Special thank you to Salim Rezaie for guest editing this post.
Out-of-hospital cardiac arrest (OHCA) affects > 300,000 people in the US each year and most of these patients are transported to the Emergency Department (ED) for further care. Currently, survival to discharge sits at around 8%. Over the last decade, it has become clear that the keys to improved return of spontaneous circulation (ROSC) and return of neurologic function (RONF) are early CPR, high-quality CPR with minimal interruptions and immediate defibrillation when appropriate. Point of care ultrasound (POCUS) has become an increasingly larger part of continued resuscitation once the cardiac arrest patient reaches the ED. However, there is limited prospective data evaluating the impact of ultrasound on OHCA care.
Is detection of cardiac activity on POCUS in patients with PEA or asystole associated with improved survival from cardiac arrest?
All patients presenting to the ED after an non-traumatic OHCA who were found to be either in asystole or PEA and had ultrasound imaging performed during their resuscitation
Cardiac ultrasound had to be performed at the beginning and end of the resuscitation.
Primary: Survival to hospital admission
Secondary: Survival to hospital discharge, ROSC
Multicenter, Non-randomized, prospective, protocol-driven observational study at 20 hospitals
Resuscitation not continued after initial ultrasound
Resuscitation efforts discontinued due to a DNR order
Resuscitation lasted < 5 minutes
- 953 patients enrolled and, ultimately, 793 included for analysis
- PEA: 414
- Asystole: 379
- Primary Outcome (Survival to hospital admission) = 14.4% (114/793)
- Survival to hospital discharge = 1.6% (13/793)
- Agreement between US interpretation and expert review k = 0.63 (moderate)
- Cardiac activity on Initial US
- 263/793 = 33%
- 54% of PEA patients had cardiac activity on initial US
- ROSC: 51% (134/263)
- Survival to admission: 28.9% (76/263). OR = 3.6 (CI 2.2-5.9)
- Survival to discharge: 3.8% (10/263). OR = 5.7 (CI 1.5 – 21.9)
- No cardiac activity on initial US
- 530/793 = 67%
- ROSC: 14.3% (76/530)
- Survival to admission: 7.2% (38/530)
- Survival to discharge: 0.6% (3/530)
- Additional Ultrasound Findings
- Pericardial Effusions n = 34
- 13 patients had pericardiocentesis performed
- Survival to discharge: 15.4% (2/13)
- Pulmonary Embolism
- 15 patients received thrombolytics for PE
- Survival to admission: 13.3% (2/15)
- Survival to discharge: 6.7% (1/15)
- Pericardial Effusions n = 34
- First large, multicenter study evaluating utility of US in cardiac arrest management
- Physicians performing US did not have to be fellowship trained or RDMS certified increasing generalizability of skills needed
- The primary endpoint was suboptimal. We should be less concerned with survival to admission or even discharge and more concerned about neurologically intact survival (not even a secondary outcome)
- Treating physicians were unblinded to US results. This can introduce bias as physicians may change their resuscitation approach based on the US (i.e. absence of activity may lead to shorter duration of resuscitation or vice versa)
- EM physicians credentialed in bedside ultrasound performed all ultrasound imaging. Not all physicians are credentialed in US
- There is no explanation to why some patients with pericardial effusion had a pericardiocentesis and others did not or how many patients were thought to have PE and did not receive thrombolytics.
“The presence of cardiac activity at the initiation of ACLS in the ED was the variable most associated with survival following cardiac arrest. Point-of-care ultrasound during cardiac arrest can identifypatients with higher likelihood of survival to hospital discharge, and can identify interventions outsideof the standard ACLS algorithm. Point-of-care ultrasound should be integrated into ACLS algorithms.”
In a small number of patients with OHCA presenting in either asystole or PEA, cardiac US identified potentially reversible pathology including pericardial tamponade and pulmonary embolism. Survival to admission and discharged is associated with the presence of cardiac activity on initial ultrasound. The absence of cardiac activity is a dismal prognostic indicator but, is not a 100% death sentence. Finally, it is critical to note that 54% of patients thought to be in “PEA” were found to have organized cardiac activity on US further questioning the sensitivity of using a person’s fingers to perform a pulse check.
Potential Impact To Current Practice
Cardiac US should be applied to all cases of non-traumatic cardiac arrest in order to search for a potentially reversible cause and to differentiate profound shock from cardiac arrest.
POCUS is a powerful tool in cardiac arrest care but is only useful if the information obtained from it is acted upon. In a small number of cases, cardiac ultrasound will reveal potentially reversible pathology in the cardiac arrest patient. Lastly, it is clear that fingers are not accurate in assessing the presence or absence of a pulse in patients in extremis. It’s time to abandon fingers for the pulse check and embrace more advanced technology.
EM Nerd: The Case of the Tell-Tale Heart
The Ultrasound Podcast: State of the Evidence Cardiac Arrest Echo