Let’s Talk About Positive Inotropes!

Imagine you have a patient who is showing signs of cardiogenic shock with a low cardiac index and low SvO2. They are hypotensive, tachycardic, with a CI < 2.2 < L/min/m2 and their SvO2 is < 65%.  Your provider may want to start a positive inotrope.

What does this classification of cardiac medication do and what is it used for?

• Positive inotropes are used to improve cardiac output and contractility.
• They are vasopressors per say, but are not used for traditional hypotension in sepsis for example.
• The most commonly used IV drips are dobutamine and milrinone. Studies suggest that they have similar effects on patients.  However, you should use milrinone in patients with renal impairment.

Dobutamine:

Initial: 2 to 5 mcg/kg/minute

Usual Range: 2 – 10 mcg/kg/min

Max: 40 mcg/kg/min

Effects:  Increased CO and heart rate, and decrease in SVR

• Watch out for tachycardia, hypokalemia, HTN or hypotension, dyspnea, and ventricular ectopy!

Milrinone:

0.375 – 0.75 mcg/kg/min

Can start with a bolus of 50 mcg/kg over 10 minutes

Effects: Increase CO, and decrease BP, SVR, PAOP, and PAOP

• Watch out for hypotension, hypokalemia, ventricular arrhythmias, and thrombocytopenia!

When starting these medications, you will want to monitor your patients heart rate, rhythm, blood pressure and hemodynamics to see if you are getting the desired effects!  Both medications have a pretty quick onset, so be sure to monitor your patient closely.

Always know what you are titrating! What is the goal for your patient?  If you are not sure, clarify with your provider.  If you want more education on cardiac medications, be sure and check out the following courses and content from Nicole! She is such a great resource!

Check out her Cardiac Boot Camp course here! This course dives deep on cardiac topics such as physiology & assessment, cardiovascular medications, heart failure management, acute coronary syndrome, valvular dysfunction and updates in cardiac arrest.

Want to get certified in Cardiac Medicine?  Take a look at her Cardiac Medicine Certification course here.

If you want to have the ultimate resource at the bedside in the ICU, check out the Critical Care Survival Guide here!  It truly is your bedside bestie!

References:

https://www-uptodate-com.offcampus.lib.washington.edu/contents/dobutamine-drug-information?search=cardiogenic%20shock%20treatment&topicRef=83&source=see_link

https://www-uptodate-com.offcampus.lib.washington.edu/contents/inotropic-agents-in-heart-failure-with-reduced-ejection-fraction?search=positive%20inotropes&source=search_result&selectedTitle=1~150&usage_type=default&display_rank=1

https://www-uptodate-com.offcampus.lib.washington.edu/contents/dobutamine-drug-information?source=auto_suggest&selectedTitle=1~1—1~4—dobut&search=dobutamine

https://www-uptodate-com.offcampus.lib.washington.edu/contents/milrinone-drug-information?search=dobutamine%20and%20milrinone&topicRef=3488&source=see_link