Cardiac arrest with initial arrest rhythm of pulseless electrical activity: do rhythm characteristics correlate with outcome?

Association Between QRS Characteristics in Pulseless Electrical Activity and Survival Outcome in Cardiac Arrest Patients: A Systematic Review and Meta-Analysis

OBJECTIVE

Recent studies have shown inconsistent results regarding the association between QRS characteristics and survival outcomes in patients with cardiac arrest and pulseless electrical activity (PEA) rhythms. This meta-analysis aimed to identify the usefulness of QRS width and frequency as prognostic tools for outcomes in patients with cardiac arrest and PEA rhythm.

METHODS

Extensive searches were conducted using Medline, Embase, and the Cochrane Library to find articles published from database inception to 4 June 2023. Studies that assessed the association between the QRS characteristics of cardiac arrest patients with PEA rhythm and survival outcomes were included. The Newcastle-Ottawa Scale was used to assess the methodological quality of the included studies.

RESULTS

A total of 9727 patients from seven observational studies were included in this systematic review and meta-analysis. The wide QRS group (QRS ≥ 120 ms) was associated with significantly higher odds of mortality than the narrow QRS group (QRS < 120 ms) (odds ratio (OR) = 1.86, 95% confidence interval (CI) = 1.11-3.11, I2 = 58%). The pooled OR for mortality was significantly higher in patients with a QRS frequency of < 60/min than in those with a QRS frequency of ≥ 60/min (OR = 1.90, 95% CI = 1.19-3.02, I2 = 65%).

CONCLUSIONS

Wide QRS width or low QRS frequency is associated with increased odds of mortality in patients with PEA cardiac arrest. These findings may be beneficial to guide the disposition of cardiac arrest patients with PEA during resuscitation.

Heart rate and QRS duration as biomarkers predict the immediate outcome from pulseless electrical activity

INTRODUCTION

Pulseless electrical activity (PEA) is commonly observed in in-hospital cardiac arrest (IHCA). Universally available ECG characteristics such as QRS duration (QRSd) and heart rate (HR) may develop differently in patients who obtain ROSC or not. The aim of this study was to assess prospectively how QRSd and HR as biomarkers predict the immediate outcome of patients with PEA.

METHOD

We investigated 327 episodes of IHCA in 298 patients at two US and one Norwegian hospital. We assessed the ECG in 559 segments of PEA nested within episodes, measuring QRSd and HR during pauses of compressions, and noted the clinical state that immediately followed PEA. We investigated the development of HR, QRSd, and transitions to ROSC or no-ROSC (VF/VT, asystole or death) in a joint longitudinal and competing risks statistical model.

RESULTS

Higher HR, and a rising HR, reflect a higher transition intensity ("hazard") to ROSC (p < 0.001), but HR was not associated with the transition intensity to no-ROSC. A lower QRSd and a shrinking QRSd reflect an increased transition intensity to ROSC (p = 0.023) and a reduced transition intensity to no-ROSC (p = 0.002).

CONCLUSION

HR and QRSd convey information of the immediateoutcome during resuscitation from PEA. These universally available and promising biomarkers may guide the emergency team in tailoring individual treatment.

Association of Initial Pulseless Electrical Activity Heart Rate and Clinical Outcomes Following Adult Non-Traumatic Out-of-Hospital Cardiac Arrest

OBJECTIVE

Studies evaluating the prognostic value of the pulseless electrical activity (PEA) heart rate in out-of-hospital cardiac arrest (OHCA) patients have reported conflicting results. The objective of this study was to evaluate the association between the initial PEA heart rate and favorable clinical outcomes for OHCA patients.

METHODS

The present post-hoc cohort study used the Resuscitation Outcomes Consortium Cardiac Epidemiologic Registry Version 3, which included OHCA patients in seven US and three Canadian sites from April 2011 to June 2015. The primary outcome was survival to hospital discharge and the secondary outcome was survival with a good functional outcome. For the primary analysis, the patients were separated into eight groups according to their first rhythms and PEA heart rates: (1) initial PEA heart rate of 1-20 beats per minute (bpm); (2) 21-40 bpm; (3) 41-60 bpm; (4) 61-80 bpm; (5) 81-100 bpm; (6) 101-120 bpm; (7) over 120 bpm; (8) initial shockable rhythm (reference category). Multivariable logistic regression models were used to assess the associations of interest.

RESULTS

We identified 17,675 patients (PEA: 7,089 [40.1%]; initial shockable rhythm: 10,797 [59.9%]). Patients with initial PEA electrical frequencies ≤100 bpm were less likely to survive to hospital discharge than patients with initial shockable rhythms (1-20 bpm: adjusted odds ratio [AOR] = 0.15 [95%CI 0.11-0.21]; 21-40 bpm: AOR =0.21 [0.18-0.25]; 41-60 bpm: AOR =0.30 [0.25-0.36]; 61-80 bpm: AOR =0.37 [0.28-0.49]; 81-100 bpm: AOR =0.55 [0.41-0.65]). However, there were no statistical outcome differences between PEA patients with initial electrical frequencies of >100 bpm and patients with initial shockable rhythms (101-120 bpm: AOR =0.65 [95%CI 0.42-1.01]; >120 bpm: AOR =0.72 [95%CI 0.37-1.39]). Similar results were observed for survival with good functional outcomes (101-120 bpm: AOR =0.60 [95%CI 0.31-1.15]; >120 bpm: AOR =1.08 [95%CI 0.50-2.28]).

CONCLUSIONS

We observed a good association between higher initial PEA electrical frequency and favorable clinical outcomes for OHCA patients. As there is no significant difference in outcomes between patients with initial PEA heart rates of more than 100 bpm and those with initial shockable rhythms, we can hypothesize that these patients could be considered in the same prognostic category.

A Machine Learning Model for the Prognosis of Pulseless Electrical Activity during Out-of-Hospital Cardiac Arrest

Pulseless electrical activity (PEA) is characterized by the disassociation of the mechanical and electrical activity of the heart and appears as the initial rhythm in 20–30% of out-of-hospital cardiac arrest (OHCA) cases. Predicting whether a patient in PEA will convert to return of spontaneous circulation (ROSC) is important because different therapeutic strategies are needed depending on the type of PEA. The aim of this study was to develop a machine learning model to differentiate PEA with unfavorable (unPEA) and favorable (faPEA) evolution to ROSC. An OHCA dataset of 1921 5s PEA signal segments from defibrillator files was used, 703 faPEA segments from 107 patients with ROSC and 1218 unPEA segments from 153 patients with no ROSC. The solution consisted of a signal-processing stage of the ECG and the thoracic impedance (TI) and the extraction of the TI circulation component (ICC), which is associated with ventricular wall movement. Then, a set of 17 features was obtained from the ECG and ICC signals, and a random forest classifier was used to differentiate faPEA from unPEA. All models were trained and tested using patientwise and stratified 10-fold cross-validation partitions. The best model showed a median (interquartile range) area under the curve (AUC) of 85.7(9.8)% and a balance accuracy of 78.8(9.8)%, improving the previously available solutions at more than four points in the AUC and three points in balanced accuracy. It was demonstrated that the evolution of PEA can be predicted using the ECG and TI signals, opening the possibility of targeted PEA treatment in OHCA.

Association between wide QRS pulseless electrical activity and hyperkalemia in cardiac arrest patients

AIM

We evaluated the relationship between hyperkalemia and wide QRS complex in patients with pulseless electrical activity (PEA) cardiac arrest.

METHODS

This was a single-center, retrospective observational study of patients over the age of 18 treated for cardiac arrest at a tertiary referral hospital whose initial electrocardiogram rhythm was PEA from February 2010 to December 2019. Wide QRS PEA was defined as a QRS interval of 120 ms or more. Hyperkalemia was defined as serum potassium level > 5.5 mmol/L. The primary outcome was hyperkalemia. Multivariable logistic regression analysis was used to evaluate the relationship between wide QRS and hyperkalemia.

RESULTS

Among 617 patients, we analyzed 111 episodes in the wide QRS group and 506 episodes in the narrow QRS group. The potassium level in the wide QRS group was significantly higher than in the narrow QRS group (5.4 mmol/L, IQR 4.4-6.7 vs. 4.6 mmol/L, IQR 4.0-5.6, P < 0.001). Among all patients, 49.6% (n = 55/111) in the wide QRS group had hyperkalemia, which was significantly higher than the 26.7% (n = 135/506) in the narrow QRS group (P < 0.001). In multivariable logistic regression analysis, wide QRS PEA was significantly associated with hyperkalemia (odds ratio = 2.86, 95% confidence interval: 1.80-4.53, P < 0.001).

CONCLUSIONS

Wide QRS PEA as an initial cardiac rhythm was significantly associated with hyperkalemia in cardiac arrest patients.

QRS complex characteristics and patient outcomes in out-of-hospital pulseless electrical activity cardiac arrest

BACKGROUND

Pulseless electrical activity (PEA) is increasingly observed in out-of-hospital cardiac arrest (OHCA), but outcomes are still poor. We aimed to assess the relationship between QRS characteristics and outcomes of patients with OHCA with initial PEA (OHCA-P).

METHODS

This prospective observational study included patients aged at least 18 years who developed OHCA-P between 1 January 2016 and 31 December 2018, and were enrolled in the Daegu Emergency Medical Services registry, South Korea. We performed multivariable logistic regression analyses to identify the associations between QRS characteristics and OHCA-P outcomes, in which QRS complexes were considered separately (model 1) and simultaneously (model 2). The primary outcome was survival to hospital discharge and the secondary outcome was a favourable neurological outcome.

RESULTS

Of the 3659 patients with OHCA, 576 were enrolled (median age 73 years; 334 men). A higher QRS amplitude was associated with survival to hospital discharge and a favourable neurological outcome in model 1 (adjusted OR (aOR) 1.077 and 1.106, respectively; 95% CI 1.021 to 0.136 and 1.029 to 1.190, respectively) and model 2 (aOR 1.084 and 1.123, respectively; 95% CI 1.026 to 1.145 and 1.036 to 1.216, respectively). A QRS width of <120 ms was associated with survival to hospital discharge and a favourable neurological outcome in model 1 (aOR 3.371 and 4.634, respectively; 95% CI 1.633 to 6.960 and 1.562 to 13.144, respectively) and model 2 (aOR 3.213 and 5.103, respectively; 95% CI 1.568 to 6.584 and 1.682 to 15.482, respectively). Survival to hospital discharge and neurological outcome were not associated with QRS frequency.

CONCLUSION

OHCA-P outcomes were better when the initial QRS complex showed a higher amplitude or narrower width.

Cardiac arrest with pulseless electrical activity rhythm in newborn infants: a case series

The 2015 neonatal resuscitation guidelines added ECG to assess an infant's heart rate when determining the need for resuscitation at birth. However, a recent case report raised concerns about this technique in the delivery room. We report four cases of pulseless electrical activity during neonatal cardiopulmonary resuscitation in levels II-III neonatal intensive care units in Canada (Edmonton [n=3] and Winnipeg [n=1]).Healthcare providers should be aware that pulseless electrical activity can occur in newborn infants during cardiopulmonary resuscitation. We propose an adapted neonatal resuscitation algorithm to include pulseless electrical activity. Furthermore, in compromised newborns, heart rate should be assessed using a combination of methods/techniques to ensure accurate heart rate assessment. When ECG displays a heart rate but the infant is unresponsive, pulseless electrical activity should be suspected and chest compression should be started.

Non-perfusing cardiac rhythms in asphyxiated newborn piglets

Aim

We recently demonstrated that asphyxiated piglets commonly had bradycardia displayed on electrocardiography (ECG) while no carotid blood flow (CBF) or audible heart sounds could be detected. Such pulseless electrical activity (PEA) in newborn infants has not previously been thoroughly described. The aim of this study was to further investigate the occurrence of non-perfusing cardiac rhythms in asphyxiated piglets and the potential implications for the success of cardiopulmonary resuscitation (CPR) and short-term survival.

Methods

Neonatal piglets (1–4 days, 1.7–2.4kg) had their right common carotid artery exposed and enclosed with a real-time ultrasonic flow probe. Heart rate (HR) was continuously measured and recorded using ECG. This allowed simultaneous monitoring of HR via ECG and CBF. The piglets were asphyxiated until cardiac arrest, defined as no CBF and no audible beat upon precordial auscultation. CPR was performed until return of spontaneous circulation (ROSC, defined as a HR ≥100 bpm). ECG traces were retrospectively assessed.

Results

Nine out of 21 piglets (43%) had QRS-complexes on their ECG while no CBF and no audible heart sounds could be detected. Five (56%) of the piglets with PEA and 12/12 (100%) piglets with asystole at cardiac arrest obtained ROSC (p = 0.02). Thirty-three per cent of the piglets with PEA versus 58% with asystole survived to 4 hours post-ROSC (p = 0.39).

Conclusion

Cardiac arrest in the presence of a non-perfusing cardiac rhythm on ECG is common in asphyxiated piglets. Clinical arrest in the presence of a non-perfusing cardiac rhythm on ECG may reduce the success of CPR.

Factors determining level of hospital care and its association with outcome after resuscitation from pre-hospital pulseless electrical activity

Background

Patients resuscitated from out-of-hospital cardiac arrest (OHCA) with pulseless electrical activity (PEA) as initial cardiac rhythm are not always treated in intensive care units (ICUs): some are admitted to high dependency units with various level of care, others to ordinary wards. Aim of this study was to describe the factors determining level of hospital care after OHCA with PEA, post-resuscitation care and survival.

Methods

Adult OHCA patients with PEA (n = 221), who were resuscitated in southern Finland between 2010 and 2013 were included, provided patient survived to hospital admission. The patients were divided into four groups according to the level of hospital care provided: ordinary ward and Level 1–3 ICUs. Differences in patient characteristics, post-resuscitation care and survival were compared between the groups.

Results

Most patients (62.4%) were treated at Level 2 ICUs. Longer time to ROSC and advanced age decreased admission rate to Level 2 or 3 post-resuscitation care, whereas good pre-arrest CPC (1–2) increased the admission rate to Level 2/3 ICUs independently. Treatment with targeted temperature management (TTM) (4.1%) or early coronary angiography (3.2%) were very rare. Prognostic decisions were made earlier in the lower treatment intensity groups (p < 0.01). One-year survival rate was 24.0, 17.1% survived with good neurological outcome. Neurological outcome was better with more intensive care. After adjustment, level of care was not independent predictor for outcome: only return of spontaneous circulation (ROSC) time, cardiac arrest cause and pre-arrest performance affected independently to 1-year survival, age and ROSC for neurologic outcome.

Conclusions

PEA are usually admitted to Level 2 ICUs for post-resuscitation care in the capital area of Finland. Age, ROSC and pre-arrest CPC were independent predictors for level of post-resuscitation care. TTM and early CAG were rare and provided only for Level 3 ICU patients. Prognostication was earlier in lower level of care units. Good neurologic survival was more common with more intensive level of post-resuscitation care. After adjustment, level of care was not independent predictor for survival or neurologic outcome: only ROSC, cardiac arrest cause and pre-arrest performance predicted 1-year survival; age and ROSC neurologic outcome.

ECG changes during resuscitation of patients with initial pulseless electrical activity are associated with return of spontaneous circulation

BACKGROUND

Pulseless electrical activity (PEA) is a frequent initial rhythm in cardiac arrest, and ECG characteristics have been linked to prognosis. The aim of this study was to examine the development of ECG characteristics during advanced life support (ALS) and cardiopulmonary resuscitation (CPR) in cardiac arrest with initial PEA, and to assess any association with survival.

METHODS

Patients with in-hospital cardiac arrest with initial PEA at St. Olav Hospital (Trondheim, Norway) over a three-year period were included. A total of 2187 combined observations of QRS complex rate (heart rate) and QRS complex width for the duration of ALS were determined from defibrillator recordings from 74 episodes of cardiac arrest.

RESULTS

Increasing heart rate and decreasing QRS complex width during ALS was significantly more prevalent in patients who obtained return of spontaneous circulation compared to patients who were declared dead.

CONCLUSION

Changes in ECG characteristics during ALS in cardiac arrest presenting as PEA are related to prognosis. An increase in heart rate was observed in the last 3-6 min before ROSC was obtained.

Initial electrical frequency predicts survival and neurological outcome in out of hospital cardiac arrest patients with pulseless electrical activity

BACKGROUND

Outcome is generally poor in out of hospital cardiac arrests (OHCA) with initial non-shockable rhythms. Termination of resuscitation rules facilitate early prognostication at the scene to cease resuscitation attempts in futile situations and to proceed advanced life support in promising conditions. As pulseless electrical activity (PEA) is present as first rhythm in every 4th OHCA we were interested if the initial electrical frequency in PEA predicts survival.

METHODS

All patients >18 years of age with non-traumatic OHCA and PEA as first rhythm between August 2013 and August 2015 from the Vienna Cardiac Arrest Registry were included in this retrospective observational study. Defibrillator and epidemiological data from the emergency medical system as survival data were processed considering the initial electrical activity in PEA and 30 days survival.

RESULTS

Out of 2149 OHCA patients, a total of 504 PEA patients were eligible for analyses. These patients were stratified into 4 groups according the initial electrical frequency in PEA: 10-24/min, 25-39/min, 40-59/min, >60/min. Compared to a frequency >60/min all other subgroups were associated with higher mortality especially those with an initial electrical frequency 10-24 (adjusted OR 0.56 (0.39-0.79) p = .001 for each category chance). QRS duration in PEA did not influence outcome. Patients in the >60/min group showed a 30-days-survival rate of 22% and a good neurological outcome in 15% of all patients - comparable to shockable cardiac arrest rhythms.

CONCLUSION

Regardless of other resuscitation factors, higher initial electrical frequency in PEA is associated with increased odds of survival and good neurological outcome.

Electrocardiography vs. Auscultation to Assess Heart Rate During Cardiac Arrest With Pulseless Electrical Activity in Newborn Infants

Background: In 2015, the neonatal resuscitation guidelines incorporated the use of electrocardiography (ECG) to monitor heart rate of newborns. However, previous studies have indicated that cardiac arrest with pulseless electrical activity rhythm (PEA) may occur in the delivery room, rendering this method problematic. Objective: To evaluate the accuracy of ECG and auscultation to assess heart rate during PEA. Methods: A total of 45 piglets (age 1-3 days, weight 1.7-2.3 kg) were exposed to 30 min normocapnic alveolar hypoxia followed by asphyxia until asystole, achieved by disconnecting the ventilator and clamping the endotracheal tube. During asphyxia, heart rate (HR) was assess using auscultation, ECG, and carotid blood flow (CBF). At the time of asystole (defined as zero CBF) HR auscultated using a neonatal/infant stethoscope was compared to ECG traces. Results: The median (IQR) duration of asphyxia was 325 (200-491) s. In 8 (18%) piglets, CBF, ECG, and auscultation identified asystole. In 22 (49%) piglets no CBF and no audible heart sounds, were observed, while ECG displayed a HR ranging from 17 to 75/min. Fifteen (33%) piglets remained bradycardic (defined as HR of < 100/min) after 10 min of asphyxia, which was identified by CBF, ECG, and auscultation. The overall accuracy of ECG and auscultation in the detection of HR were 51 and 80%, respectively (p = 0.004). Conclusion: In cases with PEA ECG is not superior in correctly identifying HR in newborn piglets.

Utility of prehospital electrocardiogram characteristics as prognostic markers in out-of-hospital pulseless electrical activity arrests

Background

It is unclear if there are predictors of survival, including ECG characteristics, that can guide resuscitative efforts in pulseless electrical activity (PEA) cardiac arrests. We studied the predictive potential of presenting prehospital ECGs on survival for patients with out-of-hospital cardiac arrest (OHCA) with PEA.

Methods

We studied prehospital ECGs of patients with OHCA prospectively enrolled between June 2007 and November 2009 at the Ottawa/OPALS (Ontario Prehospital Advanced Life Support Study) site of the Resuscitation Outcomes Consortium PRIMED study (Prehospital Resuscitation using an IMpedance valve and Early versus Delayed analysis). We included adult non-traumatic OHCA with PEA rhythm where resuscitation was attempted. We measured HR, QRS interval and presence of P waves, and determined their impact on return of spontaneous circulation (ROSC) and survival to hospital discharge (SHD) using multivariate regression analysis.

Results

The demographic characteristics of the 332 included cases were the following: mean age 71.8, male 58.4%, SHD 5.4% and ROSC at ED arrival 26.5%. Survivors had similar HR (56.8 vs 52.0 beats per minute (bpm), p=0.53) and QRS intervals (128.7 vs 129.6 ms, p=0.95) compared with non-survivors. Prehospital ECG characteristics did not predict SHD or ROSC on multivariate analyses. Patients with initial HR <30 bpm had a 3.8% survival rate; those with both HR <30 bpm and QRS≥120 ms had a 3.7% survival rate. Location of arrest predicted SHD (adjusted OR (AdjOR)=1.49, 1.11 to 1.99; p=0.007). Atropine use negatively predicted SHD (AdjOR=0.06, 0.02 to 0.22; p<0.001). Predictors of ROSC ALS paramedic on scene (AdjOR=8.90, 1.11 to 71.41; p=0.04) and successful intubation (AdjOR=3.35, 1.75 to 6.39; p<0.001). Atropine use negatively predicted ROSC (AdjOR=0.27, 0.14 to 0.50; p<0.001).

Conclusions

Presenting prehospital ECG characteristics did not predict SHD or ROSC in OHCA PEA victims and should not be used to guide termination of resuscitation. Location of arrest was a positive predictor for SHD; atropine use was a negative predictor. ALS paramedic on scene and successful intubation were positive predictors of ROSC; atropine use was a negative predictor.

Trial registration number

NCT00394706; post-results.

Pediatric Cardiac Arrest Due to Trauma

Survival from pediatric cardiac arrest due to trauma has been reported to be 0.0%-8.8%. Some argue that resuscitation efforts in the case of trauma-related cardiac arrests are futile. We describe a successful outcome in the case of a child who suffered cardiac arrest caused by external traumatic airway obstruction. Our case illustrates how to deal with pediatric traumatic cardiac arrests in an out-of-hospital environment. It also illustrates how good clinical treatment in these situations may be supported by correct treatment after hospital admission when it is impossible to ventilate the patient to provide sufficient oxygen delivery to vital organs. This case relates to a lifeless child of 3-5 years, blue, and trapped by an electrically operated garage door. The first ambulance arrived to find several men trying to bend the frame and the door apart in order to extricate the child, who was hanging in the air with head and neck squeezed between the horizontally-moving garage door and the vertical door frame. One paramedic found a car jack and used it to push the door and the frame apart, allowing the lifeless child to be extricated. Basic life support was then initiated. Intubation was performed by the anesthesiologist without drugs. With FiO2 1.0 the first documented SaO2 was <50%. Restoration of Spontaneous Circulation was achieved after thirty minutes, and she was transported to the hospital. After a few hours she was put on venous-arterial ECMO for 5.5 days and discharged home after two months. Outpatient examinations during the rest of 2013 were positive, and the child found not to be suffering from any injuries, either physical or mental. The last follow-up in October 2014 demonstrated she had made a 100% recovery and she started school in August 2014.