Mechanism of death: there's more to it than sudden cardiac arrest

On the ethical permissibility of in situ reperfusion in cardiac transplantation after the declaration of circulatory death

Transplant surgeons in the USA have begun performing a novel organ procurement protocol in the setting of circulatory death. Unlike traditional donation after circulatory death (DCD) protocols, in situ normothermic perfusion DCD involves reperfusing organs, including the heart, while still contained in the donor body. Some commentators, including the American College of Physicians, have claimed that in situ reperfusion after circulatory death violates the widely accepted Dead Donor Rule (DDR) and conclude that in situ reperfusion is ethically impermissible. In this paper I argue that, in terms of respecting the DDR, in situ reperfusion cardiac transplantation does not differ from traditional DCD cardiac transplantation. I do this by introducing and defending a refined conception of circulatory death, namely vegetative state function permanentism I also argue against the controversial brain occlusion feature of the in situ reperfusion DCD protocol, on the basis that it is ethically unnecessary and generates the problematic appearance of ethical dubiousness.

Unpacking the sepsis controversy

Despite its many definitions and revisions, consensus statements and clinical guidelines, the term 'sepsis' continues to be referred to as a discrete clinical entity that is often claimed to be a direct cause of mortality. The assertion that sepsis can be defined as a 'life-threatening organ dysfunction caused by a dysregulated host response to infection,' has led to a field dominated by failed clinical trials informed by host-centered, pathogen-agnostic, animal experiments in which animal models do not recapitulate the clinical condition. The observations from the National Health Service from England that claim that 77.5% of sepsis deaths occur in those aged 75 years or older and those from the USA indicating that most patients dying of sepsis have also been diagnosed with 'hospice qualifying conditions,' seem to refute the assertion that sepsis is caused by, rather than associated with, a 'dysregulated host response.' This piece challenges the current conceptual framework that forms the basis of the sepsis definition. Here we posit that as a result of both its definition and the use of inappropriate animal models, ineffective clinical treatments continue to be pursued in this field.

Automated loss of pulse detection on a consumer smartwatch

Out-of-hospital cardiac arrest is a time-sensitive emergency that requires prompt identification and intervention: sudden, unwitnessed cardiac arrest is nearly unsurvivable1-3. A cardinal sign of cardiac arrest is sudden loss of pulse4. Automated biosensor detection of unwitnessed cardiac arrest, and dispatch of medical assistance, may improve survivability given the substantial prognostic role of time3,5, but only if the false-positive burden on public emergency medical systems is minimized5-7. Here we show that a multimodal, machine learning-based algorithm on a smartwatch can reach performance thresholds making it deployable at a societal scale. First, using photoplethysmography, we show that wearable photoplethysmography measurements of peripheral pulselessness (induced through an arterial occlusion model) manifest similarly to pulselessness caused by a common cardiac arrest arrhythmia, ventricular fibrillation. On the basis of the similarity of the photoplethysmography signal (from ventricular fibrillation or arterial occlusion), we developed and validated a loss of pulse detection algorithm using data from peripheral pulselessness and free-living conditions. Following its development, we evaluated the end-to-end algorithm prospectively: there was 1 unintentional emergency call per 21.67 user-years across two prospective studies; the sensitivity was 67.23% (95% confidence interval of 64.32% to 70.05%) in a prospective arterial occlusion cardiac arrest simulation model. These results indicate an opportunity, deployable at scale, for wearable-based detection of sudden loss of pulse while minimizing societal costs of excess false detections7.

Contextualizing Pseudo-Pulseless Electrical Activity in Cardiac Arrest: A Meta-Analysis and Systematic Review

OBJECTIVE

Nonshockable cardiac arrest rhythms have demonstrably poor outcomes. Pseudo-pulseless electrical activity (PEA), a subset of PEA in which visible cardiac contractility is present, is being described more frequently in recent literature. Physiology suggests that presence of cardiac motion even without a palpable pulse is energetically more favorable than true PEA, which is more like asystole. Therefore, we hypothesize that there is an increase in the survivability of PEA compared with asystole which may in part be due to a subset of pseudo-PEA.

METHODS

A PICOST research question was generated which guided the composition of a systematic review and meta-analysis in line with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses checklist.

RESULTS

A total of 494,355 patients were identified from 12 pieces of literature. Meta-analyses revealed an overall increased survivability of PEA compared with asystole (odds ratio [OR] 2.08, 95% confidence interval [CI] 1.52-2.86). When differentiating between location of arrest, PEA was more survivable in both in-hospital cardiac arrest and out-of-hospital cardiac arrest than asystole (out-of-hospital cardiac arrest OR 4.17, 95% CI 3.78-4.60, and in-hospital cardiac arrest OR 1.60, 95% CI 1.42-1.79). Finally, when comparing neurological outcome of PEA with asystole, PEA was more favorable (OR 3.32, 95% CI 1.39-7.94).

CONCLUSION

Pseudo-PEA may be one of the explanations attributed to better outcomes of PEA, especially neurological, due to the presence of cerebral and coronary flow. The presence of PEA likely requires evidence-based tailored management with presence of pseudo-PEA being more like a profound shock state. More evidence is required to investigate the true incidence of pseudo-PEA and its outcomes compared with true PEA.

Does a Transition to Single-Occupancy Patient Rooms Affect the Incidence and Outcome of In-Hospital Cardiac Arrests?

BACKGROUND

It is proposed that patients in single-occupancy patient rooms (SPRs) carry a risk of less surveillance by nursing and medical staff and that resuscitation teams need longer to arrive in case of in-hospital cardiac arrest (IHCA). Higher incidences of IHCA and worse outcomes after cardiopulmonary resuscitation (CPR) may be the result.

OBJECTIVES

Our study examines whether there is a difference in incidence and outcomes of IHCA before and after the transition from a hospital with multibedded rooms to solely SPRs.

METHODS

In this prospective observational study in a Dutch university hospital, as a part of the Resuscitation Outcomes in the Netherlands study, we reviewed all cases of IHCA on general adult wards in a period of 16.5 months before to 16.5 months after the transition to SPRs.

RESULTS

During the study period, 102 CPR attempts were performed: 51 in the former hospital and 51 in the new hospital. Median time between last-seen-well and start basic life support did not differ significantly, nor did median time to arrival of the CPR team. Survival rates to hospital discharge were 30.0% versus 29.4% of resuscitated patients (p = 1.00), with comparable neurological outcomes: 86.7% of discharged patients in the new hospital had Cerebral Performance Category 1 (good cerebral performance) versus 46.7% in the former hospital (p = .067). When corrected for telemetry monitoring, these differences were still nonsignificant.

CONCLUSIONS

The transition to a 100% SPR hospital had no negative impact on incidence, survival rates, and neurological outcomes of IHCAs on general adult wards.

Prediction of survival in out-of-hospital cardiac arrest: the updated Swedish cardiac arrest risk score (SCARS) model

Aims

Out-of-hospital cardiac arrest (OHCA) is a major health concern worldwide. Although one-third of all patients achieve a return of spontaneous circulation and may undergo a difficult period in the intensive care unit, only 1 in 10 survive. This study aims to improve our previously developed machine learning model for early prognostication of survival in OHCA.

Methods and results

We studied all cases registered in the Swedish Cardiopulmonary Resuscitation Registry during 2010 and 2020 (n = 55 615). We compared the predictive performance of extreme gradient boosting (XGB), light gradient boosting machine (LightGBM), logistic regression, CatBoost, random forest, and TabNet. For each framework, we developed models that optimized (i) a weighted F1 score to penalize models that yielded more false negatives and (ii) a precision-recall area under the curve (PR AUC). LightGBM assigned higher importance values to a larger set of variables, while XGB made predictions using fewer predictors. The area under the curve receiver operating characteristic (AUC ROC) scores for LightGBM were 0.958 (optimized for weighted F1) and 0.961 (optimized for a PR AUC), while for XGB, the scores were 0.958 and 0.960, respectively. The calibration plots showed a subtle underestimation of survival for LightGBM, contrasting with a mild overestimation for XGB models. In the crucial range of 0-10% likelihood of survival, the XGB model, optimized with the PR AUC, emerged as a clinically safe model.

Conclusion

We improved our previous prediction model by creating a parsimonious model with an AUC ROC at 0.96, with excellent calibration and no apparent risk of underestimating survival in the critical probability range (0-10%). The model is available at www.gocares.se.

Pulseless electrical activity and asystolic cardiac arrest in infants: identifying factors that influence outcomes

BACKGROUND

There is limited information on pulseless electrical activity (PEA)/asystolic cardiac arrest (CA) in the infant population. The aim is to describe the incidence and factors associated with outcomes in infants with PEA/asystolic CA.

METHODS

Single-center retrospective chart review study of infants less than one year of age who suffer in-hospital PEA/asystolic CA from January 1 2011 to June 30 2019. The primary outcome was the return of spontaneous circulation. The secondary outcome was survival to discharge.

RESULTS

CA occurred in 148 infants and PEA/asystolic was found in 38 (26%). Of those 29 (76%) achieved ROSC, and 12 (32%) survived to discharge. Infants on inotrope support or receiving longer duration of chest compressions and epinephrine had increase mortality. All infants with respiratory etiology of arrest survived to hospital discharge.

CONCLUSION

PEA/asystolic CAs are uncommon. Poor prognostic indicators include the need for pre-arrest inotrope support and increased duration of chest compressions.

Pulseless Electrical Activity: Echocardiographic Explanation of a Perplexing Phenomenon

Pulseless electrical activity (PEA) is considered an enigmatic phenomenon in resuscitation research and practice. Finding individuals with no consciousness or pulse but with continued electrocardiographic (EKG) complexes obviously raises the question of how they got there. The development of monitors that can display the underlying rhythm has allowed us to differentiate between VF, asystole, and PEA. Lack of clear understanding of the emergence of PEA has limited the research and development of interventions that might improve the low rates of survival typically associated with PEA. Over 30 years of studying and practicing resuscitation have allowed the authors to see a substantial rise in PEA with variable survival rates, based on the patients' illness spectrum and intensity of monitoring. This paper presents a small case series of individuals with brain death whose family members consented to the echocardiographic observation of the dying process after disconnection from life support. The observation from these cases confirms that PEA is a late phase in the clinical dying process. Echocardiographic images delineate the stages of pseudo-PEA with ineffective contractions, PEA, and then asystole. The process is contiuous with none of the sudden phase shifts seen in dysrhythmic events such as VF, VT or SVT. The implications of these findings are that PEA is a common manifestation of tissue hypoxia and metabolic substrate depletion. Our findings offer prospects for studies of the development of interventions to improve PEA survival.

Immunohistochemical Markers of Apoptotic and Hypoxic Damage Facilitate Evidence-Based Assessment in Pups with Neurological Disorders

Seizures in puppies often present a diagnostic challenge in terms of identifying and treating the underlying cause. Dog breeds with mutations of the MDR1-gene are known to show adverse reactions to certain drugs, yet metabolic imbalance exacerbated by physiologically immature organs and other contributing pathologies require consideration before arriving at a diagnosis. This study analysed the brains of two male, 5-week-old Australian Shepherd siblings that died after displaying severe neurological symptoms upon administration of MilproVet® to treat severe intestinal helminth infection. Despite the initial symptoms being similar, their case histories varied in terms of the symptom duration, access to supportive therapy and post-mortem interval. Histopathology and immunohistochemistry were used to obtain more information about the phase of the pathological processes in the brain, employing protein markers associated with acute hypoxic damage (β-amyloid precursor protein/APP) and apoptosis (diacylglycerolkinase-ζ/DGK-ζ, apoptotic protease activating factor 1/Apaf1, and B-cell lymphoma related protein 2/Bcl-2). The results seem to reflect the course of the animals' clinical deterioration, implicating that the hypoxic damage to the brains was incompatible with life, and suggesting the usefulness of the mentioned immunohistochemical markers in clarifying the cause of death in animals with acute neurological deficits.

Cardiac Implantable Devices Management in Medical Assistance in Dying (MAiD): Review and Recommendations for Cardiac Device Clinics

The Medical Assistance in Dying (MAiD) program has been steadily expanding in Canada, and is expected to continue to do so. There are a substantial number of Canadians with pacemakers and defibrillators, many of whom are potential MAiD recipients. There is a need for review and reflection of standardization of cardiac device management in MAiD patients, not only due to ethical concerns, but also because of the complexity of management at end of life. This document examines the status and role of cardiac devices (pacemakers and intracardiac defibrillators) and their physiological interactions and influences during the MAiD process, and recommendations for their management.

Pulseless Electrical Activity: Detection of Underlying Causes in a Prehospital Setting

The proportion of out-of-hospital cardiac arrests (OHCAs) with pulseless electrical activity (PEA) as initial rhythm is increasing. PEA should be managed by identifying the underlying cause of the arrest and treating it accordingly. This often poses a challenge in the chaotic prehospital environment with only limited resources available. The aim of this study was to review the diagnostic tools available in a prehospital setting, and their interpretation during cardiac arrest (CA) with PEA as initial rhythm. A systematic literature search of the PubMed database was performed. Articles were assessed for eligibility by title, abstract, and full text. Ultrasonography has become a great asset in detecting underlying causes, and a variety of protocols have been proposed. There are currently no studies comparing these protocols regarding their feasibility and their effect on patient survival. Further research concerning the relationship between electrocardiogram characteristics and underlying causes is required. Limited evidence suggests a role for point-of-care testing in detecting hyperkalemia and a role for capnography in the diagnosis of asphyxia CA. Multiple studies describe a prognostic potential. Although evidence about the prognostic potential of cerebral oximetry in OHCA is accumulating, its diagnostic potential is still unknown. In the management of OHCA, anamnestic and clinical information remains the initial source of information in search for an underlying cause. Ultrasonographic evaluation should be performed subsequently, both for detecting an underlying cause and discriminating between true PEA and pseudo PEA. Comparative studies are required to identify the best ultrasonographic protocol, which can be included in resuscitation guidelines.

Management of Arrhythmias Associated with COVID-19

Purpose of Review

Cardiac arrhythmias are known complications in patients with COVID-19 infection that may persist even after recovery from infection. A review of the spectrum of cardiac arrhythmias due to COVID-19 infection and current guidelines and assessment or risk and benefit of management considerations is necessary as the population of patients infected and covering from COVID-19 continues to grow.

Recent Findings

Cardiac arrhythmias such as atrial fibrillation, supraventricular tachycardia, complete heart block, and ventricular tachycardia occur in patients infected, recovering and recovered from COVID-19.

Summary

Personalized care while balancing risk/benefit of medical or invasive therapy is necessary to improve care of patients with arrhythmias. Providers must provide thorough follow-up care and use necessary precaution while caring for COVID-19 patients.

Clinical and cardiac characteristics of COVID-19 mortalities in a diverse New York City Cohort

Introduction

Electrocardiographic characteristics in COVID‐19‐related mortality have not yet been reported, particularly in racial/ethnic minorities.

Methods and Results

We reviewed demographics, laboratory and cardiac tests, medications, and cardiac rhythm proximate to death or initiation of comfort care for patients hospitalized with a positive SARS‐CoV‐2 reverse‐transcriptase polymerase chain reaction in three New York City hospitals between March 1 and April 3, 2020 who died. We described clinical characteristics and compared factors contributing toward arrhythmic versus nonarrhythmic death. Of 1258 patients screened, 133 died and were enrolled. Of these, 55.6% (74/133) were male, 69.9% (93/133) were racial/ethnic minorities, and 88.0% (117/133) had cardiovascular disease. The last cardiac rhythm recorded was VT or fibrillation in 5.3% (7/133), pulseless electrical activity in 7.5% (10/133), unspecified bradycardia in 0.8% (1/133), and asystole in 26.3% (35/133). Most 74.4% (99/133) died receiving comfort measures only. The most common abnormalities on admission electrocardiogram included abnormal QRS axis (25.8%), atrial fibrillation/flutter (14.3%), atrial ectopy (12.0%), and right bundle branch block (11.9%). During hospitalization, an additional 17.6% developed atrial ectopy, 14.7% ventricular ectopy, 10.1% atrial fibrillation/flutter, and 7.8% a right ventricular abnormality. Arrhythmic death was confirmed or suspected in 8.3% (11/133) associated with age, coronary artery disease, asthma, vasopressor use, longer admission corrected QT interval, and left bundle branch block (LBBB).

Conclusions

Conduction, rhythm, and electrocardiographic abnormalities were common during COVID‐19‐related hospitalization. Arrhythmic death was associated with age, coronary artery disease, asthma, longer admission corrected QT interval, LBBB, ventricular ectopy, and usage of vasopressors. Most died receiving comfort measures.