Pseudo-pulseless Electrical Activity Research Articles

Pseudo-pulseless electrical activity in foreign body airway obstruction

Pseudo-pulseless electrical activity in foreign body airway obstruction

Unveiling pseudo-pulseless electrical activity (pseudo-PEA) in ultrasound-integrated infant resuscitation

Point-of-care ultrasound (POCUS) holds immense potential to manage critically deteriorating infants within the neonatal intensive care unit (NICU) and is increasingly used in neonatal clinical practice worldwide. Recent ultrasound-based protocols such as the Sonographic Assessment of liFe-threatening Emergencies-Revised (SAFE-R) and Crashing Neonate Protocol (CNP) offer step-by-step guidance for diagnosing and addressing reversible causes of cardiorespiratory collapse. Traditionally, pulseless electrical activity (PEA) has been diagnosed solely based on absent pulses on clinical examination, disregarding myocardial activity. However, integrating POCUS into resuscitation unveils the concept of pseudo-PEA, where cardiac motion activity is observed visually on the ultrasound but fails to generate a detectable pulse due to inadequate cardiac output. Paradoxically, existing neonatal resuscitation protocols lack directives for identifying and effectively leveraging pseudo-PEA insights in infants, limiting their potential to enhance outcomes. Pseudo-PEA is extensively described in adult literature owing to routine POCUS use in resuscitation. This review article comprehensively evaluates the adult pseudo-PEA literature to glean insights adaptable to neonatal care. Additionally, we propose a simple strategy to integrate POCUS during neonatal resuscitation, especially in infants who do not respond to routine measures.Conclusion: Pseudo-PDA is a newly recognized diagnosis in infants with the use of POCUS during resuscitation. This article highlights the importance of cross-disciplinary learning in tackling emerging challenges within neonatal medicine.What is known:• Point-of-Care ultrasound (POCUS) benefits adult cardiac arrest management, particularly in distinguishing true Pulseless Electrical Activity (PEA) from pseudo-PEA.• Pseudo-PEA is when myocardial motion can be seen on ultrasound but fails to generate palpable pulses or sustain circulation despite evident cardiac electrical activity.What is new:• Discuss recognition and management of pseudo-PEA in infants.• A proposed algorithm to integrate POCUS into active neonatal cardiopulmonary resuscitation (CPR) procedures.

Elderly Woman With Altered Mental Status

A 77-year-old woman presented to the emergency department with sudden onset of altered mental status at home. Her family found her lying down on the stairwell with groans of pain. On physical examination, she was comatose without clinically detectable pulses; however, residual cardiac activity (pseudopulseless electrical activity) was observed during point-of-care ultrasound investigation. Her left leg was slightly pale compared with her right leg. The rest of the examination was unremarkable. Point-of-care ultrasound was performed (Figure 1 and Video 1), and the diagnosis was confirmed by contrast-enhanced computed tomography (CT) (Figure 2).

Abstract 14095: Use of Femoral Arterial Doppler Velocity to Detect Perfusing Pulses During Cardiac Arrest

Introduction: Manual pulse detection is inaccurate in cardiac arrest(CA) and Doppler ultrasound may detect blood flow without an adequate perfusion blood pressure (pseudo-pulseless electrical activity). The purpose of this study is to assess whether maximum femoral arterial velocity during a pulse check is correlated with arterial line systolic blood pressure (SBP) and whether it can be used to accurately identify a SBP of ≥60mmHG. Methods: This is a prospective study of CA patients at a quaternary care Emergency Department. During a pulse check, a linear ultrasound was placed at the common femoral artery and the presence or absence of an arterial Doppler waveform, the associated maximum velocity value, and arterial line SBP were recorded simultaneously. The correlation between SBP and maximum waveform velocity was assessed. Arterial SBPs were dichotomized as <60mmHG or ≥60mmHg, as this was deemed as an adequate perfusion pressure, and a receiver operator characteristic curve analysis was performed to determine optimal cutoff value of maximum velocity associated with SBP ≥60mmHG. Sensitivity (Sn), specificity (Sp), and accuracy (Acc) of manual palpation and femoral artery pulse wave doppler for detection of SBP ≥60mmHg were calculated. Results: A total of 51 patients and 183 pulse checks were analyzed. There was a strong correlation between arterial line SBP and maximum waveform velocity (Spearman correlation coefficient: 0.92; p<0.001). The optimal cutoff value of waveform velocity associated with a SBP ≥60mmHG was 20 cm/second (Sn: 0.89; specificity: 0.94; area under the curve: 0.98) with an Acc of 0.92. To detect SBP ≥60mmHg, manual palpation had a Sn of 0.45, Sp of 0.82, and Acc of 0.67 McNemar's test showed that Sn (p<0.001), Sp (p=0.009), and Acc (p<0.001) was significantly higher for doppler ultrasound >=20cm/sec compared with manual palpation. Conclusion: In this study, during a pulse check, patients with a femoral arterial doppler waveform with a maximum velocity greater than 20cm/sec had a high probability of having a SBP ≥60mmHg, and improved Sn, Sp and Acc over manual palpation. The results demonstrate femoral arterial doppler maximum velocity is an accurate and objective tool to determine the presence of a pulse with adequate perfusion pressures.

205 Arterial Doppler Ultrasound to Improve Detection of ROSC in Cardiac Arrest

Determination of the presence of a pulse is critical in the management of cardiac arrest (CA) patients. However, reports have demonstrated the inaccuracy of manual pulse detection. Additionally, Doppler ultrasound may be too sensitive for pulse detection and could detect flow without adequate blood pressure needed for perfusion. The purpose of this study is to assess the sensitivity, specificity, and accuracy of doppler femoral pulse detection in comparison to manual femoral pulse detection using an arterial line as the gold standard in CA patients. This is a prospective study of non-traumatic CA patients who occurred in a quarternary care emergency department (ED). All patients had an arterial line in place to serve as the gold standard for pulse detection. During a pulse check, the presence or absence of a femoral artery Doppler waveform and manual femoral pulse, as well as the systolic blood pressure (SBP) on the arterial line, were recorded simultaneously. Two physicians reviewed all Doppler waveform images to confirm presence or absence of a pulse. We calculated the sensitivity, specificity, and accuracy of both Doppler ultrasound and manual palpation for determining the presence of any pulse. We then calculated the same measurements using an arterial line SBP ≥60mmHg as consensus agreement believed this to be the minimum pressure indicating the presence of a pulse with an adequate perfusing blood pressure. We enrolled 46 patients and performed a total of 167 pulse checks. The sensitivity of Doppler ultrasound detection of a pulse at any blood pressure was 0.92 (95% CI: 0.87, 0.97) with a specificity of 0.98 (95% CI: 0.94, 1.00), and accuracy of 0.94 (95% CI: 0.89, 0.97). The sensitivity and specificity of manual palpation of a pulse was 0.36 (95% CI: 0.27, 0.44) and 0.90 (95% CI: 0.82, 1.00), respectively, with an accuracy of 0.53 (95% CI: 0.45, 0.60). When a SBP ≥60mmHg was used to indicate the presence of an adequate pulse, the sensitivity of Doppler ultrasound was 1.00 (95% CI: 1.00, 1.00), however the specificity was 0.55 (95% CI: 0.46, 0.64) with an accuracy 0.71 (95% CI: 0.63, 0.77), while manual palpation had a sensitivity of 0.45 (95% CI: 0.32, 0.58), with a specificity of 0.82 (95% CI: 0.74, 0.89 and an accuracy of 0.69 (95% CI: 0.6, 0.76). This study indicates that while accuracy of Doppler ultrasound for pulse detection is superior to manual palpation, the overall accuracies are similar when a SBP ≥60mmHg is used to indicate the presence of a pulse perfusing blood pressure. This study identifies the need to determine if doppler ultrasound waveforms can further distinguish between an adequately perfusing pulse and pseudo pulseless electrical activity.

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

AimPseudo-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. MethodsUsing 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). ResultsAmong 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. ConclusionsIn 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.

Rhythms and prognosis of patients with cardiac arrest, emphasis on pseudo-pulseless electrical activity: another reason to use ultrasound in emergency rooms in Colombia

BackgroundThe cardiac arrest is still an emergency with a bad prognosis. The growing adoption of bedside ultrasound allowed to classify PEA in two groups: the true PEA and the pseudo-PEA. pPEA is used to describe a patient who has a supposed PEA in the absence of pulse, with evidence of some cardiac activity on the bedside ultrasound.ObjectiveThis work aims to assess the bedside ultrasound use as a predictor for ROSC and survival at discharge in cardiac arrest patients and compare the pseudo-pulseless electrical activity to other cardiac arrest rhythms, including shockable rhythms.Materials and methodsThis is an observational, historic cohort study carried out in the emergency room of the University Hospital Mayor Méderi. Data were collected from all the adult patients treated for cardiac arrest from June 2018 to 2019. An ultrasound was performed to every cardiac arrest patient.ResultsOf a total of 108 patients, the median of the age was 71 years, 65.8% were male subjects, and the most frequent cause for cardiac arrest was the cardiogenic shock (32.4%). ROSC was observed in 41 cases (37.9%) and survival at discharge was 18 cases (16.7%). VF/VT and pPEA were the two rhythms that showed the highest ROSC and survival at discharge. For the pPEA group, we were able to conclude that the cardiac activity type is related to ROSC.ConclusionThere is a significant difference for ROSC and survival at discharge prognosis among the cardiac arrest rhythms, with better outcomes for VF/VT and pPEA. Among patients with PEA, a routine ultrasound assessment is recommended. The type of cardiac activity recorded during the ultrasound of the cardiac arrest patient might be related to the ROSC and survival at discharge prognosis.

Abstract 293: Detection of Pseudo-Pulseless Electrical Activity with Electrical Impedance Tomography

Introduction: Pseudo-Pulseless Electrical Activity (p-PEA) is a lifeless form of profound cardiac shock characterized by measurable cardiac mechanical activity without clinically detectable pulses. p-PEA may constitute up to 40% of reported cases of cardiac arrest and its management may be different from ventricular fibrillation or even true-PEA. Currently, diagnosis of p-PEA requires either echocardiography or intravascular catheterization, neither of which are ideal in the prehospital setting. Electrical impedance tomography (EIT) uses skin surface electrodes to generate images based on cross sectional resistance. We investigated the ability of EIT and machine learning (ML) to detect p-PEA. Methods: Female swine (N = 14) under intravenous anesthesia were instrumented with aortic and central venous micromanometer catheters. p-PEA was induced by ventilation with 6% O 2 in 94% N 2 , defined as a systolic aortic pressure less than 40 mmHg. Continuous EIT renderings were obtained from circumferential thoracic and abdominal electrode arrays. A deep learning model was utilized to detect p-PEA using EIT sequences. Twelve pigs were randomly selected as training data and 2 pigs as a test set. EIT images were saved as 30 second clips, resulting in 3033 clips generated. To increase generalizability, random epochs ranging from 30 - 100% of the total clip length were generated, resulting in a model capable of detecting this disease state with limited video fragments. Results: This technique yielded a receiver operator characteristic curve - area under the curve (ROC-AUC) of 0.91 for detection of p-PEA in the testing dataset (Figure 1), with 84% accuracy, 88% sensitivity, and 84% specificity. Conclusions: EIT combined with machine learning may be able to reliably delineate p-PEA in a hypoxic porcine model. This approach may be promising for non-invasive operator-independent p-PEA detection.

Abstract 301: Aortic and Central Venous Pressure Wave Synchronization in Pseudo-Pulseless Electrical Activity

Introduction: Pseudo-Pulseless Electrical Activity (p-PEA) is a lifeless form of profound cardiac shock characterized by measurable cardiac mechanical activity without clinically detectable pulses. p-PEA may constitute up to 40% of reported cases of cardiac arrest and its etiologies and physiology are distinctly different from ventricular fibrillation or even true-PEA. In the normal physiologic state, there is an expected delay between the central venous (CV) and aortic (Ao) pressure waveforms corresponding to atrial kick and ventricular systole, respectively. We studied this relationship in hypoxic porcine p-PEA. Hypothesis: Development of p-PEA may be associated with changes in Ao and CV waveform synchronization. Methods: Female swine (N = 14) under intravenous anesthesia were instrumented with Ao and CV micromanometer catheters. ECG and ET-CO 2 were measured continuously. p-PEA was induced by ventilation with 6% oxygen in 94% nitrogen, and was defined as a systolic aortic pressure less than 40 mmHg. After 2 min. of p-PEA, 100% O 2 , CPR, and epinephrine were administered in a stepwise progression until ROSC was achieved. Results: One min. before the onset of hypoxia, the mean CV to Ao waveform delay was 0.161 sec. (SE ± 0.0015) across 52 experiments (n = 4797). This delay shortened during development of the p-PEA disease state (Figure 1), where the average delay decreased to 0.057 seconds (SE ± 0.0012) across 52 experiments (n = 3969, P < 10-6). There were statistically significant differences (P < 10-6) in waveform delays in between cohorts of animals who required more interventions to achieve ROSC, with shorter delay periods in both baseline and disease states correlating strongly with greater interventions. Conclusions: Development of the hypoxic p-PEA state may be associated with a loss of the normal CV to Ao pressure waveform delay. The degree of this loss may be associated with the severity of p-PEA disease state and predictive of the therapy required for ROSC.

Abstract 295: Deep Learning and Electrical Impedance Tomography in the Prediction of Interventions Needed to Resuscitate From Hypoxic Pseudo-Pulseless Electrical Activity

Introduction: Pseudo-Pulseless Electrical Activity (p-PEA) is a form of profound cardiac shock defined as measurable cardiac activity without clinically detectable pulses. p-PEA has a distinct physiology and etiology from VF and true-PEA, and may constitute up to 40% of reported cases of cardiac arrest. Electrical impedance tomography (EIT) uses cutaneous electrodes to generate images based on cross sectional resistance. We utilized EIT to predict the number of interventions required to achieve ROSC from p-PEA. Methods: Female swine (N = 14) under intravenous anesthesia were instrumented with aortic and central venous micromanometer catheters. p-PEA was induced by ventilation with 6% oxygen in 94% nitrogen and was defined as a systolic aortic pressure less than 40 mmHg. Continuous EIT renderings were obtained from circumferential cutaneous thoracic and abdominal electrode arrays. A deep learning model was utilized to detect features within the EIT video clips of the p-PEA disease state to predict the number of treatments required to achieve ROSC. Twelve pigs were randomly selected as training data and 2 pigs as a test set. EIT images were saved as 30 second clips, resulting in 1630 clips generated. To increase generalizability, random epochs ranging from 30 - 100% of the total clip length were generated, resulting in a model capable of detecting this disease state with limited video fragments. Data were labeled based on the number of interventions required to achieve ROSC (100% O 2 , 100% O 2 + CPR, 100% O 2 + CPR + Epi, ROSC not achieved). Results: This approach yielded receiver operator characteristic curves - area under the curve (ROC-AUC, Figure 1) values of 0.75 for micro (weighted) AUC and 0.78 for macro (unweighted) AUC on a 4 class prediction model. Conclusion: EIT combined with machine learning may differentiate the required treatments needed to achieve ROSC in p-PEA.

Abstract 291: Return of Spontaneous Circulation Detection in Pseudo-Pulseless Electrical Activity Using Plethysmography

Background: Pseudo-Pulseless Electrical Activity (p-PEA) is a lifeless form of profound cardiac shock characterized by measurable cardiac mechanical activity without clinically detectable pulses. p-PEA may constitute up to 40% of reported cases of cardiac arrest and its physiology is different from ventricular fibrillation or even True-PEA. There have been promising studies showing that pulse oximetry plethysmography (POP) can be used to monitor the quality of cardiopulmonary resuscitation (CPR) and detect return of spontaneous circulation (ROSC) during undifferentiated PEA. However, the utility of POP has not been characterized in p-PEA. Methods: Pigs (N = 14) were instrumented with aortic and central venous micro-manometer catheters. A POP device was attached to the left ear at the cauda helicis. Hypoxic p-PEA was induced using a 94% N 2 , 6% O 2 mix. Hemodynamic and POP amplitudes were recorded. Mean amplitudes were then calculated for baseline, untreated p-PEA, CPR (if administered), and during ROSC, which was defined as a positive MAP incline to a stable plateau pressure. POP amplitudes were then analyzed as relative increase ratios of ROSC compared to disease state. Results: There were statistically significant increases in relative POP amplitudes in ROSC from the p-PEA disease state (Figure 1). In pigs that required CPR for ROSC, the mean ROSC to CPR POP ratio was 1.204 (P<0.01, 95% CI [1.26 - 3.33]). Pigs that did not require CPR for ROSC had a mean ROSC to pseudo-PEA ratio of 2.17 (p<0.01, 95% CI [1.26 - 3.33]). The mean ratio difference between pigs requiring CPR and those that did not was 0.049. Conclusions: These data suggest that measurement of POP may delineate the degree of interventions required to achieve ROSC, and can be used in detection of ROSC. If confirmed clinically, POP may be a promising non-invasive operator-independent method that may improve the management of PEA.

Abstract 292: Detection of Return of Spontaneous Circulation in Pseudo-Pulseless Electrical Activity Using Trans-thoracic and Trans-abdominal Bioimpedance

Introduction: Pseudo-Pulseless Electrical Activity (p-PEA) is a lifeless form of profound cardiac shock characterized by measurable cardiac mechanical activity without clinically detectable pulses. Patients in pseudo-PEA carry different prognoses than those in true PEA and may require different therapies. Noninvasive technologies capable of detecting return of spontaneous circulation (ROSC) are needed to guide transition therapy from ACLS to critical care. Electrical impedance (EI) measurements across the thorax and abdomen may reflect the state of the cardiovascular system and change with ROSC. Hypothesis: EI measured across the chest wall or abdomen can detect ROSC in p-PEA. Methods: Female swine (N = 14) under intravenous anesthesia were instrumented with aortic and central venous micromanometer catheters. EI was measured with cutaneous belts around the chest and abdomen (Swisstom). p-PEA was induced by ventilation with 6% oxygen in 94% nitrogen and was defined as a systolic aortic pressure < 40 mmHg. Experiments in which ROSC occurred within 20 seconds of starting 100% FiO 2 were studied. EI waveforms were analyzed with fast fourier transforms, and the dominant frequencies of p-PEA and ROSC signals were subtracted to create a difference distribution. Results: With onset of ROSC, there was a characteristic frequency increase in EI measurable across both chest and abdominal bands. Fourier transform analysis demonstrated a significant difference in dominant frequencies between resuscitation and p-PEA. The median difference between resuscitation and p-PEA dominant frequencies were 5.49 in the thorax [95% CI 3.48 - 7.50] and 6.65 in the abdomen [95% CI 3.63 - 9.67]. Conclusions: There appear to be characteristic EI frequency patterns and changes in p-PEA and ROSC. If confirmed clinically, this indicates that EI may be a promising technology for non-invasive monitoring in cardiac arrest.

Abstract 294: A Machine Learning Approach in Using Capnography to Predict Resuscitation Interventions Required in Hypoxic Pseudo-Pulseless Electrical Activity Resuscitation

Introduction: Pseudo-Pulseless Electrical Activity (p-PEA) is a lifeless form of profound cardiac shock characterized by measurable cardiac mechanical activity without clinically detectable pulses. Patients in pseudo-PEA carry different prognoses than those in true PEA and may require different therapies. End-tidal carbon dioxide (ET-CO 2 ) has been studied in ventricular fibrillation and true PEA, but not in p-PEA. We evaluated the ability of capnography to predict the need for CPR in p-PEA. Methods: Female swine (N = 14) under intravenous anesthesia were instrumented with aortic and central venous micromanometer pressure catheters. ECG and ET-CO 2 were measured continuously. p-PEA was induced by ventilation with 6% oxygen in 94% nitrogen and was defined as a systolic aortic pressure less than 40 mmHg. Pigs were grouped into cohorts based on the interventions required to achieve ROSC: 100% O 2 , 100% O 2 + CPR, 100% O 2 + CPR + epinephrine. One hundred 4 sec. snippets of ET-CO 2 data were randomly sampled during the p-PEA state, and the mean, maximum, slope, and r-value of each epoch was used to train 7 machine learning algorithms to predict which intervention cohort they belonged to. Data was split randomly into 60% training and 40% testing sets. Results: Ensemble approaches were highly successful, with the gradient boosting model achieving an AUC of 0.91 on ROC curves (Figure 1), with an accuracy 0.83, sensitivity 0.86, specificity 0.78. Conclusions: In porcine hypoxic p-PEA, machine learning derived models of ET-CO2 appeared able to predict the degree of interventions needed for ROSC. If confirmed clinically, such an approach may be useful in guiding treatment of this increasingly common type of cardiac arrest.

Ultrasonographic Assessment During Cardiopulmonary Resuscitation.

The US-CAB (Ultrasound, Circulation/Airway/Breathing) protocol integrates several sonographic techniques into a structured assessment of the circulation, airway, and breathing status of a patient during cardiopulmonary resuscitation (CPR) in an advanced life support-compliant manner. US-C provides a subxiphoid view of the heart, to look for potentially reversible causes of disease, such as pericardial effusion, pulmonary embolism, hypovolemia, and acute coronary thrombosis. Sonographic cardiac activity during CPR not only helps differentiate pseudo-pulseless electrical activity (PEA) from true PEA but also represents a higher chance of the return of spontaneous circulation (ROSC) and survival. Evaluation of the inferior vena cava (IVC) shows the fluid status of the patient and indicates the best methods to use for fluid resuscitation. If aortic dissection is suspected, a subxiphoid view of the aorta is suggested for identifying an intimal flap. Once intubation is done, tracheal ultrasound (US-A) at the suprasternal notch helps differentiate endotracheal intubation (one air-mucosal interface with one comet-tail) from esophageal intubation (double tract sign). Immediately following US-A, bilateral lung US (US-B) should be done to confirm proper bilateral ventilation using the lung sliding sign. In addition, US-C can be serially followed to see the dynamic changes in the cardiac chambers and IVC, or any cardiac contraction suggestive of ROSC. US-B can also detect coexisting lung or pleural pathologies without interfering with the performance of CPR. The main concern when implementing this method is maintaining high-quality CPR without delays in chest compressions when performing US-CAB. Rigorous training and continued practice are key to minimize any interruptions during resuscitation.

Intravenous calcium as a pressor in a swine model of hypoxic pseudo-pulseless electrical mechanical activity\u2014a preliminary report

BackgroundPseudo-pulseless electrical activity (pseudo-PEA) is a lifeless form of profound cardiac shock characterized by measurable cardiac mechanical activity without clinically detectable pulses. Pseudo-PEA may constitute up to 40% of reported cases of cardiac arrest. Resuscitation from pseudo-PEA is often associated with hypotension refractory to catecholamine pressors. We hypothesized that this post-resuscitation state may be associated with hypocalcemic hypotension responsive to intravenous calcium.MethodsUsing pre-existing data from our hypoxic swine pseudo-PEA model, we measured blood pressure, hemodynamics, and electrolytes. Physiological data were analyzed on a heartbeat by heartbeat basis. The midpoint of the calcium response was defined using change of curvature feature detection. Hemodynamic parameters were shifted such that the value at the midpoint was equal to zero.ResultsIn 9 animals with refractory hypotension, we administered 37 boluses of intravenous calcium in the dosage range of 5-20 mg. Comparisons were made between the average values in the time period 40-37 s before the midpoint and 35-40 s after the midpoint. Of the 37 administered boluses, 34 manifested a change in the blood pressure, with mean aortic pressure, systolic and diastolic pressures all increasing post bolus administration.ConclusionsAdministration of intravenous calcium may be associated with a pressor-like response in refractory hypotension after resuscitation from pseudo-PEA. Relative ionized hypocalcemia may cause hypotension after resuscitation from pseudo-PEA. Therapy with intravenous calcium should be further investigated in this setting.

Hemodynamic responses to guideline compliant chest compressions during pseudo-pulseless electrical activity in swine

Hemodynamic responses to guideline compliant chest compressions during pseudo-pulseless electrical activity in swine

LO018: The utility of ECG characteristics as prognostic markers in pulseless electrical activity arrests: a retrospective observational cohort study

Introduction: Compared to pseudo-pulseless electrical activity (PEA with myocardial contractions present), true PEA is hypothesized to carry a poorer prognosis and to show bradycardia and a wide QRS complex on ECG. Our objective was to study the predictive potential of ECG characteristics on survival to hospital discharge (SHD) for out-of-hospital cardiac arrest (OHCA) patients with PEA initial rhythm. Methods: We studied a cohort of OHCA patients prospectively enrolled between Sept. 2007 and Oct. 2009 at the Ottawa/OPALS site (13 cities, 7 EMS, and 6 Fire services) of the ROC PRIMED study. We included adult (≥ 18) non-traumatic OHCA with PEA initial rhythm where resuscitation was attempted, and for which ECG characteristics were available. We measured mean heart rate (HR), mean QRS interval, and presence of P waves (each with kappa agreement) using the first six QRS complex available. We report patient and system characteristics using descriptive statistics and determined the impact of ECG characteristics (HR, QRS width, P waves) on return of spontaneous circulation (ROSC) and SHD using multivariate regression analysis. Results: Demographics of 332 included cases were: mean age 71.7; male 58.4%; home residence 76.5%; bystander witnessed 56.3%; bystander CPR 28.5%; interval from dispatch to paramedic arrival 6min:24sec; ROSC at ED arrival 26.5%; SHD 5.4%. Survivors had higher mean HR (66.1 vs. 52.0 bpm, p=0.83; kappa=0.69) and shorter mean QRS intervals (108.3 vs. 129.6 ms, p=0.01; kappa=0.74) compared to non-survivors. Presence of p waves could not reliably be ascertained (kappa=0.35). Predictors of ROSC were: ALS paramedic on scene (AdjOR=8.90, 95%CI 1.11-71.41; p=0.04), successful intubation (AdjOR=3.35, 1.75-6.39; p=0.0002), and use of atropine (AdjOR=0.27, 0.14 - 0.50; p<0.0001). Predictors of survival were: location of arrest (AdjOR=1.49, 1.11 - 1.99; p=0.007), and use of atropine (AdjOR=0.06, 0.02-0.22; p<0.0001). Despite various cutoff explorations, ECG characteristics were not predictive of ROSC or survival in multivariate analyses. Survivors had HR as low as 6 bpm and QRS as wide as 357 ms. Conclusion: Early ECG characteristics could not predict ROSC or SHD in a population of OHCA PEA victims, and should not be used to terminate resuscitation efforts. Atropine administration was consistently associated with decreased likelihood of ROSC and survival.

A novel hands-free carotid ultrasound detects low-flow cardiac output in a swine model of pulseless electrical activity arrest

Objective To determine if a hands-free, noninvasive Doppler ultrasound device can reliably detect low-flow cardiac output by measuring carotid artery blood flow velocities. We compared the ability of observers to detect carotid artery flow velocity differences between pseudo-pulseless electrical activity (PEA) and true-PEA cardiac arrest. Methods Five swine were instrumented with aortic (Ao) and right atrial pressure-transducing catheters. The Doppler ultrasound device was adhered to the neck over the carotid artery. Continuous electrocardiogram, pressure readings, and Doppler signal were recorded. Each swine underwent multiple episodes of fibrillation and resuscitation. Episodes of true-PEA and pseudo-PEA were retrospectively identified from all resuscitation attempts by examination of electrocardiogram and Ao waveforms. The sensitivity and specificity of the device to detect pseudo-PEA was obtained using observers blinded to Ao waveform recordings. Results There was good interobserver reliability related to identification of pseudo- and true-PEA ( κ = 0.873). The observers blinded to Ao waveform recordings agreed on 8 of the 9 episodes of pseudo-PEA, whereas 4 false positives of 26 true-PEA events were reported (sensitivity, 0.89; specificity, 0.85). The Doppler device was able to detect carotid flow velocity over a wide range of Ao blood pressures. Conclusions This hands-free, noninvasive Doppler ultrasound device can reliably differentiate pseudo-PEA from true-PEA during resuscitation from cardiac arrest, detecting pressure gradient changes of less than 5 mm Hg through to normotension. This device distinguishes conditions of no cardiac output from low cardiac output and may have applications for use during resuscitation from various etiologies of arrest and shock.

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

This study evaluated the ability of focused echocardiography (FE) and capnography to differentiate between pulseless electrical activity (PEA) and pseudo-PEA in out-of-hospital cardiac arrest, and the potential survival benefits with modified treatment. In PEA patients with stable end-tidal carbon dioxide pressure (P(et)CO(2)) during the compression pause and concomitant FE showing cardiac kinetic activity, the compression pause was prolonged for 15 s and an additional 20 IU vasopressin was administered. If pulselessness persisted, compressions were continued. Fifteen of the 16 patients studied (94%) achieved restoration of spontaneous circulation (ROSC); eight patients (50%) attained a good neurological outcome (Cerebral Performance Category 1 - 2). In an historical PEA group with stable P(et)CO(2) values (n = 48), ROSC was achieved in 26 patients (54%); four patients (8%) attained Cerebral Performance Category 1 - 2. Echocardiographical verification of the pseudo-PEA state enabled additional vasopressor treatment and cessation of chest compressions, and was associated with significantly higher rates of ROSC, survival to discharge and good neurological outcome.

A swine model of pseudo-pulseless electrical activity induced by partial asphyxiation

The incidence of pulseless electrical activity (PEA) as a presenting rhythm during cardiac arrest is increasing. The current animal models of PEA arrest, post-countershock or total asphyxiation, unreliably generate PEA for a specific time period. Neither of these models predictably generate pseudo-PEA. The purpose of this study was to create an animal model of pseudo-PEA that will allow for a prolonged time period in this arrest state for future research. In a laboratory setting, five ventilated swine on inhaled anesthesia and 100% oxygen with continuous EKG recordings were instrumented with central aortic and venous pressure-transducing catheters. Animals were then switched to intravenous anesthesia while being ventilated with a 16% oxygen/84% nitrogen mix. Continuous EKG, aortic and venous pressures were recorded to a computerized data collection program. Arterial blood gas samples were taken every 10min. Time until onset of pseudo-PEA, duration of pseudo-PEA, and cardiac rhythm during pseudo-PEA were recorded. Mean time to onset of pseudo-PEA was 80.6+/-47.3min. Mean duration of pseudo-PEA was 18.6+/-6.2min. Mean arterial pH at pseudo-PEA onset was 7.20+/-0.05 with a mean associated base excess of -11.4+/--5.94. No significant differences were noted in other recorded variables. Partial asphyxiation using a 16% oxygen/84% nitrogen mix is a reliable laboratory method to create a prolonged state of pseudo-PEA in a swine model. The mechanism generating pseudo-PEA is hypoxemia-induced systemic acidosis. This model will allow sufficient time in this low-flow cardiac state for future research to be conducted.