mean pressure in the superior vena cava or right atrium, providing an accurate assessment of fluid volume status.

Primary Goal to prevent deficits in patients at risk and to correct deficits and their underlying causes too.

Management:Assess intake and output collect assessment data through the health history interview and physical examination.Assess vital signs- BP, Pulse, temperature.Weigh the patient dailyMonitor the intake of oral fluids as prescribed. Oral fluid replacement is preferred when the patient is able to drink and retain fluids.

Administer intravenous fluid.Monitor for indicators of fluid overload.Monitor laboratory values.Replacement of electrolytes through intravenous, oral routes etc.

Home Care:Maintaining adequate fluid intakelearn how to monitor fluid imbalance.How to prevent fluid deficit avoid exercise in extreme heat increase fluid intake during hot weather. when vomiting take small frequent amount of ice chips, clear liquid, ice tea, flat cola, or ginger ale; Reduce intake of coffee, tea, and alcohol. (dehydrating agents).Replacement of fluid lost in diarrhea with clear fluids like juice, coconut water etc and ORS Solutions.Alternate sources of fluid; gelatin, frozen fruits, or ice cream.

B. FLUID VOLUME EXCESS results when both the water and sodium are retained in the body.

Other associated diagnosis are: Risk for Impaired Skin Integrity.Risk for Impaired Gas Exchange.Activity Intolerance.Causes:It maybe caused by fluid overload (excess water and sodium intake) or by impairment of the mechanisms that maintain homeostasis. The excess fluid can lead to intravascular fluid (hypervolemia)and interstitial fluid (edema).

a. Organ Failure Heart failure, liver cirrhosis, renal failure, adrenal gland disorders.b. Drugs corticosteroid administrationc. Stress conditions causing the release of ADH and aldosteroned. Excessive intake of food high in sodium contente. Excess administration of IVF containing high concentration of sodium content

Manifestations:1. Increase in total body water causes weight gain (more than 5% of body weight) over a short period.2. Circulatory overload causes manifestations such as:-- Full, bounding pulse(pounding or racing)- Distended neck and peripheral veins- venous pressure - Cough, Dyspnea (labored or difficult breathing) orthopnea (difficulty in breathing when in supine).

- Moist crackles (rales) in the lungs, pulmonary edema - Urine output (polyuria)- Ascites (excess fluid in the peritoneal cavity)- Peripheral edema, ANASARCA (generalized edema)

- Dilution of plasma by excess fluid causes Hematocrit value

- Possible cerebral edema can lead to altered mental status.

Diagnostic Tests:1. Serum electrolytes and serum osmolality

serum osmolality usually remain within normal limits.

2. Serum Hematocrit and Hemoglobin often are due to plasma dilution from excess extracellular fluid.

Additional tests of renal and liver function ( such as KFT, serum creatinine, BUN (blood urea nitrogen)and LFT) may be ordered to determine the cause of fluid volume excess.

Primary Goal focuses on prevention in patients at risk, treating and correcting the underlying causes.

Management

Monitor vital signs, heart sounds, CVP, and volume peripheral arteries.

Presence and extent of Edema, particularly in lower extremities, the back, sacral, and peri-orbital areas.

Obtain daily weights.

Administer oral fluids cautiously, adhering to any prescribed fluid restriction.

Provide oral hygiene it contributes to client comfort

Educating client and family members about the sodium-restricted diet.

Administer prescribed diuretics.

Proper position of patient- support pillows on extremities. Semi 30-45degree) to high-fowlers ( 60 degree) position for dyspniec patient.

Monitor oxygen saturation levels(Spo2) for evident impaired gas exchange.

Monitor laboratory values, including electrolytes level

ELECTROLYTE BALANCE

ELECTROLYTES

Are substances that dissociate in solution to form charged particles called ion.

Cations are positively charged ions.Anions are negatively charged electrolytes.Example:(NaCl) in solution dissociates into : a sodium ion, a cation carrying a positive charge (Na+) and a chloride ion, an anion carrying a negative charge (Cl-)

Functions of Electrolytes:Assist in regulating water balance.Help regulate and maintain acid-base balanceContribute to enzymatic reactions.Are essential for carrying out neuromuscular activity.

VALUES mEq/L and mg/dL:Note: Concentration of electrolytes in body fluids generally is measured in milli equivalents per liter of water (mEq/L).Ex. 100 mEq of (Na+) can combine with 100 mEq/L of (Cl-) to form (NaCl).

Note: Other electrolytes are measured by weight in milligrams per 100 ml (1 deciliter) of water (mg/dL). Ex. Calcium, magnesium and phosphorus are often measured by weight in milligrams per deciliter.

NORMAL VALUES FOR ELECTROLYTESAND SERUM OSMOLALITY

SodiumNormal level : 135-145mEq/L.It is the single most abundant electrolyte in the ECFHolds a central position in fluid and electrolyte balanceIt is the only electrolyte exerting significant osmotic pressureSodium salts:Account for 90-95% of all solutes in the ECFContribute 280 mosm of the total 300 mosm ECF solute concentrationRegulated by dietary intake, aldosterone & kidneys

Hyponatremia (Na < 135mEq/L)

Occurs with net loss of sodium or net water excess Kidney disease with salt wasting, adrenal insufficiency, GI losses, increased sweating, diuretics.

S&S: Altered mental status, postural hypotension, postural dizziness, abdomen cramping, diarrhoea, tachycardia, convulsions and coma

TreatmentDetermine if hyponatremia AcuteChronic

Acute serum sodium

Hypernatremia (Na > 145mEq/L)

Caused by - Increased water loss- Water deprivation - Excess salt intake - Hypertonic solutions - Excess aldosterone - Diabetes Insipidus

Correction of Hypernatremia Treat the underlying causeAsymptomatic 5% dextrose in H2O0.45% Saline preferable in hyperosmolar diabetic coma. Very large volumes of 5litres a day may be needed to be given.Symptomatic Serum sodium > 160mEq/LtSerum osmolality > 350mOsmTreatment0.9% saline to correct volume deficit after volume restoration changed to a hypotonic I.V. fluidCorrect over a period of 48 hrs as rapid correction may lead to cerebral oedema.

PotassiumMajor cation in intracellular compartmentsRegulates metabolic activities, necessary for glycogen deposits in liver and skeletal muscle, transmission and conduction of nerve impulses, normal cardiac conduction and skeletal and smooth muscle contraction Regulated by dietary intake and renal excretionNormal level 3.5-5.0mEq/LBody conserves potassium poorlyIncreased urine output decreases serum K+

- For every 3 k+ ions going out 2 Na+ ions and 1 H+ enter the cell resulting in intracellular acidosis and extracellular alkalosis

Potassium Balance

Clinical Signs and SymptomsCardiacFlattened T wave.Dysarrhythmias ST depression Hypotension2. NeuromuscularWeaknessRespiratory failure - Confusion3. RenalPolyureaMetabolic alkalosisDecreased GFR4. Metabolic Glucose intolerance secondary to decreased insulin release

Correction of alkalosis/acidosis, Volume deficits

Other electrolyte disturbances.

Replace GI fluids upto upper limits of loss if person has normal renal function.

4. Oral supplements : Increased intake of fresh fruits and vegetables or potassium supplements of 20 to 40mmol daily.

5. Patients with high renal losses (use potassium sparings diuretics E.g. Spironolactone.)

Treatment

In emergency situation 20-40mEq / hr of potassium can be given with frequent monitoring of cardiac status and serum potassium levels. In non-emergency situations 10mEq of potassium / hr Use glucose free solutions as glucose drives potassium intracellularly.In the absence of specific indications potassium should not be given

To oliguric patients

During the first 24 hours following severe surgical stress or trauma.

Remember

Hyperkalemia (K+ > 5.3mEq/L)Clinical Signs and Symptoms

CardiacPeaked T waveQRS widening.ST depressionBradycardiaHeart blockAsystoleVentricular fibrillationNeuromuscularWeaknessParesthesia

Respiratory Faliure

Diagnosis

ECG changesSerum potassium levelECG FeatureHypokalaemia HyperkalaemiaP waveNormal / amplitude / absentQRS interval Wide with normal shape wide & slurredQT interval NormalT wave flat or inverted Tall, tent like

MANAGEMENT OF SEVERE ACUTE HYPERKALAEMIA (K+ > 7mmol/L) Identify and treat causeSpecially check renal function10 20 mL intravenous 10% Calcium Chloride/ Calcium Gluconate over 10 min in patients with ECG abnormalities 50 mL 50% dextrose plus 10 units short acting insulin over 2-3minMonitor plasma glucose and K+ over next (30-60 min)Regular Salbutomol nebulizersConsider oral or rectal Ca+2Resonium (ion exchange resin)Haemodialysis for persistent hyperkalemia.

CalciumStored in bone, plasma and body cells90% in bones1% in ECFIn plasma, binds with albuminNecessary for bone and teeth formation, blood clotting, hormone secretion, cell membrane integrity, cardiac conduction, transmission of nerve impulses, and muscle contractionNormal level 4.5-5.5mEq/L or 8 11 mg%Regulated by CalitoninParatharmone Calcitriol

Hypercalcemia (Ca+2 > 5mEq/L) > 15mg % Frequently symptom of underlying disease with excess bone resorption and release of calcium

Hyperparathyroidism, malignant neoplastic disease, Pagets disease, Osteoporosis, prolonged immobization, acidosis

S&S: anorexia, nausea and vomiting, weakness, kidney stonesDiagnosis Radiographs show bone resorbtionCardiac irregularities

Hypocalcemia (Ca+2 < 4.0mEq/L)

Seen in - severe illness - hypoalbuminemia, hypoparathyroidism - Vitamin D deficiency, Pancreatitis, Alkalosis - Massive blood transfusion with citrate

S&S: numbness and tingling, hyperactive reflexes, tetany, muscle cramps, pathological fracture

Chloride BalanceMajor anion in ECFNormal level 95-108mEq/LFollows sodiumRegulated by dietary intake and the kidneysDisturbance usually seen with acid-base imbalanceHyperchloremia (Na >145, Bicarb 7.45)Excess vomiting or N/G drainage; loop diuretics because of sodium excretionLeads to metabolic alkalosis due to reabsorption of bicarbonate to maintain electrical neutrality .

Magnesium BalanceNormal conc. 1.5 2.4 mg%Essential for proper functioning of enzyme systemsDepletion characterised by neuromuscular & CNS hyperactivity.

Mg+2 Chvostek & Trousseau sign PR & QT interval

Treatment if < 1.5mg% = 1 mEq/ Kg if 1.5 1.8mg% = o.5mEq/ kg Mg+2Respiratory Depression BP, Cardiac arrest, Hyporeflexia

Treatment Calcium InfusionLoop diuretics with NSMgCl2 / MgSo4

Chvostek & Trousseau sign

TheChvostek signis a clinicalsignof existing nerve hyperexcitability (tetany) seen inhypocalcemia.When thefacial nerveis tapped at the angle of the jaw (i.e.masseter muscle), the facial muscles on the same side of the face will contract momentarily (typically a twitch of the nose or lips) because ofhypocalcemiawith resultant hyperexcitability of nerves. Though classically described inhypocalcemia, this sign may also be encountered inrespiratory alkalosis, such as that seen inhyperventilation.

Trousseau sign is amedical signobserved in patients with hypocalcemia.

A blood pressure cuffis placed around the arm and inflated to a pressure greater than thesystolic blood pressureand held in place for 3 minutes. This will occlude thebrachial artery. In the absence of blood flow, the patient's hypocalcemia and subsequent neuromuscular irritability will induce spasm of the muscles of the hand and forearm. The wrist andmetacarpophalangeal jointsflex and the fingersadduct.

Solute Overview Intracellular v/s Extracellular

Ionic composition very differentTotal ionic concentration very similarTotal osmotic concentrations virtually identical Osmolarity is identical in all body fluid compartments

Body control systems regulate ingestion and excretion: - constant total body water - constant total body osmolarity Homeostatic mechanisms respond to changes in ECF No receptors directly monitor fluid or electrolyte balance. Respond to changes in plasma volume or osmotic concentrations

Principles of Body Water Distribution

Disorders in the fluid balance are classified in three general categories.

Disturbances of - Volume- Concentration- Composition

Classification of Body Fluid Changes

Renal insufficiency, Chronic heart faliureCirrhosis Drugs NSAIDS, MineralocorticiodsECF is diluted sodium content is normal but excess water is present called as Hypotonic HydrationThe resulting hyponatremia promotes net osmosis into tissue cells, causing swelling.These events must be quickly reversed to prevent severe metabolic disturbances.ECF EXCESS

Disorders of Water Balance: Hypotonic HydrationExcessive H2O enters the ECF12ECF osmotic pressure falls3H2O moves into cells by osmosis; cells swell

ECF Deficit

CAUSES1. Loss of GI fluids due to: a. Vomiting b. Diarrhea c. Nasogastric suction d. Fistular drainage2. Soft tissue injuries and infections3. Intra-abdominal and Intra-peritoneal inflammatory processes4. Burns5. Insensible losses6. Sweat

DehydrationExcessive loss of H2O from ECF123ECF osmotic pressure risesCells lose H2O to ECF by osmosis; cells shrinkECF Deficit : When salt depletion is greater, fluid loss is borne by ECFLab Test: Hematocrit value of 45% indicates an ECF deficit.

ICF Deficit : When water depletion is predominant, the greatest fluid loss is sustained by the intracellular compartment Lab Test :The sodium concentration is an indirect measure of the fluid.Higher sodium value indicates an ICF Deficit

Clinical EvaluationChanges in body weight should be recorded accurately and repeatedly on a day to day basis.

Weight loss > 300 to 500gms per day indicate dehydration secondary to decreased fluid intake and / or increased water losses.

Water lossDegree of Dehydration4% of body wt Mild6% Moderate8% Severe

Principles of Fluid Therapy

Whenever fluid therapy is contemplated in a patient, the following basic questions must be considered.Does the patient need fluid..?Which fluid would be most suitable..?How much fluid is needed..?At what rate..?Which route is to be used..?What are the likely complications..?

Does the Patient Need Fluids.. Pre-existing disease processesCancer, cardiovascular, renal, GIAgeInfants have higher % water- loss felt fasterElderly kidneys decreased filtration rate, less functioning nephrons, dont excrete mediations as fastAcute illnessSurgery, burns, respiratory disorders, head injuryEnvironmental Vigorous exercise, temperature extremesDietFluids and electrolytes gained through dietMedications Side-effects may cause fluid and/or electrolyte imbalances

Medications Likely to Cause F&E ImbalancesDiureticsMetabolic alkalosis, hyperkalemia, hypokalemiaSteroidsMetabolic alkalosisPotassium supplementsGI disturbancesRespiratory center depressants (narcotic analgesics)Respiratory acidosisAntibioticsNephrotoxicity, hyperkalemia, hypernatremiaCalcium carbonate Metabolic alkalosisMagnesium hydroxide (Milk of Mag)hypokalemia

Diagnostics HematocritIf no anemia, can indicate hydration statusBlood creatinineMeasure kidney functionExcreted at constant level if no kidney diseaseBUNIndicates kidney functionMay be affected by cell destruction or steroid therapyDecrease may indicate malnutrition or hepatic damageIncreases with decrease in ECF volumeSerum and urinary electrolyte levelsUrine specific gravity

Assessment of Intravascular Depletion5%thirst, dry mucous membranes,UO 1-2 ml/kg/hr10%tachycardia, oliguria, UO 0.5-1 ml/kg/hr15%-20%tachycardia, hypotension,severe oliguria, UO < 0.5 ml/kg/hr

What Fluids to Give..Choice of a particular fluid depends on Volume statusConcentration abnormalityCompositional abnormality

Crystalloids: - contain Na as the main osmotically active particle - useful for volume expansion (mainly interstitial space) - for maintenance infusion - correction of electrolyte abnormality

Crystalloids Isotonic crystalloids - Lactated Ringers, 0.9% NaCl - only 25% remain intravascularly Hypertonic saline solutions - 3% NaCl - 7% NaCl

Hypotonic solutions - 0.45% NaCl - less than 10% remain intra- vascularly, inadequate for fluid resuscitation

Colloid Solutions Contain high molecular weight substances do not readily migrate across capillary walls

Preparations - Albumin: 5%, 25% - Dextran

Crystalloids and Colloids

CrystalliodColloidIntravascular persistancePoorGoodHaemodynamic stabilisationTransientt1/2 ~ 30 minsProlongedt1/2 ~ 90 minsRequired infusion volumeLargeRatio 4:1 to lossModerateRatio 2:1 to lossRisk of tissue oedemaObviousInsignificantEnhancement of capillary perfusionPoorGoodRisk of anaphylaxisNilLow to moderatePlasma colloid osmotic pressureReducedMaintainedCostInexpensive

Expensive

Oral electrolyte solution: This solution is isotonic and provides a rich source of Na+, K+, Cl- and dextrose. The sodium citrate tends to correct any acidosis.

IV fluids: 0.9% Sodium Chloride - iso osmolar with plasma - serves a good replacement solution for ECF volume - 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 alkalosis What solution to give

Dextrose 5% in Water It provides 50gms of dextrose / L.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.

Dextrose 5% with 0.9% 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

Lactated Ringers Solution This is slightly hypo osmolar compared to plasmaMinimum effect on pH & normal body fluid compositionReplaces both G.I. & ECF lossesUsed 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 - Potassium may be added to be used for maintenance requirements in uncomplicated pt requiring only a short period of parenteral fluids.

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

Practical Crystalloid TherapyIf you infuse NaCl 0.9% 1000ml, all the Na+ will remain in the ECFAs NaCl is isotonic there is no change in ECF osmolality and no water exchange occurs across the cell membraneNaCl expands ECF onlyIntravascular volume will be increased by 250ml

Practical Crystalloid TherapyIf you infuse glucose 5% 1000ml, the glucose will enter the cell and be metabolisedThe water expands both ECF and ICF in proportion to their volumesThe ECF volume will increase by 333mlIntravascular volume will only increase by approximately 100ml

Colloid SolutionsHuman 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.

Dextran

Its a polysaccharide in 0.9% NaCl / 5% DextroseTwo types 40 lasts for 6 hrs70 lasts for 24 hrsFacilitates agglutination of RBC. Thus interferes with susequent cross matching of blood

As in normal health - 0ral Route.

- However when rapid correction of hypovolaemia and other electrolyte abnormalities indicated i.v. route provides a quick access to circulation. - Other routes of parenteral therapy include - Subcutaneous - Per Rectal

What Route to be Used..

Fluid Balance in Pre Op. PeriodCorrect 3rd space lossesCorrect Na+ balanceK+ to be corrected only when adequate urine output maintainedCheck if blood replacement is requiredCalculate Allowable Blood LossPrevention of volume depletion

Third Space LossesIsotonic transfer of ECF from functional body fluid compartments to non-functional compartments.Depends on location and duration of surgical procedure, amount of tissue trauma, ambient temperature, room ventilationReplacement of 3rd space lossesMinimum trauma : 3 4 ml / kg / hrModerate trauma : 5- 6 ml / kg /hrSevere trauma : 7 8 ml / kg / hrSurgeon must remember that by 72 hours post op., this 3rd space loss becomes mobilised which results in increased intravascular volume

Intra Op. Fluid ManagementIf pre-op. volume deficit not addressed --- hypotension3rd space losses to be addressed because ofTissue TraumaExtensive DissectionMay vary from min. to 3 Lt.But no lab methods to exactly quantify fluid lossSo, clinically useful guidelines areReplacement of ECF should begin intra op. Blood should be replaced to maintain an acceptable RBC mass irrespective of any additional fluid/ electrolyte therapyBalanced salt sol. needed intra op. ~ 0.5 1 Lt/ hr. Only max. of 3 Lt. req. during 4 hr major abdominal surgery

Post Op. Fluid Management0 24 hrs.Increased secretion of aldosterone & ADHNa+ & water retentionIf blood loss is there, replace itReplace NPO fluid deficitDNS or RLShould not administer K+ unless definitive deficiency present

24 48 hrs

Replace insensible losses which may vary from 900 1500 ml/ hr because of - Hyper Ventilation- Fever- Tracheostomy upto 1200 ml/ dayLoss replaced by DNS since kidneys conserve Na+ even at this stage .If N-G aspiration is going on then add 1 Lt. of 0.9 NaCl

48 72 hrs.Replace insensible lossesBetter to give isotonic DNS & RL1 Lt Darrows solution to combat K+ loss. This is more important if N-G aspiration is still going on to cover K+ loss via GI secretions

Importance of I/O chartsOutput = urine + vomitus + aspiration + 1000 ml insensible losses + 500 1000 ml sweating lossTotal this has to be replaced

Post Op. Urine OutputOliguria is common in immediate post op. period becauseSurgical stress affects Adrenal Cortex - increase ADH & AldosteroneInsufficient post op. analgesia sympathetic activity increasedGeneral anesthetics decrease glomerular blood flow & thus GFRPersistent oliguria< 20 ml / hr in adults< 1 ml / hr / kg in childrenIf urine output < 0.5 ml / hr / kg for 3 or more hrs. indicative of Acute renal failure

Monitoring urine output, heart rate, BP on repeated basis and comparing them to measure fluid intake assists in determining fluid requirement .Normal urinary output Adult 0.5-1 ml / kg / hrChild 2 ml / kg / hr adequate oxygen saturation

End Parameters for Fluid Replacement Therapy

Fluid Regulation in Young

In neonates most significant source of water loss is insensible water loss through skin ~ 7ml / kg / hrUnder normal renal functionInfants & neonates 2 ml / kgToddlers & school age 1 ml / kg Daily K+ req. = 2mEq/ kg Na+ req. = 3 mEq/ kgReplacement by isotonic sol. with osmolality of ~ 285Maintenance fluid rate 0 10 kg - 4 ml / kg / hr10 20 kg - 40 ml + 2 ml / kg / hr > 20 kg - 60 ml + 1 ml / kg / hr

Blood Replacements

Blood weightage males 66 ml / kg - females 60 ml / kg

Indications If Hb. < 6 gm%Ongoing fluid loss of 100 ml/ hrSevere HaemorrhageGive early in active bleeding

HemodilutionIndicated in surgeries where intra op. blood loss of 2 or more units is anticipated.Removal of arterial/ venous blood pre op. followed by plasma volume restoration with crystalloids/ colloidsBlood reinfused only after cessation of bleeding

Conclusion Surgical management & medical management of oral and maxillofacial surgery patients are intertwined intimately.

The management of fluids & electrolytes & the usage of blood products are governed by basic principles outlined in this seminar.

A favourable surgical outcome is predicated on optimal comprehensive care.

Assessment of intravascular depletion

5% Deficitthirst, dry mucous membranes,UO 1-2 ml/kg/hr10%tachycardia, oliguria, UO 0.5-1 ml/kg/hr15%-20%tachycardia, hypotension,severe oliguria, UO < 0.5 ml/kg/hr

Fluid loss in different types of surgeryHelen G, Lee C, Jason A, Peter. Fluid and electrolyte management. Oral maxillofacial Surg Clin N Am 18 (2006) 7 - 17

Type of surgeryFluid volume { ml/kg/hr }Least trauma only maintenance fluidMinimal trauma 4Moderate trauma 6Severe trauma 1o

Maintainance of fluidsHoliday Segar formula: 4ml/kg for 1st 10kg body wt.[wt.X4ml/hr]2ml/kg for the next 10kg body wt[40+2Xwtml/hr]1ml/kg of body wt over20kg [60+1Xwt ml/hr]

4/2/1 Rule 4 ml/kg/hr for first 10 kg (=40ml/hr) then 2 ml/kg/hr for next 10 kg (=20ml/hr) then 1 ml/kg/hr for any kgs over that This always gives 60ml/hr for first 20 kg then you add 1 ml/kg/hr for each kg over 20 kg

This boils down to: Weight in kg + 40 = Maintenance IV rate/hour. For any person weighing more than 20kg

4/2/1 rule a.k.a Weight+40I prefer the 4/2/1 rule (with a 120 mL/h limit)

Maintenance of fluids

For the first 0 to 10 kg give 100 ml/kg/day

For the next 10 to 20 kg give an additional 50ml/kg/day

For weight > 20 kg give 20 ml/kg/day.

Intra OP Fluid Replacement : Guidelines Correction fluid deficit due to starvation : = duration of starvation in hours X 2 ml/kg+ Maintenance Requirement for the period of surgery : = duration of surgery in hours X 2 ml/kg+ Correction of operative loss

REFERENCES :Human Anatomy & Physiology Marieb .Bailey & Love short practice of surgery. Text Book Of Surgery -S.DasHelen G, Lee C, Jason A, Peter. Fluid and electrolyte management. Oral maxillofacial Surg Clin N Am 18 (2006) 7 17 Principles of Surgery SchwartzPrinciples of Surgery Sabiston Essentials of Human Anatomy & Physiology MariebHuman Physiology A. K. Jain

REFERENCES : Fluid And Electrolytes Physiology - Alan .D .Kaye &W. Grogono Fluid And Electrolytes & Shock - Richard Mullins Text Book Of Physiology Sherwood Guidelines On Fluid Balance Dr . Sanjay Pandey Disorders Of Fluid & Electrolute Balance Glen Matfin & Carol Porth

THE END

Thank you

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