Wed3November0844PM 13

During cardiac arrest due to ventricular fibrillation (VF), intravenous adrenaline 1 mg every three to five minutes is indicated in the Advanced Life Support algorithm following three DC shocks.

Which of the following options is the most important reason for using adrenaline?

(Please select 1 option)

Vasodilatation of the pulmonary circulation, ensuring maximal uptake of oxygen from the lungs

Coarsening of ventricular fibrillation, increasing the success of defibrillation

Preferential distribution of blood to the coronary and cerebral circulation This is the correct answer

Positive inotrope effect Incorrect answer selected

There is good evidence that the use of adrenaline decreases the mortality from VF cardiac arrest

Explanation

The rationale for recommending use of epinephrine for treatment of cardiac arrest is primarily based on the alpha-adrenergic (a1) vasoconstrictor effect of this drug.

Vasoconstriction increases cerebral and coronary blood flow by increasing mean arterial, aortic diastolic and cerebral perfusion pressures. Adrenaline is also a ß1 and ß2 adrenoreceptor agonist being an inotrope, chronotrope and bronchodilator. Improved success of defibrillation is a secondary benefit.

Vasopressin, a nonadrenergic endogenous peptide that induces peripheral, coronary, and renal vasoconstriction via stimulation of the V1 receptors, lacks the adverse effects of epinephrine and has therefore gained much attention as a substitute vasopressor. Another possible advantage is that through V2 receptor stimulation, vasopressin may induce vasodilation and therefore lessen the end-organ hypoperfusion thought to occur with epinephrine.

Despite the widespread use of epinephrine during resuscitation, and several studies involving vasopressin, there is no placebo controlled study that shows that the routine use of any vasopressor at any stage during human cardiac arrest increases survival to hospital discharge. Current evidence is insufficient to support or refute the routine use of any particular drug or sequence of drugs. Despite the lack of human data, the use of epinephrine is still recommended, based largely on animal data.

Answer Statistics

1

2%

2

22%

3

49%

4

22%

5

8%

Times answered: 270