Compression of the left ventricular outflow tract during cardiopulmonary resuscitation

Development and Implementation of a Multicenter Registry for Resuscitation-Focused Transesophageal Echocardiography

STUDY OBJECTIVE

To evaluate the clinical effect, safety, and clinical outcomes of focused transesophageal echocardiography (TEE) in the evaluation of critically ill patients in the emergency department (ED) and ICUs.

METHODS

We established a prospective, multicenter, observational registry involving adult critically ill patients in whom focused TEE was performed for evaluation of out-of-hospital cardiac arrest (OHCA), inhospital cardiac arrest, evaluation of undifferentiated shock, hemodynamic monitoring, and/or procedural guidance in the ED, ICU, or operating room setting. The primary objective of the current investigation was to evaluate the clinical influence and safety of focused, point-of-care TEE in critically ill patients. Data elements included patient and procedure characteristics, laboratory values, timing of interventions, clinical outcomes, and TEE video images.

RESULTS

A total of 1,045 focused TEE studies were collected among 916 patients from 28 hospitals, including 585 (64%) intraarrest and postarrest OHCA and inhospital cardiac arrest, 267 (29%) initial evaluation of undifferentiated shock, 101 (11%) procedural guidance, and 92 (10%) hemodynamic monitoring. TEE changed management in 85% of patients with undifferentiated shock, 71% of patients with inhospital cardiac arrest, and 62% of patients with OHCA. There were no reported esophageal perforations or oropharyngeal injuries, and other procedural complications were rare.

CONCLUSIONS

A prospective, multicenter, and multidisciplinary TEE registry was successfully implemented, and demonstrated that focused TEE is safe and clinically impactful across multiple critical care applications. Further studies from this research network will accelerate the development of outcome-oriented research and knowledge translation on the use of TEE in emergency and critical care settings.

Left of sternum compressions are associated with higher systolic blood pressure than lower half of sternum compressions in cardiac arrest

INTRODUCTION

Limited evidence supports guidelines to perform chest compressions at the lower half of the sternum. Imaging studies suggest this location may obstruct blood flow. Our primary aim was to compare the highest arterial line systolic blood pressure (SBP) during lower-half-of-sternum chest compressions (CC) versus those left-of-sternum, where the left ventricle is more likely located. Secondarily, we compared the highest end-tidal CO2 (ETCO2).

METHODS

We conducted a retrospective cohort study of video-recorded, adult Emergency Department (ED) cardiac arrest resuscitations where changes in CC location were attempted to improve physiologic parameters (SBP, ETCO2). We excluded epigastric and right-of-sternum compressions. Four CC zones were analyzed: recommended lower-half-of-sternum; left of lower-half-of-sternum; high left lateral; low left lateral. We combined all left-of-sternum compressions for analysis using linear mixed-effects models and multivariable mixed-effects controlling for manual vs. mechanical CCs.

RESULTS

Among 24 patients analyzed, 20 (83.3 %) had initial compressions at the lower-half-of-sternum. 11 patients had 28 lower-half-of-sternum and 32 left-of-sternum CC intervals with available SBPs. In the mixed-effects model, least squares mean (LSMean) SBP was higher with left-of-sternum CCs (108.5 mmHg [95 % CI 88.3-128.8 mmHg]) versus lower-half-of-sternum CCs (66.7 mmHg [95 % CI 46.5-86.9 mmHg], p < 0.001). 18 patients had 44 lower-half-of-sternum and 32 left-of-sternum CC intervals with available ETCO2. In the mixed-effects model, LSMean ETCO2 was similar at the lower-half-of-sternum (20.4 mmHg [95 % CI 16.0-24.9 mmHg]) and left-of-sternum (22.6 mmHg [95 % CI 17.6-27.6 mmHg], p = 0.300). Results were similar when controlling for manual vs. mechanical CCs.

CONCLUSIONS

In our pilot, retrospective, observational study of select ED cardiac arrest patients, left-of-sternum chest compressions are associated with higher SBP than lower-half-of-sternum compressions, while ETCO2 was similar.

Comparing sternal versus left-sided chest compressions for thoracoabdonimal injuries and compression biomechanics: A clinical-grade cadaver study

Background

The lower half of the sternum is currently recommended as the area of compression (AOC) in CPR. Compressions over this area often result in outflow obstruction and inadequate compression of the left ventricle. Alternative left-sided chest compressions that target the left ventricle may improve cardiac arrest outcomes. However, little is known about the risks of thoracoabdominal injuries or the biomechanics of left-sided compressions.

Methods

The objective of this study was to examine the thoracoabdominal injury patterns and compression biomechanics during standard (control) and left-sided (experimental; off sternum, patient left, 6th rib) chest compressions. N = 6 clinical-grade cadavers (control n = 2; experimental n = 4) underwent six 2-minute rounds of chest compressions with intermittent fluoroscopy. Chest compression depth, recoil, and rate were standardized using compression feedback devices. Post-CPR dissection was used to examine for thoracoabdominal injuries.

Results

Standard compressions resulted in rib fractures (n = 1 [50%]). Left-sided compressions resulted in rib fractures (n = 4 [100%]), flail chest segments (n = 3 [75%]), and internal thoracic artery injury (n = 1 [25%]). No abdominal organ injuries were identified in either group (N = 6 [0%]). During compression, each condition yielded a different pattern of chest wall deformity (standard - regular trapezoid [midline, comparable left-right sides, flat top, and bottom]; left-sided - irregular trapezium [left-sided, unequal sides, leftward sloped top]).

Conclusion

Experimental left-sided compressions consistently produced rib fractures and flail chest segments. Findings should be interpreted with caution due to the limited sample size. Further studies investigating the biomechanics and outcomes of left sided chest compressions are warranted.

Retrospective Review of the Image Quality of Monoplane Transesophageal Echocardiography in Prehospital Out-of-Hospital Cardiac Arrest: A Single Center Pilot Study

OBJECTIVES

Out of Hospital Cardiac Arrest (OHCA) is a frequently encountered pathology with resultant poor outcomes in the majority of patients. Echocardiography has been utilized to help guide clinical decision making and monitor effectiveness of resuscitative efforts. Transthoracic echocardiography (TTE) the mainstay of point-of-care ultrasound (POCUS) real time resuscitative imaging has limitations, most notably is the disruption of closed chest compressions. Trans-esophageal echocardiography (TEE) is an emerging technology in emergency care and can potentially overcome these limitations but image quality and accuracy of use in the prehospital environment remains unknown. Our primary objective is to identify the accuracy of Emergency Medical Services (EMS) fellow physicians in performing TEE via the identification of key cardiac structures. Secondarily we assess image quality as well as accuracy on cardiac activity interpretation as compared to TEE-experienced cardiologists.

METHODS

A pilot study using descriptive analysis of a retrospective case-series with specific focus on inter-rater reliability as well as pragmatic management alterations based on real-time image interpretation by EMS physicians. After focused education, 13 patients were eligible for prehospital TEE who suffering OHCA from July 2022 to June 2023. Ultrasound (US) images were interpreted by EMS fellow physicians and over-read by cardiologists with specific focus on inter-rater reliability. After collection of patients presenting data and US images, analysis was performed.

RESULTS

Of 13 patients initially screened, 10 patients were included in a study with a median age of 50 years old (41-70). Three patients were excluded due to equipment malfunction or insufficient image capture. An interrater reliability identified a kappa of 0.96 with respect to identification of cardiac structures and a kappa of 0.65 for identification of cardiac activity.

CONCLUSIONS

In this small study of prehospital TEE, EMS fellow physicians had high inter-rater reliability in image interpretation pertaining to anatomy and cardiac activity when compared with cardiologists. Further research is needed to determine its efficacy, safety, and widespread application in the prehospital setting.

Transoesophageal echocardiography in cardiac arrest: From the emergency department to the intensive care unit

Cardiac arrest is a hyper-acute condition with a high mortality that requires rapid diagnostics and treatment. As such, point-of-care ultrasound (POCUS) has become a valuable tool in the assessment of these patients. While transthoracic echocardiography (TTE) is the more conventional modality used to find reversible causes of cardiac arrest, transoesophageal echocardiography (TOE) has been increasingly utilised due to its superior image quality, continuous imaging, and ability to be operated away from the patient's chest. TOE also has a number of applications in the aftermath of cardiac arrest, such as during the initiation of extracorporeal cardiopulmonary resuscitation (ECPR) and the subsequent monitoring of extracorporeal membranous oxygenation (ECMO). As TOE has evolved, multiple variations have been developed with different utilities. In this article, we will review the evidence supporting the use of TOE in cardiac arrest and where the different forms of TOE can be applied to evaluate the cardiac arrest patient in a timely and accurate manner.

Optimal Chest Compression Point During Pediatric Resuscitation: Implications for Pediatric Resuscitation Practice by CT Scans

OBJECTIVES

Current European guidelines for pediatric cardiopulmonary resuscitation (CPR) recommend the lower half of the sternum as the chest compression point (CP). In this study, we have used thoracic CT scans to evaluate recommended and optimal CP in relation to cardiac anatomy and structure.

DESIGN

Analysis of routinely acquired thoracic CT scans acquired from 2000 to 2020.

SETTING

Single-center pediatric department in a German University Hospital.

PATIENTS

Imaging data were obtained from 290 patients of 3-16 years old.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

We measured and analyzed 14 thoracic metrics in each thoracic CT scan. In 44 of 290 (15.2%) scans, the recommended CP did not match the level of the cardiac ventricles. Anatomically, the optimal CP was one rib or one vertebral body lower than the recommended CP, that is, the optimal CP was more caudal to the level of the body of the sternum in 67 of 290 (23.1%) scans. The recommended compression depth appeared reasonable in children younger than 12 years old. At 12 years old or older, the maximum compression depth of 6 cm is less than or equal to one-third of the thoracic depth.

CONCLUSIONS

In this study of thoracic CT scans in children 3-16 years old, we have found that optimal CP for CPR appears to be more caudal than the recommended CP. Therefore, it seems reasonable to prefer to use the lower part of the sternum for CPR chest compressions. At 12 years old or older, a compression depth similar to that used in adults-6 cm limit-may be chosen.

Echocardiographic clues of the "atrial pump mechanism" during cardiopulmonary resuscitation

Instead of the ventricles, atria may be the cardiac structures mainly compressed during cardiopulmonary resuscitation (CPR). This study aimed to assess the prevalence and the mechanical characteristics of atrial compression, named the "atrial pump mechanism", in patients undergoing CPR. A retrospective cohort study was conducted on patients with witnessed refractory out-of-hospital cardiac arrest who were admitted to a tertiary referral center for extracorporeal CPR. The area of maximal compression (AMC) by chest compressions was assessed by transesophageal echocardiography. Right atrial wall excursion (RAWE), left atrial fractional shortening (LAFS), right ventricular fractional area change (RVFAC), and left ventricular fractional shortening (LVFS) were measured. Common carotid and middle cerebral artery peak velocities were assessed using color-Doppler imaging as markers of cardiac outflow and cerebral perfusion. Forty patients were included in the study. Five (12.5%) had AMC over the atria. The atrial pump pattern was characterized by marked atrial compression with higher RAWE and LAFS values compared to the other patients (p < 0.001). Common carotid Doppler and transcranial Doppler-velocity patterns were detectable in all patients with open left ventricular outflow tract, without differences between patients. CPR was successful in four patients (80%) with atrial pump compared to 14 (40%) with no atrial pump mechanism (p = 0.155). In this series of selected patients with witnessed cardiac arrest, the prevalence of the atrial pump mechanism was not negligible. It may contribute to forward blood flow and the maintenance of cerebral perfusion during prolonged cardiopulmonary resuscitation.

Development of artificial intelligence-driven biosignal-sensitive cardiopulmonary resuscitation robot

AIM OF THE STUDY

We evaluated whether an artificial intelligence (AI)-driven robot cardiopulmonary resuscitation (CPR) could improve hemodynamic parameters and clinical outcomes.

METHODS

We developed an AI-driven CPR robot which utilizes an integrated feedback system with an AI model predicting carotid blood flow (CBF). Twelve pigs were assigned to the AI robot group (n = 6) and the LUCAS 3 group (n = 6). They underwent 6 min of CPR after 7 min of ventricular fibrillation. In the AI robot group, the robot explored for the optimal compression position, depth and rate during the first 270-second period, and continued CPR with the optimal setup during the next 90-second period and beyond. The primary outcome was CBF during the last 90-second period. The secondary outcomes were coronary perfusion pressure (CPP), end-tidal carbon dioxide level (ETCO2) and return of spontaneous circulation (ROSC).

RESULTS

The AI model's prediction performance was excellent (Pearson correlation coefficient = 0.98). CBF did not differ between the two groups [estimate and standard error (SE), -23.210 ± 20.193, P = 0.250]. CPP, ETCO2 level and rate of ROSC also did not show difference [estimate and SE, -0.214 ± 7.245, P = 0.976 for CPP; estimate and SE, 1.745 ± 3.199, P = 0.585 for ETCO2; 5/6 (83.3%) vs. 4/6 (66.7%), P = 1.000 for ROSC).

CONCLUSION

This study provides proof of concept that an AI-driven CPR robot in porcine cardiac arrest is feasible. Compared to a LUCAS 3, an AI-driven CPR robot produced comparable hemodynamic and clinical outcomes.

Cardiopulmonary Resuscitation Without Aortic Valve Compression Increases the Chances of Return of Spontaneous Circulation in Out-of-Hospital Cardiac Arrest: A Prospective Observational Cohort Study

OBJECTIVES

Following current cardiopulmonary resuscitation (CPR) guidelines, which recommend chest compressions at "the center of the chest," ~50% of patients experiencing out-of-hospital cardiac arrest (OHCA) undergo aortic valve (AV) compression, obstructing blood flow. We used resuscitative transesophageal echocardiography (TEE) to elucidate the impact of uncompressed vs. compressed AV on outcomes of adult patients experiencing OHCA.

DESIGN

Prospective observational cohort study.

SETTING

Single center.

PATIENTS

This study included adult OHCA patients undergoing resuscitative TEE in the emergency department. Patients were categorized into AV uncompressed or AV compressed groups based on TEE findings.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

The primary outcome was sustained return of spontaneous circulation (ROSC). The secondary outcomes included end-tidal co2 (Et co2 ) during CPR, any ROSC, survival to ICU and hospital discharge, post-resuscitation withdrawal, and favorable neurologic outcomes at discharge. Additional analyses on intra-arrest arterial blood pressure (ABP) were also conducted. The sample size was pre-estimated at 37 patients/group. From October 2020 to January 2023, 76 patients were enrolled, 39 and 37 in the AV uncompressed and AV compressed groups, respectively. Intergroup baseline characteristics were similar. Compared with the AV compressed group, the AV uncompressed group had a higher probability of sustained ROSC (53.8% vs. 24.3%; adjusted odds ratio [aOR], 4.72; p = 0.010), any ROSC (56.4% vs. 32.4%; aOR, 3.30; p = 0.033), and survival to ICU (33.3% vs. 8.1%; aOR, 6.74; p = 0.010), and recorded higher initial diastolic ABP (33.4 vs. 11.5 mm Hg; p = 0.002) and a larger proportion achieving diastolic ABP greater than 20 mm Hg during CPR (93.8% vs. 33.3%; p < 0.001). The Et co2 , post-resuscitation withdrawal, and survival to discharge revealed no significant intergroup differences. No patients were discharged with favorable neurologic outcomes. Uncompressed AV seemed critical for sustained ROSC across all subgroups.

CONCLUSIONS

Absence of AV compression during OHCA resuscitation is associated with an increased chance of ROSC and survival to ICU. However, its effect on long-term outcomes remains unclear.

Physiology-Guided Resuscitation: Monitoring and Augmenting Perfusion during Cardiopulmonary Arrest

Given the high morbidity and mortality associated with cardiopulmonary arrest, there have been multiple trials aimed at better monitoring and augmenting coronary, cerebral, and systemic perfusion. This article aims to elucidate these interventions, first by detailing the physiology of cardiopulmonary resuscitation and the available tools for managing cardiopulmonary arrest, followed by an in-depth examination of the newest advances in the monitoring and delivery of advanced cardiac life support.

Wolf Creek XVII Part 6: Physiology-Guided CPR

Introduction

Physiology-guided cardiopulmonary resuscitation (CPR) offers the potential to optimize resuscitation and enable early prognosis.

Methods

Physiology-Guided CPR was one of six focus topic for the Wolf Creek XVII Conference held on June 14-17, 2023 in Ann Arbor, Michigan, USA. International thought leaders and scientists in the field of cardiac arrest resuscitation from academia and industry were invited. Participants submitted via online survey knowledge gaps, barriers to translation and research priorities for each focus topic. Expert panels used the survey results and their own perspectives and insights to create and present a preliminary unranked list for each category, which was then debated, revised and ranked by all attendees to identify the top 5 for each category.

Results

Top knowledge gaps include identifying optimal strategies for the evaluation of physiology-guided CPR and the optimal values for existing patients using patient outcomes. The main barriers to translation are the limited usability outside of critical care environments and the training and equipment required for monitoring. The top research priorities are the development of clinically feasible and reliable methods to continuously and non-invasively monitor physiology during CPR and prospective human studies proving targeting parameters during CPR improves outcomes.

Conclusion

Physiology-guided CPR has the potential to provide individualized resuscitation and move away from a one-size-fits-all approach. Current understanding is limited, and clinical trials are lacking. Future developments need to consider the clinical application and applicability of measurement to all healthcare settings. Therefore, clinical trials using physiology-guided CPR for individualisation of resuscitation efforts are needed.

Real-time feedback on chest compression efficacy by hands-free carotid Doppler in a porcine model

Aim

Current guidelines for cardiopulmonary resuscitation (CPR) recommend a one-size-fits-all approach in relation to the positioning of chest compressions. We recently developed RescueDoppler, a hands-free Doppler ultrasound device for continuous monitoring of carotid blood flow velocity during CPR. The aim of the present study is to investigate whether RescueDoppler via real-time hemodynamic feedback, could identify both optimal and suboptimal compression positions.

Methods

In this model of animal cardiac arrest, we induced ventricular fibrillation in five domestic pigs. Manual chest compressions were performed for ten seconds at three different positions on the sternum in random order and repeated six times. We analysed Time Average Velocity (TAV) with chest compression position as a fixed effect and animal, position, and sequential time within animals as random effects. Furthermore, we compared TAV to invasive blood pressure from the contralateral carotid artery.

Results

We were able to detect changes in TAV when altering positions. The positions with the highest (range 19 to 48 cm/s) and lowest (6-25 cm/s) TAV were identified in all animals, with corresponding peak pressure 50-81 mmHg, and 46-64 mmHg, respectively. Blood flow velocity was, on average, highest at the middle position (TAV 33 cm/s), but with significant variability between animals (SD 2.8) and positions within the same animal (SD 9.3).

Conclusion

RescueDoppler detected TAV changes during CPR with alternating chest compression positions, identifying the position yielding maximal TAV. Future clinical studies should investigate if RescueDoppler can be used as a real-time hemodynamical feedback device to guide compression position.

Study of risk factors for injuries due to cardiopulmonary resuscitation with special focus on the role of the heart: A machine learning analysis of a prospective registry with multiple sources of information (ReCaPTa Study)

Background

The study of thoracic injuries and biomechanics during CPR requires detailed studies that are very scarce. The role of the heart in CPR biomechanics has not been determined. This study aimed to determine the risk factors importance for serious ribcage damage due to CPR.

Methods

Data were collected from a prospective registry of out-of-hospital cardiac arrest between April 2014 and April 2017. This study included consecutive out-of-hospital CPR attempts undergoing an autopsy study focused on CPR injuries. Cardiac mass ratio was defined as the ratio of real to expected heart mass. Pearson's correlation coefficient was used to select clinically relevant variables and subsequently classification tree models were built. The Gini index was used to determine the importance of the associated serious ribcage damage factors. The LUCAS® chest compressions device forces and the cardiac mass were analyzed by linear regression.

Results

Two hundred CPR attempts were included (133 manual CPR and 67 mechanical CPR). The mean age of the sample was 60.4 ± 13.5, and 56 (28%) were women. In all, 65.0% of the patients presented serious ribcage damage. From the classification tree build with the clinically relevant variables, age (0.44), cardiac mass ratio (0.26), CPR time (0.22), and mechanical CPR (0.07), in that order, were the most influential factors on serious ribcage damage. The chest compression forces were greater in subjects with higher cardiac mass.

Conclusions

The heart plays a key role in CPR biomechanics being cardiac mass ratio the second most important risk factor for CPR injuries.

Point-of-Care Ultrasound (POCUS) in Adult Cardiac Arrest: Clinical Review

Point-of-Care Ultrasound (POCUS) is a rapid and valuable diagnostic tool available in emergency and intensive care units. In the context of cardiac arrest, POCUS application can help assess cardiac activity, identify causes of arrest that could be reversible (such as pericardial effusion or pneumothorax), guide interventions like central line placement or pericardiocentesis, and provide real-time feedback on the effectiveness of resuscitation efforts, among other critical applications. Its use, in addition to cardiovascular life support maneuvers, is advocated by all resuscitation guidelines. The purpose of this narrative review is to summarize the key applications of POCUS in cardiac arrest, highlighting, among others, its prognostic, diagnostic, and forensic potential. We conducted an extensive literature review utilizing PubMed by employing key search terms regarding ultrasound and its use in cardiac arrest. Apart from its numerous advantages, its limitations and challenges such as the potential for interruption of chest compressions during image acquisition and operator proficiency should be considered as well and are discussed herein.

Optimal chest compression position for cardiopulmonary resuscitation determined by computed tomography image: retrospective cross-sectional analysis

The objective of this study was to determine the height of optimal hand position for chest compression during adult cardiopulmonary resuscitation (CPR) from the tip of the sternal xiphoid process (TOX) along with the relative heights of the left ventricular outflow tract (LVOT) and abdominal organs among the Thai population. The retrospective cross-sectional study was conducted through a review of medical records and contrast-enhanced chest computed tomography. The total of 204 Thai patients without obvious chest deformity at Ramathibodi Hospital from January to June 2018 was included as part of a multi-regional study. The heights of the level of maximal LV width (LVmax), LOVT, top of liver and stomach with respect to TOX were measured on midline sagittal image. Mean age and body mass index (BMI) were 59.5 years and 23.9 kg/m2, respectively. One hundred and one subjects (49.5%) had pulmonary diseases. Mean height of the LVmax from TOX was 37.7 mm, corresponding to 20% of the sternal length (SL) in the inspiration arm raised position (IAR). The adjusted height of LVmax from TOX in the expiration arm-down position (EAD) was 89.7 mm (48% of SL). The inter-nipple line was at 84.5 mm (45.1% of SL) from TOX on IAR. Among 178 and 109 subjects whose uppermost part of the liver and stomach were above TOX, 80.4% and 94.5% were located within the lower half of the sternum, respectively. The adjusted optimal hand position for chest compression during CPR was at approximately 89.7 mm from TOX in EAD (48% of SL). The hand position at the upper part of the lower half of the sternum is closest to the adjusted LVmax and has a better chance to avoid compression of intraabdominal organs.Trial registration This trial was retrospectively registered on 2 February 2023 in the Thai Clinical Trial Registry, identification number TCTR 20230202006.

Role of point-of-care ultrasound in critical care and emergency medicine: update and future perspective

Point-of-care ultrasound (POCUS) is a rapidly developing technology that has the potential to revolutionize emergency and critical care medicine. The use of POCUS can improve patient care by providing real-time clinical information. However, appropriate usage and proper training are crucial to ensure patient safety and reliability. This article discusses the various applications of POCUS in emergency and critical care medicine, the importance of training and education, and the future of POCUS in medicine.

Feasibility of resuscitative transesophageal echocardiography at out-of-hospital emergency scenes of cardiac arrest

Guidelines recommend the use of ultrasound in cardiac arrest. Transthoracic echocardiography, has issues with image quality and by increasing hands-off times during resuscitation. We assessed the feasibility of transesophageal echocardiography (TEE), which does not have both problems, at out-of-hospital cardiac arrest (OHCA) emergency scenes. Included were 10 adults with non-traumatic OHCA in Vienna, Austria. An expert in emergency ultrasound was dispatched to the scenes in addition to the resuscitation team. Feasibility was defined as the ability to collect specific items of information by TEE within 10 min. Descriptive statistics were compiled and hands-off times were compared to a historical control group. TEE examinations were feasible in 9 of 10 cases and prompted changes in clinical management in 2 cases (cardiac tamponade: n = 1; right ventricular dilatation: n = 1). Their mean time requirement was 5.1 ± 1.7 (2.8-8.0) min, and image quality was invariably rated as excellent or good during both compressions and pauses. No TEE-related complications, or interferences with activities of advanced life support were observed. The hands-off times during resuscitation were comparable to a historical control group not involving ultrasound (P = 0.24). Given these feasibility results, we expect that TEE can be used routinely at OHCA emergency scenes.

Prone restraint death: Possible role of the Valsalva maneuver

There is an on-going debate about the safety of prone restraint and the exact role of the prone position in physical restraint death. Cardiac arrest in prone restraint death is essentially the end-result of a violent physical altercation wherein a combative individual suddenly loses consciousness while trying to counteract an opposing force. The direct correlations of increased static weight force with decreased inferior vena cava diameter, decreased cardiac output, and decreased stroke volume in prone restraint studies suggest that decreased venous return and decreased cardiac output could have a significant role to play in prone restraint death. Although the degree of changes observed in those studies might not be sufficient to cause cardiac arrest, they could predispose people who instinctively try to free themselves of the restraints to severe complications. The Valsalva maneuver, or forceful expiration against a closed airway, is frequently performed spontaneously in daily activities involving straining and resistance exercise, but has never been considered in restraint death. Pre-existing diminished venous return could increase the risk of major complications in individuals performing the Valsalva maneuver. A substantial decrease in venous return and cardiac output could increase the risk of cerebral hypoperfusion, loss of consciousness, hypoventilation, and sudden death. By increasing the risk of increased intra-abdominal pressure and its negative effect on venous return, high body mass index may be a significant risk factor in prone restraint death. The Valsalva maneuver may have different roles in prone restraint cardiac arrest and might be overlooked in prone restraint death.

The Lancet Commission to reduce the global burden of sudden cardiac death: a call for multidisciplinary action

Despite major advancements in cardiovascular medicine, sudden cardiac death (SCD) continues to be an enormous medical and societal challenge, claiming millions of lives every year. Efforts to prevent SCD are hampered by imperfect risk prediction and inadequate solutions to specifically address arrhythmogenesis. Although resuscitation strategies have witnessed substantial evolution, there is a need to strengthen the organisation of community interventions and emergency medical systems across varied locations and health-care structures. With all the technological and medical advances of the 21st century, the fact that survival from sudden cardiac arrest (SCA) remains lower than 10% in most parts of the world is unacceptable. Recognising this urgent need, the Lancet Commission on SCD was constituted, bringing together 30 international experts in varied disciplines. Consistent progress in tackling SCD will require a completely revamped approach to SCD prevention, with wide-sweeping policy changes that will empower the development of both governmental and community-based programmes to maximise survival from SCA, and to comprehensively attend to survivors and decedents' families after the event. International collaborative efforts that maximally leverage and connect the expertise of various research organisations will need to be prioritised to properly address identified gaps. The Commission places substantial emphasis on the need to develop a multidisciplinary strategy that encompasses all aspects of SCD prevention and treatment. The Commission provides a critical assessment of the current scientific efforts in the field, and puts forth key recommendations to challenge, activate, and intensify efforts by both the scientific and global community with new directions, research, and innovation to reduce the burden of SCD worldwide.

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.

Rescue Transesophageal Echocardiography: A Narrative Review of Current Knowledge and Practice

Perioperative transesophageal echocardiography (TEE) has been part of clinical activity for more than 40 years. During this period, TEE has evolved in terms of technology and clinical applications beyond the initial fields of cardiology and cardiac surgery. The benefits of TEE in the diagnosis and management of acute hemodynamic and respiratory collapse have been recognized in noncardiac surgery and by other specialties too. This natural progress led to the development of rescue TEE, a relatively recent clinical application that extends the use of TEE and makes it accessible to a large group of clinicians and patients requiring acute care. In this review, the authors appraise the current clinical applications and evidence base around this topic. The authors provide a thorough review of the various image acquisition protocols, clinical benefits, and compare it with the more frequently used transthoracic echocardiography. Furthermore, the authors have reviewed the current training and credentialing pathways. Overall, rescue TEE is a highly attractive and useful point-of-care examination, but the current evidence base is limited and the technical protocols, training, and credentialing processes are not standardized. There is a need for adequate guidelines and high-quality research to support its application as a bedside rescue tool.

Indications, Clinical Impact, and Complications of Critical Care Transesophageal Echocardiography: A Scoping Review

BACKGROUND

Critical care transesophageal echocardiography (ccTEE) is an increasingly popular tool used by intensivists to characterize and manage hemodynamics at the bedside. Its usage appears to be driven by expanded diagnostic scope as well as the limitations of transthoracic echocardiography (TTE) - lack of acoustic windows, patient positioning, and competing clinical interests (eg, the need to perform chest compressions). The objectives of this scoping review were to determine the indications, clinical impact, and complications of ccTEE.

METHODS

MEDLINE, EMBASE, Cochrane, and six major conferences were searched without a time or language restriction on March 31st, 2021. Studies were included if they assessed TEE performed for adult critically ill patients by intensivists, emergency physicians, or anesthesiologists. Intraoperative or post-cardiac surgical TEE studies were excluded. Study demographics, indication for TEE, main results, and complications were extracted in duplicate.

RESULTS

Of the 4403 abstracts screened, 289 studies underwent full-text review, with 108 studies (6739 patients) included. Most studies were retrospective (66%), performed in academic centers (84%), in the intensive care unit (73%), and were observational (55%). The most common indications for ccTEE were hemodynamic instability, trauma, cardiac arrest, respiratory failure, and procedural guidance. Across multiple indications, ccTEE was reported to change the diagnosis in 52% to 78% of patients and change management in 32% to79% patients. During cardiac arrest, ccTEE identified the cause of arrest in 25% to 35% of cases. Complications of ccTEE included two cases of significant gastrointestinal bleeding requiring intervention, but no other major complications (death or esophageal perforation) reported.

CONCLUSIONS

The use of ccTEE has been described for the diagnosis and management of a broad range of clinical problems. Overall, ccTEE was commonly reported to offer additional diagnostic yield beyond TTE with a low observed complication rate. Additional high quality ccTEE studies will permit stronger conclusions and a more precise understanding of the trends observed in this scoping review.

Left ventricle segmentation in transesophageal echocardiography images using a deep neural network

PURPOSE

There has been little progress in research on the best anatomical position for effective chest compressions and cardiac function during cardiopulmonary resuscitation (CPR). This study aimed to divide the left ventricle (LV) into segments to determine the best position for effective chest compressions using the LV systolic function seen during CPR.

METHODS

We used transesophageal echocardiography images acquired during CPR. A deep neural network with an attention mechanism and a residual feature aggregation module were applied to the images to segment the LV. The results were compared between the proposed model and U-Net.

RESULTS

The results of the proposed model showed higher performance in most metrics when compared to U-Net: dice coefficient (0.899±0.017 vs. 0.792±0.027, p<0.05); intersection of union (0.822±0.026 vs. 0.668±0.034, p<0.05); recall (0.904±0.023 vs. 0.757±0.037, p<0.05); precision (0.901±0.021 vs. 0.859±0.034, p>0.05). There was a significant difference between the proposed model and U-Net.

CONCLUSION

Compared to U-Net, the proposed model showed better performance for all metrics. This model would allow us to evaluate the systolic function of the heart during CPR in greater detail by segmenting the LV more accurately.

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-to-Left Shunts Occur During Cardiopulmonary Resuscitation: Echocardiographic Observations

OBJECTIVES

A significant proportion of the population has a patent foramen ovale (PFO). The intracardiac pressure during cardiopulmonary resuscitation (CPR) may differ from that of normal circulation, which may result in a right-to-left shunt in the presence of a PFO. In this study, transesophageal echocardiography (TEE) was conducted to evaluate whether CPR carried out in patients after cardiac arrest causes right-to-left shunt.

DESIGN

A retrospective observational study.

SETTING

One academic medical center from January 2017 to April 2020.

PATIENTS

Patients older than 20 years who suffered from nontraumatic out-of-hospital cardiac arrest (OHCA) and underwent intra-arrest TEE.

MEASUREMENT AND MAIN RESULTS

Patients who had microbubbles resulting from fluid injection in the right atrium, as indicated on TEE imaging, were included in the analysis. The presence of right-to-left shunt was defined as the appearance of microbubbles in the systemic circulation, including the left atrium, left ventricle, or aorta. A total of 97 patients were included in the final analysis. A right-to-left shunt was observed in 21 patients (21.6%), and no shunt was found in 76 patients (78.4%). The degree of the right-to-left shunt, determined by the number of microbubbles, was mild in 11 patients (52.4%), moderate in eight (38.0%), and severe in two (9.6%). Multivariate analysis showed that no factors were associated with the presence of right-to-left shunt during CPR.

CONCLUSIONS

Right-to-left shunts can be appreciated during CPR in patients who experience OHCA. Further studies are needed to verify its clinical significance.

Biomechanical response of human rib cage to cardiopulmonary resuscitation maneuvers: Effects of the compression location

The biomechanical response of a human rib cage to cardiopulmonary resuscitation maneuvers was investigated by means of finite element simulations. We analyzed the effect of the location where the force was applied on the achieved compression depths and stress levels experienced by the breastbone and ribs. For compression locations on the breastbone, a caudal shift of the application area toward the breastbone tip resulted in a 17% reduction of the force required to achieve a target 5 cm compression depth. We found that the use of compression regions located on the costal cartilages would involve higher risk of rib fractures.

Optimal Landmark for Chest Compressions during Cardiopulmonary Resuscitation Derived from a Chest Computed Tomography in Arms-Down Position

Compressions at the left ventricle increase rate of return of spontaneous circulation. This study aimed to identify the landmark of the point of maximal left ventricular diameter on the sternum (LVmax) by using chest computed tomography (CCT) in the arms-down position, which was similar to an actual cardiac arrest patient. A retrospective study was conducted between September 2014 and November 2020. We included adult patients who underwent CCT in an arms-down position and measured the rescuer’s hand. We measured the distance from the sternal notch to LVmax (DLVmax), to the lower half of sternum (DLH), and to the point of maximal force of hand, which placed the lowest palmar margin of the rescuer’s reference hand at the xiphisternal junction. Thirty-nine patients were included. The LVmax was located below the lower half of the sternum; DLVmax and DLH were 12.6 and 10.0 cm, respectively (p < 0.001). Distance from the sternal notch to the point of maximal force of the left hand, with the ulnar border located at the xiphisternal junction, was close to DLVmax; 11.3 and 12.6 cm, respectively (p = 0.076). In conclusion, LVmax was located below the lower half of the sternum, which is recommended by current guidelines.

Initiation of Invasive Arterial Pressure Monitoring by Critical Care Transport Crews

Noninvasive blood pressure monitoring is convenient in the prehospital setting, but its use in the critically ill patient should be carefully considered given documented inaccuracies. Countless therapeutic patient interventions are based on blood pressure parameters, and the prehospital paramedic, nurse, and physician should strongly consider the use of invasive blood pressure monitoring, especially during critical care transport. Radial artery cannulation for arterial blood pressure monitoring is a safe and effective procedure that can reasonably be performed in the prehospital setting by both physicians and nonphysicians. Critical care transport teams should consider clinical guidelines that outline indications and training to safely implement this as a clinical skill.

A cadaveric model for transesophageal echocardiography transducer placement training: A pilot study

BACKGROUND

Transesophageal echocardiography (TEE) is used in the emergency department to guide resuscitation during cardiac arrest. Insertion of a TEE transducer requires manual skill and experience, yet in some residency programs cardiac arrest is uncommon, so some physicians may lack the means to acquire the manual skills to perform TEE in clinical practice. For other infrequently performed procedural skills, simulation models are used. However, there is currently no model that adequately simulates TEE transducer insertion. The aim of this study is to evaluate the feasibility and efficacy of using a cadaveric model to teach TEE transducer placement among novice users.

METHODS

A convenience sample of emergency medicine residents was enrolled during a procedure education session using cadavers as tissue models. A pre-session assessment was used to determine prior knowledge and confidence regarding TEE manipulation. Participants subsequently attended a didactic and hands-on education session on TEE placement. All participants practised placing the TEE transducer until they were able to pass a standardized assessment of technical skill (SATS). After the educational session, participants completed a post-session assessment.

RESULTS

Twenty-five residents participated in the training session. Mean assessment of knowledge improved from 6.2/10 to 8.7/10 (95% confidence interval [CI] of knowledge difference 1.6-3.2, P<0.001) and confidence improved from 1.6/5 to 3.1/5 (95% CI of confidence difference 1.1-2.0, P<0.001). There was no relationship between training level and the delta in knowledge or confidence.

CONCLUSIONS

In this pilot study, the use of a cadaveric model to teach TEE transducer placement methods among novice users is feasible and improves both TEE manipulation knowledge and confidence levels.

Performance of an automated ultrasound device in identifying and tracing the heart in porcine cardiac arrest

BACKGROUND

While intra-arrest echocardiography can be used to guide and monitor chest compression quality, it is not currently feasible on the scene of out-of-hospital cardiac arrests. Rapid and automated sonographic localization of the heart may provide first-responders guidance to an optimal area of compression without requiring them to interpret ultrasound images. In this proof-of-concept porcine study, we sought to describe the performance of an automated ultrasound device in correctly identifying and tracing the borders of the heart in three distinct states: pre-arrest, arrest, and late arrest.

METHODS

An automated ultrasound device (bladder scanner) was placed on the chests of 7 swine, along the left sternal border (4th-8th intercostal spaces). Scanner-generated images were recorded for each space during pre-arrest, arrest, and finally late arrest. 828 images of the LV and LV outflow tract were randomized and 150 (50/state) selected for analysis. Scanner tracings of the heart were then digitally obscured to facilitate tracing by expert reviewers who were blinded to the physiologic state. Reviewer tracings were compared to bladder scanner tracings; with concordance between these images determined via Sørensen-Dice index (SDI).

RESULTS

When compared to human reviewers, the bladder scanner was able to identify and trace the borders during cardiac arrest. The bladder scanner performed best at the time of arrest (SDI 0.900 ± 0.059). As resuscitation efforts continued and time from initial arrest increased, the scanner's performance decreased dramatically (SDI 0.597 ± 0.241 in late arrest).

CONCLUSION

An automated ultrasound device (bladder scanner) reliably traced porcine hearts during cardiac arrest. It is possible a device could be developed to indicate where compressions should be performed without requiring the operator to interpret ultrasound images. Further investigation into rapid, automated, sonographic localization of the heart to identify the area of compression in out-of-hospital cardiac arrest is warranted.

Point-of-care ultrasound in cardiorespiratory arrest (POCUS-CA): narrative review article

The POCUS-CA (Point-of-care ultrasound in cardiac arrest) is a diagnostic tool in the Intensive Care Unit and Emergency Department setting. The literature indicates that in the patient in a cardiorespiratory arrest it can provide information of the etiology of the arrest in patients with non-defibrillable rhythms, assess the quality of compressions during cardiopulmonary resuscitation (CPR), and define prognosis of survival according to specific findings and, thus, assist the clinician in decision-making during resuscitation. This narrative review of the literature aims to expose the usefulness of ultrasound in the setting of cardiorespiratory arrest as a tool that allows making a rapid diagnosis and making decisions about reversible causes of this entity. More studies are needed to support the evidence to make ultrasound part of the resuscitation algorithms. Teamwork during cardiopulmonary resuscitation and the inclusion of ultrasound in a multidisciplinary approach is important to achieve a favorable clinical outcome.

Mathematical model of modified hybrid pump mechanism for cardiopulmonary resuscitation

BACKGROUND AND OBJECTIVE

The "Cardiac pump theory" and "Thoracic pump theory" are representative theories of cardiopulmonary resuscitation (CPR) mechanisms. Based on these theories, many studies on mathematical modeling have been performed to help understand hemodynamics during CPR. However, there are parts that do not yet properly reflect the physiology of CPR. Therefore, this study aims to develop a lumped parameter model of CPR that can more accurately reflect the current CPR physiology.

METHODS

By adding compartments of the superior and inferior vena cava of the thoracic cavity to the existing CPR model, and the "Hybrid pump" mechanism was applied to simulate CPR. To compare the hemodynamics of the conventional CPR model and the developed CPR model, various conditions, such as active compression-decompression CPR with an impedance threshold valve device (ACD-CPR+ITV), head-up-tilt (HUT), and head-down-tilt (HDT), were simulated. The coronary perfusion pressure (CPP) was compared by modulating the compression ratio of the atrium and ventricle with the thoracic pump factor.

RESULTS

The result for the comparison of coronary blood flow showed that the existing model is predominant in the compression phase, whereas the developed model is dominant in the relaxation phase. ACD-CPR + ITV results showed that the CPP decreased by 5 % in the existing model, and increased by about 46 % in the developed model, revealing a distinct hemodynamic difference between the two models. Likewise, as a result of comparing the hemodynamic differences of the two models according to the changes in tilt angle, the HUT showed similar trends, while the HDT showed slightly different results. The CPP varied accordingly with the ratio of the ventricular and atrial thoracic pump factor.

CONCLUSION

Comparison of the hemodynamics with the existing model by simulating various conditions showed that the developed CPR model reflects the CPR physiology better. The model suggests that the hemodynamics may vary depending on the ventricle and atrium compression ratio. This study may provide an important basis for helping understand various situations and patient-specific hemodynamic characteristics during CPR through in-depth research, such as patient-specific model and parameter optimization.

Optimizing hemodynamic function during cardiopulmonary resuscitation

PURPOSE OF REVIEW

The purpose of this narrative review is to provide an update on hemodynamics during cardiopulmonary resuscitation (CPR) and to describe emerging therapies to optimize perfusion.

RECENT FINDINGS

Cadaver studies have shown large inter-individual variations in blood distribution and anatomical placement of the heart during chest compressions. Using advanced CT techniques the studies have demonstrated atrial and slight right ventricular compression, but no direct compression of the left ventricle. A hemodynamic-directed CPR strategy may overcome this by allowing individualized hand-placement, drug dosing, and compression rate and depth. Through animal studies and one clinical before-and-after study head-up CPR has shown promising results as a potential strategy to improve cerebral perfusion. Two studies have demonstrated that placement of an endovascular balloon occlusion in the aorta (REBOA) can be performed during ongoing CPR.

SUMMARY

Modern imaging techniques may help increase our understanding on the mechanism of forward flow during CPR. This could provide new information on how to optimize perfusion. Head-up CPR and the use of REBOA during CPR are novel methods that might improve cerebral perfusion during CPR; both techniques do, however, still await clinical testing.

Focused Transesophageal Echocardiography During Cardiac Arrest Resuscitation: JACC Review Topic of the Week

Focused transthoracic echocardiography (TTE) during cardiac arrest resuscitation can enable the characterization of myocardial activity, identify potentially treatable pathologies, assist with rhythm interpretation, and provide prognostic information. However, an important limitation of TTE is the difficulty obtaining interpretable images due to external and patient-related limiting factors. Over the last decade, focused transesophageal echocardiography (TEE) has been proposed as a tool that is ideally suited to image patients in extremis-those in cardiac arrest and periarrest states. In addition to the same diagnostic and prognostic role provided by TTE images, TEE provides unique advantages including the potential to optimize the quality of chest compressions, shorten cardiopulmonary resuscitation interruptions, guide resuscitative procedures, and provides a continuous image of myocardial activity. This review discusses the rationale, supporting evidence, opportunities, and challenges, and proposes a research agenda for the use of focused TEE in cardiac arrest with the goal to improve resuscitation outcomes.

Use of a Simple Ultrasound Device to Identify the Optimal Area of Compression for Out-of-Hospital Cardiac Arrest

Background Despite automated defibrillation and compression-first resuscitation, out-of-hospital cardiac arrest (OHCA) survival remains low. Resuscitation guidelines recommend that chest compressions should be done over the lower half of the sternum, but evidence indicates that this is often associated with outflow obstruction. Emerging studies suggest that compression directly over the left ventricle (LV) may improve survival and outcomes, but rapid and reliable localization of the LV is a major obstacle for those first responding to OHCA. This study aimed to determine if a simplified, easy-to-use ultrasound device (bladder scanner) can reliably locate the heart when applied over the intercostal spaces of the anterior thorax in supine patients. Furthermore, we sought to describe the association between largest scan volumes and underlying cardiac anatomy with particular attention to the long axis of the LV. Methodology We recruited healthy male and female volunteers over 40 years of age. Using a bladder scanner to evaluate the left sternal border and mid-clavicular lines, we determined the maximal scan volumes at 10 intercostal spaces for each participant. Cardiac ultrasound was then used to evaluate the corresponding underlying cardiac anatomy and determine the area overlying the long-axis view of the LV. Descriptive statistics (means with standard deviations [SD], medians with interquartile ranges, and frequencies with proportions) were used to quantify demographic information, typical scan volumes across the chest, the frequencies of the best long-axis LV view location. This was then repeated for left sternal border assessments only. Kappa was determined when evaluating agreement between the largest left sternal border scan volume and the best long-axis LV view location. Results The long-axis LV was the predominant structure underlying the largest scan volume in 39/51 (76.5%) patients. When limited to left sternal border volumes only, the long axis of the LV was underlying the maximum volume intercostal space in 46/51 (90.2%; 95% confidence interval [CI]: 78.6%, 96.7%). The largest left sternal border scan volumes were located over the best long-axis LV view in 39/51 (76.5%, 95% CI: 62.5%, 87.2%) of the study participants with a Kappa statistic of 0.68 (95% CI: 0.52, 0.84; p < 0.0001).  Conclusions In this cross-sectional study of healthy volunteers, an easy-to-use ultrasound device (bladder scanner) was able to reliably localize the heart. Largest scan volumes over the left sternal border showed substantial agreement with the intercostal space overlying the long axis of the LV. Further investigations are warranted to determine if such localization is reliable in cardiac arrest patients.

CPR by foot. An alternative in special circumstances? A randomized simulation study

OBJECTIVE

To assess the differences in the quality and self-perception of CPR performed with foot technique compared to the standard technique with the hands in nursing students.

METHODS

65 university nursing students participated in a randomized simulation crossover design study. The participants randomly performed two CPR tests: CPR by foot and CPR by hands techniques. The compression-only protocol with a 2-min test was used with the Resusci Anne QCPR® manikin and Wireless Skill Reporter® software, both from Laerdal.

RESULTS

Participants had lower quality when doing CPR by foot (72%) than when doing standard CPR (91%) (p = 0.006). 95% of the participants indicated standard CPR as the technique of choice, while 92% indicated that they would use CPR by foot if it was not possible to perform standard technique.

CONCLUSIONS

CPR quality was lower when performing foot technique, although with positive results. It would be advisable for people with acquired CPR skills to know that they can do foot compressions in situations where they cannot use their hands.

[Extracorporeal cardiopulmonary resuscitation (eCPR) for out-of-hospital cardiac arrest (OHCA) : Retrospective analysis of a load and go strategy under the aspect of golden hour of eCPR]

BACKGROUND

Survival rates after an out-of-hospital cardiac arrest (OHCA) remain low. Extracorporeal cardiopulmonary resuscitation (eCPR) has been introduced as an attempt to increase survival in selected patients and observational studies have shown promising results. Nevertheless, inclusion criteria and timing of eCPR remain undefined.

OBJECTIVE

The current study analyzed a load and go strategy with respect to the golden hour of eCPR as a cut-off time for survival and favorable neurological outcome.

MATERIAL AND METHODS

This retrospective cohort study included 32 patients who underwent eCPR treatment due to an OHCA between January 2017 and September 2019. Routinely taken patient demographic data (age, BMI, sex) were analyzed. The main focus was set on processing times in the preclinical and clinical setting. Time intervals including OHCA until ambulance arrival, time on scene, transportation times and door to eCPR were extracted from emergency medical service (EMS) and resuscitation protocols. Low-flow times, survival and neurological outcome were analyzed.

RESULTS

The use of eCPR in OHCA was associated with survival to hospital discharge in 28% and a good neurological outcome in 19% of the cases. Both groups (survivor and nonsurvivor) did not differ in patient demographics except for age. Survivors were significantly younger (47 (30-60) vs. 59 (50-68) years, p = 0.035). Processing times as well as low-flow times were not significantly different (OHCA-eCPR survivor 64 (50-87) vs. non-survivor 74 (51-85) min; p-value 0.64); however, median low-flow times were outside the golden hour of eCPR (69 (52-86)).

CONCLUSION

Despite low-flow times of more than 60 min, eCPR was associated with survival in 28% after OHCA. Hence, exceeding the golden hour of eCPR cannot act as a definitive exclusion criterion for eCPR.

Transesophageal echocardiography in patients with cardiac arrest: from high-quality chest compression to effective resuscitation

BACKGROUND

Survival after cardiac arrest depends on prompt and effective cardiopulmonary resuscitation (CPR). Transesophageal echocardiography (TEE) can be applied to evaluate the effectiveness of chest compression-decompression maneuvers in the setting of cardiac arrest undergoing CPR. The efficacy of chest compression can be continuously assessed by TEE that can improve the effectiveness of CPR guiding the rescuer to optimize or correct chest compression and decompression by directly examining the movements of the cardiac walls and valve leaflets.

PURPOSE

The review describes how to perform TEE in the emergency setting of cardiopulmonary arrest, its advantages, and limitations, and ultimately propose an echo-guided approach to CPR.