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Thursday, February 19, 2015

A Nurse's Guide to Beta Blockers

Beta Blocker, Pharmacology, nursing student, nurse, heart, nclex, nurse, medicine

Beta Blockers

I'm awful at pharmacology. There's just so much to learn! Here's a quick post that gets at the nit and gritty of Beta Blockers. You know the drugs that end in "olol".

All of your patients will be on them. Why? When should you hold giving a beta blocker? When should you expect to give a beta blocker? What adverse reactions should I look out for?

Mechanism of Action

Beta Blockers do just that and block beta-adrenergic receptor sites causing vasodilation. This results in a decreased amount of contractility, decreases heart rate, decreases ventricular afterload, and decreased ventricular irritability.

When is it indicated?

You should expect to give this as one of the drugs during a suspected myocardial infarction (heart attack). Remember MONA-B.


Beta Blocker

Side note: I once got reamed for asking a professor if it would be appropriate or not to give a patient a Beta Blocker during an MI. Long story short-- YES. You would give a beta blocker, unless contraindicated-- Which we will get to that! :)

The beta blocker slows down contractility and allows the heart to pool with blood, so it can have a little bit more time to become oxygentated, which means it controls ischemia. The vessels also dilate, so again ischemia, and this will also decrease hypertension. By reducing contractility you reduce the chances of harmful arrhythmias. 

By increasing the levels of oxygen on the heart you decrease pain and reduce mortality. So beta blockers are totally acceptable, when not contraindicated.

Ok, here are the other situations in which you would be administering a beta blocker to a patient:

  • Unstable Angina
  • Non ST elevation MI
  • Prior to general surgery to reduce the risk of potential acute myocardial infarctions
  • In chronic heart disease- because you want everything to be well oxygenated
  • Stress induced PVCs
  • Hypertension
  • Arrhythmias
  • Hypertrophic Cardiomyopathy- Just read a cool post about triathlon athletes having this issue.
  • Migraine headache
Ok, so pretty much all of those disorders are being treated with beta blockers because we want to increase oxygenation in the blood.

Cardioselective or Non Cardioselective?

Lets talk beta receptors.

You have beta 1 and beta 2. What do they control?? Well unless you are a timelord (I so hope that there is some nursing Whovian reading this right now!) you only have 1 heart. So beta 1 controls your 1 heart. 

Beta 2 controls your 2 lungs.

1 = heart

2 = lungs

Get it? Got it? Good.

Beta 1 are cardioselective- because we have 1 heart. This is your Metoprolol (Lopressor) and Atenolol (Tenormin)

Beta 2 are non cardioselective- because we have 2 lungs. This affects your lungs and vascular smooth muscle. This is your Carvedilol (Coreg), Labetolol (Normodyne), and Propranolol (Inderal).


 You would hold this drug when your patient has

  • Heart rate below 60
  • PR interval greater than 0.23 seconds
  • Class IV Left Ventricular Failure
  • Cardiogenic shock
  • Prinzmetal's varient angina
  • Severe PVD
  • Asthma with reactive airways
  • Kidney disease
  • Liver disease

Adverse Effects

You'll want to monitor your patients after you give a beta blocker for:

  • Hypotension
  • Heart block
  • Severe bradycardia
  • Weakness- FALL RISK
  • Bronchospasm
  • Wheezing
  • Shortness of breath
  • Pallor/Flushing
  • Nausea/Vomiting
  • Headache
  • Fatigue/Drowsiness

These adverse effects can be brought on when taken with:

  • Calcium Channel Blockers
  • ACE Inhibitors
  • Antihypertensives
  • Antidysrhythmias

NSAIDS will decrease the effectiveness of Beta Blockers.

Alright. So that's Beta Blockers in a nut shell.

Other posts you might be interested in:

How to Pass Pharmacology
Everything You Need to Know About Diuretics

What are some areas you are struggling with in nursing school?? Pharm? Patho? Leave me a comment below and I can help you out!!




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