Should I start Vasopressors
Should I start Vasopressors

Should I start Vasopressors

Good posts start with good questions. Have an ER question? Send it here.
KEY
🔍- Deep Dive
📌- Clinical Application
🔸 - Weak Evidence
🔹 - Strong Evidence
📑 - Evidence summaries
✅ - Recommended treatment
⚠️ - Critical Information
I love resuscitating shock — it’s fun, fast, chaotic, and everything I love about EM. But it also comes with a ton of doubts. This post is a breakdown of all the questions that bothered me over the years, distilled into something I hope helps you too.
(Disclaimer: These recommendations DO NOT replace your clinical judgement. Every patient is unique.)
So let’s talk shock, or septic shock ( if you know,you know)

Step 1: Recognize Septic Shock?

According to the Surviving Sepsis Campaign (SSC)
“Septic shock is a subset of sepsis with circulatory and metabolic abnormalities large enough to substantially increase mortality.”
But more importantly for us:
⚠️
Clinical definition = Sepsis + BOTH:
  • Persistent hypotension needing vasopressors to maintain MAP ≥ 65, despite fluids
  • Lactate ≥ 2 mmol/L
✅
Once you recognize shock → resuscitation begins immediately.

Step 2: Fluids

How much?

🔸30 mL/kg crystalloid within the first 3 hours (SSC guideline)

But ER doctors must do better.

notion image
Fluid resuscitation must be individualized.
Assess:
  • Fluid Responsiveness (FR)
  • Fluid Tolerance (FT)

Quick & Oversimplified Guide

FT
FR
Management
✔
✔
Give fluids
✘
✘
Early pressors
✔
✘
Early pressors
✘
✔
Early pressors
⚠️
Low diastolic BP (DAP) → low vascular tone → start NE early
Not a fluid post — that’s coming next 😄
Let’s move on.

Step 3: 1st Vasopresor

Which Pressor First?

🔹Norepinephrine (Noradrenaline) (SSC guidelines)

Why?

  • Potent α-1 + mild β-1 effect
  • Raises MAP with minimal tachycardia

Why NOT the others first?

Dopamine
❌ More arrhythmias
❌ Higher mortality
→ No role in septic shock
Epinephrine
❌ Tachyarrhythmias
❌ Increases lactate
✔ Good in bradycardia / myocardial dysfunction
→ Second/third line
Vasopressin
Not first line because of:
❌ Cost
❌ Availability
✔ Excellent add-on to NE

When to start pressors?

Immediately if MAP < 65
Do NOT wait to finish 30 mL/kg.
✅
Reassess after 10 mL/kg over 10 minutes:
If MAP is still low → start pressors early.

Why early norepinephrine (NE)?

Because septic shock ≠ pure hypovolemia.
  • NE ↑ preload and cardiac output
  • Less time in hypotension → less AKI
  • Improves microcirculation
  • Avoids fluid overload
  • Early BP control = lower mortality
  • CENSER Trial: early NE → better shock control at 6 hours

Peripheral or Central Line?

🔸SSC recommends: Start NE peripherally if needed.
Do NOT delay vasopressors waiting for a central line.
⚠️
Do NOT give vasopressin peripherally.

What Dose of NE?

  • Start: 0.1 mcg/kg/min
  • Titrate to MAP ≥ 65
  • No absolute “maximum” dose

Then why add a second pressor?

To reduce total catecholamine exposure:
  • High NE doses may impair immunity
  • Promote bacterial growth
  • Cause myocardial injury
  • Increase oxidative stress
This principle is called decatecholaminization.

Step 4: 2nd Vasopressor

When to Start the Second Pressor?

👉 When NE = 0.25–0.5 mcg/kg/min and MAP still inadequate.
Instead of escalating NE further.
⚠️
Remember: Reduction of NE dose with MAP ≥ 65 by 6 hours → better outcomes.
✅
Also: Always start steroids when you add a second pressor.

Which Pressor Next?

🔸Vasopressin - (SSC Guideline)

Why Vasopressin?

  • Relative vasopressin deficiency in septic shock
  • Less atrial fibrillation when added to NE
      • (McIntyre et al., JAMA 2018)
  • Lower RRT requirement (VANISH)
  • Improved survival in less severe shock (VASST subgroup)
  • Catecholamine-sparing effect (less NE needed)

Dose

0.03 U/min
⚠️
Vasopressin is never titrated.
Higher doses → cardiac, digital, and splanchnic ischemia.

Should you consider a loading bolus?

Why?
  • Half-life: 15–20 minutes
  • Infusion alone may take ~30 min to show effect
  • 1-unit bolus → rapid MAP rise
  • VALOR Trial: responders had MAP ↑ >18–22 mm + fewer ischemic complications
Why not?
  • Overshoot MAP
  • Ischemia (cardiac, digital. mesentric)
  • VALOR Trial : Not a mortality study, Sample size relatively small
  • No major guideline recommends this yet

When to AVOID Vasopressin

  • Systemic hypoperfusion (cold extremities, mottling)
  • High risk of digital or splanchnic ischemia

When Vasopressin Is GREAT

  • Warm vasoplegic shock (low SVR, high CO)
  • Tachyarrhythmias
  • RV failure
⚠️
A Caveat
🔸If myocardial dysfunction is present:
👉 Use epinephrine, or NE + dobutamine
(No evidence that dobutamine is superior to epinephrine.)

Step 5: 3rd Vasopressor

Still in Shock? Now what?
Before escalating, reconsider your diagnosis.
Remember Hickam’s dictum: “A patient can have as many diseases as he damn well pleases.”
🔸Epinephrine (SSC Guideline)
Especially useful in:
  • Bradycardia
  • Depressed systolic function
  • Refractory shock
notion image
📌

How to Choose Your Pressor (4-Question Method)

Now that you understand each drug, choose based on these:

1️⃣ Peripheral vs Central Access

  • Vasopressin → avoid peripherally
  • NE → safe peripherally short-term

2️⃣ Heart Rate & EF

  • Bradycardia / low EF → NE, Epinephrine
  • Tachycardia / good EF → Vasopressin

3️⃣ RV Failure

  • NE may worsen RV afterload
  • Choose Vasopressin or Epinephrine

4️⃣ When in doubt

👉 Start Norepinephrine.

Want to Read More?

  1. Surviving Sepsis Campaign: International Guidelines for Management of Sepsis and Septic Shock 2021. Critical Care Medicine 49(11):p e1063-e1143, November 2021. | DOI: 10.1097/CCM.0000000000005337
  1. Kattan, Eduardo, et al. "The emerging concept of fluid tolerance: a position paper." Journal of Critical Care 71 (2022): 154070.
  1. Singer M, Deutschman CS, Seymour CW, et al. The Third International Consensus Definitions for Sepsis and Septic Shock (Sepsis-3). JAMA. 2016;315(8):801–810. doi:10.1001/jama.2016.0287
  1. Permpikul, Chairat, et al. "Early use of norepinephrine in septic shock resuscitation (CENSER). A randomized trial." American journal of respiratory and critical care medicine 199.9 (2019): 1097-1105.
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What they asked…

This is an ongoing project that attempts to address questions that have appeared in past examination papers.
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Disclaimer : For educational use only — always follow your clinical judgment and local protocols.