Contents General Description

History

Fluids and Human Body

Uses of IV Fluids

Goals of IV Fluids

Assessment of Fluid volume status

Specific Description

Concept of Osmosis

Osmolarity

Tonicity

Body Fluid compartments

Impact of IV Fluid on Fluid

Compartments

Something About Colloids

Crystalloid

Categories of colloid & Crystalloid

Down sides

Rule of 4:2:1

Drip Rate

Pre, intra & post Operative Maintenance

Complications

Take home message

HISTORY

The first record available that shows an understanding of

the need for fluid in injured patients was apparently from

Ambroise Paré (1510-1590), who urged the use of clysters

(enemas to administer fluid into the rectum) to prevent

“noxious vapors from mounting to the brain.”

The term shock appears to have been first used in 1743 in

a translation of the French treatise of Henri Francois Le

Dran regarding battlefield wounds.

In 1830, Herman provided one of the first clear

descriptions of intravenous (IV) fluid therapy. In response

to a cholera epidemic, he attempted to rehydrate patients

by injecting 6 ounces of water into the vein

0.9% normal saline originated during the cholera pandemic

that afflicted Europe in 1831, but an examination of the

composition of the fluids used by physicians of that era

found no resemblance to normal saline. The origin of the

concept of normal saline remains unclear

Sydney Ringer found three ingredients essential were potassium, calcium, and bicarbonate. Ringer’s solution soon became ubiquitous in physiologic laboratory experiments.

In 1932, attempting to develop an alkalinizing solution to administer to his acidotic patients, Hartmann modified Ringer’s solution by adding sodium lactate. The result was lactated Ringer’s (LR), or Hartmann’s solution.

By world war II, shock was recognized as the single most common cause of treatable morbidity and mortality. Out of necessity, efforts to make blood transfusions available heightened and led to the institution of blood banking for transfusions.

It maintains the shape and integrity of all cells in the body

It maintains blood pressure/ volume

A transport medium for ;

Delivery of nutrients and oxygen to the tissues

Removal of waste products from the body

A medium for all the biochemical reactions necessary for life

Approximately 60% of the body is water!

Resuscitation

Rehydration / Replacement

Maintenance

Special purpose

To maintain adequate oxygen delivery to the tissues

To maintain normal electrolytes concentration

To maintain normoglycemia

Look at the patient:

- Pulse

- Blood pressure

- Capillary refill

- Skin turgor

- Mucous membranes

- Peripheral circulation

“If the eyes are the windows to the soul,

then the kidneys are the windows to the

body”

Sandra Ouellette.

The principle of osmosis and tonicity.

The different fluid compartment of the body

Predict the effect that specific types of IV fluids

will have on the volume within different body fluid

compartments.

The Spontaneous movement of water across a

semipermeable membrane from a region of low

solute concentration to one of high solute

concentration , which tends to equalize the

solute concentrations on either side of the

membrane.

OSMOLALITY

Measure of a fluid’s capability to create osmotic pressure

is called osmolality or osmotic (osmolar) concentration of

a solution. In simple words, it is the concentration of

osmotically active substance in the solution. Osmolality is

expressed as the number of particles (osmoles) per

kilogram of solution (osmoles/kg H2O).

OSMOLARITY

Osmolarity is another term to express the osmotic

concentration. It is the number of particles (osmoles) per

liter of solution (osmoles/L).

The hydrostatic pressure necessary to counteract the process

of osmosis

The total number of solute particles per volume of solution

The difference in the osmolarity of two solutios on either side

of a semipermeable membrane.

Extracellular Fluid

(1/3 TBW)

Capillary Membrane

Tonicity #Osmolarity

Osmilarity is dependent upon all particles of solute

Tonicity is dependent just upon those particles when exert an

osmotic force (i.e. those which cannot permeate through cell

membrane

Example: Urea creates osmolarity but does not contribute to

tonicity since it freely moves through the cell membrane

IV Fluid containing osmotic pressure due to presence of large

molecules is called colloid

Osmotic pressure due to such molecules is sometimes

referred to as oncotic pressure

If Oncotic pressure in an infused fluid exceeds that in the

plasma, it can pull water from interstitial space into the

intravascular space.

List the categories of IV fluids , and several examples of each (e.g.

NS, D5W, LR,albumin, hydroxyethyl starch, etc….)

Constitunts of common IV Fluids

Primary Indication, contraindications aside effects of common IV

fluids.

Relatively high tendency

to stay intravacualr

Examples: Albumin

Fresh frozen Plasma

Dextran

Hydroxyethyl starch

Electrolyte-Free Water

Examples: D5W, D10W

Blood

Examples: Packed RBCs

FLUID Na+

mEq/L

Cl

mEq/L-

K+

mEq/L

Ca2+

mEq/L

Glucose

g/L

Buffer Osmolarity

mOsm/L

Tonocity Typical

Indication

Normal

Plasma

140 100 4 2.4 0.85 HCO3-

24mEq/L

290 N/A N/A

0.9%

Saline

(a.k.a NS)

154 154 0 0 0 0 308 Isotonic Resuscitation

0.45%

saline

(a.k.a)1/2

NS

77 77 0 0 0 0 154 Hypotenic Maintenance

3% Saline 513 513 0 0 0 0 1026 Hypertoni

c

Severe

Hyponatremia

D51/2

NS+

20mEqKC

L

77 97 20 0 50 0 446 Hypertoni

c--

Hypotonic

Maintanance

D5W 0 0 0 0 50 0 252 Hypotonic Hypernatremia

Hypoglycemia

Lactated

Ringer’s

(LR)

13 109 4 3 0 Lactate

28mEq/L

273 Isotonic Resuscitation

Large volume s of NS can lead to a normal anion gap

metabolic acidosis

LR is relatively contraindicated in:

Hyperkalemia (due to presence of K+) usually a

minimal concern

Concurrent blood transfusion ( due to binding of

Ca+ with citrate in blood products)

Colloids can be divided in to natural (e.g. albumin, FFP) and

synthetic (e.g. Dextran , hydroxyethyl starch, gelatins )

Volume expansion due to colloid is determined by its molecular

wight and concentration.

Colloid fluids can be either saline based solutions or balanced

solutions

Colloids are typically only used for resuscitation in severe

hypovolemia

Exception include use of albumin in cirrhotic patients and renal

failure

FLUID Avg

Molecular

Weight(kD)

Osmotic

Pressure(m

mHg)

Initial

Volume

expamsion

Duration of

Volume

expansion

4-5%

Albumin

69 20-30 70-100% 12-24 hrs

20-25% 69 70-100 300-500% 12-24 hrs

10% Dextran

40

40 20-60 100-200% 1-2 hrs

6%

Hydroxyethyl

Starch

(Hespan)

450 25-30 100-200% 8-36 hrs

To about the rule of maintenance fluid and rate of IV drip

0-10 kgs 4ml/kg/hr

10-20 kgs 2ml/kg/hr

>20 kgs 1 ml/kg/hr

For Example :

1. 1.5 kg pt

so

1.5kg x 4= 20ml/hr

2.15kg

so

10 x 4 = 40ml/hr

5 x 2 = 10 ml/hr

50ml/ hr

3. 25kgs

10 x 4 = 40ml/hr

10 x 2 =20 ml/hr

5 x 1 = 5 ml/hr

65ml/hr

In adult > 20 kgs

Simply add age with 40

For example:

A 25 kgs pt

then 40 + 25 = 65ml/kg/hr

A certain amount of liquid, a time period, and a drop factor (gtts/mL)

x Drop Factor (gtts/mL) = Y (Flow Rate in gtts/min) Volume (mL)

Time in min

Formula:

Example: Calculate the IV flow rate for 1200 mL of NS to be infused in 6 hours. The infusion set is calibrated for a drop factor of 15 gtts/mL.

Time (min) x Drop Factor (gtts/mL) = Y (Flow Rate in gtts/min)

Convert 6 hours to minutes.

min ← hr ( x by 60 ) 6 hr x 60 = 360 min

1200 mL

360 min x 15 gtts/mL = 50 gtts/min

Volume (mL)

Example: Calculate the IV flow rate for 200 mL of 0.9% NaCl IV over 120 minutes. Infusion set has drop factor of 20 gtts/mL.

Time (min) x Drop Factor (gtts/mL) = Y (Flow Rate in gtts/min)

200 mL

120 min x 20 gtts/mL = 33 gtts/min

Volume (mL)

Pre-operative fluid therapy

IV Fluid Calculation

4 mL/kg for first 10 kg

2 mL/kg for next 10 kg

1 mL/kg for every kg over 20 kg

E.g. for 45-kg patient:

10 kg × 4 mL / kg = 40 mL

10 kg × 2mL / kg = 20 mL

25 kg ×1mL / kg = 25mL

Maintenance rate = 85mL/hr, 2000 ml/day

Alternative approach is to replace the calculated daily

water losses in urine, stool, and insensible loss with a

hypotonic saline solution.

An appropriate choice of 5% dextrose in 0.45% sodium

chloride at 100 ml/h as initial therapy, with potassium

added for patients with normal renal function.

Volume deficits should be considered in patients who

have obvious GI losses, such as through emesis or

diarrhea, as well as in patients with poor oral intake

secondary to their disease.

Intra-operative fluid therapy

With the induction of anesthesia, compensatory

mechanisms are lost, and hypotension will

develop if volume deficits are not appropriately

corrected.

In addition to measured blood loss, major open

abdominal surgeries are associated with

continued extracellular losses in the form of

bowel wall edema, peritoneal fluid, and the

wound edema during surgery.

Large soft tissue wounds, complex fractures with

associated soft tissue injury, and burns are all

associated with additional third-space losses that must

be considered in the operating room. These functional

losses have been referred to as parasitic losses,

sequestration, or third-space edema, because the lost

volume no longer participates in the normal functions of

the ECF.

Replacement of ECF during surgery often requires 500

to 1000 ml/h of a balanced salt solution to support

homeostasis.

Post-operative fluid therapy

Postoperative fluid therapy should be based on the

patient’s current estimated volume status and

projected ongoing fluid losses.

Any deficits from either preoperative or intraoperative

losses, third-space losses should be included in fluid

replacement strategies.

The adequacy of resuscitation should be guided by

the restoration of acceptable values for vital signs and

urine output.

If uncertainty exists, particularly in patients with renal

or cardiac dysfunction, a central venous catheter may

be inserted to help guide fluid therapy.

In the initial postoperative period, an isotonic solution

should be administered.

After the initial 24 to 48 hours, fluids can be changed to

5% dextrose in 0.45% saline in patients unable to

tolerate enteral nutrition.

If normal renal function and adequate urine output are

present, potassium may be added to the IV fluids.

Daily fluid orders should begin with assessment of the

patient’s volume status and assessment of electrolyte

abnormalities. All measured losses, including losses

through vomiting, nasogastric suctioning, drains, and

urine output, as well as insensible losses, are replaced

with the appropriate parenteral solutions.

Infiltration

Extravasation

Infection

Thrombophlebitis

Severed catheter

Fluid overload

Air embolism

Fluid is like “prescription” so give it with caution.

Children are more vulnerable for rapid fluid loss.

Maintenance calculation by “4-2-1” rule or Holliday Segar’s formula.

Vigilant Monitoring of WEIGHT, URINE OUTPUT, SERUM SODIUM CONCENTRATION while giving fluid is must.

As far as possible try to give maintenance fluid requirement orally.

0.45% DNS + 20 mEq/l KCl is ideal fluid in most of the children requiring maintenance therapy.

Replacement of fluids should be prompt & appropriate.