Blood Pressure Question
List of stuff we know:
· Man’s peripheral blood vessels dilated and his BP is low
· Difficulty breathing
· Bronchioles are constricted
· Allergic response to anesthetic
The question asks:
They gave him epinephrine. What will it do, and is it the proper treatment?
SNS is fight or flight system
Epinephrine = adrenalin, produced in adrenal cortex
Epinephrine binds to adrenergic receptors:
Alpha-1 – cause blood vessels to constrict in skin, guts, and kidneys
Alpha-2 – stops the SNS when enough epinephrine has been released
Beta-1 – increase heart rate and strength
Beta-2 – dilates bronchioles
His blood vessels are dilated now. Epinephrine would attach to alpha-1 receptors and constrict them and fix this problem.
His bronchioles are constricted. Epinephrine would attach to the beta-2 receptors and dilate them and fix this problem. This will also fix his problems with breathing.
He has low BP. Epinephrine will attach to beta-1 receptors and increase heart rate and strength and fix this problem. Constricting blood vessels by attaching to alpha-1 receptors will also help raise BP by sending more blood to the heart.
What will epinephrine do? -- answered above.
Is it the proper treatment – yes, because when it binds to the receptors it reverses the problems and improves his condition.
How will his taking beta-blockers affect the usefulness of epinephrine in this emergency? – the beta blockers will stop the beta-1 and beta-2 receptors from responding to epinephrine. If those don’t respond, then: the beta-2 receptors won’t dilate the bronchioles so they will remain constricted and the beta-1 receptors won’t raise the heart rate so it will remain low.
The alpha receptors aren’t blocked, so epinephrine can still attach to alpha-1 receptors to constrict blood vessels in the skin, gut, and kidneys and alpha-2 receptors can still shut off the SNS.
The epinephrine will be much less effective. It will raise BP a little, by constricting the blood vessels using the alpha-1 receptors. It won’t be able to raise blood pressure very well because it can’t make the heart beat faster, and it won’t dilate the bronchioles so his breathing problems will not be solved.