The Right Ventricle Is Dilated During Resuscitation From Cardiac Arrest Caused by Hypovolemia: A Porcine Ultrasound Study

Ultrasound during Advanced Life Support-Help or Harm?

Ultrasound is used in cardiopulmonary resuscitation (CPR) and advanced life support (ALS). However, there is divergence between the recommendations of many emergency and critical care societies who support its use and the recommendations of many international resuscitation organizations who either recommend against its use or recommend it only in limited circumstances. Ultrasound offers potential benefits of detecting reversable causes of cardiac arrest, allowing specific interventions. However, it also risks interfering with ALS protocols and increasing unhelpful interventions. As with many interventions in ALS, the evidence base for ultrasound use is weak, and well-designed randomized trials are needed. This paper reviews the current theory and evidence for harms and benefits.

Animal research in cardiac arrest

The purpose of this narrative review is to provide an overview of lessons learned from experimental cardiac arrest studies, limitations, translation to clinical studies, ethical considerations and future directions. Cardiac arrest animal studies have provided valuable insights into the pathophysiology of cardiac arrest, the effects of various interventions, and the development of resuscitation techniques. However, there are limitations to animal models that should be considered when interpreting results. Systematic reviews have demonstrated that animal models rarely reflect the clinical condition seen in humans, nor the complex treatment that occurs during and after a cardiac arrest. Furthermore, animal models of cardiac arrest are at a significant risk of bias due to fundamental issues in performing and/or reporting critical methodological aspects. Conducting clinical trials targeting the management of rare cardiac arrest causes like e.g. hyperkalemia and pulmonary embolism is challenging due to the scarcity of eligible patients. For these research questions, animal models might provide the highest level of evidence and can potentially guide clinical practice. To continuously push cardiac arrest science forward, animal studies must be conducted and reported rigorously, designed to avoid bias and answer specific research questions. To ensure the continued relevance and generation of valuable new insights from animal studies, new approaches and techniques may be needed, including animal register studies, systematic reviews and multilaboratory trials.

Sodium Bicarbonate and Calcium Chloride for the Treatment of Hyperkalemia-Induced Cardiac Arrest: A Randomized, Blinded, Placebo-Controlled Animal Study

OBJECTIVES

Current international guidelines recommend administrating calcium chloride and sodium bicarbonate to patients with hyperkalemia-induced cardiac arrest, despite limited evidence. The aim of this study was to evaluate the efficacy of calcium chloride and sodium bicarbonate on return of spontaneous circulation (ROSC) in a pig model of hyperkalemia-induced cardiac arrest.

DESIGN

A randomized, blinded, placebo-controlled experimental pig study. Hyperkalemia was induced by continuous infusion of potassium chloride over 45 minutes followed by a bolus. After a no flow period of 7 minutes, pigs first received 2 minutes of basic cardiopulmonary resuscitation and subsequently advanced life support. The first intervention dose was administered after the fifth rhythm analysis, followed by a defibrillation attempt at the sixth rhythm analysis. A second dose of the intervention was administered after the seventh rhythm analysis if ROSC was not achieved. In case of successful resuscitation, pigs received intensive care for 1 hour before termination of the study.

SETTING

University hospital laboratory.

SUBJECTS

Fifty-four female Landrace/Yorkshire/Duroc pigs (38-42 kg).

INTERVENTIONS

The study used a 2 × 2 factorial design, with calcium chloride (0.1 mmol/kg) and sodium bicarbonate (1 mmol/kg) as the interventions.

MEASUREMENTS AND MAIN RESULTS

Fifty-two pigs were included in the study. Sodium bicarbonate significantly increased the number of animals achieving ROSC (24/26 [92%] vs. 13/26 [50%]; odds ratio [OR], 12.0; 95% CI, 2.3-61.5; p = 0.003) and reduced time to ROSC (hazard ratio [HR] 3.6; 95% CI, 1.8-7.5; p < 0.001). There was no effect of calcium chloride on the number of animals achieving ROSC (19/26 [73%] vs. 18/26 [69%]; OR, 1.2; 95% CI, 0.4-4.0; p = 0.76) or time to ROSC (HR, 1.5; 95% CI, 0.8-2.9; p = 0.23).

CONCLUSIONS

Administration of sodium bicarbonate significantly increased the number of animals achieving ROSC and decreased time to ROSC. There was no effect of calcium chloride on the number of animals achieving ROSC or time to ROSC.

The role of point-of-care ultrasound (POCUS) imaging in clinical outcomes during cardiac arrest: a systematic review

BACKGROUND

Cardiac arrest in hospital and out-of-hospital settings is associated with high mortality rates. Therefore, a bedside test that can predict resuscitation outcomes of cardiac arrest patients is of great value. Point-of-care ultrasound (POCUS) has the potential to be used as an effective diagnostic and prognostic tool during cardiac arrest, particularly in observing the presence or absence of cardiac activity. However, it is highly susceptible to "self-fulfilling prophecy" and is associated with prolonged cardiopulmonary resuscitation (CPR), which negatively impacts the survival rates of cardiac arrest patients. As a result, the current systematic review was created to assess the role of POCUS in predicting the clinical outcomes associated with out-of-hospital and in-hospital cardiac arrests.

METHODS

The search for scientific articles related to our study was done either through an electronic database search (i.e., PubMed, Medline, ScienceDirect, Embase, and Google Scholar) or manually going through the reference list of the relevant articles. A quality appraisal was also carried out with the Quality Assessment of Diagnostic Accuracy Studies tool (QUADAS-2), and the prognostic test performance (sensitivity and sensitivity) was tabulated.

RESULTS

The search criteria yielded 3984 articles related to our topic, of which only 22 were eligible for inclusion. After reviewing the literature, we noticed a wide variation in the definition of cardiac activity, and the statistical heterogeneity was high; therefore, we could not carry out meta-analyses. The tabulated clinical outcomes based on initial cardiac rhythm and definitions of cardiac activity showed highly inconsistent results.

CONCLUSION

POCUS has the potential to provide valuable information on the management of cardiac arrest patients; however, it should not be used as the sole predictor for the termination of resuscitation efforts.

Guidance for clinical practice using emergency and point-of-care ultrasonography

Owing to the miniaturization of diagnostic ultrasound scanners and their spread of their bedside use, ultrasonography has been actively utilized in emergency situations. Ultrasonography performed by medical personnel with focused approaches at the bedside for clinical decision-making and improving the quality of invasive procedures is now called point-of-care ultrasonography (POCUS). The concept of POCUS has spread worldwide; however, in Japan, formal clinical guidance concerning POCUS is lacking, except for the application of focused assessment with sonography for trauma (FAST) and ultrasound-guided central venous cannulation. The Committee for the Promotion of POCUS in the Japanese Association for Acute Medicine (JAAM) has often discussed improving the quality of acute care using POCUS, and the "Clinical Guidance for Emergency and Point-of-Care Ultrasonography" was finally established with the endorsement of JAAM. The background, targets for acute care physicians, rationale based on published articles, and integrated application were mentioned in this guidance. The core points include the fundamental principles of ultrasound, airway, chest, cardiac, abdominal, and deep venous ultrasound, ultrasound-guided procedures, and the usage of ultrasound based on symptoms. Additional points, which are currently being considered as potential core points in the future, have also been widely mentioned. This guidance describes the overview and future direction of ultrasonography for acute care physicians and can be utilized for emergency ultrasound education. We hope this guidance will contribute to the effective use of ultrasonography in acute care settings in Japan.

Focused Ultrasonography in Cardiac Arrest

Rapid diagnostic tools available to the emergency physician caring for cardiac arrest patients are limited. Focused ultrasound (US), and in particular, focused echocardiography, is a useful tool in the evaluation of patients in cardiac arrest. It can help identify possible causes of cardiac arrest like tamponade and pulmonary embolism, which can guide therapy. US can also yield prognostic information, with lack of cardiac activity being highly specific for failure to achieve return of spontaneous circulation. US may also be used to aid in procedural guidance. Recently, focused transesophageal echocardiography has been used in the emergency department setting.

Differential diagnosis and cause-specific treatment during out-of-hospital cardiac arrest: a retrospective descriptive study

BACKGROUND

The cardiopulmonary resuscitation (CPR) guidelines recommend identifying and correcting the underlying reversible causes of out-of-hospital cardiac arrest (OHCA). However, it is uncertain how often these causes can be identified and treated. Our aim was to estimate the frequency of point of care ultrasound examinations, blood sample analyses and cause-specific treatments during OHCA.

METHODS

We performed a retrospective study in a physician-staffed helicopter emergency medical service (HEMS) unit. Data on 549 non-traumatic OHCA patients who were undergoing CPR at the arrival of the HEMS unit from 2016 to 2019 were collected from the HEMS database and patient records. We also recorded the frequency of ultrasound examinations, blood sample analyses and specific therapies provided during OHCA, such as procedures or medications other than chest compressions, airway management, ventilation, defibrillation, adrenaline or amiodarone.

RESULTS

Of the 549 patients, ultrasound was used in 331 (60%) and blood sample analyses in 136 (24%) patients during CPR. A total of 85 (15%) patients received cause-specific treatment, the most common ones being transportation to extracorporeal CPR and percutaneous coronary intervention (PCI) (n = 30), thrombolysis (n = 23), sodium bicarbonate (n = 17), calcium gluconate administration (n = 11) and fluid resuscitation (n = 10).

CONCLUSION

In our study, HEMS physicians deployed ultrasound or blood sample analyses in 84% of the encountered OHCA cases. Cause-specific treatment was administered in 15% of the cases. Our study demonstrates the frequent use of differential diagnostic tools and relatively infrequent use of cause-specific treatment during OHCA. Effect on protocol for differential diagnostics should be evaluated for more efficient cause specific treatment during OHCA.

The Incremental Role of Multiorgan Point-of-Care Ultrasounds in the Emergency Setting

Point-of-care ultrasonography (POCUS) represents a goal-directed ultrasound examination performed by clinicians directly involved in patient healthcare. POCUS has been widely used in emergency departments, where US exams allow physicians to make quick diagnoses and to recognize early life-threatening conditions which require prompt interventions. Although initially meant for the real-time evaluation of cardiovascular and respiratory pathologies, its use has been extended to a wide range of clinical applications, such as screening for deep-vein thrombosis and trauma, abdominal ultrasonography of the right upper quadrant and appendix, and guidance for invasive procedures. Moreover, recently, bedside ultrasounds have been used to evaluate the fluid balance and to guide decongestive therapy in acutely decompensated heart failure. The aim of the present review was to discuss the most common applications of POCUS in the emergency setting.

Transesophageal Echocardiography in Patients in Cardiac Arrest: The Heart and Beyond

Point of care ultrasound involves different ultrasound modalities and is useful to assist management in emergent clinical situations such as cardiac arrest. The use of point of care ultrasound in cardiac arrest has mainly been described using transthoracic echocardiography as a diagnostic and as a prognostic tool. However, cardiac evaluation using transthoracic echocardiography might be challenging because of patient-related or technical factors. Furthermore, its use during pulse check pauses has been associated with delays in chest compression resumption. Transesophageal echocardiography (TEE) overcomes these limitations by providing reliable and continuous imaging of the heart without interfering with cardiopulmonary resuscitation. In this narrative review we describe the role of TEE during cardiopulmonary resuscitation in 4 different applications: (1) chest compression quality feedback; (2) rhythm characterization; (3) diagnosis of reversible causes; and (4) procedural guidance. Considering its limitations, we propose an algorithm for the integration of TEE in patients with cardiac arrest with a focus on these 4 applications and extend its use to extracardiac applications.

Right Ventricular Dilation in Cardiac Arrest May Have Complicated Implications: A Case Report

Right ventricular (RV) dilation has been observed in patients in cardiac arrest. Historically, this phenomenon is almost always attributed to massive pulmonary embolism. However, recent advancements have revealed that there are many other causes of RV dilation in cardiac arrest. In this case report, we present the case of an elderly woman who was found in cardiac arrest with an initial normal left ventricle to RV ratio with subsequent development of RV dilation in the midst of resuscitation without changes to other hemodynamic parameters. This case further bolsters the complex nature of cardiac physiology in cardiac arrest and the need for further investigation.

Transoesophageal echocardiography in cardiac arrest: A systematic review

AIMS

To identify, appraise and synthesize all available clinical evidence to evaluate the diagnostic role of transoesophageal echocardiography (TEE) during resuscitation of in-hospital (IHCA) and out-of-hospital cardiac arrest (OHCA) in the identification of reversible causes of cardiac arrest and cardiac contractility.

METHODS

We conducted a systematic review following PRISMA guidelines. Medline, EMBASE, Web of Science Core Collection, Proquest Dissertations, Open Grey, CDSR, Cochrane Central, Cochrane Clinical Answers, and the clinicaltrials.gov registry were searched for eligible studies. Studies involving adult patients, with non-traumatic cardiac arrest in whom TEE was used for intra-arrest evaluation, were included. Case studies and case series, animal studies, reviews, guidelines and editorials were excluded. The QUADAS-2 tool was used for quality assessment of all studies.

RESULTS

Eleven studies with a total of 358 patients were included. Four studies involved perioperative IHCA, three involved OHCA, and four were mixed population settings. Overall, the risk of bias in the selected studies was either high or unclear due to evidence or lack of information. In all 11 studies, TEE allowed the identification of reversible causes of arrest. We found significant heterogeneity in the criteria used to interpret findings, TEE protocol used, and timing of TEE.

CONCLUSION

Due to heterogeneity of studies, small sample size and inconsistent reference standard, the evidence for TEE in cardiac arrest resuscitation is of low certainty and is affected by a high risk of bias. Further studies are needed to better understand the true diagnostic accuracy of TEE in identifying reversible causes of arrest and cardiac contractility.

[Adult advanced life support]

These European Resuscitation Council Advanced Life Support guidelines are based on the 2020 International Consensus on Cardiopulmonary Resuscitation Science with Treatment Recommendations. This section provides guidelines on the prevention of and ALS treatments for both in-hospital cardiac arrest and out-of-hospital cardiac arrest.

European Resuscitation Council Guidelines 2021: Adult advanced life support

These European Resuscitation Council Advanced Life Support guidelines, are based on the 2020 International Consensus on Cardiopulmonary Resuscitation Science with Treatment Recommendations. This section provides guidelines on the prevention of and ALS treatments for both in-hospital cardiac arrest and out-of-hospital cardiac arrest.

Adult Advanced Life Support: 2020 International Consensus on Cardiopulmonary Resuscitation and Emergency Cardiovascular Care Science with Treatment Recommendations

This 2020 International Consensus on Cardiopulmonary Resuscitation and Emergency Cardiovascular Care Science With Treatment Recommendations for advanced life support includes updates on multiple advanced life support topics addressed with 3 different types of reviews. Topics were prioritized on the basis of both recent interest within the resuscitation community and the amount of new evidence available since any previous review. Systematic reviews addressed higher-priority topics, and included double-sequential defibrillation, intravenous versus intraosseous route for drug administration during cardiac arrest, point-of-care echocardiography for intra-arrest prognostication, cardiac arrest caused by pulmonary embolism, postresuscitation oxygenation and ventilation, prophylactic antibiotics after resuscitation, postresuscitation seizure prophylaxis and treatment, and neuroprognostication. New or updated treatment recommendations on these topics are presented. Scoping reviews were conducted for anticipatory charging and monitoring of physiological parameters during cardiopulmonary resuscitation. Topics for which systematic reviews and new Consensuses on Science With Treatment Recommendations were completed since 2015 are also summarized here. All remaining topics reviewed were addressed with evidence updates to identify any new evidence and to help determine which topics should be the highest priority for systematic reviews in the next 1 to 2 years.

Adult Advanced Life Support: 2020 International Consensus on Cardiopulmonary Resuscitation and Emergency Cardiovascular Care Science With Treatment Recommendations

This 2020 International Consensus on Cardiopulmonary Resuscitation and Emergency Cardiovascular Care Science With Treatment Recommendations for advanced life support includes updates on multiple advanced life support topics addressed with 3 different types of reviews. Topics were prioritized on the basis of both recent interest within the resuscitation community and the amount of new evidence available since any previous review. Systematic reviews addressed higher-priority topics, and included double-sequential defibrillation, intravenous versus intraosseous route for drug administration during cardiac arrest, point-of-care echocardiography for intra-arrest prognostication, cardiac arrest caused by pulmonary embolism, postresuscitation oxygenation and ventilation, prophylactic antibiotics after resuscitation, postresuscitation seizure prophylaxis and treatment, and neuroprognostication. New or updated treatment recommendations on these topics are presented. Scoping reviews were conducted for anticipatory charging and monitoring of physiological parameters during cardiopulmonary resuscitation. Topics for which systematic reviews and new Consensuses on Science With Treatment Recommendations were completed since 2015 are also summarized here. All remaining topics reviewed were addressed with evidence updates to identify any new evidence and to help determine which topics should be the highest priority for systematic reviews in the next 1 to 2 years.

Point-of-care cardiac ultrasound during cardiac arrest: a reliable tool for termination of resuscitation?

PURPOSE OF REVIEW

Point-of-care ultrasound (POCUS) is commonly used during cardiac arrest to screen for potential causes and to inform termination of resuscitation. However, unique biases and limitations in diagnostic and prognostic test accuracy studies lead to potential for misinterpretation. The present review highlights recent evidence regarding POCUS in cardiac arrest, guides the incorporation of POCUS into clinical management, and outlines how to improve the certainty of evidence.

RECENT FINDINGS

Multiple frameworks organize and direct POCUS during cardiac arrest. Although many are proofs of concept, several have been prospectively evaluated. Indirect evidence from undifferentiated shock suggests that POCUS offers better specificity than sensitivity as a diagnostic aid. The prognostic accuracy of POCUS during cardiac arrest to predict subsequent clinical outcomes is better characterized, but subject to unique biases and confounding. Low certainty direct evidence suggests that POCUS offers better specificity than sensitivity as a prognostic aid.

SUMMARY

POCUS findings might indicate a particular diagnosis or encourage the continuation of resuscitation, but absence of the same is not sufficient in isolation to exclude a particular diagnosis or cease resuscitation. Until the evidence to support POCUS during cardiac arrest is more certain, it is best characterized as a diagnostic and prognostic adjunct.

Prognostication with point-of-care echocardiography during cardiac arrest: A systematic review

AIM

To conduct a prognostic factor systematic review on point-of-care echocardiography during cardiac arrest to predict clinical outcomes in adults with non-traumatic cardiac arrest in any setting.

METHODS

We conducted this review per PRISMA guidelines and registered with PROSPERO (ID pending). We searched Medline, EMBASE, Web of Science, CINAHL, and the Cochrane Library on September 6, 2019. Two investigators screened titles and abstracts, extracted data, and assessed risks of bias using the Quality in Prognosis Studies (QUIPS) template. We estimated prognostic test performance (sensitivity and specificity) and measures of association (odds ratio). Grading of Recommendations Assessment, Development and Evaluation (GRADE) methodology evaluated the certainty of evidence.

RESULTS

In total, 15 studies were included. We found wide variation across studies in the definition of 'cardiac motion' and timing of sonographic assessment. Most studies were hindered by high risks of bias from prognostic factor measurement, outcome measurement, and lack of adjustment for other prognostic factors. Ultimately, heterogeneity and risk of bias precluded meta-analyses. We tabulated ranges of prognostic test performance and measures of association for 5 different combinations of definitions of 'cardiac motion' and sonographic timing, as well as other miscellaneous sonographic findings. Overall certainty of this evidence is very low.

CONCLUSIONS

The evidence for using point-of-care echocardiography as a prognostic tool for clinical outcomes during cardiac arrest is of very low certainty and is hampered by multiple risks of bias. No sonographic finding had sufficient and/or consistent sensitivity for any clinical outcome to be used as sole criterion to terminate resuscitation.

An impedance threshold device did not improve carotid blood flow in a porcine model of prolonged cardiac arrest

BACKGROUND

An impedance threshold device (ITD) was developed to increase venous return to the heart and therefore increase cardiac output and organ blood flow during cardiopulmonary rescue (CPR). Basic CPR aims to maintain coronary and cerebral blood flow at the minimum level necessary for survival. The present study compared the effects of an ITD on cerebral blood flow assessed as blood flow in both carotid arteries to the blood flow of a control group during prolonged CPR.

METHODS

Fourteen anaesthetized pigs were monitored during 60 min of CPR after induced ventricular fibrillation. The primary outcome was blood flow in both carotid arteries, and the secondary outcomes were blood pressure, acid-base parameters, plasma potassium, and plasma lactate. The pigs were randomized to mechanical compressions and ventilation with an ITD added to the ventilation or to a control group treated only with mechanical compressions and ventilation. The time course for the parameters was tested using analysis of variance.

RESULTS

The cumulative carotid blood flow in the ITD group decreased from 64 to 42 ml/min, and it decreased from 69 to 51 ml/min in the control group during 60 min of CPR. The difference was not significant. The secondary outcome measures were also not significantly different.

CONCLUSIONS

This study did not show any beneficial effect of an ITD on carotid blood flow.

The Maximum Diameter of the Left Ventricle May Not Be the Optimum Target for Chest Compression During Cardiopulmonary Resuscitation: A Preliminary, Observational Study Challenging the Traditional Assumption

OBJECTIVE

Researchers have assumed that compressing the point beneath which the left ventricle (LV) diameter is maximum (P_max.LV) would improve cardiopulmonary resuscitation outcomes. Defining the midsternum, the currently recommended location for chest compression, as the reference (x = 0), the lateral deviation (x_max.LV) of personalized P_max.LV has become estimable using posteroanterior chest radiography. The authors investigated whether out-of-hospital cardiac arrest (OHCA) patients, whose x_max.LV was closer to the midsternum and thus had their P_max.LV compressed closer during cardiopulmonary resuscitation, showed better chances of return of spontaneous circulation (ROSC) and survival to discharge.

DESIGN

Retrospective, cross-sectional study.

SETTING

A university hospital.

PARTICIPANTS

Adult OHCA patients with available previous posteroanterior chest radiography.

INTERVENTION

None.

MEASUREMENTS AND MAIN RESULTS

For each clinical outcome, multivariable logistic regression was performed, grouping x_max.LV into tertiles and adjusting the variables selected among the core elements of the Utstein template showing possible differences (p > 0.10) in univariate analysis. Odds ratios were presented as OR (95% confidence interval). Among 268 cases (age 64.4 ± 15.8 y, female 89 [33.2%]), 123 (45.9%) achieved ROSC and 40 (14.9%) survival to discharge. Compared with the third tertile of x_max.LV (59 to ∼101 mm), the first (31 to ∼48 mm) and second (48 to ∼59 mm) tertiles, which had a P_max.LV closer to the midsternum, were negatively associated with ROSC (OR 0.502 [0.262-0.960]; p = 0.037 and OR 0.442 [0.233-0.837]; p = 0.012, respectively) and survival to discharge (OR 0.286 [0.080-1.03]; p = 0.055 and OR 0.046 [0.007-0.308]; p = 0.002, respectively).

CONCLUSIONS

OHCA patients with a P_max.LV located closer to the midsternum showed worse chances of ROSC and survival to discharge, which challenges the traditional assumption of identifying P_max.LV as the optimum compression point.

Bedside ultrasound in cardiac standstill: a clinical review

Patients with cardiac arrest present as a relatively frequent occurrence in the Emergency Department. Despite the advances in our understanding of the pathophysiology of cardiac arrest, managing the condition remains a stressful endeavor and currently implemented interventions, while beneficial, are still associated with a disappointingly low survivability. The majority of modern Advanced Life Support algorithms employ a standardized approach to best resuscitate the 'crashed' patient. However, management during resuscitation often encourages a 'one-size-fits-all' policy for most patients, with lesser attention drawn towards causality of the disease and factors that could alter resuscitative care. Life support providers are also often challenged by the limited bedside predictors of survival to guide the course and duration of resuscitation. Over the recent decades, point-of-care ultrasonography (PoCUS) has been gradually proving itself as a useful adjunct that could potentially bridge the gap in the recognition and evaluation of precipitants and end-points in resuscitation, thereby facilitating an improved approach to resuscitation of the arrested patient. Point-of-care ultrasound applications in the critical care field have tremendously evolved over the past four decades. Today, bedside ultrasound is a fundamental tool that is quick, safe, inexpensive and reproducible. Not only can it provide the physician with critical information on reversible causes of arrest, but it can also be used to predict survival. Of note is its utility in predicting worse survival outcomes in patients with cardiac standstill, i.e., no cardiac activity witnessed with ultrasound. Unfortunately, despite the increasing evidence surrounding ultrasound use in arrest, bedside ultrasound is still largely underutilized during the resuscitation process. This article reviews the current literature on cardiac standstill and the application of bedside ultrasound in cardiac arrests.

Impact of right ventricular dysfunction on mortality in adults with cardiac arrest undergoing coronary angiogram

OBJECTIVE

We sought to identify the impact of echocardiographic right ventricular (RV) systolic dysfunction on mortality in adults with cardiac arrest (CA).

METHODS

The study population included 147 adults hospitalized with CA who underwent both echocardiogram and coronary angiogram at an academic tertiary medical center. The primary outcome of interest was all-cause in-hospital mortality.

RESULTS

Of the 147 patients studied, 20 (13.6%) had evidence of RV systolic dysfunction while 127 (86.4%) did not. Patients with RV dysfunction had higher rates of prior surgical and percutaneous coronary revascularization. They also had higher rates of mechanical ventilation, therapeutic hypothermia, vasopressor and inotrope use, and a trend towards higher rates of mechanical support. Coronary angiogram revealed higher rates of multivessel disease, right coronary artery intervention, and glycoprotein IIb-IIIa inhibitor use in those with RV dysfunction, alongside with lower echocardiographic left ventricular ejection fraction. In-hospital mortality rates were higher in adults with RV dysfunction compared to those without (55% vs 11%, p < 0.001). In multivariate analysis, RV dysfunction was the strongest independent predictor of higher mortality [odds ratio 4.71, 95% confidence interval 1.27-17.50].

CONCLUSIONS

In this observational contemporary study, RV dysfunction was independently associated with higher mortality in adults with CA undergoing coronary angiogram. RV dysfunction may be useful for risk stratification and management in this high-mortality population.

Decision-making in cardiac arrest: physicians' and nurses' knowledge and views on terminating resuscitation

Introduction

Many cardiopulmonary resuscitation (CPR) attempts are unsuccessful and must be terminated. On the contrary, premature termination results in a self-fulfilling prophecy. This study aimed to investigate 1) physicians’ self-assessed competence in terminating CPR, 2) physicians’ and nurses’ knowledge of the European Resuscitation Council guidelines on termination, and 3) single factors leading to termination.

Methods

Questionnaires were distributed at advanced cardiac life support (ACLS) courses at a university hospital in Denmark. Participants included ACLS health care providers, ie, physicians and nurses from cardiac arrest teams, intensive care and anesthetic units or medical wards with a duty to provide ACLS. Physicians were divided into junior physicians (house officers) and experienced physicians (specialist registrars and consultants).

Results

Overall, 308 participants responded (104 physicians and 204 nurses, response rate: 98%). Among physicians, 37 (36%) did not feel competent to decide when to terminate CPR (junior physicians: n=16, 64%, compared with experienced physicians: n=21, 28%, P=0.002). Two (2%) physicians and one (0.5%) nurse were able to state the contents of termination guidelines. Several factors were reported to impact termination, including absence of a pupillary light reflex (physicians: 17%, nurses: 22%) and cardiac standstill on echocardiography (physicians: 18%, nurses: 20%). Moreover, nine (9%) physicians and 35 (17%) nurses would terminate prolonged CPR despite a shockable rhythm present.

Conclusion

One-third of all physicians did not feel competent to decide when to terminate CPR. Physicians’ and nurses’ knowledge of termination guidelines was poor, and both professions reported unvalidated or controversial factors as a single reason for terminating CPR.

A low end-tidal CO2/arterial CO2 ratio during cardiopulmonary resuscitation suggests pulmonary embolism

INTRODUCTION

Identifying reversible causes of cardiac arrest is challenging. The diagnosis of pulmonary embolism is often missed. Pulmonary embolism increases alveolar dead space resulting in low end-tidal CO2 (EtCO2) relative to arterial CO2 (PaCO2) tension. Thus, a low EtCO2/PaCO2 ratio during resuscitation may be a sign of pulmonary embolism.

METHODS

Post hoc analysis of data from two porcine studies comparing ultrasonographic measurements of right ventricular diameter during resuscitation from cardiac arrest of different causes. Pigs were grouped according to cause of arrest (pulmonary embolism, hypovolemia, primary arrhythmia, hypoxia, or hyperkalaemia) and EtCO2/PaCO2 ratios were compared.

RESULTS

Data from 54 pigs were analysed. EtCO2 levels at the third rhythm analysis were significantly lower when cardiac arrest was caused by pulmonary embolism than by primary arrhythmia, hypoxia and hyperkalaemia, but there was no significant difference between pulmonary embolism and hypovolemia. In contrast, PaCO2 levels were higher in cardiac arrest caused by pulmonary embolism than in the other causes of cardiac arrest. Consequently, the EtCO2/PaCO2 ratio was lower in pulmonary embolism 0.2 (95%CI 0.1-0.4), than in hypovolaemia 0.5 (95%CI 0.3-0.6), primary arrhythmia 0.7 (95%CI 0.7-0.8), hypoxia 0.5 (95%CI 0.4-0.6), and hyperkalaemia 0.6 (95%CI 0.6-0.7).

CONCLUSION

A low EtCO2/PaCO2 ratio during cardiopulmonary resuscitation suggests pulmonary embolism.

Point-of-Care Ultrasound in the Periarrest Setting-Lessons Learned: A Case Report

Point-of-care ultrasound may elucidate reversible causes of cardiac arrest, and its use is supported by international guidelines in the periarrest setting. We present a case in which the treatment of cardiac arrest caused tension pneumothoraces and cardiac tamponade by pneumopericardium. Both pneumothorax and tamponade were expected to be identified with ultrasound, but were not. Subcutaneous emphysema precluded the diagnosis of pneumothorax. Cardiac imaging was false negative for tamponade, because the latter was caused by air and not fluid. Diagnoses are not to be excluded with inconclusive point-of-care ultrasound examinations, which should prompt further clinical evaluation and imaging.

Échographie et prise en charge de l’arrêt cardiaque

L’arrêt cardiorespiratoire (ACR) est une situation fréquente pour les structures d’urgences et de réanimation, et l’utilisation de l’échographie y est recommandée par les sociétés savantes. Elle doit impérativement se faire sans augmentation des temps d’interruption du massage cardiaque externe. Après formation, elle permet de détecter rapidement et facilement la présence d’une contractilité myocardique qui est un élément pronostique important pouvant aider dans la décision d’arrêter la RCP. Le recours à des protocoles bien établis avec des équipes entraînées permet d’éviter une interruption prolongée de la RCP. Cependant, aucune étude humaine de grande ampleur n’a permis de décrire de manière fiable pendant l’ACR la sémiologie échographique des causes curables que constituent l’hypovolémie, l’embolie pulmonaire, la tamponnade et le pneumothorax compressif.

Standardized model of porcine resuscitation using a custom-made resuscitation board results in optimal hemodynamic management

AIM

Standardized modeling of cardiac arrest and cardiopulmonary resuscitation (CPR) is crucial to evaluate new treatment options. Experimental porcine models are ideal, closely mimicking human-like physiology. However, anteroposterior chest diameter differs significantly, being larger in pigs and thus poses a challenge to achieve adequate perfusion pressures and consequently hemodynamics during CPR, which are commonly achieved during human resuscitation. The aim was to prove that standardized resuscitation is feasible and renders adequate hemodynamics and perfusion in pigs, using a specifically designed resuscitation board for a pneumatic chest compression device.

METHODS AND RESULTS

A "porcine-fit" resuscitation board was designed for our experiments to optimally use a pneumatic compression device (LUCAS® II, Physio-Control Inc.), which is widely employed in emergency medicine and ideal in an experimental setting due to its high standardization. Asphyxial cardiac arrest was induced in 10 German hybrid landrace pigs and cardiopulmonary resuscitation was performed according to ERC/AHA 2015 guidelines with mechanical chest compressions. Hemodynamics were measured in the carotid and pulmonary artery. Furthermore, arterial blood gas was drawn to assess oxygenation and tissue perfusion. The custom-designed resuscitation board in combination with the LUCAS® device demonstrated highly sufficient performance regarding hemodynamics during CPR (mean arterial blood pressure, MAP 46 ± 1 mmHg and mean pulmonary artery pressure, mPAP of 36 ± 1 mmHg over the course of CPR). MAP returned to baseline values at 2 h after ROSC (80 ± 4 mmHg), requiring moderate doses of vasopressors. Furthermore, stroke volume and contractility were analyzed using pulse contour analysis (106 ± 3 ml and 1097 ± 22 mmHg/s during CPR). Blood gas analysis revealed CPR-typical changes, normalizing in the due course. Thermodilution parameters did not show persistent intravascular volume shift.

CONCLUSION

Standardized cardiopulmonary resuscitation is feasible in a porcine model, achieving adequate hemodynamics and consecutive tissue perfusion of consistent quality.

Reduced right ventricular diameter during cardiac arrest caused by tension pneumothorax - a porcine ultrasound study

INTRODUCTION

Advanced life support (ALS) guidelines recommend ultrasound to identify reversible causes of cardiac arrest. Right ventricular (RV) dilatation during cardiac arrest is commonly interpreted as a sign of pulmonary embolism. The RV is thus a focus of clinical ultrasound examination. Importantly, in animal studies ventricular fibrillation and hypoxia results in RV dilatation. Tension pneumothorax (tPTX) is another reversible cause of cardiac arrest, however, the impact on RV diameter remains unknown.

AIM

To investigate RV diameter evaluated by ultrasound in cardiac arrest caused by tPTX or hypoxia.

METHODS

Pigs were randomized to cardiac arrest by either tPTX (n = 9) or hypoxia (n = 9) and subsequently resuscitated. Tension pneumothorax was induced by injection of air into the pleural cavity. Hypoxia was induced by reducing tidal volume. Ultrasound images of the RV were obtained throughout the study. Tension pneumothorax was decompressed after the seventh rhythm analysis. The primary endpoint was RV diameter after the third rhythm analysis.

RESULTS

At cardiac arrest the RV diameter was 17 mm (95% CI: 13; 21) in the tPTX group and 36 mm (95% CI: 33; 40) in the hypoxia group (P < 0.01, n = 9 for both). At third rhythm analysis RV diameter was smaller in the tPTX group: 12 mm (95% CI: 7; 16) vs. hypoxia group: 28 mm (25; 32) (P < 0.01). After decompression no difference existed between groups: tPTX 29 mm (95% CI: 23; 34) vs. hypoxia 29 mm (95% CI: 20; 38).

CONCLUSION

The RV diameter is smaller during cardiopulmonary resuscitation in cardiac arrest caused by tPTX when compared with hypoxia. The difference disappears after tPTX decompression.