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Compartments

• Water is the most abundant constituent in the body, accounting for 50% of body weight in women and 60% in men.

• Total body water is distributed into two major compartments : 55 -75 % is intracellular (ICF) and 25 -45% is extracellular (ECF).

• The extracellular fluid is comprised of intravascular (IVF) and interstitial fluid (IF).

As a function of

Homeostasis

• To maintain fluid balance an average normal adult requires 2 – 3L/day.

• This accounts for insensible and urinary loss. The insensible losses include respiratory tract(500 -700 ml/day), the skin (350ml/day) and feces(100 ml/day).

• Insensible loss accelerate dramatically in the setting of fever (500 ml/day per 1 C), sweating (upto 1500ml/d) and GI losses.

How to calculate plasma osmalility ?

• Plasma osmolality = 2 * Na + [ Glucose (mg/dl) /18] + [BUN(mg/dl)/2.8]

Fluids are classifieds as crystalloids or colloids based on their ability to diffuse through a parchment membrane.

Crystalloid fluids are electrolyte solution with small molecules that can diffuse freely throughout the extracellular space.

NORMAL SALINE

• NS or isotonic saline contains 154 mEql of Na+ & Cl.

• Infusion of 1L of 0.9% NaCl adds 275ml to plasma volume and 825ml to interstitial volume.

• Total volume expansion is slightly greater than infused volume. This is the result of a fluid shift from intracellular to extracellular space, which occurs because 0.9% NaCl is slightly hypertonic to ECF.

Features

• It is the preferred agent in resuscitation.

• Usual dose for resuscitation is 1-2L in adults & 20ml/kg in pediatrics.

• A loss of 1L of blood requires 3L of fluids to be replaced it is based on the fact that only 30% of the infused volume stays intravascular.

Indication

• Water and salt depletion as diarrhea, vomiting, excessive diuresis or excessive prespiration.

• Treatment of hypovolemic shock.

• Treatment of alkalosis with dehydration.

• DKA

• Fluid challenge in prerenal ARF

• Irrigation for washing of body fluids.

• Treatment of hypercalcemia

Disadvantage

• Resuscitation with NS can lead to neutrophil activation.

• Hypercholermic acidosis is produced due to infusion of large volumes and not of any clinical importance.

• Intracellular potassium depletion

Caution

• NS has to be used cautiously or avoided in hypertensive or preeclamptic patients and in patients with edema due to CCF, renal failure and cirrhosis.

RINGER LACTATE SOLUTION

• During 1880, Sydney Ringer, a British physician developed a solution containing calcium & potassium in a sodium chloride diluent. It was actually intended to promote contraction of heart of frog. It was Alexis hartmann who proposed the addition of sodium lactate to the solution to provide a buffer for the treatment of metabolic acidosis and this solution is called Lactated Ringer's solution also known as Hartmann's solution.

Features

• RL contains Na:130mEq/l, Cl^-: 109mEq/L, K⁺: 4mEq/L, Ca²⁺: 3mEq/L, Lactate : 28mEq/L.The concentration of potassium and calcium is approximately equal to ionised levels in plasma. Therefore it is considered as the most physiological fluid.

• The chloride concentration of RL is 109mEq/L which is almost the plasma chloride levels thereby avoids the risk of hypercholremic acidosis. The lactate in RL accepts a proton and subsequently is metabolised to CO2 & water by leading to release of CO2 in the lung & excretion of water by kidneys.

• NS/RL is the preferred agent in fluid resuscitation.

• 1-2L is administered in adults, 20 ml/kg in pediatric age group.

Indication

• Correction of severe hypovolemia

• DKA

• Replace fluids in postoperative patients, burns, fractures, peritoneal irrigation.

• Diarrhea induced hypovolemia with hypokalemic metabolic acidosis

Disadvantage

• In normal healthy individuals administration of RL doesn't rise blood lactate levels.

• The effect of RL in critically ill patients, patients with circulatory or hepatic insufficiency is not known. But it is believed that RL doesn’t increase the lactate levels significantly because only 25% of administrated fluids stays intravascular . That means administration of 1L of fluid will cause a rise of lacate by 4.6mmol/L.

• Drugs like amphotericin, ampicillin, thiopental should not be infused along with RL because calcium in ringers solution can bind to certain drugs.

• Calcium in Ringer's can bind with citrated anticoagulant in blood products which can inactivate the anticoagulant and promote the formation of clots in donor blood.

• Risk of hyperkalemia in patients with renal failure due to potassium content in RL is minimal.

• Contraindicated in addison's disease.

• In liver disease with severe hypoxia & shock.

5% DEXTROSE

• 1L provides 50gms

• 5% Dextrose corrects dehydration and supplies energy. They are distributed in all compartments and used in intracellular dehydration.

• Contraindication : Cerebral oedema, Neurosurgical procedures, stroke, hypovolemic shock.

• Precautions :

  • IV administration of dextrose solution can cause pain, thrombophlebtis, vein irritation.

  • Prolonged IV administration can cause hypokalemia, hypomagnesemia, hypophosphatemia.

ISOLYTE G

• One L contains : Glucose :50gms, Chloride: 150mEq, Sodium: 65mEq, Ammonium: 69mEq, potassium 17mEq.

• It is used in vomiting and continuous gastric aspiration to replace loss of gastric juice. Because it cause hypochloremic, hypokalemic metabolic alkalosis.

• Ammonia in the fluid is converted into urea and H+ ions by liver and the H+ replaces the lost H+ from the gastric juice.

• It is contraindicated in

  • Hepatic failure

  • Renal failure as it may cause ureamic acidosis

  • Metabolic acidosis

ISOLYTE M

• 1L contains glucose50gms, Chloride: 38mEq, Sodium : 40mEq, Phosphate :15mEq; Acetate :20mEq, Potassium:35mEq.

• It is the richest source of potassium.

• It is used to correct hypokalemia secondary to diarrhea,billous vomiting, prolonged infusion of potassium free IV fluids, ulcerative colitis.

• It can used for parenteral therapy.

• It is contraindicated in renal failure, adrenocortical insufficiency, burns, hyponatremia.

ISOLYTE P

• 1L contains glucose:50gm, Chloride: 22mEq, Sodium:25mEq, Phosphate :3mEq, Magnesium:3mEq, Potassium: 20mEq, Acetate:23mEq.

• Mainly used in infants to provide fluid in infants and children to provide daily water and electrolyte.

• Contraindication: Hyponatremia, renal failure, hypovolemic shock

COLLOIDS

• Colloids are large molecules so they stay in the intravascular system and therefore they are more effective plasma volume expander than crystalloids.

• They include

  • Albumin

  • Dextran

  • Gelatin

  • Hydroxy ethyl starch

DEXTRAN

• Dextrans are glucose polymer produced by a bacterium (Leuconostoc) incubated in a sucrose medium.

• Two forms are available

  • 10% Dextran -40 (Molecular weight 40,000)

  • 6% Dextran- 70 (Molecular weight 70,000)

Features

• Both expands intravascular volume better than 5% albumin or 6% hetastarch.

• Both preparation have a colloid osmotic pressure of 40mmHg.

• They also cause improvement in microcirculation, prevents aggregation of RBC.

Indication

• Correction of hypovolemia

• Prophylaxis of DVT , postoperative & post traumatic thromboembolism.

• To improve blood flow and microcirculation in threatened vascular gangrene.

Side effects

• Acute renal failure

• Causes dose related bleeding tendency that involves impaired platelet aggregation, decreased level of factor VIII & von willebrand factor and enhanced fibrinolysis.

• Anaphylatic reaction

• They can coat the surface of RBC & interfere with ability to cross match blood.

Precaution

• In cardiac failure, CLD, active hemorrhage

• Correct any dehydration if present.

Administration

• Dextran 40/Dextran 70 is given as an IV infusion as 10% solution in 0.9% NS or 5%D.

• 500ml rapid infusion. 1^St 24hrs max dose is 20ml/kg . Subsequent dose is 10ml/kg for 5days.

GELATIN

• It is a sterile pyrogen free, colloidal plasma volume substitute, which contains polymer of the degraded gelatin with electrolytes. Prepared from bovine collagen.

• It contains 35 gm of degraded gelatin , Na+,Cl : 145mEq; Calcium : 12.5mEq, Potassium: 5.1mEq.

• It is less costlier but less effective than other agents to built intravascular volume.

Indication

• For rapid expansion of intravascular volume and correction of hypotension in shock, burns, trauma and intra or postoperative blood loss.

• Prophylactic use in major surgery to reduce total volume of fluid replacement.

• For priming of heart lung machine.

Adverse effect

• Hypersensitivity

• Bronchospasm, hypotension.

Precaution

• Contains calcium so should not be mixed with citrated blood as calcium may cause clotting.

It is available in India as haemaccel.

HETASTARCH

• It is a synthetic colloid available in 6% solution in isotonic saline.

• It has molecular weight of 45000.

• Expanded volume lasts for 24hrs.

• Circulating starch molecules undergo hydrolysis by amylase enzyme in blood, the cleaved small molecules are excreted by kidney.

Features

• It is non antigenic.

• It is less costlier than albumin & potency is comparable to 5% albumin.

• It doesnot interfere with blood grouping or cross matching.

Disadvantage

• Increase in level of serum amaylase upto 3-5 days after of administration makes diagnosis to pancreatitis difficult.

• Like other colloids they have no oxygen carrying capacity & should not allow hematocrit to fall below 30.

• Causes dose related bleeding tendency that involves impaired platelet aggregation, decreased level of factor VIII & von willebrand factor and enhanced fibrinolysis.

Adverse effect

• Vomiting, utricaria, wheeze

Updated on 29/5/2013

Reference :

• Tintinalli

• The ICU : Paul marino

• Practical guidelines on fluid therapy ; Dr. Sanjay pandya

• Resuscitation Fluids. John A Myburgh. Critical Care Medicine, Review Article. NEJM. 2013

• Annual update in intensive care and emergency medicine 2014 ; J.L. Vincent