In this post, I review some experts’ advice on when to use a norepinephrine infusion and when to use an epinephrine infusion.
However, it can take a long time to get a catecholamine infusion started. Push dose epinephrine can be a lot faster.
And that is why it is important to know when and how to prepare and use push dose epinephrine as you can prepare the syringe ahead of time. Please see Resources (8), (9), and (10).
Some hypotensive patients are so unstable that they require a pressor (epinephrine or norepinephrine) to maintain coronary perfusion pressure while, for example, fluids in sepsis or blood [and surgery] in trauma are are in progress for the underlying problem.
But which should we use while we continue to address the underlying problem?
The doctors of Emergency Medicine Cases, in the case of severe hemodynamic instability [in cases of beta blocker and calcium channel blocker overdose], recommend: (1)
- the use of epinephrine if poor cardiac contractility is noted on bedside ultrasound
- the use of norepinephrine if good cardiac contractility is noted on bedside ultrasound.
The reasons for the above recommendations [which also apply to other causes of severe hemodynamic instability compromising cardiac perfusion pressure and thus cardiac function] are:
- If poor cardiac contractility is noted on bedside cardiac ultrasound, then the heart isn’t squeezing well enough. And epinephrine will improve the squeeze.
- If good cardiac contractility is noted on ultrasound, then we will presume that the severe hypotension is due to inadequate peripheral resistance. And norepinephrine will increase peripheral resistance.
The dosage of epinephrine, for profound bradycardia or hypotension, is: (2) [p48]
2 to 10 mcg per minute infusion; titrate to patient
The indications for norepinephrine are: (2) [p 58]
Severe cardiogenic shock and hemodynamically significant hypotension (SBP < 70 mm Hg) with low total peripheral resistance.
Agent of last resort for management of ischemic heart disease and shock.
The dosage of IV administration of norepinephrine is: (2) [p58]
Initial rate: 0.1 to 0.5 mcg/kg per minute (for 70-kg patient: 7 to 35 mcg per minute); titrate to response.
Do not administer in same IV line as alkaline solutions.
Poison/drug induced hypotension may require higher doses to achieve adequate perfusion.
In the septic shock algorithm for Pediatric Advanced Life Support section (2) p 89, the Handbook recommends that for hypotensive vasodilated (warm) shock, the clinician should begin norepinephrine. And for hypotensive vasoconstricted (cold) shock: Begin epinephrine rather than norepinephrine.
Resource (3) below is a blog post on my notes of Dr. Weingart’s excellent podcast #138 about vasopressors. [The podcast is outstanding and my notes on it are serviceable and worth reading]. And in this podcast Dr. Weingart reminds us that with vasopressors we are trying to accomplish three goals:
- First, to try to maintain an adequate coronary perfusion pressure so that the heart can continue to pump
- Second, to increase venous return (which is the first effect of norepinephrine, a balanced arterial and venous pressor and our vasopressor of choice) and thus you are increasing cardiac output [and hence blood pressure] by increasing preload rather than by increasing after load.
- Third, “Our last goal is to avoid gut ischemia.” If you give too much vasopressor, say, for example, because you haven’t given enough fluid, you can cause gut damage by gut ischemia. And gut ischemia can cause bacterial translocation and it may be the mechanism of serious infections post cardiac arrest or in cases of non-bacterial sepsis. For pretty much everyone our goal is a MAP 65.
And Dr. Weingart continues in EMCrit podcast #138:
- So if the patient is still hypotensive with a norepinephrine drip of 20 mcg/min you have reached a stop point [- meaning that before you add a second pressor you want to rethink all factors in the case to make sure you haven’t missed something.
- See EMCrit podcast #87] And the things (Stop Points) you want to think about, from #87, are:
- Volume – Have you given enough volume?
- Ionized Calcium – Get a stat ionized calcium to make sure the patient is not low as intropes won’t work with a low ionized calcium.
- Inotropy – Is the heart just not beating well and it needs an inotrope added to the norepinephrine. So put on echo probe and assess the heart qualitatively:
- Is the heart contracting vigorously (hyperdynamic) [in which case the problem is more vasopression needed
- Consider adding vasopressin which is a pure vasopressor -Dr. Weingart recommends, in #138 – “The doses we use for things like septic shock, which now is at 0.03 units per minute (it used to be 0.04 units per minute). We put them on a fixed dose. We don’t titrate it. We just leave it there in the background.”]
- Or is the heart just kind of lagging and beating sluggishly.
- In this case you need inotropy [consider adding dobutamine (which has vasodilating properties) or perhaps better add epinephrine at a dose of 0.01-0.08 mcg/kg/min [according to his comment in response to mjanderson972 in #138]
- Is the heart contracting vigorously (hyperdynamic) [in which case the problem is more vasopression needed
- Does the patient have occult bleeding?
- For example, from a GI bleed in which there is no vomitting or diarrhea (melena) so hemoccult the stool and recheck the hemoglobin/hematocrit.
- Does the patient have an endocrine deficiency?
- Adrenal insufficiency? Perhaps the patient needs a stress dose of hydrocortisone 100 to 150 mg IV push.
- Severe hypothyroidism? The following is from Myxedema Coma or Crisis from emedicine.medscape.com
- Despite the term myxedema coma, many patients do not present in coma, but manifest variable degrees of altered consciousness. [1]
- Myxedema coma is a medical emergency that requires immediate attention. If the diagnosis is suspected, immediate management is necessary before confirming the diagnosis due to the high associated mortality rate.
- For treatment details, see Myxedema Coma or Crisis Treatment and Management.
- Does the patient have a really unusual problem contributing to the refractory hypotension?
- For example, abdominal compartment syndrome in a medical patient. Usually this problem occurs in surgery patients.
In Resource (4) Dr. Weingart reminds us that in non-traumatic shock [as we do in traumatic shock] we need to perform the Rapid Ultrasound for Shock and Hypotension – the RUSH Exam and his podcast shows us how. And here are two links to YouTube videos on the RUSH exam:
Resources:
(1) EM Cases Episode 90 – Low and Slow Poisoning discusses the treatment of hypotension and bradycardia due to calcium channel blocker overdose, beta blocker overdosage, or digoxin overdosage. This is from the January 2017 podcast of Emergency Medicine Cases.
(2) 2015 Handbook of Emergency Cardiovascular Care for Healthcare Providers, 2015 American Heart Association
(3) Vasopressor Basics (and Much More)–#138 from Dr. Weingart
Posted on May 25, 2015 by Tom Wade MD
(4) Rapid Ultrasound for Shock and Hypotension – the RUSH Exam from Dr. Weingart of EMCrit.
(5) Podcast 87 – Mind of the Resuscitationist: Stop Points
November 26, 2012 by Scott Weingart:
In this Mind of the Resuscitationist Episode, I [Dr. Weingart] discuss stop points: one for when you are using multiple vasopressors and especially about a cognitive stop point whenever things are going south.
(6) Use of Vasoactive Medicines for Septic Shock in Pediatric Advanced Life Support (PALS) Posted on December 23, 2014 by Tom Wade MD
(7) Epinephrine for SHOCK
BY SEAN FOX · PUBLISHED OCTOBER 7, 2016 · UPDATED OCTOBER 6, 2016
(8) Another Great YouTube Video from Dr. Mellick–Pediatric Pulse Dose Pressor Administration Posted on October 2, 2014 by Tom Wade MD
(9) Pulse Dosing of Epinephrine or Phenylephrine for Hypotension
Posted on September 10, 2013 by Tom Wade MD [Note that the experts I follow no longer recommend using phenylephrine]
(10) EM Podcast 6—Push Dose Pressors from Dr. Weingart and EMCrit.
