Download Intravenous Fluids Dr. Jimeno Adapted from the lecture entitled

Intravenous Fluids
Dr. Jimeno
Adapted from the lecture entitled: Fluid Management Online
Intravenous Fluids: A Clinical Approach
By Jai Radhakrishnana, MD
Division of Nephrology
Outline:

Review of normal physiology of lfuid and
electrolyte flux: volume of distribution

Types of intravenous fluids

Composition of IV fluids

Types of fluid depletion

Specific clinical examples and treatment
Composition of Body Fluids
Total body water

Male: 60%; Female: 50% because of
difference of adiposity

Extracellular fluid: 25-45%
o Plasma (intravascular) 25%
o Interstitial (extravascular) 75%
o Na, Cl, HCO3

Intracellular fluid 55-75%
o K, organophosphate esters

Thus, sodium for volume, potassium for cell
function!
Volume distribution of water
“Third Space”

Acute sequestration in a body compartment
that is not in equilibrium with ECF

Examples:
o Intestinal obstruction
o Severe pancreatitis
o Peritonitis
o Major venous obstruction
o Capillary leak syndrome
o Burns
Daily fluid balance



Intake: 1-1.5 L
Insensible loss
o Lungs 0.3 L
o Sweat 0.1 L
Urine 1.0 to 1.5 L
Example: Math for a 70 kg male
ECF Compartments
o
o

Principles of treatment

How much volume?
o Need estimate of fluid deficit

Which fluid?
o Which fluid compartment is
predominantly affected?
o Need evaluation of other acid/
base/electrolyte/nutrition issues
Indications for prescription of IV fluids

Highest priority
o Defend hemodynamics

Re-expand a severely
contracted ECF volume

Prevent a fall in BP when
venous tone is low (e.g.
anesthesia)
o Return the ICF volume towards
normal

Moderate priority
o 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
o To provide glucose as fuel for the
brain e.g. during hypoglycemia
IV Fluid supermarket

Crystalloids
o Dextrose in water

D5W

D10W

D50W
o Saline

Isotonic (0.9% or
“normal”)

Hypotonic (0.45%, 0.25%)


Combo



Ringer’s

Hypertonic
D5NM/D5NR
D5NSS
D10NS
lactate “physiologic”
Contains: K, HCO3, Mg, Ca
Colloids
o Albumin

5% in NS

25% (salt poor)
o Dextrans
o Hydroxyethyl starch (HES);
hetastarch
o Haemaccel
o Gelofusine
Blood
Types of IV Fluids

2 types of fluids that are used for
intravenous infusions: crystalloids and
colloids

Crystalloids are aqueous solutions of mineral
salts or water soluble molecules

Colloids contain larger insoluble molecules
(particles suspended in solution), such as
gelatin; blood itself is a colloid
Crystalloids

Intravenous infusion fluids are composed of
solutions of crystalline substances, such as
sodium chloride, potassium chloride or
glucose

Water and salts = water and electrolytes
Colloids

Name given to microparticulate dispersal of
one substance in another

Colloid vs solution? Colloids are physically
separable (they may be separated by ultrafiltration or centrifugation), whereas a
solution requires chemical separation or
chemical reaction (you cannot filter the
sugar out of your tea, nor centrifuge it out)

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

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
Colloids 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
Until recently they were regarded as the gold
standard for intravascular resuscitation
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
Efficacy and safety of colloids

Conflicting evidence because of their
efficacy;

Conesus 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
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

Hypovolemic patients given albumin instead
of saline does not reduce mortality

Albumin does not reduce mortality in
critically ill patients with burns and
hypoalbuminemia

In children with severe malaria,
resuscitation with albumin has lower
mortality than resuscitation with saline
infusion or Gelofusine

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
Properties of IV Fluids
The amount of solute in a solution influences two
related, but subtly different properties: osmolarity and
tonicity
Osmolarity

Osmolarity refers to the amount of solute,
whereas tonicity refers to 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) and is also dependent on
whether the solute can pass freely through
the cell membrane
Tonicity

A complex concept because cell permeability
varies with cell type and circumstances

Example: in a non-diabetic, glucose is a
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
Tonicity and Osmolarity

Most solutions aim to be iso-osmloar to
reduce osmotic damage to blood cells and
irritation to the veins

However, a hyperosmolar solution such as
5% glucose with 20 mmol KCl can actually
be effectively hypotonic as the glucose is
rapidly absorbed into the cells leaving only
the 20 mmol KCl and electrolyte-free water
Water balance

Normal Plasma Osmolarity: 285-295
mOsm/kg
o Works within a narrow range
o Senses 1-2% tonicity change
o To achieve steady state

INTAKE should
approximately equal
EXCRETION
o Intake regulated by thirst receptors
o Excretion regulated by AVP
(vasopressin)
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
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
may lead to cerebral edema and rarely,
central pontine demyelinosis; use with
caution!
Table of electrolyte- study this table very well and
imagine it to simulate the normal physiologic
conditions
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 ECF space.
This fluid distributes itself evenly across the
ECF and intravascular space, in turn leading
to intravascular repletion

Large volumes will cause HYPERnatremia
and Intracellular dehydration
Saline Solution
0.9% Normal saline – “salt and water”
Table: glucose





Principal fluid used for intravascular
resuscitation and replacement of salt loss
e.g. diarrhea and vomiting
Cotains: 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
o Of 1 litre – 750 mL ECF; 250 mL
intravascular fluid
So for 100 ml blood loss – need to give 400
ml Normal saline [only 25% remains
intravascular]
Correction in the table: Glucose 5% saline 0.45% 
comment: 50 g glucose
Figure: Illustrating 1 liter 0.9% saline
Figure: Illustrating 1 liter 5% dextrose (D5W)
HYPOtonic saline
0.45 NSS = half normal saline

Reserved for severe hyperosmolar states
e.g. H.O.N.K 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
Volume Deficit-Clinical Types

Total body water:
o Water lass (diabetes insipidus,
osmotic diarrhea)

Extracellular:
o Salt and water loss (secretory
diarrhea, ascites, edema)
o Third spacing

Intravascular:
o Acute hemorrhage
Figure: 1 Liter D5NM/D5NR
Figure: Colloid: 1 liter 5% albumin
Intravascular Depletion

Hemodynamic effects
o BP HR JVP
o Cool extremities
o Reduced sweating
o Dry mucus membranes

ECF depletion
o Skin turgor, sunken eyeballs
o Weight
o Hemodynamic effects

Water depletion
o Thirst
o Hypernatremia
Example: GI bleed
A 55 year old patient presents with massive
hematemsis (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



A comparison of Albumin and Saline for Fluid
resuscitation in the ICU (graph)
What is the nature of his fluid deficit?
What IV fluid resuscitation would you
prescribe?
What do you expect the hematocrit to be:
o At presentation
o 12 hours after NSS
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
Exam: BP 80/70 HR 130 supine
Labs: Na = 130, K = 2.8, HCO3 = 12
ABC: 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?
Example: Hyperosmolar State
An 85 year old nursing home resident with dementia,
and known diabetes was admitted with confusion
1.
Exam: Disoriented
BP: 110/70 supine 90/70 sitting. Decreased skin
turgor.
Labs: Na = 150 meq/L Wt. = 50kg
BUN/Cr = 50/1.8
Blood sugar = 1200 mg/dl
Hct = 45
Osm = 300
3.


What is the pathogenesis of her fluid and
electrolyte disorder?
How would you treat her?
Calculation of Water Deficit
Healthy
Dehydration
Osm(P na) x volume  Osm (P Na) x volume
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
Example: Intubated patient
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.
Exam: BP = 120/70 and HR-91 bpm
Labs:
Plasma sodium = 128 mmol/L
Potassium = 3.6 mmol/L
Adequate urine output


Is there a fluid deficit?
What will be your IVF order?
o While he is still NPO?
o On NGT for feeding?
Example: 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 5 cms, +++
ascites, no peripheral edema, + asterixis
Labs:
Bun = 12 mg/dL
Crea = 2 mg/dL,
Alb = 2.0 g/dL
Urine volume has been 200 cc/24 hours.

Comment on his fluid status

If volume-depleted, how would you treat
him?
Case scenarios
2.
4.
Unconscious 25 year old, previously healthy,
found inside a locked room.
Unconscious, known diabetic, diaphoretic,
tachycardic, afebrile, BP = 150/90 mmHg
Patient with a stab wound on the abdomen,
BP = 80/60 mmHg, awake, restless
IVF to follow for a patient with urosepsis,
sodium is 15- mmol/L, weak, BP = 100/70
mmHg