Understanding cardiac gtts

[squirtle]

I could really use a little direction... I work in the SICU but posted here as it has specific regard to my cardiac pts.

I have been trying for some time to really understand the gtts that we use on a daily basis and how they act on the body but I seem to have some sort of block in my head when it comes to comprehending the information presented to me Sometimes I feel like I am back in school trying to make sense of algebra- something I was never able to do. :icon_roll

I am going to try and explain my confusion in hopes that someone may have an idea of how I can better learn this material.

I have bought several books, have bookmarked several websites and something just doesn't click. As an example, I was reading about dobutamine and dopamine today. I don't truly understand the differences between the two. The more I read, the more confused I become. I try to understand vaso- renal dosing vs bp control and become confused by what I read. Why do we like levo in some pts and epi in others? I am not really looking for an answer to those questions specifically- but perhaps a suggestion on a book or some teaching material that goes back to basics and will help me understand why certain drugs act a certain way.

Thank you for any direction you can give me.

[Esme12, ASN, BSN, RN]

go here.......icufaq's.org index

and here....http://www.ccmtutorials.com/

It's a great free source...you will love it.

[Esme12, ASN, BSN, RN]

critical care drip power point very good!!!!

http://som.unm.edu/programs/BATCAVE/docs/ICUDrips-FINAL.pdf

[BelgianRN]

Please delete any knowledge you retain on renal dose of dopamine it's a myth but some old school folk keep believing in it. But it kills more patients than it helps recover :)

[meandragonbrett]

A key thing to understanding these gtts is to have a good foundation on the functioning of the sympathetic nervous system and what agonism and antagonism of the various receptors will cause when you activate or block the receptors.

[CrufflerJJ, BSN, RN, EMT-P]

Dopamine appears to be the preferred pressor to get the heart rate up to 130-150 in ED prior to xferring the patient to the ICU (seriously!). Levo is decent for sepsis. Epi drips are sort of a last resort.

Pressors are all different. Learn the alpha-beta-other receptor effects of each. Some are better at boosting pressure without generating ectopies (such as Neo), while others (Dopamine) are great at generating PVCs/ectopic beats even at lower doses. Others such as levophed are good at boosting pressure at low doses, yet could cause ectopies at higher doses. Vasopressin can boost pressure in cases where regular catecholamines fail (then again, it can also cause clamping off of arteries/ischemia/tissue death....there's no free lunch). Dobutamine is typically used to increase cardiac output (contractility) in CHF with mimimal ectopies, although it can cause a drop in BP due to vasodilation.

Please note that pH impacts the effectiveness of many pressors. If your pt has a lactic acid of 12.3, a pH of 6.8, and looks like death warmed over, pressors aren't going to work all that well.

[missnurse01, MSN, RN]

another thing to consider is your hosp. I have worked in different parts of the country and have found that I just have to ask what the docs there prefer. Last place I was at would put everything on before they ever ever did levo, here levo is first choice. I was amazed at differences everywhere!

[CalvinJ]

Id have to agree with Cruffler. Basically, the drips are chosen depending on the cause of hemodynamic instability. The drip of choice would depend whether the problem is the pump or the squeeze.Basically Dobutamine highly affects the beta1 receptors which are specific to the heart so it would be the best choice for weak left ventricle patients. Levophed is is potent on alpha receptors which targets the blood vessels making it the drip of choice for sepsis or SIRS. Dopamine on the other hand, affects both alpha and beta receptors distributedly and depending on the dosage will the hemodynamics respond. Thats why they would use Dopamine in the ED more frequently because it hits more receptors than dobu an levo. Emergencies call for hitting 2 birds with one stone rather than making test diagnoses. Dopamine is a precursor of noradrenaline the body which helps in targeting alpha receptors fr vasoconstriction.Overall, if you're at the cardiac SICU then I guess you're drips would probably be either dobu or levo most usually even both depending on the patient's condition. Many post op patient are usually having SIRS so most doctors would see levophed as the drug of choice in order to help maintain a desirable BP. Hydrating would be another option just to maintain a good blood pressure as for bypass patients. For patients with underlying CHF causing poor ventricular EF, he/she would most likely respond to dobutamine more than the others in maintaing good pressures. Cheers! :)

[CalvinJ]

Id have to agree with Cruffler. To understand the drips I guess understanding hemodynamics is essential. Understand the adrenergic receptors since those are the targets of the drips and compare the effect of each drug to the alpha and beta receptors. :)Basically, the drips are chosen depending on the cause of hemodynamic instability. The drip of choice would depend whether the problem is the pump or the squeeze.Basically Dobutamine highly affects the beta1 receptors which are specific to the heart so it would be the best choice for weak left ventricle patients. Levophed is is potent on alpha receptors which targets the blood vessels making it the drip of choice for sepsis or SIRS. Dopamine on the other hand, affects both alpha and beta receptors distributedly and depending on the dosage will the hemodynamics respond. Thats why they would use Dopamine in the ED more frequently because it hits more receptors than dobu an levo. Emergencies call for hitting 2 birds with one stone rather than making test diagnoses. Dopamine is a precursor of noradrenaline the body which helps in targeting alpha receptors fr vasoconstriction.Overall, if you're at the cardiac SICU then I guess you're drips would probably be either dobu or levo most usually even both depending on the patient's condition. Many post op patient are usually having SIRS so most doctors would see levophed as the drug of choice in order to help maintain a desirable BP. Hydrating would be another option just to maintain a good blood pressure as for bypass patients. For patients with underlying CHF causing poor ventricular EF, he/she would most likely respond to dobutamine more than the others in maintaing good pressures. Cheers! :)

[IHeartDukeCTICU]

hmm pretty interesting to see what you all use at your facilities. I work in the CT-ICU and I'd say most of our post-op patients come out on epi for inotropy & vasoconstritcion r/t SIRS/myocardial stunning. Also, first line vasopressor here is vasopressin. I believe that was r/t multiple studies showing pt's with severe SIRS/SVR syndrome were shown to have abnormally low levels of endogenous vasopressin. However we do start weaning the epi & vaso off within the first few hours and transition them to dopa if they still need inotropic support. We almost never use dob though, must be a surgeon preference. That and we also take alot of high risk hearts who need more of the dopa renal vasodilation effects in addition to some inotropy.

[missnurse01, MSN, RN]

hmm pretty interesting to see what you all use at your facilities. I work in the CT-ICU and I'd say most of our post-op patients come out on epi for inotropy & vasoconstritcion r/t SIRS/myocardial stunning. Also, first line vasopressor here is vasopressin. I believe that was r/t multiple studies showing pt's with severe SIRS/SVR syndrome were shown to have abnormally low levels of endogenous vasopressin. However we do start weaning the epi & vaso off within the first few hours and transition them to dopa if they still need inotropic support. We almost never use dob though, must be a surgeon preference. That and we also take alot of high risk hearts who need more of the dopa renal vasodilation effects in addition to some inotropy.

I also think it is very interesting how different surgeons prefer different things across the country. Epi is pretty rare here, although when I was in NM we used it alot. We never use dopa post OHS here. We use dobuta on nearly everyone, mostly just for decreasing SVR. Compared to other places I have been we definitely do much sicker hearts here, more co-morbidities to begin with. Whenever I go to a new place I am always asking what there preference is, what they want off first etc etc. It's interesting to hear how others do it!

[Sugarcoma, RN]

Squirtle, I too had difficultly with drips. Why one instead of the other etc. It was not until I pulled out my pharm book and read and re-read the CNS/ANS chapters and really got a good understanding of alpha and beta receptors that things started to click for me.

I have a book of index cards and I made cards for the receptors and what they do. Then made a card for each medication and which receptor/s it works on. As others have stated you also need to have a decent grasp of hemodynamics. I literally had to write out the definitions in "stupid speak" of inotrope, chronotrope, etc.

Finally it never hurts to ask the doc why are you using this med in this instance? I do this with all cardiac meds because I had a very poor knowledge of them and could not wrap my head around why this beta blocker instead of this one etc? If the docs aren't receptive try a coworker you admire/respect.

Finally I have found the book Drugs for the Heart to be very helpful. It is a little bit overkill but has a chapter entitled What drug for which condition which I have found very helpful. I picked up a used copy for less than 20 on Amazon.