Epinephrine plus chest compressions is superior to epinephrine alone in a hypoxia-induced porcine model of pseudo-pulseless electrical activity.

AIM: Pseudo-pulseless electrical activity (pseudo-PEA) is a global hypotensive ischemic state with retained coordinated myocardial contractile activity and an organized ECG with no clinically detectable pulses. The role of standard external chest compressions (CPR) and its associated intrinsic hemodynamics remains unclear in the setting of pseudo-PEA. We undertook an experimental trial to compare epinephrine alone versus epinephrine with CPR in the treatment of pseudo-PEA. METHODS: Using a porcine model of hypoxic pseudo-PEA, we randomized 12 Yorkshire male swine to resuscitation with epinephrine only (control) (0.0015 mg/kg) versus epinephrine plus standard CPR (intervention). Animals who achieved return of spontaneous circulation (ROSC) were stabilized, fully recovered to hemodynamic and respiratory baseline, and rearrested up to 6 times. Primary outcome was ROSC defined as a sustained systolic blood pressure (SBP) of 60 mmHg for 2 min. Secondary outcomes included time to ROSC, coronary perfusion pressure (CoPP), and end-tidal carbon dioxide (ETCO2). RESULTS: Among 47 events of pseudo-PEA in 12 animals, we observed significantly higher proportion of ROSC when treatment included CPR (14/21 - 67%) compared to epinephrine alone (4/26 - 15%) (p = 0.0007). CoPP, aortic pressures and ETCO2 were significantly higher, and right atrial pressures were lower in the intervention group. CONCLUSIONS: In a swine model of hypoxia-induced pseudo-PEA, epinephrine plus CPR was associated with improved intra-arrest hemodynamics and higher probability of ROSC. Thus, epinephrine plus CPR may be superior to epinephrine alone in the treatment of patients with pseudo-PEA.

Quantitative characterization of left ventricular function during pulseless electrical activity using echocardiography during out-of-hospital cardiac arrest.

BACKGROUND: Several prospective studies have demonstrated that the echocardiographic detection of any myocardial activity during PEA is strongly associated with higher rates of return of spontaneous circulation (ROSC). We hypothesized that PEA represents a spectrum of disease in which not only the presence of myocardial activity, but more specifically that the degree of left ventricular (LV) function would be a predictor of outcomes. The purpose of this study was to retrospectively assess the association between LV function and outcomes in patients with OHCA. MATERIALS AND METHODS: Using prospectively obtained data from an observational cohort of patients receiving focused echocardiography during cardiopulmonary resuscitation (CPR) in the Emergency Department (ED) setting, we analyzed 312 consecutive subjects with available echocardiography images with initial rhythm of PEA. We used left ventricular systolic fractional shortening (LVFS), a unidimensional echocardiographic parameter to perform the quantification of LV function during PEA. Regression analyses were performed independently to evaluate for relationships between LVFS and a primary outcome of ROSC and secondary outcome of survival to hospital admission. We analyzed LVFS both as a continuous variable and as a categorial variable using the quartiles and the median to perform multiple different comparisons and to illustrate the relationship of LVFS and outcomes of interest. We performed survival analysis using Cox proportional hazards model to evaluate the hazard corresponding to length of resuscitation. RESULTS: We found a positive association between LVFS and the primary outcome of ROSC (OR 1.04, 95%CI 1.01-1.08), but not with the secondary outcome of survival to hospital admission (OR 1.02, 95%CI 0.96-1.08). Given that the relationship was not linear and that we observed a threshold effect in the relationship between LVFS and outcomes, we performed an analysis using quartiles of LVFS. The predicted probability of ROSC was 75% for LVFS between 23.4-96% (fourth quartile) compared to 47% for LVFS between 0-4.7% (first quartile). The hazard of not achieving ROSC was significantly greater for subjects with LVFS below the median (13.1%) compared to the subgroup with LVFS greater than 13.1% (p < 0.05), with the separation of the survival curves occurring at approximately 40 min of resuscitation duration. CONCLUSIONS: Left ventricular function measured by LVFS is positively correlated with higher probability of ROSC and may be associated with higher chances of survival in patients with PEA arrest.

Evaluation of out-of-hospital cardiac arrest using transesophageal echocardiography in the emergency department.

BACKGROUND: Transesophageal echocardiography (TEE) has been proposed as a modality to assess patients in the setting of cardiac arrest, both during resuscitation care and following return of spontaneous circulation (ROSC). In this study we aimed to assess the feasibility and clinical impact of TEE during the emergency department (ED) evaluation during out-of-hospital cardiac arrest (OHCA). MATERIALS AND METHODS: We conducted a prospective observational study consisting of a convenience sample of adult patients presenting to the ED of an urban university medical center with non-traumatic OHCA. TEE was performed by emergency physicians following intubation. Images and clinical data were analyzed. TEE was used intra-arrest in order to assist in diagnosis, assess cardiac activity and determine CPR quality by assessing area of maximal compression (AMC), using a 4 view protocol. RESULTS: A total of 33 OHCA patients were enrolled over a one-year period, 21 patients (64%) presented with ongoing CPR and 12 (36%) presented with ROSC. The 4-view protocol was completed in 100% of the cases, with an average time from ED arrival to TEE of 12 min (min 3 max 30 SD 8.16). Fine ventricular fibrillation (VF) was recognized in 4 (12%) cases thought to be in asystole, leading to defibrillation, and 2 cases of pseudo-PEA were identified. Right ventricular (RV) dilation, was seen in 12 (57%) intraarrest cases. Intra-cardiac thrombus was found in one case, leading to thrombolysis. The AMC was identified over the aortic root or LVOT in 53% of cases. TEE was found to have diagnostic, therapeutic or prognostic clinical impact in 32 of the 33 cases (97%). CONCLUSIONS: TEE is feasible and clinically impactful during OHCA management. Resuscitative TEE may allow for characterization of cardiac activity, including identification of pseudo-PEA and fine VF, determination of reversible pathology, and optimization of CPR quality.