What is the Bezold-Jarisch reflex?
Mechanoreceptors in the left ventricle activate
inhibitory vagal afferents to increase sympathetic tone and guard the body
against hypotension. This protective physiologic response occurs during times
of severe stress, such as hemorrhage. The Bezold-Jarisch reflex is a
para-doxical activation of these left ventricular receptors by a decrease in
venous return, causing a decrease in sympa-thetic tone with an increase in
vagal outflow. This pro-duces severe bradycardia and hypotension, which can
lead to asystole.
Patients undergoing shoulder repair are at risk
for acti-vating this reflex. The “beach chair” position causing pool-ing of
blood in the lower extremities, patient anxiety and the addition of epinephrine
to the arthroscopy infusate are all factors contributing to this phenomenon.
Ephedrine is the treatment of choice because it
has a direct action on the heart and peripheral activation of cat-echolamines. Fluid
resuscitation is important to prevent further stimulation of these receptors.
If progression to asystole occurs, epinephrine is essential. Atropine will not
adequately treat this event, should it occur.
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