Treatment of Shock & Vasopressor Agents 143the inability of the ventricle of fill during
diastole markedly limiting the stroke
volume and cardiac output. Another cause
is massive pulmonary embolism
In pericardial temponade, administra-
tion of sympathomimetic amines e.g. nore-
pinephrine and/or dopamine may improve
haemodynamics temporarily and surgical
pericardial drainage is the only effective
treatment.
DISTRIBUTIVE SHOCK
Anaphylactic, septic and neurogenic
shock are the examples of distributive shock
and all of which usually cause profound
decrease in periperal vascular resistance.
In anaphylactic shock, when a sensitized
person is re-exposed to the specific antigen
and due to antigen-antibody reaction there
is large amount of histamine release along
with other mediators of anaphylaxis,
resulting in fall in blood pressure with savere
allergic reaction and bronchospasm.
Penicillin is the common example of
anaphylactic shock in sensitized individuals.
Epinephrine is a life saving drug of choice
in this type of case. Dopamine may be given
in severe vasomotor collapse. Septic shock is
characterized by a low systemic vascular
resistance and an elevated cardiac output and
it usually begins with a nidus of infection that
releases microbes and/or one or more
mediators e.g. histamine, kinine,
prostaglandins, endorphins, TNF, interlukin
1 & 2 etc. into the blood stream which
produce vascular dilatation and
vasoconstriction (some PG’s & leukotrienes).
The peripheral vasodilatation result in a
reduced systemic vascular resistance and
high cardric output.
Management of septic shock may be
carried out in three simultaneous ways,
firstly, the nidus of infection must be
identified and eliminated, using surgical
drainage and antimicrobial therapy.
Sacondly, using cardiovascular monitoring
and support, adequate organ system
perfusion and function must be maintained.
Thirdly, to interrupt the pathogenic
sequence leading to septic shock.
Neurogenic shock is generally occur in
abdominal trauma, spinal anasthesia, spinal
cord injury and is managed by vasopressor
agents e.g. dopamine.