shock & )plasma expanders, mbbs 2012
Post on 30-Oct-2014
372 Views
Preview:
TRANSCRIPT
Dr.U.P.RathnakarMD.DIH.PGDHM
[Plasma expanders]
MBBS iii Sem. 15 NOV 12
ShockCirculatory failure: oxygen delivery (DO2) fails to meet the metabolic requirements of the tissues
CO=
Capacity= Blood volume=
5L
5L5L
CO=
Capacity= Blood volume=
?3L
3L5L
Hypovolemic shock
Volume failure
Capacity=5L
Volume=3L
Hypovolemic shock
Capacity=5L
Volume=5LCardiogenic shock
Pump failure
CO= ?3LVolume failure
CO=
Capacity=
Blood volume=
3L
5L
8L
Distributive shock
Distribution failure
Capacity=5L
Volume=3L
Hypovolemic shock Cardiogenic shock
Capacity=5L
Volume=5L
Volume failure Pump failure
Capacity=5L
Volume=3L
Hypovolemic shock Cardiogenic shock
Capacity=5L
Volume=5L
Capacity=8L
Blood Volume=5L
Distributive shock
Capacity=5L
Volume=5L
Obstructive shock
Distribution failure
Volume failure Pump failure
CO= 3L
Stages of shock
Non-progressive stage
Progressive stage
Refractory [irreversible] stage
Distribution failure
Volume failure
Pump failure
Hypovolemic shock
Cardiogenic shock
Distributive shock
Obstructive shock
Pharmacotherapy of shock
1. Managing specific causes2. Managing associated
hemodynamic alterations3. Undertaking life saving &
life sustainable measures
Distribution failure
Pump failure
Distributive shock
Obstructive shock
Cardiogenic shock
Hypovolemic shock
Agents used to treat hemodynamic dysfunction:1.Sympathomimetic amines [Dopamine,
dobutamine etc.]2.Glucocorticoids3.Blood and plasma expanders
DopamineDose dependent action
2-5 ug/kg/min [D1]
5 to 10 [D1 & β1]
11-20 [β1]
More than 20 ug/kg/min[α1 ]
D1 receptors-renal, mesenteric, and cerebral circulations and increases blood flow
Increase in urinary sodium and water excretion
Stimulates β1-receptors in the heart & increase in cardiac output.
Cardiac
α-receptors-progressive vasoconstriction, and increase in ventricular afterload -limits the ability of dopamine to augment cardiac output.
DobutamineCardioselectivePostive inotropic1-10mcg/kg/min. i.v.
Nor-adrenalineWhen dopamine & dobutamine fail1-8mcg/min
AdrenalineAnaphylactic shock
GlucocorticoidsMethyl prednisolone, dexamethasone
1
2
3
4
Other drugs used in shockOxygenNaloxone [Opioid antagonist]VasoconstrictorsVasopressin
Volume replacements
1.Whole blood and plasma2.Plasma expandersa. Colloids
b. Crystalloids• Hydroxyethyl starch
Colloidal plasma expanders
Physiology of plasma expanders
Replace the lost volume. This way remaining RBCs can oxygenate body
tissue. Normal human blood has a significant excess
oxygen transport capability, -Provided blood volume is maintained by volume expanders,
Since the lost blood was replaced with a suitable fluid, the now diluted blood flows more easily, even in the small vessels. As a result of chemical changes, more oxygen is released to the tissues.
Ultimately red blood cell levels drop too low for adequate tissue oxygenation, even if volume expanders maintain circulatory volume.
Plasma expanders[Colloidal]
Colloidal plasma expanders-Substances of high Mol.Wt.-Remain long time in blood stream-Augment the volume of circulating fluid
-By increasing the osmotic pressure
Plasma expanders
Requirements of an ideal plasma expander:
1. Oncotic pressure comparable to plasma.
2. Remain in the circulation for an adequate period and
3. Disposed of either by metabolic degradation or by excretion.
4. Not antigenic or pyrogenic.5. Not interfere with grouping and cross
matching of blood.
Use of plasma expanders:Hypovolemic shock.Burns.Severe trauma.Endotoxin shock.
Contraindications:Severe anaemia.Cardiac failure.Pulmonary oedema.Renal insufficiency.
Dextran
It is a Polysaccharide[ made of many glucose molecules].
Dextran 70 (MW – 70,000) & Dextran 40 ( MW – 40,000).Oncotic pressure similar to plasma proteins and expands plasma volume for about 24 hours.
Large doses do not induce antibody formation.
They may interfere with coagulation and platelet function and also blood grouping.
Dextran – 70:Excreted very slowly by glomerular
filtration and some amount deposited in RE cells.
Dextran – 40Reduces blood viscosity.Excreted through renal tubules and
occasionally may produce acute renal failure. Precautions should be taken.
CautionDextran does not provide necessary
electrolytes and can cause hyponatremia or other electrolyte disturbances
Dextran- other usesAntithrombotic in microsurgeries In some eye drops as a lubricant To solubilize other factors, e.g. iron (=iron
dextran)Used in laboratory tests
Contraindications:Allergy.Heart failure.Acute oliguric renal failure.Hypofibrinogenemia.Thrombocytopenia.
Hydroxyethyl starch[HES]: Compared to dextrans –Maintains blood volume longer.Does not cause acute renal failure or
coagulation disturbances.Adverse effects:Anaphylactoid reactionsMild fever, Chilling, periorbital edema,
urticaria, itching and chills.
Polyvinylpyrrolidone[PVP]:Synthetic polymer,MW- 40,000.Interferes with blood grouping and cross
matching.Releases histamine.Binds to penicillin and insulin.
Gelatin polymer[Haemaccel]:Does not interfere with grouping and cross
matching.Expands plasma volume for about 12
hours.Not antigenicHypersensitivity and hypotension can
occur.
Crystalloids
Normal saline:Very limited duration of action.
Dextrose:Osmolality is lower than serum.Useful when kidney function is impaired.
Human albumin:Obtained from pooled human plasma.Crystalloid solutions must be infused
concurrently for better action.Does not interfere with coagulation.Used as a vehicle for transfusing packed
red cells.
Pharmacotherapy of shockDrug therapy aims at:Managing specific causesVolume,cardiac function,relieving obstruction etc.Managing associated hemodynamic
alterationsDopamine or dobutamine, glucocorticoids, volume replacements &expandersUndertaking life saving & life
sustainable measures
Shock & Plasma expandersEnlist the principles of pharmacotherapy of
shockEnumerate plasma expandersIndications and CIs of plasma expanders
PleaseKeep theWorldClean
Thank You
Future of our planet lies in our hands
top related