March 24, 2023

Beta Blockers and Asthma/COPD

Beta-blockers and asthma and copd in this video i’m going to talk about the relationship between these medications and asthma and copd patients so first what is a beta-blocker these are medications that block the beta receptor and most beta blockers block 2 beta receptors they block beta 1 and they block beta 2 now where are these receptors located beta 1 receptor is

Located on the heart and beta 2 receptor is located on the lungs and the way i like to remember it is we have one heart but we have two lungs now when the beta 1 receptor is blocked what actually happens you get a decrease in the heart rate and similarly if you were to activate the beta 1 receptor the heart rate would increase now let’s turn our attention to the beta

2 receptor if you block a beta 2 receptor what happens you get bronchoconstriction and what that means is that the airways will narrow and similarly if you activate the beta 2 receptor you will get bronchodilation and medications that are used to help somebody with asthma or copd do this they bronchodilator example albuterol but this video is not about albuterol

It’s about beta blockers so very important to understand this so this one shows that beta 1 receptors are on the heart beta 2 receptors on the lungs and please remember that the beta 1 receptor when it’s blocked it will decrease the heart rate and when the beta 2 receptor is blocked it will cause bronco constriction so now let’s first talk about beta-blockers and

High blood pressure beta blockers are often prescribed to treat hypertension now why is that why do beta blockers help somebody with high blood pressure well a lot of it has to do with this formula this formula essentially is cardiac output equals stroke volume times heart rate and if you remember a beta blocker decreases the heart rate so if you decrease the heart

Rate according to this equation you would also decrease the cardiac output and that would in turn lower the blood pressure less cardiac output means less volume means less pressure so now let’s talk about asthma and copd and what would happen if you gave somebody a beta blocker you would get bronchoconstriction which is something you do not want because you would

Worsen the patient’s asthma or copd so we come to the big question what to do if you have a patient who has high blood pressure hypertension and asthma or copd if do you give a beta blocker or not well this is the solution you give something called a beta one selective beta blocker these are also referred to as cardio selective and the reason is they only work

On beta one receptor so the only thing they will do is decrease the heart rate they will not affect the beta 2 receptor you give this beta one selective beta blocker helps lower the blood pressure doesn’t touch the lung you don’t get any adverse pulmonary side effects sounds easy right but it’s never easy because at high doses sometimes these beta when selected

Beta blockers can also cause some level of bronchoconstriction so in the real world a lot of physicians avoid beta blockers altogether in patients that have asthma or copd but on medical licensing exams trust me this is very high yield and they will test you on this so i want you to remember four medications that are indeed beta one selective also known as cardio

Selective atenolol a spute alone metoprolol and esmolol which is given iv so a typical exam question will be have a patient who has high blood pressure but also has say asthma or copd you want to give them a beta blocker and you want to select a beta one selective beta blocker so it will give you a bunch of beta blockers and they’ll say which one should you choose so

Choose the one that is beta one selective now also keep in mind that you have non-selective beta blockers as well these are the ones that work on both beta 1 and beta 2 and i’ll just give you about four propranolol carvedilol labetalol and timolol which is actually an eye drop given in glaucoma these are by far the most popular ones that are non selective so keep

Those in mind because these are the ones you want to avoid in a patient who has asthma or copd if you are treating that patients blood pressure so now let’s take a look at a few vignettes 54 year old man with emphysema which is a component of copd presents to his physician with a blood pressure of 157 over 100 over the next several months the physician prescribes

Angiotensin converting enzyme inhibitors ace inhibitors diuretics and calcium channel blockers but the patient has to discontinue each because of undesirable side effects the physician then decides to prescribe a beta and tagging estab aida blocker which of the following beta antagonists would be most appropriate for this particular patient so don’t get confused

Beta antagonist just means beta blocker so based on our video you choose a beta blocker that is beta 1 selective and of the answer choices listed which one is that that would be a metoprolol a 38 year old man has his blood pressure measured on three different occasions in clinic yielding values of 145 over 95 160 over 105 150 over 100 careful history reveals that

He has had problems with asthma since childhood the decision is made to treat the patient with a beta blocker again similar concept you would use a beta 1 selective and of the answer choice is listed the beta 1 selective drug is atenolol choice 8 and finally a 32 year old woman comes to the office for a prescription of propranolol for stage fright she tells you that

She is a professional singer and lately she has been experiencing butterflies and palpitations before performances she has been so worried about having one of these symptoms that she is having trouble sleeping at night she tells you that a friend of hers has a similar problem and propranolol has cured her she has been a patient of yours for the past 10 years and

You remember that she has severe asthma requiring many hospitalizations the most recent being 2 weeks ago her asthma attacks have been increasingly more severe and have been occurring at an increased frequency she tells you that she is in a rush and all she needs is the prescription the most appropriate next step is let’s talk a little bit about this this is not

A blood pressure patient right so why is she taking propanolol well do you remember what / peƱarol does it blocks beta 1 receptors and that will decrease heart rate so because of that sometimes it’s given to patients to reduce anxiety for example if you get on stage and you’re nervous your heart will start beating fast so they give propranolol sometimes to lower

The heart rate to calm the patient down it has been used so that’s why she was given propranolol and that’s why she wants it i guess but she has asthma so because she’s taking prepare all her asthma is getting worse because propranolol also blocks beta 2 and that’s causing bronchoconstriction so prepend law is not a good medication for her because it’s making her

Asthma worse so she should discontinue the prepare all and doctor can probably prescribe her something else that will help alleviate her stage fright so the one that is correct is choice b explained that propranolol is not a good choice for her

Transcribed from video
Beta Blockers and Asthma/COPD By CanadaQBank