Episode 34- Adult ACLS: Updated recommendations and clinical pearls

Hello and welcome to Episode 34 of ER-Rx. In part one of our cardiac arrest series, we review the adult AHA BLS and ACLS guidelines published in October of 2020, and then next then time we will go over the pediatric guidelines. My goal for the episode is to focus on key updates and reaffirmed recommendations from the previous guidelines, as well as some of my favorite pearls that you can immediately bring to your own practice. For more detail, I encourage all of you to read the guidelines for yourselves- especially the special guidance on cardiac arrest in patients with known or suspected COVID- which I have linked in the references.

Overall, the main concepts of cardiac arrest remain the same and include immediate CPR, defibrillation of shockable rhythms, and post-ROSC supportive care. These are the most important things we have to do to give our patients the best chance at survival. But there are other smaller things that we can keep in mind during a cardiac arrest that may make a big difference for our patients.

First, let’s look at the drugs. And how should we give the drugs? The guidelines now recommend the IV route above the IO route- citing new evidence that shows better clinical outcomes in some retrospective studies. They recommend IO access only if IV access fails or if it’s just not possible to obtain (2b; B-NR).

One of the most common drugs that we give, IV or IO, is epinephrine, and a major update from previous guidelines is highly recommending that epi be given as soon as possible in non-shockable rhythms (PEA and asystole). This is because newer systematic reviews and meta analyses have shown significantly higher rates of ROSC and survival to hospital discharge with giving epi, and some observational studies showed better outcomes when epi was given sooner rather than later. (2a; C-LD) We all know that we give epi every 3-5 minutes, but to keep it easy, it can also be given every other cycle of CPR- which should be every 4 minutes. This is the approach I have started taking, and it makes things easier for the team because you don’t have to constantly remember what time the last dose was given, and you’re not randomly giving epi in the middle of a cycle (2a; C-LD). Of course, for shockable rhythms, epi is given after the second shock to prioritize defibrillation and CPR efforts (2b; C-LD).

The guidelines also discuss the use of non-vasopressor medications. Remember that none of these medications have been shown to improve overall survival, although they may have some slight benefit in highly selected situations that we should remember. The guidelines recommend that either lidocaine or amiodarone can be considered for shockable rhythms unresponsive to defibrillation. Both of these agents show improved survival to hospital admission, but not to survival with good neurological outcomes. Continuous infusions of lidocaine may also be considered during EMS transport after successful defibrillation with the hope of reducing recurrence of VF/ pVT (2b; B-R).

The next agents are ones that are typically not routinely recommended and can even cause harm. One of my favorite examples is sodium bicarbonate. Sodium bicarb is not recommended for routine use because it hasn’t shown any improvement in outcomes (No benefit; B- R). On the contrary, there is some evidence that it may actually worsen survival and neurological recovery. I often see sodium bicarb given to patients who are acidotic- either as a cause or as a consequence of cardiac arrest- due to some perceived theoretical and in vitro benefit. But although studies have shown that giving sodium bicarb can improve your acid-base status, this did not affect ROSC or other survival outcomes. Remember that sodium bicarb can and should be considered in the setting of hyperkalemia and certain drug overdoses.

Along the same lines, the routine administration of calcium is not recommended outside of the settings of hyperkalemia, hypermagnesemia, or calcium channel blocker overdose (No benefit; B-NR).

Magnesium has also not shown any benefits on patient outcomes regardless of arrest rhythm (2b; CL-D). It’s not effective for the treatment of any ventricular arrhythmia with normal QT intervals. It is, however, effective in rhythms with prolonged QT intervals, including torsades. But even in the setting of torsades, magnesium is only given to prevent recurrence of the arrhythmia, not to break it. Of course, magnesium is recommended in severe forms of hypomagnesemia that may have caused the cardiac arrest.

Remember that IV bolus administration of potassium in suspected hypokalemia is not recommended due to the unknown efficacy of this intervention and safety concerns of bolusing potassium- so please don’t do this (Harm; CL-D).

In terms of drug antidotes, the guidelines state that in presumed opioid-related arrests, priority should still be given to calling 9-1-1 and starting CPR before naloxone administration. This is because naloxone does not have a proven benefit in any outcomes during cardiac arrest (1; CE-O). Obviously if your patient still has a pulse but is in respiratory arrest and we are presuming opioid overdose, we should give naloxone along with standard BLS/ACLS interventions (2b; B-NR). The guidelines do recommend against the use of flumazenil in patients with undifferentiated coma, citing a meta-analysis of over 900 patients showing that adverse events such as arrhythmia, seizures, and hypotension were more common in patients who received flumazenil (Harm; B-R). We can simply support the patient until the drug wears off.

Switching gears from medications, the guidelines have some good discussions on other things you may commonly see in the ER. One popular tool is mechanical CPR devices such as the LUCAS. The guidelines recommend against the routine use of these devices, stating that they haven’t demonstrated a benefit when compared to manual CPR. However, we still routinely use them at my site, if the patient can fit in it, since it frees up staff for other tasks (No benefit; B-R). The guidelines also recommend against the routine use of impedance threshold devices such as the ResQPOD as it did not show any improvements in patient outcomes. And remember if you use this device, it has to be disconnected immediately if your patient achieves ROSC (No benefit; A).

Another thing mentioned is “anticipatory defibrillator charging,” where a manual defibrillator is pre-charged during chest compressions before a scheduled rhythm check. Typically, the team will pause chest compressions, check a rhythm, and if it is shockable, they will resume chest compressions while the device is charging, only to stop compressions again once the defibrillator is charged. This can cause more hands-off time than is necessary. With charging the defibrillator prior to the 2-minute pulse check, if the rhythm is shockable, we can shock right away (2b; C-EO). Also remember to immediately resume chest compressions after a shock is delivered unless there is an obvious sign of ROSC, because even if defibrillation was successful, we typically see a period of asystole or PEA prior to ROSC (2b; C-LD). And while we’re talking about non-med related things, there is also a cool section on “pseudo-electric” therapies, including the “pre-cordial thump,” “fist pacing,” and “cough CPR,” none of which routinely recommended but are still very interesting so if you have time- look into this.

And finally, when should we stop resuscitation efforts? In intubated patients, failure to achieve an end tidal CO2 > 10 mm Hg after 20 minutes may be a key decision in a multimodal approach to decide to stop efforts (2b; CL-D). Keep in mind that in non-intubated patients there is no specific end tidal CO2 value to guide us (Harm; C-EO). The guidelines also state that if 1) the arrest was not witnessed, 2) the patient did not receive bystander CPR, 3) the patient never achieved ROSC, and 4) no shock was delivered, that we should consider termination of resuscitation prior to even bringing a patient into the ER. This is because in a meta-analysis of 2 published studies in over 10,000 patients, only 0.01% of patients who met all of those 4 criteria survived to discharge (1; B-NR).

As always, thank you all so much for your time. Please remember to tune in next time, when we discuss some key points from the pediatric cardiac arrest guidelines.