How to Run a Code Blue Like a Boss: Master ACLS Algorithms!

How to Run a Code Blue Like a Boss: Master ACLS Algorithms!
Photo by Michel E / Unsplash

In this article, we’re going to cover advanced cardiac life support (ACLS) algorithms for treating patients in various dysrhythmias which could result in a code blue.

This post will be broken down into the following sections:

  • Pre-code blue (bradycardia and SVT or VT with a pulse)
  • Code blue (VF/pulseless VT, PEA/Asystole)
  • Post-code blue (ROSC)
Before we begin, if you need to quickly brush up on your rhythms, then check out our EKG Megathread.
How to Interpret & Read EKGs Like a Boss: Master Heart Rhythms
In this post, we’re going to learn all about heart rhythms, so the next time you do an electrocardiogram (EKG/ECG), you’ll know what’s going on. This post can also come in handy if you plan to work on a nursing floor with telemetry, or if you

Pre-code Blue ACLS Scenarios

Not all situations may result in a full-blown code blue, but they may devolve into one. In many of these situations, you might consider calling for a rapid response team (RRT).


Bradycardia is an ACLS protocol that we need to cover. If the patient is in the 30s, for example, they could lose responsiveness, develop severe hypotension, and require immediate medical attention. For this rhythm, the patient would have to be “symptomatic” for us to treat it.

Symptomatic bradycardia is defined as a heart rate less than 60/min that elicits signs and symptoms, but the heart rate will usually be less than 50/min. Symptomatic bradycardia exists when the following 3 criteria are present:

  1. The heart rate is slow
  2. The patient has symptoms
  3. The symptoms are due to the slow heart rate


Atropine is indicated in treating severe bradycardia. The dosing is 0.5mg IV push, every 3-5 minutes and you may repeat up to a total dose of 3mg.

Alternatives to atropine are dopamine and epinephrine drips.

Transcutaneous pacing (TCP)

Preparation for TCP should be taking place as atropine is being given. If atropine fails to alleviate symptomatic bradycardia, TCP should be initiated. Ideally, the patient should receive sedation prior to pacing, but if the patient is deteriorating rapidly, it may be necessary to start TCP prior to sedation.

For the patient with symptomatic bradycardia with signs of poor perfusion, transcutaneous pacing is the treatment of choice.

Of note, other sinus brady-similar rhythms that would be treated under this ACLS protocol also include heart blocks with a low pulse such as a 3rd-degree AV blocks (AVBs), or severe 2nd-degree AVBs.

Supraventricular tachycardia (SVT) & ventricular tachycardia (VT) with a pulse

SVT and VT with a pulse are generally treated the same, and the treatment course depends on whether or not the patient is stable or unstable. Unstable would be any loss of consciousness, hypotension, etc.

Stable treatment

If the patient is stable, the first recommendation is to have them perform a vagal maneuver to attempt to slow the heart rate down.

If that doesn’t work, and if SVT were to continue long enough, the patient may require adenosine to slow the heart and attempt a reset to a normal rhythm. If the patient receives adenosine, expect a massive pause in the heartbeat, which occurs during the “reset” period, and can last a few seconds.

Dosing for adenosine is 6mg IV push followed by 12mg IV push if unsuccessful.

Unstable treatment

If the patient is having unstable SVT, they would probably require transcutaneous pacing via synchronized cardioversion to slow the heart rate.

The appropriate voltage for cardioversion SVT is 50-100 J.

A good way to remember how to treat SVT is “Stable vagal, unstable cable,” where cable means to hook the patient up to the monitor/defibrillator and cardiovert them.

Code Blue ACLS Scenarios


Ventricular fibrillation (VF) & pulselss ventricular tachycardia (VT)

Both VF and pulseless VT rhythms are treated the same way… code blue with prioritized defibrillation ASAP!

Start CPR

You will immediately start CPR when either of these occurs. You need to assess for a pulse in less than 10 seconds, and then get on the chest.

  • High-quality compressions and rescue breaths are done at a rate of over 100 bpm and a ratio of 30:2
  • In the hospital with an advanced airway, you just do CPR compressions continuously until the 2 minute before a rhythm check (or as soon as the defibrillator is hooked up and ready to analyze the rhythm).

In the meantime, respiratory should be responding to begin intubation and manage the airway, someone else should be ensuring IV/IO access, and someone else should be hooking the patient up to the defibrillator.

2-minute rhythm check & defibrillation

Every 2 minutes, you will stop compressions and assess for a rhythm and typically a simultaneous pulse check as well. If there is no pulse or the rhythm is VF or asystole (these will never have a pulse), then defibrillate and continue CPR ASAP.

It is at this point that you can give the first dose of epinephrine (epi). Dosing is 1mg IV Push every 4 minutes.

Subsequent 2-minute checks

Again you will stop compressions and check for a rhythm.  If it is shockable, then defibrillate and resume CPR until the next 2-minute check.

At this time you can begin assessing for causes of this situation.  Assess for various H’s&T’s:

  • Hypovolemia
  • Hypoxia
  • Hydrogen ion (acidosis)
  • Hyper-/hypokalemia
  • Hypoglycemia
  • Hypothermia
  • Toxins
  • Tamponade (cardiac)
  • Tension pneumothorax
  • Thrombosis (coronary and pulmonary)

After considering various causes for the patient’s cardiac arrest, you want to start administering possible treatments, for example:

  • Starting IV fluids for suspected hypovolemia
  • Giving sodium bicarbonate for suspected acidosis
  • Administering calcium gluconate for suspected hyperkalemia, etc.

Of course, you will continue alternating between epi and vasopressin as often as you can during the code.

This process will continue on until the patient either:

  1. Re-establishes a pulse or ROSC
  2. Converts to an unshockable rhythm
  3. Is pronounced dead after a certain amount of time when every attempt to resuscitate has been futile

Pulseless electrical activity (PEA) & Asystole

PEA and asystole are treated the same way.

Unlike VF and pulseless VT, you will not be defibrillating the patient in these rhythms, but the rest of the treatment will be the same as we previously discussed.

You will still:

  • Perform high-quality CPR with compressions and rescue breaths
  • Give epi, fluids, and other ACLS drugs
  • Assess for possible causes including H’s & T’s
  • Perform 2-minute rhythm and pulse checks

Once again, you will continue this code blue cycle until:

  1. The return of a pulse or ROSC
  2. The patient has a rhythm change that may require defibrillation (VF or pulseless VT)
  3. The patient is pronounced dead after a certain amount of time when every attempt to resuscitate has been futile

Post-Code Blue:  Return of Spontaneous Circulation (ROSC)

The best outcome of a code blue is when the patient survives and enters what is called ROSC.

In ROSC, the patient will have a pulse, and compressions and defibrillation will no longer be required. The patient may or may not be breathing on their own at this point, so rescue breaths may need to continue.

If we achieve ROSC, we will transition to post-code blue care, which requires the following elements:

  • Maintaining adequate BP with IV fluids and vasopressor drips such as dopamine, epinephrine, or norepinephrine
  • Maintaining adequate oxygenation and ventilation support if needed (most accurately verified by waveform capnography if intubated)
  • Treating underlying H’s & T’s
  • Therapeutic hypothermia for patients with a suspected MI that caused the code blue
  • Transfer to the cath lab for percutaneous coronary intervention (PCI) for suspected MI

Congratulations, code master!

You’re gonna ace ACLS class!

These are the main components of ACLS class. You should definitely be familiar with the bradycardia, SVT (stable/unstable), VT/VF, PEA/Asystole, and ROSC algorithms.

As part of your class, you will likely have to run a simulated “mega-code” which will take you through these various algorithms usually starting out with a precode situation like bradycardia or SVT, then converting to a code blue via pulseless VT/VF or PEA/Asystole, and finishing off with ROSC and postcode care.