I don’t know if this has ever happened to you but when I was still a registrar, often I’d be in the midst of a resuscitation or major trauma case someone much cleverer than me would suggest a novel treatment that’d I’d never heard of and I’d be too embarrassed to admit that I had no idea what they were talking about.
‘Good idea’ I’d nod in agreement unconvincingly. ‘Let’s go for it’
One such time was during the resuscitation of a woman in her 60’s who had been transferred to Virchester with a thoracic dissection for the cardiothoracic surgeons. Pre-hospital she’d deteriorated and gone into PEA cardiac arrest. We carried out standard advanced life support, poured in O type blood and during a pause in CPR I did a quick xiphoid view with the cardiac ultrasound probe. We could see the ventricles contracting weakly but no pulse could be felt.
‘That’s pseudo-PEA’ my consultant declared. ‘Let’s carry on’.
Sadly the odds were stacked against our patient and although she did get a ROSC and palpable pulse her dissection was deemed unsurvivable by the surgeons and active treatment was withdrawn.
This was the first time I’d heard the phrase pseudo-PEA (also known as low flow PEA, near-PEA or PEA-like status) as it wasn’t something I’d been taught on Advanced Life Support courses. I’ve since become more familiar with the phrase and it’s implications but for people less familiar this recent paper is an excellent review. The abstract is below, but as we always say, please go read the full paper yourself before drawing any conclusions or changing your practice.1
What is Pseudo-PEA and how does it differ from ‘true’ PEA?
True PEA is the presence of organized electrical activity on cardiac monitor without a palpable pulse and no cardiac motion on POCUS.
Pseudo-PEA is organized electrical activity on cardiac monitor without a pulse but with cardiac motion on point of care ultrasound (POCUS).
What kind of paper is this?
This is a narrative review paper that evaluates the diagnosis and management of patients in pseudo-PEA and discusses the impact on emerging patient outcomes. A thorough review of the literature was undertaken by the authors looking for the following search terms: ‘‘pseudo pulseless electrical activity”, ‘‘pseudo PEA”, ‘‘near PEA”, ‘‘near pulseless electrical activity”, and ‘‘pseudo electromechanical dissociation”. A total of 9 articles were deemed suitable for review. Full details of the search strategy are shown in Fig. 1 of the paper.
What were the main results?
–Use of Ultrasound in diagnosing pseudo-PEA
POCUS is the main way of diagnosing pseudo-PEA. In a study by Salen et al211 out of 34 (32%) patients studied who were in PEA were found to have cardiac activity on ultrasound.
Zengin et al3 compared transthoracic echocardiograph and ultrasound doppler in cardiac arrests. TTE was found to be faster and more accurate than doppler ultrasound and manual pulse checks. In 37 cases of PEA TTE identified 7 (19%) cases of pseudo PEA vs 2 cases with ultrasound doppler of the left femoral artery.
Whilst transthoracic echocardiography may be quicker and simpler it can’t be done during active chest compressions. This is where Transoesophageal echocardiography (TOE) may be of benefit and has been used by Teran et al4 during cardiac arrests. Although the numbers are small (33 patients) TOE has shown some promise and can be used to give good quality cardiac images, real time feedback on the quality of CPR and can differentiate fine VF from asystole and pseudo-PEA from true PEA.
–Therapeutic approach to Pseudo-PEA
Diagnosing pseudo-PEA is critical as management can differ from true PEA. Prosen et al5 used TTE to diagnose pseudo-PEA and then gave an IV bolus of 20 IU of vasopressin to these patients then waited 15 seconds without chest compressions before feeling for a palpable pulse and then continuing CPR if no pulse was palpable. 15/16 (94%) of patients achieved ROSC and of these, eight patients (50%) attained a good neurological outcome (Cerebral Performance Category 1 – 2). The benefit of vasopressin was thought to be due to haemodynamic stabilization with peripheral vasoconstriction.
Paradis et al6 looked at the effects of CPR synchronised to systole or diastole in pigs induced into pseudo-PEA. Peak aortic pressure in systolic synchronization was 86.7 vs 69.3 in diastolic synchronization (P < 0.0001), and coronary perfusion pressure in systolic synchronization was 37.6 vs 30.2 in diastolic synchronization (P = 0.0001). This suggests that synchronizing external chest compressions with cardiac systole is beneficial rather than diastolic synchronization for pseudo-PEA patients. The reason for this benefit is that chest compressions are not impairing ventricular filling during systole. Only 8 subjects were included but this potentially could be very useful if similar findings were replicated in humans.
-Prognosis of patients in pseudo-PEA
We’re all aware of the poor prognosis of patients in cardiac arrest but three studies have shown increased rates of ROSC in patients with pseudo-PEA compared to true PEA. Chardoli et al7 found ROSC in 43% of pseudo-PEA patients compared 0% (no ROSC) in true PEA7.
In another study by Flato et al8 in ICU patients out of 27 patients with pseudo-PEA, 6 survived to hospital discharge, whereas out of 5 patients with true PEA, none of them survived to hospital discharge.
The most comprehensive paper was a systematic review and metanalysis by Wu et al9 combining 11 studies and 777 patients in PEA. It found that Pseudo-PEA patients more likely to obtain ROSC (RR 4.35, p < 0.00001). 15 patients survived to discharge all of them were in pseudo-PEA.
What’s the bottom line?
It’s really important to differentiate pseudo-PEA from true-PEA because ROSC and survival rates are higher in pseudo-PEA.
The evidence for the different management options vasopressin and CPR synchronised to systole are limited but make sense physiologically and would be important areas for future research. Indeed a further paper looking at synchronous CPR in pigs has just been published showing further promise.
POCUS should be a core skill for all emergency physicians and will help us make a diagnosis of pseudo-PEA.
True PEA has a worse prognosis than pseudo-PEA so diagnosing that may aid decision making in cessation of cardiac arrest.
42-86% of all PEA is pseudo-PEA. As this is more common than people probably realise more research should be done in this area to try to improve outcomes for patients. (Salen et al)
Thanks for reading, I’d love to hear your comments and who knows maybe this will help you be the ‘clever’ doctor the next time you see a patient in PEA (or is it actually pseudo-PEA?).
Please See also
- 1.Rabjohns J, Quan T, Boniface K, Pourmand A. Pseudo-pulseless electrical activity in the emergency department, an evidence based approach. The American Journal of Emergency Medicine. October 2019. doi:10.1016/j.ajem.2019.158503
- 2.Salen P, Melniker L, Chooljian C, et al. Does the presence or absence of sonographically identified cardiac activity predict resuscitation outcomes of cardiac arrest patients? The American Journal of Emergency Medicine. July 2005:459-462. doi:10.1016/j.ajem.2004.11.007
- 3.Zengin S, Gümüşboğa H, Sabak M, Eren Ş, Altunbas G, Al B. Comparison of manual pulse palpation, cardiac ultrasonography and Doppler ultrasonography to check the pulse in cardiopulmonary arrest patients. Resuscitation. 2018;133:59-64. doi:10.1016/j.resuscitation.2018.09.018
- 4.Teran F, Dean A, Centeno C, et al. Evaluation of out-of-hospital cardiac arrest using transesophageal echocardiography in the emergency department. Resuscitation. 2019;137:140-147. doi:10.1016/j.resuscitation.2019.02.013
- 5.Prosen G, Križmarić M, Završnik J, Grmec Š. Impact of Modified Treatment in Echocardiographically Confirmed Pseudo-Pulseless Electrical Activity in Out-of-Hospital Cardiac Arrest Patients with Constant End-Tidal Carbon Dioxide Pressure during Compression Pauses. J Int Med Res. August 2010:1458-1467. doi:10.1177/147323001003800428
- 6.Paradis NA, Halperin HR, Zviman M, Barash D, Quan W, Freeman G. Coronary perfusion pressure during external chest compression in pseudo-EMD, comparison of systolic versus diastolic synchronization. Resuscitation. October 2012:1287-1291. doi:10.1016/j.resuscitation.2012.02.016
- 7.Chardoli M, Heidari F, Rabiee H, Sharif-Alhoseini M, Shokoohi H, Rahimi-Movaghar V. Echocardiography integrated ACLS protocol versus conventional cardiopulmonary resuscitation in patients with pulseless electrical activity cardiac arrest. Chin J Traumatol. 2012;15(5):284-287. https://www.ncbi.nlm.nih.gov/pubmed/23069099.
- 8.Flato U, Paiva E, Carballo M, Buehler A, Marco R, Timerman A. Echocardiography for prognostication during the resuscitation of intensive care unit patients with non-shockable rhythm cardiac arrest. Resuscitation. 2015;92:1-6. doi:10.1016/j.resuscitation.2015.03.024
- 9.Wu C, Zheng Z, Jiang L, et al. The predictive value of bedside ultrasound to restore spontaneous circulation in patients with pulseless electrical activity: A systematic review and meta-analysis. Erdoes G, ed. PLoS ONE. January 2018:e0191636. doi:10.1371/journal.pone.0191636