Some slides were taken from:

Fluid Management OnlineIntravenous Fluids: A Clinical Approach

JAI RADHAKRISHNAN, MDDivision of Nephrology

Other references:

The Washington Manual of Medical Therapeutics

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Outline

Review of normal physiology of fluid and electrolyte flux: Volume of distribution

Concepts of osmolality and tonicity Types of Intravenous Fluids Composition of IV Fluids Types of fluid depletion Specific clinical examples and

treatment2

Composition of Body Fluids Total Body Water

Male: 60% Female: 50% Difference due to adiposity

Extracellular Fluid 25-45% Plasma (intravascular) 25% Interstitial (extra-vascular) 75%

Na, Cl, HCO3

Intracellular Fluid 55-75% K, organic phosphate esters

Thus, sodium for volume, potassium for cell function!

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Volume of Distribution of Water

60%-Males

50%-Females

H2O

Solids

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Intracellular

(2/3)

Extracellular

(1/3)

Solids 40% of Wt

H2O H2O

Na

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Intra-vascular1/4

E.C.F. COMPARTMENTS

Interstitial 3/4

H2O H2O

NaNa

Colloids & RBC

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“Third Space”

Acute sequestration in a body compartment that is not in equilibrium with ECF

Examples: Intestinal obstruction Severe pancreatitis Peritonitis Major venous obstruction Capillary leak syndrome Burns

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Daily Fluid Balance

Intake

Insensible Losses (approx 500mL)-Lungs 0.3L-Sweat 0.1 L

Urine: 1.0 to 1.5L

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Daily Fluid Balance Sum of the - Urine output (500-1,500 ml/day) necessary

to excrete the daily solute load + - the insensible water losses from the skin

and respiratory tract MINUS - Amount of water produced from the

endogenous metabolism (200-350 ml/day) [UO + Insensible water loss] – endogenous

metab = [1,500 + 500] – 250 = 1750 mL

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More on Insensible Losses Insensible losses from skin and respiratory

tract depend on respiratory rate, ambient temperature, humidity and body temperature

Water losses increase by 100-150 ml/day for each degree of body temperature

Fluid loss from sweating: highly variable (100-2,000 mL/hour) depending on physical activity, ambient and body temperatures

Mechanical ventilation with humidified gases may minimize losses from the respiratory tract

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Other causes of water loss Gastrointestinal Losses: vary in composition

and volume depending on their source Renal losses of sodium are usually minimal,

but maybe significant in diuretic therapy, recovery phase of acute tubular necrosis (ATN), post-obstructive diuresis or mineralocorticoid deficiency

Rapid internal fluid shifts: peritonitis, pancreatitis, extensive burns, severe nephrotic syndrome, ileus or intestinal obstruction, crush injuries, rhabdomyolysis [3rd SPACING]

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MATH-70 kg male

Total body water=60% body wt

=0.6X70=42 liters

ECF=1/3

0.3X42=13 liters

ICF=2/3

0.6 X42=25 liters

Blood=1/4 (ECF)

0.25X13=3. 3 liters

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Principles of Treatment

How much volume? Need to estimate the fluid deficit

Which fluid? Which fluid compartment is

predominantly affected? Need evaluation of other

acid/base/electrolyte/nutrition issues.

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Indications for Prescription of IV Fluids

I. Highest priority a) Defend haemodynamics

1. Re-expand a severely contracted ECF volume

2. Prevent a fall in BP when venous tone is

low (e.g., anesthesia)

b) Return the ICF volume towards normal

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Indications for Prescription of IV Fluids

Moderate priority 1. Re-expand a modestly contracted

ECF volume Replace ongoing losses Avoid oliguria Giving maintenance fluids to match

insensible losses : Match estimated electrolyte-free water loss in sweat and in the GI tract

2. To provide glucose as fuel for the brain e.g. during hypoglycemia

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The IV Fluid Supermarket Crystalloids

Dextrose in water D5W D10W D50W

Saline Isotonic (0.9% or “normal”) Hypotonic (0.45%, 0.25%) Hypertonic

Combo D5NM/D5NR D5NSS D10NS

Ringer’s lactate “physiologic” (K, HCO3, Mg, Ca)

Colloids Albumin

5% in NS 25% (Salt Poor)

Dextrans Hydroxyethyl starch

(HES); Hetastarch Haemaccel Gelofusine

Blood

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Types of Intravenous Fluids 2 types of fluids that are used for

intravenous infusions: crystalloids and colloids.

Crystalloids are aqueous solutions of mineral salts or other water soluble molecules.

Colloids contain larger insoluble molecules (particles suspended in solution), such as gelatin; blood itself is a colloid

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Crystalloids

Intravenous infusion fluids which are composed of solutions of crystalline substances, such as sodium chloride, potassium chloride or glucose.

(Water and salts = water and electrolytes)

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What are Colloids?

Colloid is the name given to a microparticulate dispersal of one substance in another.

Colloid vs solution? Colloids are physically separable (they may be separated by ultra-filtration or centrifugation), whereas a solution requires chemical separation such as evaporation or chemical reaction (you cannot filter the sugar out of your tea, nor centrifuge it out).

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Colloids in Medicine

In medicine, the term "colloids” refers to IV fluids formed by a colloidal suspension of large molecules in a water- or saline-based medium.

Suspensions of macromolecules, usually in a saline medium.

These may be physiological (such as 4.5% albumin), semi-synthetic such as succinylated gelatine (which in turn is solubilised bovine), or semi-synthetic such as hydroxyethyl starch

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Colloids Contain particles which do not readily cross

semi-permeable membranes such as the capillary membrane

These large molecules tend to remain in the vascular compartment after infusion ------ > exert an osmotic pressure which tends to keep water in the vascular compartment, thereby helping to expand the circulating blood volume and resist redistribution

Thus the volume infused stays (initially) almost entirely within the intravascular space

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Colloids Stay in the intravascular compartment for a

prolonged period compared to crystalloids However, leak out of the intravascular space

when the capillary permeability significantly changes e.g. severe trauma or sepsis, burns

Until recently they were regarded as the gold standard for intravascular resuscitation (see next slide)

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.

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Efficacy & Safety of Colloids Conflicting evidence about their efficacy; Consensus view: in acute volume

replacement, they are no better than crystalloids, and may be harmful in some circumstances.

Foreign proteins such as gelatin or HES may provoke anaphylaxis in rare circumstances.

However, there are strong adherents to their use.

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Colloids versus Crystalloids Colloids preserve a high colloid osmotic

pressure in the blood, while, on the other hand, this parameter is decreased by crystalloids due to hemodilution.

However, there is still controversy to any actual difference in efficacy.

Another difference is that crystalloids generally are much cheaper than colloids.

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Colloids versus Crystalloids for Fluid Resuscitation Evidence Base Colloids have no clinical advantage

compared to crystalloids for fluid resuscitation in critically ill adult or children

Hypo-volemic patients given albumin instead of saline does not reduce mortality

Albumin does not reduce mortality in critically ill patients with burns and hypo-albuminemia

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In children with severe malaria, resuscitation with albumin has lower mortality than resuscitation with saline infusion or Gelofusine/ Gelafundin (HES)

In critical traumatic brain injury treatment with albumin compared to saline is likely to be ineffective or harmful

intensive care serum albumin concentration is irrelevant, outcome is the same with saline or albumin

http://www.ganfyd.org/index.php

Colloids versus Crystalloids for Fluid Resuscitation

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Properties of IV Fluids

The amount of solute in a solution influences two related, but subtly different properties: osmolality and tonicity

Osmolality versus tonicity Osmolality refers to the amt of solute= solute or

particle concentration Tonicity: osmotic effect of the solution in

relation to another solution across a semi-permeable membrane.

Osmolality is independent of the context whereas Tonicity is defined relative to a reference point

(usually blood or intracellular osmolality); dependent on whether the solute can pass freely through the cell membrane. 27

Osmolality versus tonicity Solutes that are restricted to the ECF

(Na+ and accompanying anions) or the ICF (K+ salts and organic phosphate esters) determine the effective osmolality or tonicity of the compartment

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Tonicity

A complex concept because cell permeability varies with cell type and circumstances.

For example, in a non-diabetic, glucose is s rapidly transported into cells and so exerts little persisting osmotic effect, whereas in an insulin-deficient Type 1 diabetic glucose cannot enter the cells and remains in the intravascular space where it exerts a hypertonic effect.

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Tonicity and Osmolality

Most solutions aim to be iso-osmolar to reduce osmotic damage to blood cells and irritation to the veins

However, a hyperosmolar solution such as 5% glucose with 20mmol KCl can actually be effectively hypotonic as the glucose is rapidly absorbed into the cells leaving only the 20mmol KCl and electrolyte-free water

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Water Balance [N] Plasma Osmolarity: 285-295

mOsm/kg Works within a narrow range Senses 1-2% tonicity change To achieve steady state

INTAKE should approximately equal EXCRETION

Intake regulated by thirst receptors Excretion regulated by AVP

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Presenting the

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Crystalloids

The most commonly used crystalloid fluid is normal saline, a solution of sodium chloride at 0.9% concentration, which is close to the concentration in the blood (isotonic)

Ringer’s lactate or Ringer's acetate is another isotonic solution often used for large-volume fluid replacement

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Crystalloids

A solution of 5% dextrose and water, sometimes called D5W, is often used instead if the patient is at risk for having low glucose or high sodium

The choice of fluids may also depend on the chemical properties of the medications being given.

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Commonly Used Parenteral Solutions

IV Solution Osmolality

(mOsm/kg)

[Glucose]

(g/L)

[Sodium] (mmol/L)

[Cl-] (mmol/L)

5% D/W 278 50 0 0

10% D/W 556 100 0 0

50% D/W 2778 500 0 0

0.45% NaCl * 154 ----- 77 77

0.9% NaCl* 308 ----- 154 154

3% NaCl 1026 ----- 513 513

Lactated Ringer’s**

274 ----- 130 109* also available with 5% dextrose

** also contains 4 mmol K+, 1.5 mmol Ca++, 28 mmol lactate 36

Saline solutions

0.9% Normal Saline – ‘Salt and water’ Principal fluid used for intravascular resuscitation &

replacement of salt loss e.g diarrhea and vomiting Contains: Na+ 154 mmol/l, K+ - Nil, Cl- - 154 mmol/l;

But K+ is often added IsoOsmolar compared to normal plasma Distribution: Stays almost entirely in the Extracellular

space

Of 1 litre – 750ml ECF; 250ml intravascular fluid So for 100 ml blood loss – need to give 400ml

normal saline [only 25% remains intravascular]

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Total body water

ECF=1 liter ICF=0

Intravascular

=1/4 ECF=250 ml

1 Liter 0.9% saline

Interstitial=3/4 of ECF=750ml

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0.45 NSS= Half normal salineHYPOtonic saline Reserved for severe hyperosmolar states (for

maintenance fuids) e.g. H.H.S or DKA and severe dehydration

Leads to HYPOnatremia if plasma sodium is normal

May cause rapid reduction in serum sodium if used in excess or infused too rapidly. This may lead to cerebral edema and rarely, central pontine demyelinosis ; Use with caution!

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Hypertonic Saline

1.8, 3.0, 7.0, 7.5 and 10% Saline Reserved for plasma expansion with colloids In practice rarely used in general wards; Reserved

for high dependency, specialist areas Distributed almost entirely in the ECF and

intravascular space. This leads to an osmotic gradient between the ECF and ICF, causing passage of fluid into the EC space. This fluid distributes itself evenly across the ECF and intravascualr space, in turn leading to intravascular repletion.

Large volumes will cause HYPERnatraemia and Intracelullar dehydration.

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Glucose solutions

5% Dextrose (often written D5W) – ‘Sugar and Water’

Primarily used to maintain water balance in patients who are not able to take anything by mouth;

Commonly used post-operatively in conjunction with salt retaining fluids i.e saline

Provides some calories [ 10% of daily requirements]

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

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D5W Distribution: <10% Intravascular; > 66%

intracellular When infused is rapidly redistributed into

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

For every 100ml blood loss – need 1000ml dextrose replacement [10% retained in intravascular space]

Common cause of iatrogenic hyponatremia in surgical patient

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1 liter 5% Dextrose (D5W)

Total body water=1 liter

ECF=1/3 = 300ml ICF=2/3 = 700ml

Intravascular

=1/4 of ECF~75ml

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Total body water

ECF=1 liter ICF=0

Intravascular

=1/4 ECF=250 ml

1 Liter D5NM/D5NR

Interstitial=3/4 of ECF=750ml

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Colloid: 1 liter 5% Albumin

Intravascular=1 liter

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A Comparison of Albumin and Saline for Fluid Resuscitation in the Intensive Care Unit

N Engl J Med. 2004 May 27;350(22):2247-56. 47

Volume Deficit-Clinical Types Total body water:

Water loss (diabetes insipidus, osmotic diarrhea)

Extracellular: Salt and water loss (secretory diarrhea,

ascites, edema) Third spacing

Intravascular: Acute hemorrhage

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Clinical Diagnosis Intravascular depletion

Hemodynamic effects BP HR JVP Cool extremities Reduced sweating Dry mucus membranes

• E.C.F. depletion– Skin turgor, sunken eyeballs – Weight – Hemodynamic effects

•Water Depletion

ThirstHypernatremia

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Example- GI Bleed

A 55 year old patient presents with massive hematemesis (vomiting blood) x 1 hour. He has a history of peptic ulcer disease.

Exam: Diaphoretic, normal skin turgor.

Supine BP: 120/70 HR 100

Sitting BP: 90/50 HR=140

Lab: Serum Na=140

What is the nature of his fluid deficit ?

What IV fluid resuscitation would you prescribe ?

What do you expect the hematocrit to be :

- at presentation ?

- after 12 hours of Normal Saline treatment?50

Example-Diarrhea and Vomiting

A 23 year old previously healthy medical student returns from vacation in Boracay with a healthy tan and severe diarrhea and vomiting x 48 hours.

Sunken eyeballs, poor skin turgor and dry mucus membranes

BP 80/70 HR 130 supine. Labs: Na 130 K=2.8

HCO3 =12ABG: 7.26/26/100

What is the nature of his fluid deficit ?

What fluid will you prescribe ?

What would happen if D5W were to be used?

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Example-Hyperosmolar State

An 85 year old nursing home resident with dementia, and known diabetes was admitted with confusion.

Exam: Disoriented, restless initially; then stuporous

BP: 110/70 supine 90/70 sitting. Decreased skin turgor.

Labs: Na= 150meq/L Wt=50kgs

BUN/Cr=50/1.8 = 27

Blood sugar= 1200 mg/dl Hct=45

What is the pathogenesis of her fluid and electrolyte disorder ?

How would you treat her ?

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Calculation of Water Deficit

Osm (P Na) x volume

Osm (P Na) x volume

Healthy Dehydrated

A 50 kg female with Na=150

•Na x Normal Body Water = Na x Current Body Water

• (140) (NBW?) = 150 x (0.5 x 50=25 liters)

•NBW (X) = 26.8 liters

•Water deficit = NBW-CBW= 26.8-25=1.8 liters

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A Cirrhotic

A 40-year-old patient with known alcoholic cirrhosis, portal hypertension and ascites is admitted with a rising creatinine.

Exam: BP 100/70 (no orthostasis), JVP 5cms, +++ascites, no peripheral edema, +asterixis.

BUN=12mg/dL Creat=2mg/dL Alb=2.0g/dL

Urine volume has been 200cc/24h.

1. Comment on his fluid status

2. If volume-depleted how would you treat him?

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Example-Post Op Abdominal DistensionA 60 year old male with pancreatic carcinoma has undergone total pancreaticoduodenectomy and gastrojejunal bypass.

On post-operative day-3 he develops abdominal distension.BP= 110/60 and HR increases from 100 to 130 on sitting. Bowel sounds are absent.

Abd XRay reveals multiple fluid levels in the abdomen. N-G suction is initiated.

What is the nature of his fluid deficit ?

How will you treat ?

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Example-Intubated pt

A 64 year old male with severe pneumonia has just been intubated. You were asked to give IVF orders since he has several IV meds.

BP= 120/70 and HR – 91 bpm

Plasma sodium = 128 mmol/L

Potassium – 3.6 mmol/L

Adequate urine output

Is there a fluid deficit ?

What will be your IVF order ?

While he is still NPO?

On NGT OF feeding?56

Case scenarios

1. Unconscious 25 year old, previously healthy, found inside a locked room

2. Unconscious, known diabetic, diaphoretic, tachycardic, afebrile, BP= 150/90 mm Hg

3. Pt with a Stab wound on the abdomen, BP=80/60 mm Hg, awake, restless

4. IVF to follow for a patient with urosepsis, sodium is 150 mmol/L, weak, BP= 100/70 mm Hg

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A Nutritional Dilemma

The patient is being treated with D5W-NS @ 100ml/hour

(5% dextrose in 0.9% saline)

Is the caloric supply adequate ?

Total volume=100mlx24h=2400ml

Total dextrose (5g/100ml)= 5x24=120g/day

Total calories=

120g x 4kcals/g=480 kcals.

**Use D10W-NS instead**58

Conclusions

Crystalloids are generally adequate for most situations needing fluid management.

The composition of the solution and rate of administration are important when addressing a specific situation.

Colloids may be indicated when more rapid hemodynamic equilibration is required (inadequate data).

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THANK YOU VERY MUCH!

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References

Reilly, RF., & Perazella, M.. Acid-Base, Fluids, and Electrolytes (Lange Instant Access). McGraw-Hill Professional. 2007

The Washington Manual of Medical Therapeutics

www.bmj.com

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