intravenous fluid therapy

Intravenous Fluid Therapy

--Dr. Mayuri

golhar

INTRODUCTION

• Surgery and anesthesia leads to fluid shifts –• Dehydrated• Old• Hypertensive pt on diuretics• Anesthetic agents block the physiological

response to hypovolemia and stress.• Mechanical ventilation supresses ADH,

ANP Na+ water retention.


FACTORS CONTROLLING BODY WATER

• ADH• Renin/ angiotensin• PTH/ calcitonins• PG, dopaminergic and a receptors• Intrinsic renal properties.


Basic Physiology of Fluid Balance

• Water is the most abundant component in the body.

• Total body water (TBW) accounts for approximately 50% of the lean body weight in women and 60% in men


Fluid Compartments

• Body fluids divided into:– Intracellular compartment – Extracellular compartment, further

divided into:• Interstitial compartment• Intravascular compartment


Fluid Compartments


Intracellular Fluid

Intracellular Fluid 2/3

Extracellular Fluid 1/3

Interstitial Fluid=75%

Intravascular Fluid=25%

Intravascular Compartment

• Consists of: – Plasma– Proteins– Ions – mainly sodium, chloride and

bicarbonates– Minor contributions come from

potassium (K+), magnesium (Mg2+), and plasma proteins (mainly albumin)

• Normal blood volume is about 72 mL/kg of body weight


Interstitial Compartment

• Larger than intravascular compartment• Water and electrolytes pass freely between

blood and interstitial spaces, which have similar ionic composition

• Plasma proteins are not free to pass out of the intravascular space unless there is damage to capillaries, e.g., septic shock or burns

• With fluid loss or fall in blood pressure, water and electrolytes pass from interstitial compartment into blood (intravascular) to maintain volume (physiologic priority)


Intracellular Compartment

• Water within cells: Largest reservoir of body water

• Ionic composition different from extracellular fluid

• Contains high concentration of potassium ions and low sodium and chloride ions

• Normal saline given IV: Tends to remain in extracellular compartment

• Glucose solution gets distributed throughout all body compartments

• Pure water given IV: Causes massive hemolysis (dangerous)


Water distribution

• Osmotic forces are the primary determinants of the water distribution in the body.

• Osmolality is determined by the number of moles of a chemical compound that contributes to the solution's osmotic pressure and is expressed as milliosmoles per kilogram of water (mOsm/kg).

• Solutes that cannot freely cross the cell membrane are restricted to a specified compartment, determine the effective osmolality (or tonicity), that is, the osmotic pressure of that compartment, and generate fluid shifts.

• On the other hand, solutes that passively equilibrate across the cell membranes (e.g., urea with its high lipid solubility) are called ineffective osmoles and do not contribute to water shifts across cell membranes.


• The distribution of water between ECF and ICF compartment depends largely on Na+ and K+ content of each compartment.

• change in osmolality in one compartment will trigger water movement across the cell membranes from the compartment of low osmolality to the one of a higher osmolality.


• The distribution of water between the intravascular and interstitial space differs from that across cell membranes.

• other mechanisms are involved in this exchangebulk flow and diffusion. The rate of exchange in either direction (i.e., net filtration) can be calculated by the law of Starling.

• There are two important, opposing hydrostatic forces: capillary (PC) and tissue (PT) hydrostatic pressure. Because PC is much greater than PT under normal circumstances, hydrostatic forces drive fluid out of the capillaries

• Normally, capillary plasma oncotic pressure (πC) is much greater than tissue (interstitial) oncotic pressure (πT), thereby reabsorbing fluid from the interstitium into the capillaries.


Principles of Fluid Therapy

• Fluid replacement should be as close as possible in volume and composition to those fluids lost

• Acute losses should be replaced quickly• Chronic losses—replace with caution; rapid

infusion may cause fluid overload and heart failure– Better replaced by oral or rectal

rehydration– Mostly deficient in water: Do not

overload with sodium


Abnormal Fluid Losses

• Normal loss of Na and K ions – 1 mmol/kg/hr• Loss of water – ½ mL/kg/hr (+ ½ mL/kg/hr by kidney)• Abnormal losses:

– Increased sweating in hot environment– Fever – 1 degree rise=10% higher than normal

fluid requirement per day– Gut losses – diarrhea– Renal losses – including diuretics and diabetes– Trauma (third space loss) – burns


Types of IV Fluids

• Crystalloids:hypotonic- 5% dextrose ,D5 1/2 NS OR

1/4NSIsotonic- 0.9%Nacl, ringer lactate, ringer

acetateHypertonic- 3%,5%, 7.5% Nacl.• Colloids:Hydroxyethyl starchesGelatinsDextranAlbumin.


• Crystalloids are aqueous solutions of inorganic and small organic molecules, the main solute being either normal saline or glucose. Depending on the concentration of the solute, manufactured crystalloid solutions are isotonic, hypotonic, and hypertonic.

• Colloids, in contrast, are homogeneous noncrystalline substances containing large molecules.

• colloids have much greater capacity to remain within the intravascular space, these solutions may restore the plasma volume more efficiently and may act as volume expanders.


Distribution of IV Fluids in Body Compartments

Distribution of 1,000 mL of fluid

given IV

Intracellular Fluid

Interstitial Fluid

Intravascular Fluid

5% Dextrose 666 249 83

Crystalloid 0 750 250

Colloid

Immediate

0 0 1,000

After 4 hours

0 750 250

Blood 0 0 1,000


CRYSTALLOIDS

• Crystalloid solutions are safe, nontoxic, reaction free, and inexpensive.

• Besides different tonicity, crystalloids can be further categorized into unbalanced (unphysiologic electrolyte composition, no buffers) and balanced (physiologic mixture of electrolytes with buffers) formulations.

• A major disadvantage of hypotonic and isotonic crystalloids is the limited ability to remain within the intravascular space.

• Therefore, to maintain an effective circulating volume, administration of large volumes of crystalloid solutions is required. Accumulation of fluid in the interstitial space with edema formation occurs as a typical side effect.


ISOTONIC


• NaCl is the predominant salt in crystalloids and Na+ equilibrates over the whole ECF compartment, only 25% of the administered crystalloid solution remains intravascular.

• So to replace an intravascular fluid loss with isotonic crystalloid solutions, 3-4 times the volume lost has to be administered.

• Normal saline - nongap, hyperchloremic metabolic acidosis with impaired end organ perfusion and function if large volumes are given intravenously.

• buffers in lactated Ringer's solution (i.e., lactate) or Plasma-Lyte (i.e., acetate and gluconate) are being metabolized to HCO3

- in the liver and may result in a metabolic alkalosis & should be used with caution in patients with preexisting hyperkalemia (e.g., end-stage renal disease) because of their K+ content.

• calcium present in lactated Ringer's solution prohibits its use in the presence of citrated blood products and may precipitate different drugs (e.g., amphotericin B, thiopental).


0.9% NaCl• 500ml, isotonic ( na-154, cl-154)• Ph –acidic to prevent degradation during

sterilization• Mol wt-58• Uses-1. Along with insulin in diabetic patients2. Dehydration- vomiting, sweating, heat

stroke3. Irrigation fluidSide effects1. No calories2. Hyperchloremic acidosis3. Sodium retention- risk in ccf, liver kidney

dysfunction4. Other prepeartion-0.45%, 3,5,7.5%-

hypertonic.


RINGER LACTATE• 500 ml ( 130, 5, 4, 111, 29)• Ph-acidic• Lactatebicarbonate, glucose

CO2 + H20• Uses-1.Fluid therapy intra, post-op2.Preloading and maintainance

( blocks)3.DiabeticsOther preparations-Ringer acetateHartmanns solution



HYPOTONIC


Na

Cl gluco

HYPOTONIC

• Hypotonic crystalloids provide free water to patients with hypertonic dehydration or hypernatremia.

• Several formulations are available, such as D5W, 1/2 NS, and 1/4NS with or without D5W.

• The intravascular volume effect is minor in comparison with that of isotonic crystalloids.

• D5W consists entirely of free water because glucose is being metabolized and water equally distributes in the ICF and ECF compartments only 8% of the administered D5W remains in the intravascular space.

• dextrose-containing solutions should be used with caution ,hyperglycemic-induced hyperosmolality, osmotic diuresis, and cerebral acidosis are known complications.


5% DEXTROSE• 500ml bottle containing dextrose in water• 5 gms of dextrose in 100ml (25gms/500 ml)• 1gm-4.1cal & 0.6 water for oxidation.• Mol wt-109, acidic pH to prevent

degradation of sugar• This prevents hemolysis and is isotonic with

plasma• Uses-1. minimizes hypoglycemia, hydration.2. Carrier for drugs3. Maintain patency of Iv lineSide effects-1. diuresis, 2. electrolyte imbalance, 3. hyperventilation, 4. rise in ICP, & foetal hypoglcemia



5% DEXTROSE IN SALINE

• Dextrose on 5gms/100ml in 0.9 NaCl

• It provides electrolytes.Other formulations5% with 0.45% Nacl5% with 033% Nacl ( sweat loss)\5% with 0.22% Nacl 2.5% dextrose in 0.45

%Nacl(children)10% , 25, 50 % dextrose



Na Cl PH

HYPERTONIC• Hypertonic solutions such as 7.5% NaCl -

severe hyponatremia. • Hypertonic saline alone or combined with

colloids refers to the concept of “small volume resuscitation” in patients with severe hemorrhage–

1. improve microcirculation, 2. decreased intracerebral pressure, 3. Induce stress protein response and cellular

protection and4. A balanced inflammatory response.


HYDROXYETHYL STARCH• Hydroxyethyl starches are modified natural

polysaccharides similar to glycogen.• They are derived from amylopectin, a highly

branched corn or potato starch. • Starches are rapidly being cleaved by α-

amylase, and, as a result, plasma levels of α-amylase may significantly increase after administration of starches (typically twofold to fivefold). To delay α-amylase breakdown with subsequent elimination from the blood, natural starches are being substituted with hydroxyethyl groups (carbon position C2, C3, and C6), resulting in the clinically used HES preparations.

• Their most important physicochemical characteristics are the molar substitution,

C2/C6 ratio, and molecular weight. .Intravenous Fluid Therapy

• Molar substitution (MS) is defined as the mol hydroxyethyl residues per mol glucose subunits.

• According to the MS, hydroxyethyl starch preparations can be classified into solutions with

1. high (hetastarch, hexastarch; 0.7 and 0.6, i.e., 7 and 6 hydroxyethyl groups for every 10 glucose units, respectively),

2. medium (pentastarch; 0.5), and3. low substitution (tetrastarch; 0.4). High

MS prolongs degradation




The C2/C6 ratio:• refers to the pattern of hydroxyethylation at

the carbon atoms of the glucose rings and is considered high (>8) or low (<8).

• Substituted hydroxyethyl groups at the C2 position are being cleaved much more slowly than at position C6. Therefore, formulations with high C2/C6 ratio are being slowly

degraded and have longer plasma half-lives.


• The low-molecular-weight fraction (<60-70 kD) is rapidly excreted by the kidneys

• the larger molecules have to be hydrolyzed by serum α-amylase before elimination. As a result, the plasma half-life of an HES preparation increases with increasing molecular weight.

• The plasma expanding effect (volume effect) primarily depends on the

1. concentration of the HES solution. 2. Specific physicochemical properties


EFFECTS

1. Vascular resistance is reduced by lowering whole blood viscosity,

2. enhance venous return and increase cardiac output.

3. The net result would be improved blood fluidity, which might beneficially influence tissue perfusion and oxygenation


SIDE EFFECTS• Negative effects on coagulation have been

reported especially by first-generation preparations with high MS (hetastarches).

1. decrease the levels of von Willebrand factor (vWF) and associated factor VIII activity (acquired, type I von Willebrand–like syndrome),

2. impair platelet function (coating), and may induce platelet damage.

3. Patients with blood group O have significantly lower levels of vWF/VIII and these levels are further reduced.

4. renal dysfunction probably because of hyperviscosity of the urine in dehydrated patients.

5. Pruritus and allergic reactions.


GELATINS• Produced by degradation of bovine collagen

and chemical modifications, gelatins are polydispersed colloidal solutions.

• Three types 1. oxy-crosslinked, 2. urea-crosslinked, 3. and succinylated gelatins. 4. molecular weight (average 30-35 kD),

concentrations (3.5%-5.5%) and volume-restoring efficacy (volume effect 70%-100%).


• Small molecular weight, gelatins are rapidly being cleared from the bloodstream by glomerular filtration (>80% are being excreted unchanged by the kidneys) and, to a minor extent, undergo cleavage by proteases into small peptides in the reticuloendothelial system.

• Therefore, repeated infusions of gelatins are necessary to maintain adequate blood volume


• Gelatins do not accumulate in the body, have no dose limitations, and appear to be almost without adverse effects on the kidneys.

• It seems that hemostasis could be impaired by an interference of gelatin with the function of coagulation factors.

• Disadvantages of gelatins are their bovine & have a potential of transmitting prion diseases (e.g., bovine spongiform encephalopathy).

• most frequent incidence of allergic reactions among all colloids (six times higher compared with HES; incidence 0.35%


HAEMACCEL

• 500ml, 3.5% solution• 100ml- 3.5 gms of gelatin• Stable for 3years• Mw wt- 30000-350000• Half life- 2-4 hoursa) Uses- hypovolemiab)Vasovagal shockc) Prelaodingd)haemodilution


s


DEXTRANS• Dextrans are polydispersed colloids -

synthesized from sucrose by the bacterium Leuconostoc mesenteroides.

• The formulations most frequently selected are dextran 40 and dextran 70, with molecular weights of 40 and 70 kD, respectively.

• After intravenous administration, small dextran molecules less than 50 kD are rapidly eliminated by the kidneys (filtration). All other molecules are being metabolized to carbon dioxide and water by cell-bound enzymes in the kidneys, liver, and spleen.

• Dextran solutions decrease blood viscosity, improved microcirculatory blood and tissue perfusion.

• Dextran 40 effectively reduce whole blood viscosity than all other plasma substitutes , also helps in keeping microvascular anastomoses patent.



• Dextran infusion induces a dose-dependent hyperfibrinolysis and an acquired von Willebrand's syndrome with decreased levels of vWF and associated factor VIII

• Maximal daily dosage recommendation of 1.5 g dextran/kg body weight to avoid serious bleeding complications.

• Impaired renal function -tubular obstruction, swelling, and vacuolization of tubular cells (osmotic nephrosis–like lesions) due to the production of hyperviscous urine.

• Anaphylactic reactions.TREATMENT-dextran 1 (Promit), a low-molecular-weight hapten, has to be administered a few minutes before any dextran infusion.

• dextran 70 -preferred for volume expansion• dextran 40 improves microcirculation, by

decreasing blood viscosity.


HUMAN ALBUMIN• Albumin is purified from human plasma and is

commercially available as a1. 5% (iso-oncotic), 2. 20%, or 25% (hyperoncotic) solution. Because

albumin is heated and sterilized by ultrafiltration, the risk of bacterial or viral disease transmission should be eliminated.

• Albumin is the most abundant plasma protein. 1. Maintains plasma oncotic pressure 2. proper distribution of body fluids between intravascular

and interstitial space. 3. acts as a transport protein by binding.4. Serum albumin concentration is an independent

predictor of mortality risk in patients with acute and chronic illness



• management of a diverse range of medical and surgical problems.

a) restoration of an effective circulating volume due to hemorrhage,

b) the acute management of burnsc) hypoproteinemia• high costs of albumin, reserved for selected

patients only. • The risk of allergic reaction is 3.4 times less

than that of gelatins and almost identical to that of HES


CRYSTALLOIDS V/S COLLOIDS

• crystalloids are 1. inexpensive 2. adverse effects are

rare or absent3. There is no renal

impairment, 4. minimal interaction

with coagulation 5. no tissue

accumulation, 6. and no allergic

reactions

• Colloids are1. better volume-

expanding properties,2. minor edema

formation3. improved

microcirculation.4. Improve tissue

oxygenation.5. expensive


BALANCED V/S UNBALANCED

• Unbalanced, unbuffered solution causes-

1. hyperchloremic metabolic acidosis,

2. organ hypoperfusion and

3. increased morbidity, 4. especially

gastrointestinal, neurologic, and renal damage,

5. as well as blood loss

• buffered balanced –

1. maintain a higher plasma pH and less chloride load, leading to

2. fewer incidences of hyperchloremic metabolic acidosis

3. reduction in postoperative morbidity. So often preferred in the perioperative period.

HES preparations is now available in balanced crystalloid solutions

(balanced HES 670/0.7 [Hextend] and balanced HES 130/0.4 [Voluven balanced

Assessment of fluid balance


Types of fluid therapy

There are two components to fluid therapy:• Maintenance therapy replaces normal

ongoing losses, and• Replacement therapy corrects any existing

water and electrolyte deficits.


Maintenance therapy

• Maintenance therapy is usually undertaken when the individual is not expected to eat or drink normally for a longer time (eg, perioperatively or on a ventilator).

• Most people are “NPO” for 12 hours each day.

• Patients who won’t eat for one to two weeks should be considered for parenteral or enteralnutrition.

• Maintenance Requirements can be broken into water and electrolyte requirements


Water

• Two liters of water per day are generally sufficient for adults;

• Most of this minimum intake is usually derived from the water contentof food and the water of oxidation, therefore

• it has been estimated that only 500ml of water needs be imbibed given normal diet and no increased losses.

• These sources of water are markedly reduced in patients who are not eating and so must be replaced by maintenance fluids


Holiday and Segar rule


BODYWT(kg)

FLUIDRATE(ml/kg)

0-10 4

11-20 2

>21 1

total

Routine intravascular fluid administration

• CVE + DEFICIT + MAINTAINANCE + LOSS + THIRD SPACE LOSS

• THIRD SPACE LOSS-as a result of tissue oedma and transcellular fluid displacement.

• CVE-compensatory intravascular volume expansion –venodilatation and cardiac depression caused by anesthesia


Pediatric patient

• Neonates have a reduced ability to dilute or concentrate urine and have increased fluid requirements.

• They should not be without fluid for > 3-4 hrs.

• 0.3% Nacl is preferred with K, dextrose should not exceed > 5mg/kg/min- 2.5% dextrose.


Patient with liver failure

• may have simultaneous hypo-hypervolumia

• Cirrhotics- low SVR, high CO & hypotension vasodilation aldosterone Na retention ECF vol expansion, acitis and portal HTN.

• Avoid fluid overload,maintain normal K and intravascular volume.

• 5% albumin is preferred over crystalloids


Heart failure

• Optimize cardiac preload, avoid overadministration Of Na, diminish oedema.

• These pts have impaired ability to excrete fluids and primary electrolyte problems.

• Intraop monitering, iv fluid challenge(500-1000ml/70kg crys) should be performed to optimize preload levels.

• ECF is already expanded so rate of fluid infusion should be very slow, if preload becomes excessive diuretics should be administered


Cerebral edema and burns patients

• Maintain cerebral perfusion, avoid increased cerebral venous pressure and hypertension and hyperglycemia.

• Free water restriction without hypovolemia is desired, Na -142-148mEq/lt. Maintaince fluids- 0.9%NaCl/ RL they avoid edema and can be used to sustain iv volume.

• BURNS– aim is to restore plasma volume, shift of ECV to burned but viable tissue,

• Tissue injurydistruption of the capillary bed vasodilation, increased permeability.

• Water, electrolytes & Protein enter the burned tissue at the expense of IVV.

• Mobilization of fluid from the normal to the injured tissue resulting in intravascular hypovolemia, tissue edema. There is also loss of water by evaporation, high metabolic rate leading to increased fluid requirement.

• So close hemodynamic monitering with titration of therapy is requuired.

• Parklands formula- RL-(0.25ml/kg) / ( %BSA burmed) / hr- 8hrs

RL-(0.125ml/kg) / (%BSAburned)/ hr- 16hrs5% dextrose in water(0.8ml/kg/)/ (% BSA

burned )/ hr+ 5% albumin(0.015ml/kg)/(%BSA burned) for 24 hrs


Preelampsia

• Aim is to restore the contracted volume and excessive intravascular fluid restoration because of normal postpartum fluid mobilization.

• Replace insensible and sensible water loss from labor.

• Plasma volume is lower in these pt because of raised venous pressure due to uterine compression , natreuresis, hypoproteinemia, vasoconstriction.

• these pt are at risk of cerebral and pulmonary odema- so isotonic fluids are prefered.


• THANK YOU…..


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intravenous fluid therapy