POCUS in Cardiac Arrest

 

Written by: David Han, MD. Edited by: Jeff Greco MD

Patient of unknown age presents to the ED with OHCA with EMS reporting a downtime of at least 30 minutes with unwitnessed cardiac arrest. When EMS arrived at the scene the patient was already undergoing compressions. Patient was intubated at the scene and brought with EMS actively compressing.

Do you reach for the ultrasound?

What we know so far

The applicability of ultrasound in cardiac arrest has not been well studied due to obvious limitations of both population size as well as applicability. There have been studies regarding out of hospital cardiac arrest (OHCA) as well as its use in the acute setting in the ED.

In one recent study authors examined 953 patients who experienced either an out of hospital cardiac arrest (OHCA) or arrest in the Emergency Department, found to be in either asystole or PEA. 

Exclusion criteria encompassed ventricular fibrillation or pulseless ventricular tachycardia, experienced ROSC after only a brief resuscitation, or who had do-not-resuscitate (DNR) orders prior to their arrest. 

Cardiac motion was then visualized on bedside US to predict ROSC, survival to hospital admission, and survival to discharge in this subset of cardiac arrest patients. 

At a brief initial glance, bedside US appears to be very unpredictable in its capabilities. With poor sensitivities and inconsistent specificities in the time to discharge.

The majority of these patients were in arrest for a prolonged period of time. They were either found in PEA or asystole or had transitioned from v-fib/v-tach to PEA or asystole during the early phase of their resuscitation. This means the majority of these patients were far into the metabolic phase of their arrest. 

Early on our traditional resuscitative strategies are more effective following the onset of arrest, but these very same strategies become decisively ineffective in the latter stages of arrest. 

Ultrasound is most usual in identifying a reversible cause of arrest; however, if no reversible cause exists POCUS does not contribute significantly to improvements of outcomes.

Reversible Causes and Their Treatment Can Include

Pericardial Effusion → Pericardiocentesis

Pericardial Effusion → Pericardiocentesis

Tension Pneumothorax → Needle thoracostomy/chest tube

Tension Pneumothorax → Needle thoracostomy/chest tube

 
Pulmonary Embolism → tPA

Pulmonary Embolism → tPA

Hypovolemia → Fluids

Hypovolemia → Fluids

Fine Ventricular Fibrillation → Defib

Fine Ventricular Fibrillation → Defib

Pulse Check

During the first round of compressions the ultrasound should be prepared. Just prior to the first rhythm/pulse check, the ultrasound should be placed on the femoral or carotid artery. During the pause, one provider should analyze the rhythm while the provider using the ultrasound assesses for the presence or absence of a femoral or carotid pulse.

POCUS pulse checks have a higher first attempt success rate of identifying a pulse than manual pulse checks during cardiac arrest. The identified vessel is less compressible and should have a pulsatile appearance during compressions. Visible pulsations can also indicate appropriate compression depth and quality. Positive pulse-wave finding during pulse checks at the carotid and femoral have been shown to have higher sensitivity as well as decrease the amount of time and confusion during cardiac arrest.

Just Beat It

ROSC is generally assessed for by looking for changes in end tidal CO2 or by assessing for the presence of a palpable pulse or obtainable blood pressure.

But there are several in-betweens that must be considered as well. A good way to break these ideas down, as suggested by Weingart et al. suggest it be seen as a spectrum of:

  1. Evidence of perfusion capable rhythm

  2. Must be cardiac contractility followed by a pulse (palpable or on POCUS)

  3. Pulse must be strong enough to generate a blood pressure (MAP > 50-55)

At the end of the day, high quality chest compressions with minimal interruptions as well as prompt electricity given the right indications is still the most important aspect of cardiac arrest.

The pulse check with US should be binary (yes/no) and should not take more than five seconds.

Ways to ensure efficient use of US in Cardiac Arrest:

  1. Have a dedicated sonographer during the resuscitation who is also not running the code. 

  2. Attempt looking for a cardiac window during chest compressions. 

    • Try the apical window if a mechanical compression device is being used

    • subxiphoid just prior to the pulse check

  3. Have the most experienced provider perform the ultrasound. 

  4. Obtain clips during the pauses and wait to analyze them during compressions. Set clip time to 10 seconds.  Begin as soon as compressions are paused.  And resume compressions as soon as 10 second clip is done recording.  Clips may also be saved retrospectively 

  5. Use a protocol designed for ultrasound in cardiac arrest. This way you can approach every non-traumatic arrest in a systematic fashion.

  6. Use TEE (transesophageal echo). 

References

  • Interest SWEI from NN conflicts of. EMCrit 257 – Pulseless Electrical Activity (PEA) is Stupid [Internet]. EMCrit Project. 2019 [cited 2020 Apr 26]. Available from: https://emcrit.org/emcrit/pea-is-stupid/.

  • Thepocusatlas.com

  • Implementation of the Cardiac Arrest Sonographic Assessment (CASA) protocol for patients with cardiac arrest is associated with shorter CPR pulse checks. Eben J Clattenburg. Resuscitation. 2018

  • Emergency department point-of-care ultrasound in out-of-hospital and in-ED cardiac arrest. Resuscitation. 2016

  • Detection of Pulmonary Embolism During Cardiac Arrest-Ultrasonographic Findings Should Be Interpreted With Caution. Rasmus Aagaard. Crit Care Med. 2017

  • Badra K, Coutin A, Simard R, Pinto R, Lee JS, Chenkin J. The POCUS pulse check: A randomized controlled crossover study comparing pulse detection by palpation versus by point-of-care ultrasound. Resuscitation. 2019;139:17—23.

 
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