Intravenous Fluid

TOTAL BODY WATER

Approx. 60% Body weightVaries with age, gender and body habitus

50% BW in females 80% BW in infants

Less in obese : fat contain little water

Body Water Compartments Intracellular volume : 2/3 of TBW

Extracellular volume : 1/3 of TBW - Intravascular : Plasma volume (1/4)- Extravascular: Interstitial fluid & others(3/4)

Preoperative Evaluation of Fluid Status

- Mental status- H/O intake and output- Blood pressure: supine and standing- Heart rate- Skin turgor- Urinary output- CVP

Orthostatic Hypotension• Systolic blood pressure decrease of greater than

20mmHg from supine to standing

• Indicates fluid deficit of 6-8% body weight- Heart rate should increase as a compensatory

measure- If no increase in heart rate, may indicate autonomic

dysfunction or antihypertensive drug therapy

Osmoles :unit for conc. Of osmotically active particles

Osmolality: osmotic active solute per volume of solution ( mOsm/L)

Osmolarity : mOsm/Kg Plasma osmolarity : 290 mOsm/kg

Tonicity ( relative osmotic activity ) Isotonic/ hypotonic/hypertonic

BASICS

Intravenous Fluids Therapy

Intravenous fluid therapy may consist ofIntravenous fluid therapy may consist of infusions of infusions of crystalloids, colloids, or a combination of both.crystalloids, colloids, or a combination of both.

IndicationsIndications Volume resuscitationVolume resuscitation Vehicle for i/v drugsVehicle for i/v drugs KVOKVO

Types

• Crystalloids• Colloids

Crystalloids Clear fluids made up of water and electrolyte

solutions; Will cross a semi-permeable membrane Grouped as isotonic, hypertonic, and hypotonic Eg:

Normal saline 0.9%,3 % Dextrose solutions 5 %,10%,20%,25%DNSRinger’s lactate Isolyte P

Crystalloids

0.9% Normal Saline Contains: Na+ 154 mmol/l, Cl- - 154 mmol/l Osm : 308mosm/l, pH 6.0 IsoOsmolar compared to normal plasma.

Indication : Intravascular resuscitation and replacement of salt loss e.g. diarrhoea

and vomiting. Also for diluting packed RBCs prior to transfusion Used for diluting Drugs

Distribution: Stays almost entirely in the extracellular space.

Of 1 litre - 750ml extra vascular fluid; 250ml intravascular fluid.

Complications: When given in large volume can produces Hyperchloremic

metabolic acidosis because of high Na+ and Cl- content.

3.0 % Saline = HYPERtonic saline

3% contain 513 mmol/l of Na+ and Cl- each,

osmol of 1026 mOsm/l; pH 5.0

Indications :Treatment of severe symptomatic

hyponatremia (coma, seizure)To resuscitate hypovolemic shock

Must be administered slowly and preferably with CV line because it carries risk of causing phlebitis, necrosis, hemolysis.

Complications : Precaution in pt. with CHF severe renal insufficiency, edema with

sod. retention.

Dextrose

5% Dextrose (often written D5W)

50g/l of glucose, 252mOsm/l, pH 4.5

Regarded as ‘electrolyte free’ – contains NO Sodium, Potassium, Chloride or Calcium

Indication : To maintain water balance in patients

who are not able to take anything by mouth;

Used post-operatively in conjunction with salt retaining fluids ie saline

Hypernatremia treatment

Less than 10% stays in the intravascular space therefore it is of limited use in fluid resuscitation.

Side effects: Iatrogenic hyponatraemia in surgical patient Hyperglycemia Not compatible with blood ,cause hemolysis

conc 5% 10% 20% 25% plasmaOsmolarity 252 505 1010 1262 290

Ringer Lactate Most physiological solution

Electrolyte composition similar to ECF

One litre of lactated Ringer's solution contains: Sodium ion= 130 mmol/L. Chloride ion = 109 mmol/L. Lactate = 28 mmol/L. Potassium ion = 4 mmol/L. Calcium ion = 1.5 mmol/L Osmolarity of 273 , pH of 6.5

Lactate is converted to bicarbonate in liver

Indications :

Deficit ,Intraoperative fluid loss

Severe hypovolemia

Precautions:

Severe metabolic acidosis ( impaired lactate conversion)

Don’t give with blood product ( Ca bind with citrate

reduced anticoagulant activity )

DNS 0.9% saline & 5% dextrose Na+ 154, Cl- 154, 5 gm. Glucose Osm : 432 mosm/L

Indication :Maintenance solutionCorrection of fluid deficit with supply of

energyCompatible with blood

IsoLyte -PMultiple electrolyte & dextrose solution

Na+ : 26K+ : 20 Mg++ : 03 Cl- : 21 Acetate : 23Ph+ : 03Isotonic

Indication :Pediatric maintenance fluid

Colloids

Particles which do not readily cross semi-permeable membranes

Stays (initially) almost entirely within the intravascular space .

Stay intravascular for a prolonged period compared to crystalloids.

However they leak out of the intravascular space when the capillary permeability significantly changes e.g. Severe trauma or sepsis.

Because of their gelatinous properties they cause platelet dysfunction and interfere with fibrinolysis and coagulation factors (factor VIII) – thus they can cause significant coagulopathy in large volumes.

Natural : Albumin Artificial : Gelatin and Dextran , HES

ALBUMIN Principal natural colloid comprising of 50-60% of all plasma proteins. Synthesized only in liver and has a half life of app. 20 days. 5% soln is iso oncotic and leads to 80% initial vol expansion 25% soln

leads to 200-400% increase in vol. Used

For emergency treatment of shock especially due to loss of plasma acute management of burns

Fluid resuscitation in ICU Hypoalbumineamia.

Side effects : pruritis, anaphylactoid reactions and coagulation

abnormalities as compared to synthetic colloids.

Disadvantages cost effectiveness volume overload (in septic shock pt albumin add to

interstitial edema)

DEXTRAN

Highly branched polysaccharide molecules Produced by synthesis using the bacterial enzyme

dextran sucrase from the bacterium Leuconostoc mesenteroids.

Most widely used are 6%(dextran 70) and 10%(dextran 40) soln.

Excreted via kidney primarily.

Used mainly to improve microcirculatory flow in microsurgical re-implantation .

Also used in extracorporeal circulation during cardiopulmnary bypass.

Side effects: Anaphylactic reactions, Coagulation abn, Interference with cross match, Ppt of ARF.

GELATINS

Large mol. wt. proteins formed from hydrolysis of collagen.

Produced by thermal degradation of cattle-bone gelatin.

Gelatins lead to 70-80% of vol expansion Indication :

Rapid expansion of intravascular volume and correction of hypotension

Advantage : cost effectiveness and no effect of renal

impairment ,does not affect coagulationDisadvantage :

HypersensitivityAnaphylactoid reactions

HYDROXYETHYL STARCHES

Derivatives of amylopectin, which is a highly branched compound of starch.

6% HES soln are isooncotic 10% soln are hyper oncotic , with a vol effect

exceeding the infused vol .(about 145%)

Duration of vol expansion is usually 8-12 H.

Advantage Cost effective: cheaper and comparable vol of expansion

to albumin.

Disadvantage: assoc. with 1st & 2nd generation HES- Coagulation abn- Accumulation- Anaphylactoid reactions- Renal impairment- Increase in amylase level

Colloid or Crystalloid ResuscitationRecommendations:

Colloid should NOT be used as the sole fluid replacement in resuscitation ,volumes infused should be limited because of side effects and lack of evidence for their continued use in the acutely ill.

Colloid may be used in limited volume to reduce volume of fluids required or until blood products are available.

In elective surgical patients Replace fluid loss with ‘physiological

Ringer’s solutions.Blood products and colloid may be

needed to replace intravascular volume acutely.

Peri- operative Fluid Requirements

• The following factors must be taken into account:• C V E• Maintenance fluid • Deficit • Third space losses• Replacement of loss

COMPENSATORY INTRAVASCULAR VOLUME EXPANSION

Fluid must be adm. to expand the blood vol to compensate for venodilation (GA,RA)

Expansion with 5-7ml/kg of crystalloid must occur before or simultaneous with the onset of anaesthesia .

Maintenance Fluid Requirements• “4-2-1 Rule”

- 4 ml/kg/hr for the first 10 kg of body weight- 2 ml/kg/hr for the second 10 kg body weight- 1 ml/kg/hr subsequent kg body weight

Eg : 70 Kg ptMaintenance fluid : 40+20+50= 110 ml/hr

Deficit • Deficit = number of hours NPO x maintenance fluid

requirement.• Measurable fluid losses, e.g. NG suctioning, vomiting, stoma

output.

70 kg pt fasting for 8 hrs Deficit : 8 X 110 = 880 ml

Half in first hr One fourth each in next two hr .

Third Space Losses

• Isotonic 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 ventilation.

Replacing Third Space Losses

Minimal Surgical Trauma: 0-2 ml/kg/hr- e.g. herniorrhaphy

Moderate Surgical Trauma: 2-4 ml/kg/hr- e.g. cholecystectomy

Severe surgical trauma: 4-6 ml/kg/hr (or even more)- e.g. major bowel resection

Blood Loss• Replace 4 cc of crystalloid solution per cc of blood

loss (crystalloid solutions leave the intravascular space)

• When using blood products or colloids replace blood loss volume per volume.

Fluid management, starting with a hemoglobin level of 15 g/dL, for a 70-kg patient undergoing gastrectomy who has been fasting for 8 hours. Maintenance rate is 110 mL/hr, Deficit of 880 mL

First hr = CVE+ Half of deficit + maintenance + loss+ third space loss 350+440+110+50 + 420

Second hr = one fourth of deficit + maintenance + loss+ third space loss 220+ 110+ 250 + 420

Third hr = one fourth of deficit + maintenance + loss+ third space loss 220+ 110+ 250 + 420

Fourth hr = Maintenance + loss+ third space loss 110+ 50 + 420

Summary

Most physiological :RL Rich in sodium : NS,DNS Rich in potassium :ISo –p Glucose free: ?RL,NS,3% saline Sodium free: Dextrose Potassium free: NS,DNS,Dextrose Can correct acidosis directly : RL,ISo-p

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