Intravenous fluid
Intravenous fluid administration should be considered as any other
pharmacological prescription.5- Regarding distribution of Glucose solutions
a) 20kg)
Further consideration
Once the maintenance requirements have been calculated, additional potential
losses need to be considered to avoid under or over hydration, the following
sources of fluid loss and the electrolyte composition of these fluids need to be
appreciated:
o Nasogastric aspirates
o Vomit
o Diarrhea
o Stoma, drains, fistula etc.e) sever sodium depletion
3- best for parenteral maintenance fluids rather than aggressive
intravascular volume repletion
a) 0.9% normal saline
b) 0.45% saline
c) Dextrose 5%
d) Ringer lactate
e) Albumin
4- Dextran (all true except one)
a) Not used for volume expansion
b) high incidence of anaphylactic reactions
c) negative effects on coagulation .In the 1930s Alexis Hartmann (American pediatrician) proposed the addition of
sodium lactate buffer to Ringer's solution for the treatment of metabolic
acidosis.The lactated Ringer's solution is also known as Hartmann's solution
28
Lactated Ringer's uses
o Have sodium, potassium and chloride contents similar to extracellular
fluid have fewer adverse effects on acid-base balance (in case of
hyperchloremic metabolic acidosis).30
Dextrose solutions disadvantages
Lactate Production: The proportion of a glucose load that contributes to lactate
formation
o 5% in healthy subjects
o 85% in critically ill patients
Thus, in patients with circulatory compromise, abnormal glucose metabolism
can transform glucose from a source of useful energy to a source of toxin
production.There are three main indications:
o Resuscitation
o Replacement
o Maintenance
For maximizing benefits and minimizing harms intravenous fluid administration
should follow the
four Ds: Drug, Dosing, Duration, De-escalation.0.9% Sodium Chloride (Normal Saline)
Indications for the use of normal saline infusion that have been approved by
the FDA:
o Extracellular fluid replacement (e.g., dehydration, hypovolemia,
hemorrhage, sepsis).Fluid's classification
I.V fluids are classified as Crystalloids or Colloids based on their ability to
diffuse through barriers separating body fluid compartments, i.e., intravascular
and extravascular (interstitial) fluid compartments.Lactated Ringer's disadvantages
o The calcium in lactated Ringers can bind to certain drugs and reduce
their bioavailability and efficacy e.g., Amphotericin, Ampicillin,
Thiopentone etc.Hydroxyethyl starches
COP 28 mm Hg
Long elimination half-life (17 days) but the oncotic effects of hetastarch
disappear within 24 hours
The earlier HES fluids were associated with coagulation dysfunction and
pruritis, but the tetrastarches used these days have no effect on bleeding
times.Infusion of 100 mL of 20% albumin can increase the plasma volume 400 to
500 mL.
It is intended for shifting fluid from the interstitial space to the vascular space
in hypoproteinemic conditions,
Should not be used for volume resuscitation in hypovolemia.25
Comparison of Plasma and Crystalloid Resuscitation Fluids
Infusion of common fluids
Infusion of 1 L of 0.9% NACL adds 275 mL to the plasma volume and 825 mL
to the interstitial volume
Note: the total volume expansion (1100 mL) slightly greater than the infused
volume.Hypotonic concentrations of sodium chloride (0.45%) are best for parenteral
maintenance fluids rather than aggressive intravascular volume repletion.Fluid resuscitation in patients with severe intravascular fluid deficits (e.g.,
hemorrhagic shock) prior to the arrival of blood for transfusion (in conjunction
with crystalloids).A Colloid solution contains large molecular weight particles such as proteins or
hydroxyethyl starches (HES) suspended in a crystalloid solution.When glucose gets utilized, only water remains,
Distribution:
o > This cause Cellular swelling
o 5% dextrose-in-water solution is not an effective volume expander.Renal impairment in critically ill patients is associated with osmotic
nephrosis like
lesions in the proximal and distal tubules.o Calcium binding to the citrated anticoagulant in blood products can
inactivate the anticoagulant and promote the formation of clots in donor
blood.24
Crystalloids and Colloids
A Crystalloid solution is an aqueous solution composed of water and small
solutes such as electrolytes and glucose.The intravascular half-life of a crystalloid solution is 20-30 min, most colloid
solutions have intravascular half-lives between 3 and 6 h.
Crystalloids when given in sufficient amounts
1.Severe intravascular fluid deficits can be more rapidly corrected using
colloid solutions.The rapid administration of large amounts of crystalloids (>4-5L) is more
frequently associated with tissue edema.The solution was designed to promote the contraction of isolated frog hearts,
and contained Ca+ and K+ in a sodium chloride diluent.Dextrose solutions
D5% is used to prevent protein breakdown in an NPO patients after
consumption of endogenous glycogen (24-48hr).This is the result of a fluid shift from the ICF to extracellular space, because
isotonic saline is slightly hypertonic to the Plasma
26
1.Lactated Ringer's
Ringer's solution: introduced in 1880 by Sydney Ringer (UK) who studied
mechanisms of cardiac contraction.o Hemaccel and gelofusine have the same concentration of sodium (154
meq/L) but gelofusine contain less chloride (120 meq/L).Fluid resuscitation in the presence of severe hypoalbuminemia or conditions
associated with large protein losses such as burns.o Polyuria
37
MCQ TEST
1- Disadvantages of glucose infusion
a) Decreased CO2 production
b) Hyperglycemia.2- Indications of normal saline (all true except one)
a) Dehydration
b) Hypovolemia
c) Hemorrhage
d) sepsis).Concept of 'four Ds' when prescribing fluids
Drug -- consider the indication for the fluid and what effect is being sought.Crystalloids passed readily through the membrane, whereas colloids did not
(Greek word-glue).Crystalloid solutions can be further categorized as hypotonic, isotonic, or
hypertonic.Some evidence suggests that marked tissue edema can impair oxygen
transport, tissue healing, and return of bowel function following major surgery.o It is used in DKA when there is severe hypovolemia and when serum
sodium less than 140meq/L.Hypertonic saline
Hypertonic 3% saline is employed in therapy of severe symptomatic
hyponatremia.Disadvantages of Glucose infusions
o Enhanced CO2 production (which can be a burden in ventilator-
dependent or COPD patients).Albumin solution 20%
COP of 70 mm Hg
Expands the plasma volume by 4 to 5 times the volume infused.o Rapidly excreted by the kidneys (shorter duration 3-4 hr).23
Tonicity, a term that is often used interchangeably with osmolarity, refers to
the effect a solution has on cell volume.Replacing an intravascular volume deficit with three to four times the
volume needed when using colloid
3.Additionally: diluents for the infusion of compatible drug additives.o It is used as a replacement fluid in burn patients when BSA >20%
(Parkland formula).o For this reason, lactated Ringer's solution is contraindicated as a diluent
for blood transfusions.D5% (D5W) is used for replacement of pure water deficits and as a
maintenance fluid for patients with hypernatremia. D20%, D25% or D50% are used in TPN (The use of 5% dextrose solutions to
provide calories is obsolete).31
Colloids
Do not pass across diffusional barriers as readily as crystalloids.Approximately half of the infused volume of 5% albumin stays in the vascular
space.o Gelofusine is compatible with blood but hemaccel contains ca+2.Not used for volume expansion because of a high incidence of anaphylactic
reactions and negative effects on coagulation.Decrease in blood viscosity and inhibition of erythrocyte aggregation.Osmolarity and Tonicity of a solution
The osmolarity of a solution is equal to the number of osmoles per liter of
solution.o Hypertonic solutions decrease cell volume.Tonicity describes the effective osmolality of a fluid.Are just as effective as colloids in restoring intravascular volume.o It is the preferred solution for diluting packed red blood cells prior to
transfusion.Hypertonic 3%, 7.5% or 23.4% saline can be used in case of severe brain
edema.0.45% Sodium Chloride
A hypotonic concentration of sodium chloride.Natural (plasma-derived) colloids:
o Human albumin.Commercially is available as 5% solution or 20% solution in an isotonic saline
diluent.5% solution has colloid oncotic pressure (COP) 20 mm Hg (similar in oncotic
activity to plasma).Gelatins
o COP 27-34 mmHg
o The cheapest colloid available.Dextran
COP 40 mm Hg (greater increase in plasma volume).* Shortcut formula:
body weight + 40 (= 80 mL/hr.o Hypotonic solutions increase cell volume.o Treatment of metabolic alkalosis in the presence of fluid loss.o Mild sodium depletion.Other indications
o Used also in traumatic brain injury or any brain edema.o Replacement fluid in hyperkalemia.o Increased mortality in septic shock.Synthetic colloids:
o Dextran (e.g., dextran 40 and dextran 70).o Gelatin (e.g., gelofusine and hemaccel).o Starch (e.g., Hydroxyethyl starch (HES)).Albumin solution
Responsible for 75% of the oncotic pressure of plasma.Acts as buffer,
antioxidant and transport protein.o Unlimited volume for resuscitation.o Unimpaired renal function and hemostasis.o Anaphylactoid reactions: direct histamine release. e) Increased mortality in septic shock.Dosing -- consider how much fluid to give.De-escalation -- consider when the fluid therapy is no longer effective or
required.o An isotonic solution has no effect on cell volume.o Increased risk of infection, Neuropathy.o Aggravation of ischemic brain injury.The oncotic effects of albumin last 12-16 hours
32
2.34
Indications for colloids
1.+ 20 mL/hr.2.4.27
2.3.4.29
5.1.3.33
4.5.2.