The role of point-of-care echocardiography during prehospital non-traumatic cardiopulmonary resuscitation - analysis of pseudo-PEA status and prehospital survival from structured case report database

The use of point-of-care ultrasound during cardiopulmonary resuscitation (CPR) may help to detect the reversible causes of cardiac arrest. Furthermore, it allows visualization of organized myocardial movements in patients with no palpable pulse but electrical activity still visible on ECG. Based on previous studies, the prognosis of patients with pseudo pulseless electric activity (pseudo-PEA) may differ from patients with true PEA (cardiac standstill).

In this study, we aimed to analyse the role of the documented pseudo-PEA status in the estimation of the probability of prehospital survival of patients requiring CPR due to non-traumatic aetiology.

1,980 cases of non-traumatic CPR cases are available in a structured form from the database of the digital case reports of the Helicopter Emergency Medical Service (HEMS) in our country from 01.01.2019 to 07.31.2024. Of them, we analysed 658 cases in which resuscitation was initially started due to a non-shockable rhythm and point-of-care echocardiography was performed during cardiac arrest. The endpoint of the study was hospital admission with spontaneous circulation. 11 patients who were transferred with continuous CPR were excluded. The available demographic, anamnestic, and clinical data were analysed using descriptive statistical methods, chi-square test, univariate and multivariate logistic regression.

Of the 647 cases, 60 patients were admitted to the hospital with maintained spontaneous circulation (9.3%). Pseudo-PEA was described in a total of 47 patients (7.3%), of whom 9 (19.1%) survived until hospital admission, while cardiac standstill was seen at the first ultrasound in 600 patients, of whom 51 (8.5%) were admitted to hospital alive (chi-square p=0.031, OR=2.55 [1.10-5.36], p=0.019).

Multivariate logistic regression analysis was performed using the following variables: age, sex, certainty or uncertainty of the timepoint of cardiac arrest, arrival time of the HEMS personnel, first end-tidal carbon dioxide pressure (etCO2) and the total number of adrenaline boluses, in addition to the documented presence or absence of pseudo-PEA. The model fit was good (AUC=0.778 [95% CI=0.720-0.836], chi-square=6.36 [df=8], Hosmer-Lemeshow p=0.607). Among the other variables, the prognostic role of documented pseudo-PEA status remained significant in estimating the probability of hospital admission with spontaneous circulation (OR=3.54 [1.40-8.38], p=0.005).

During non-traumatic out-of-hospital CPR with non-shockable initial rhythm, in the case of regular myocardial activity (pseudo-PEA) detected during point-of-care echocardiogram, the probability of admission to the hospital with maintained circulation may be higher than in the case of a cardiac standstill seen at the first ultrasound. Further studies are needed to compare possible therapeutic alternatives to improve survival chances.

ROC curve of logistic regression model