INTRODUCTION
Point-of-care echocardiography (POC Echo) is regarded as a useful adjunct in the management of cardiac arrest patients in the emergency department (ED) setting. A number of reports describe the potential prognostic and diagnostic roles of POC Echo during cardiac arrest.[1,2,3,4,5,6] POC Echo is also used to monitor and improve the quality and location of chest compressions.[5,7-10] More recently, POC transesophaeal echocardiography (TEE) has been gaining popularity among emergency physicians (EPs) in the management of cardiac arrest because higher-quality images can usually be obtained during ongoing chest compressions without being limited by body habitus or the placement of defibrillation pads. These advantages allow for improved compression fraction (shortened pulse-check pauses) during cardiopulmonary resuscitation (CPR), improved diagnostic yield, and improved chest compression quality via continuous echo monitoring.[9,11-17]
With an increased utilization of POC TEE, the American College of Emergency Physicians (ACEP) published guidelines on the use of POC TEE during cardiac arrest in 2017.[18] These guidelines outline the minimum training requirements that should be met for EPs who are already facile with POC Echo. These training requirements generally follow the educational protocol outlined by Arntfield et al[19] in 2015 with the notable exclusion of the bicaval view. The ACEP guidelines state that training can be performed on live humans or simulators; Arntfield et al[18,19] used simulators for TEE image acquisition training and airway mannequins for TEE transducer insertion training. The use of mannequins and simulators allows EPs, who have limited access to live humans for training, to acquire TEE proficiency. Although TEE simulators likely provide adequate image acquisition training for EPs, who are already experienced with POC Echo, the plastic mannequins that are designed for airway simulation are likely not ideal for simulating TEE transducer placement. More work is needed to develop an adequate simulated TEE transducer placement training model.
In this pilot study, we hypothesized that using a fresh cadaver model for TEE transducer placement training would be feasible and would increase confidence in TEE placement skills among novice users. We also assessed whether TEE knowledge or confidence was influenced by training level.
METHODS
Study design and population
This was a cross-sectional convenience sample of emergency medicine resident physicians from a single post-graduate year (PGY) 1-3 training program that participated in an annual procedure education session conducted on a single day. All session participants who had completed at least 25 POC Echo examinations prior to the education session were eligible for inclusion in the study.
Study protocol Pre-session assessment
Following recruitment and after providing informed verbal consent, participants were given a pre-session assessment to gauge existing TEE manipulation knowledge and confidence levels (supplementary file 1). The pre-session assessment consisted of 10 multiple choice questions regarding TEE manipulation knowledge as well as two questions regarding prior experience with TEE and one question regarding PGY level of training. The pre-session assessment also included a separate question regarding confidence in TEE transducer insertion. Confidence ratings were on a Likert scale of 1 (not at all confident in performing the task) to 5 (completely confident in performing the entire task independently without supervision). The assessment questions were developed by three clinical ultrasound fellowship-trained EPs and were tested on an additional five EPs with mixed prior ultrasound experience to validate that the survey items were clear, understandable, and relevant to the construct; the survey that was sent to the study population was the third iteration which had undergone minor changes to increase clarity or to decrease the potential for incorrect entries based on these initial assessment responses.
Education session
During the education session, participating residents rotated to the TEE probe insertion station in groups of five which were pre-determined by residency leadership; each group consisted of residents from each of the three PGY levels. This was the first year our institution provided a TEE probe insertion station, so none of the residents had received this education in prior years. Each group received a brief standardized didactic and hands-on educational training session, which lasted approximately 20 minutes. The training presented indications and contraindications for POC TEE, knobology, and a demonstration on correct TEE transducer placement; each of the residents then had the opportunity to practice on cadaver models. There were four fresh cadavers available for practice purposes, including the one cadaver used for demonstration and assessment purposes.
Post-session assessment
Subsequently, each participant individually completed a standardized assessment of technical skill (SATS) on a single fresh cadaver model; the SATS was assessed by two emergency ultrasound fellowship-trained EPs (supplementary file 2). The SATS was repeated if necessary until participants completed all critical elements as judged by both assessors. The two emergency ultrasound fellowship-trained study personnel who scored the SATS were trained and familiar with the research protocol prior to the event and interrater agreement was assessed using five practice subjects who were also included in the analysis.
Participants subsequently completed a post-session assessment with questions similar to the pre-session assessment (supplementary file 3).
Measurements
The delta between pre- and post-session knowledge and confidence levels were determined, and the number of attempts at the SATS for each participant was recorded.
Data analysis
Descriptive statistics with 95% confidence interval (CI) were used to analyze training level data. Cohen’s Kappa (κ) was used to assess interrater agreement between SATS scoring for the practice subjects. Wilcoxon sign-rank tests were used to compare pre- and post-session assessments and linear regression was performed between training level and assessment results. Analyses were run using Stata 15.1/SE for Windows (StataCorp, LP College Station, TX).
RESULTS
Twenty-five residents were enrolled during the education session. Twenty-four residents were novices on the POC TEE and all completed the TEE educational training. Levels of training as well as pre- and post-session knowledge assessment scores are shown in Table 1.
Table 1 Training level of participants and the pre- and post-session knowledge assessment scores
| PGY levels | Number (%, 95% CI) | Pre-session knowledge, mean±SD | Post-session knowledge, mean±SD | Knowledge difference P (95% CI) |
|---|---|---|---|---|
| 1 | 10 (40, 23-59) | 6.7±1.4 | 8.5±1.3 | 0.008 (0.5-3.1)* |
| 2 | 9 (36, 20-55) | 6.9±1.4 | 9.0±0.8 | 0.002 (1.0-3.3)* |
| 3 | 5 (20, 4-35) | 4.8±1.3 | 8.4±1.1 | 0.002 (1.8-5.3)* |
| Undeclared | 1 (4, 1-20) | 3.0 | 9.0 | NA |
| Total | 25 (100, 100-100) | 6.2±1.7 | 8.7±1.0 | <0.001 (1.6-3.2)* |
PGY: post-graduate year; CI: confidence interval; SD: standard deviation; NA: not available; *P<0.05.
Table 2 Pre- and post-session confidence assessment scores
| PGY levels | Number (%) | Pre-session confidence, mean±SD | Post-session confidence, mean±SD | Confidence difference P (95% CI) |
|---|---|---|---|---|
| 1 | 10 (40) | 1.2±0.4 | 3.0±0.5 | <0.001 (1.4-2.2)* |
| 2 | 9 (36) | 1.9±1.2 | 3.1±1.0 | 0.040 (0.0-2.5)* |
| 3 | 5 (20) | 2.0±0.7 | 3.6±0.9 | 0.010 (0.4-2.8)* |
| Undeclared | 1 (4) | 1.0 | 2.0 | NA |
| Total | 25 (100) | 1.6±0.9 | 3.1±0.8 | <0.001 (1.1-2.0)* |
PGY: post-graduate year; CI: confidence interval; SD: standard deviation; NA: not available; *P<0.05.
There was 100% agreement between the two assessors for the practice SATS (κ =1.0, 95% CI 1.0-1.0). The mean number of SATS sessions required was 1.3±0.5 (95% CI 1.0-1.6) for the PGY1, 1.1±0.3 (95% CI 0.9-1.4) for the PGY2, 1.2±0.4 (95% CI 0.6-1.8) for the PGY3 and 1.2±0.4 (95% CI 1.0-1.3) for all groups combined.
Mean TEE manipulation knowledge and confidence levels both increased after the training session (Tables 1 and 2). Participants’ level of training did not contribute to the pre-session scores nor to the post-session delta (P-value >0.05 for all training levels).
DISCUSSION
This is the first study to describe the feasibility of a cadaver model for TEE transducer placement training; one prior study describes the anatomic variation encountered in TEE placement using a cadaveric model.[20]
The relative rarity of cardiac arrest management is one of the limitations to implementing TEE training in the ED setting since the current ACEP guidelines only recommend the use of TEE during cardiac arrest. Thus, an alternative to training solely on cardiac arrest patients is needed. Arntfield et al[19] described an educational protocol that used a TEE simulator to teach image acquisition skills and an airway mannequin to simulate TEE placement since none of the current commercially available TEE simulators have human-like oropharyngeal anatomy. Although an airway mannequin may provide novice TEE users with a rudimentary idea of how to place a TEE transducer, airway mannequins are known to be limited in important aspects such as tissue rigidity, cervical spine mobility, and anatomical proportions.[21,22,23] Furthermore, none of these limitations take into account the fact that airway mannequins are designed to simulate endotracheal intubation and not TEE placement.
A cadaveric model allows novice TEE users to experience anatomic variation. The upper esophageal sphincter most commonly lies behind and to the right of the larynx; however, it may also lie directly behind the larynx or side-by-side, which will affect the placement of the TEE transducer.[20] Although rare (<1% in non-cardiac arrest patients), esophageal perforation in TEE is often due to using excessive force, poor understanding of anatomic barriers, and unexpected variations in esophageal anatomy.[24,25] The ability for novice users to experience normal anatomic variation with multiple cadavers and the resistance of human tissue is valuable.
This pilot study was designed to test the feasibility of using a cadaveric model to educate novice TEE users on transducer placement. The variance in knowledge and confidence may be used to estimate sample size for future work on the subject. Our group plans to expand this model into a mastery-learning exercise that will combine both TEE probe placement and TEE image acquisition as well as simulation of cardiac arrest cases.
Limitations
This cadaveric model for TEE transducer placement does not assess image acquisition. Unfortunately, in our laboratory, even when the thoracic and cardiac cavities are filled with saline, the cadaveric cardiac structures are barely recognizable, which limits the use of cadavers for image acquisition training. However, TEE simulators that provide image acquisition training with built-in anatomic variation and pathology are already available and may be used in conjunction with the cadaveric probe placement model.
Our model only used fresh cadavers. The mechanical properties of cadaver tissues are known to change depending on how they are preserved.[26,27] Whether there is an important difference in regards to improving successful probe placement or decreasing morbidity after training is yet to be determined.
We did not assess the financial feasibility of our training modality. We performed this study in conjunction with an annual procedure education session that used cadaver models for purposes other than TEE education. Institutions with similar training sessions would be best suited to adopt such a model without incurring extra cost, and they would also have the benefit of maximizing the use of donated human tissue. When contrasting the financial cost of cadaver models to other models available on the market, one must consider that the cost of cadaver models varies by region. Airway mannequins may be purchased at a fraction of the cost of human cadaver models; mannequins can also be re-used with some additional cost for maintenance, but they suffer from the limitations discussed earlier. Synthetic cadaver models have also been used to aid in TEE introduction training, but to date this use has not been described in the medical literature and it is unknown if there is any benefit to using these models over other airway mannequins in TEE education. The financial cost of an entire synthetic cadaver is much higher than that of a human cadaver, but the synthetic cadaver may be re-used with some additional cost for maintenance. A synthetic cadaver airway model (partial cadaver) may be similar in cost to a human cadaver in some regions. The limitations of a synthetic cadaver would be similar to any other airway mannequin as discussed earlier.
There was a single participant that did not complete question 13 of the pre-assessment to declare their PGY level of training. We included their data in the analysis under a separate “undeclared” PGY category rather than removing all of their data due to a single missing data point. Fortunately, this was the only missing data in this analysis.
This was a single education session that did not assess retention. Future work will be necessary to determine what training is required for skills retention.
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.
Funding: None.
Ethical approval: The study was approved by the Stanford University Institutional Review Board.
Conflicts of interest: The authors have no competing interests relevant to the present study.
Contributors: RWH and KLA conceived and designed the study; RWH, KRN, VL, KHP, DJ, and KLA contributed to collecting the data or analyzing and interpreting the data; RWH and KLA contributed to writing the manuscript or providing critical revisions that are important for the intellectual content, and RWH, KRN, VL, KHP, DJ, and KLA contributed substantially to approving the final version of the manuscript.
All the supplementary files in this paper are available at http://wjem.com.cn.
Reference
Rapid cardiac ultrasound of inpatients suffering PEA arrest performed by nonexpert sonographers
PMID:16199290
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Cardiac arrest presenting as pulseless electrical activity (PEA) currently has a very low survival rate. Many of the conditions underlying PEA (cardiac tamponade, hypovolemia, and pulmonary embolus) are associated with specific cardiac ultrasound findings. The aim of this study was to evaluate a rapid cardiac ultrasound assessment performed by trained nonexpert sonographers integrated into the ACLS response system at a major medical center.An emergency sonography system was created and deployed to each inpatient cardiac arrest occurring at Dartmouth Hitchcock Medical Center between November 1, 2003 and April 30, 2004. Thirteen internal medicine house officers received training to perform a limited subcostal cardiac ultrasound examination designed to diagnose cardiac tamponade, pulmonary embolus, severe hypovolemia, and lack of cardiac motion. Time from arrest alert to sonographic result, and correlation with over-reading by blinded echocardiography physicians were assessed.A complete emergency ultrasound examination was performed in five PEA arrests. The average time from arrest alert to interpretation was 7.75 min. (95% CI 2.8-18.3 min). Three of these examinations (60%, 95% CI 14.7-94.7%) were adequate for interpretation. Agreement between the nonexpert sonographer and echocardiography physician occurred in four of five (kappa=0.706) cases.Rapid cardiac sonography can be successfully integrated in the ACLS response. Nonexpert sonographers may be able to provide useful interpretive information when sufficiently trained.
C.A.U.S.E.: cardiac arrest ultra-sound exam—a better approach to managing patients in primary non-arrhythmogenic cardiac arrest
PMID:17822831
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Cardiac arrest is a condition frequently encountered by physicians in the hospital setting including the Emergency Department, Intensive Care Unit and medical/surgical wards. This paper reviews the current literature involving the use of ultrasound in resuscitation and proposes an algorithmic approach for the use of ultrasound during cardiac arrest. At present there is the need for a means of differentiating between various causes of cardiac arrest, which are not a direct result of a primary ventricular arrhythmia. Identifying the cause of pulseless electrical activity or asystole is important as the underlying cause is what guides management in such cases. This approach, incorporating ultrasound to manage cardiac arrest aids in the diagnosis of the most common and easily reversible causes of cardiac arrest not caused by primary ventricular arrhythmia, namely; severe hypovolemia, tension pneumothorax, cardiac tamponade, and massive pulmonary embolus. These four conditions are addressed in this paper using four accepted emergency ultrasound applications to be performed during resuscitation of a cardiac arrest patient with the aim of determining the underlying cause of a cardiac arrest. Identifying the underlying cause of cardiac arrest represents the one of the greatest challenges of managing patients with asystole or PEA and accurate determination has the potential to improve management by guiding therapeutic decisions. We include several clinical images demonstrating examples of cardiac tamponade, massive pulmonary embolus, and severe hypovolemia secondary to abdominal aortic aneurysm. In conclusion, this protocol has the potential to reduce the time required to determine the etiology of a cardiac arrest and thus decrease the time between arrest and appropriate therapy.
Echocardiography integrated ACLS protocol versus conventional cardiopulmonary resuscitation in patients with pulseless electrical activity cardiac arrest
PMID:23069099
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To examine the utility of bedside echocardiography in detecting the reversible causes of pulseless electrical activity (PEA) cardiac arrest and predicting the resuscitation outcomes.In this prospective interventional study, patients presenting with PEA cardiac arrest were randomized into two groups. In Group A, ultrasound trained emergency physicians performed echocardiography evaluating cardiac activity, right ventricle dilation, left ventricle function, pericardial effusion/tamponade and IVC size along with the advanced cardiac life support (ACLS) protocol. Patients in Group B solely underwent ACLS protocol without applying echocardiography. The presence or absence of mechanical ventricular activity (MVA) and evidences of PEA reversible causes were recorded. The return of spontaneous circulation (ROSC) and death were evaluated in both groups.One hundred patients with the mean age of (58+/-6.1) years were enrolled in this study. Fifty patients (Group A) had echocardiography detected in parallel with cardiopulmonary resuscitation (CPR). Among them, 7 patients (14%) had pericardial effusion, 11 (22%) had hypovolemia, and 39 (78%) were revealed the presence of MVA. In the pseudo PEA subgroup (presence of MVA), 43% had ROSC (positive predictive value) and in the true PEA subgroup with cardiac standstill (absence of MVA), there was no recorded ROSC (negative predictive value). Among patients in Group B, no reversible etiology was detected. There was no significant difference in resuscitation results between Groups A and B observed (P equal to 0.52).Bedside echocardiography can identify some reversible causes of PEA. However, there are no significant changes in survival outcome between the echo group and those with traditional CPR.
Emergency department point-of-care ultrasound in out-of-hospital and in-ED cardiac arrest
DOI:S0300-9572(16)30478-6
PMID:27693280
[Cited within: 1]
Point-of-care ultrasound has been suggested to improve outcomes from advanced cardiac life support (ACLS), but no large studies have explored how it should be incorporated into ACLS. Our aim was to determine whether cardiac activity on ultrasound during ACLS is associated with improved survival.We conducted a non-randomized, prospective, protocol-driven observational study at 20 hospitals across United States and Canada. Patients presenting with out-of-hospital arrest or in-ED arrest with pulseless electrical activity or asystole were included. An ultrasound was performed at the beginning and end of ACLS. The primary outcome was survival to hospital admission. Secondary outcomes included survival to hospital discharge and return of spontaneous circulation.793 patients were enrolled, 208 (26.2%) survived the initial resuscitation, 114 (14.4%) survived to hospital admission, and 13 (1.6%) survived to hospital discharge. Cardiac activity on US was the variable most associated with survival at all time points. On multivariate regression modeling, cardiac activity was associated with increased survival to hospital admission (OR 3.6, 2.2-5.9) and hospital discharge (OR 5.7, 1.5-21.9). No cardiac activity on US was associated with non-survival, but 0.6% (95% CI 0.3-2.3) survived to discharge. Ultrasound identified findings that responded to non-ACLS interventions. Patients with pericardial effusion and pericardiocentesis demonstrated higher survival rates (15.4%) compared to all others (1.3%).Cardiac activity on ultrasound was the variable most associated with survival following cardiac arrest. Ultrasound during cardiac arrest identifies interventions outside of the standard ACLS algorithm.Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.
Focused echocardiographic evaluation in life support and peri-resuscitation of emergency patients: a prospective trial
DOI:10.1016/j.resuscitation.2010.07.013
PMID:20801576
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Focused ultrasound is increasingly used in the emergency setting, with an ALS-compliant focused echocardiography algorithm proposed as an adjunct in peri-resuscitation care (FEEL). The purpose of this study was to evaluate the feasibility of FEEL in pre-hospital resuscitation, the incidence of potentially treatable conditions detected, and the influence on patient management.A prospective observational study in a pre-hospital emergency setting in patients actively undergoing cardio-pulmonary resuscitation or in a shock state. The FEEL protocol was applied by trained emergency doctors, following which a standardised report sheet was completed, including echo findings and any echo-directed change in management. These reports were then analysed independently.A total of 230 patients were included, with 204 undergoing a FEEL examination during ongoing cardiac arrest (100) and in a shock state (104). Images of diagnostic quality were obtained in 96%. In 35% of those with an ECG diagnosis of asystole, and 58% of those with PEA, coordinated cardiac motion was detected, and associated with increased survival. Echocardiographic findings altered management in 78% of cases.Application of ALS-compliant echocardiography in pre-hospital care is feasible, and alters diagnosis and management in a significant number of patients. Further research into its effect on patient outcomes is warranted.Copyright © 2010 Elsevier Ireland Ltd. All rights reserved.
What is the ideal approach for emergent pericardiocentesis using point-of-care ultrasound guidance?
DOI:10.5847/wjem.j.1920-8642.2021.03.001
PMID:34141029
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Traditionally performed using a subxiphoid approach, the increasing use of point-of-care ultrasound in the emergency department has made other approaches (parasternal and apical) for pericardiocentesis viable. The aim of this study is to identify the ideal approach for emergency-physician-performed ultrasound-guided pericardiocentesis as determined by ultrasound image quality, distance from surface to pericardial fluid, and likely obstructions or complications.A retrospective review of point-of-care cardiac ultrasound examinations was performed in two urban academic emergency departments for the presence of pericardial effusions. The images were reviewed for technical quality, distance of effusion from skin surface, and predicted complications.A total of 166 pericardial effusions were identified during the study period. The mean skin-to-pericardial fluid distance was 5.6 cm (95% confidence interval [95% ] 5.2-6.0 cm) for the subxiphoid views, which was significantly greater than that for the parasternal (2.7 cm [95% 2.5-2.8 cm], <0.001) and apical (2.5 cm [95% 2.3-2.7 cm], <0.001) views. The subxiphoid view had the highest predicted complication rate at 79.7% (95% 71.5%-86.4%), which was significantly greater than the apical (31.9%; 95% 21.4%-44.0%, <0.001) and parasternal (20.2%; 95% 12.8%-29.5%, <0.001) views.Our results suggest that complication rates with pericardiocentesis will be lower via the parasternal or apical approach compared to the subxiphoid approach. The distance from skin to fluid collection is the least in both of these views.Copyright: © World Journal of Emergency Medicine.
Evaluation of out-of-hospital cardiac arrest using transesophageal echocardiography in the emergency department
DOI:10.1016/j.resuscitation.2019.02.013 URL [Cited within: 1]
RESCUE transesophageal echocardiography for monitoring of mechanical chest compressions and guidance for extracorporeal cardiopulmonary resuscitation cannulation in refractory cardiac arrest
DOI:10.1002/jcu.22788
PMID:31820822
There is a growing interest in using point-of-care transesophageal echocardiography (TEE) during cardiac arrest. TEE is effective at identifying the etiology of sudden cardiovascular collapse and guiding management during the resuscitation. In selected patients with refractory cardiac arrest, extracorporeal cardiopulmonary resuscitation (ECPR) can be considered. ECPR requires percutaneous vascular access for the implantation of veno-arterial extracorporeal membrane oxygenation circuit. We present a case of prolonged cardiac arrest in which rescue TEE was pivotal in narrowing the differential diagnosis, monitoring of mechanical chest compression performance, and guiding cannulation for ECPR.© 2019 Wiley Periodicals, Inc.
Focused transesophageal echocardiography by emergency physicians is feasible and clinically influential: observational results from a novel ultrasound program
DOI:10.1016/j.jemermed.2015.09.018
PMID:26508495
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Emergency physicians frequently employ transthoracic echocardiography (TTE) to assist in diagnosis and therapy for patients with circulatory failure or arrest. In critically ill patients, transesophageal echocardiography (TEE) offers several advantages over TTE, including reliable, continuous image acquisition and superior image quality. Despite these advantages, TEE is not widely used by emergency physicians.Report the feasibility, findings, and clinical influence observed from the first described TEE program implemented in an emergency department (ED) point-of-care ultrasound program.This was a retrospective review of all ED TEE examinations carried out between February 1, 2013 and January 30, 2015. TEE images and report details (including operator, indication, findings, and clinical recommendation[s]) were exported from the institutional ultrasound archive and analyzed. The electronic chart of each patient was subsequently reviewed for the presence of any complications related to the examination and their clinical course in the hospital.A total of 54 TEE examinations were performed by 12 different emergency physicians. All patients were intubated, and 98% of the examinations were determinate. The most common indications for TEE were intracardiac arrest care in 23 (43%), postarrest management in 14 (26%), and undifferentiated hypotension in 16 (40%). Probe insertion was successful in all cases. TEE imparted a diagnostic influence in 78% of cases and impacted therapeutic decisions in 67% of cases.From our analysis of a single-center experience, ED-based TEE showed a high degree of feasibility and clinical utility, with a diagnostic and therapeutic influence seen in the majority of cases. Focused TEE demonstrated strongest uptake among intubated patients with either undifferentiated shock or cardiac arrest.Copyright © 2016 Elsevier Inc. All rights reserved.
Guiding cardiopulmonary resuscitation with focused echocardiography: a report of five cases
DOI:10.1080/10903127.2019.1626955 URL [Cited within: 1]
Transesophageal echocardiography during cardiopulmonary resuscitation is associated with shorter compression pauses compared with transthoracic echocardiography
DOI:10.1016/j.annemergmed.2019.01.018 URL [Cited within: 1]
Diagnostic accuracy of transesophageal echocardiography during cardiopulmonary resuscitation
PMID:9283540
We sought to establish the diagnostic accuracy of transesophageal echocardiography (TEE) during cardiopulmonary resuscitation.Because of its bedside diagnostic capabilities, excellent cardiac images and lack of interference with resuscitation efforts, TEE is ideally suited to determine the cause of a circulatory arrest that is not due to severe arrhythmia. However, the diagnostic accuracy of TEE during resuscitation is unknown.TEE was performed in patients with prolonged circulatory arrest. The TEE diagnoses were compared with diagnoses from autopsy, surgery and clinical follow-up.Of the 48 study patients (29 male, 19 female, mean age +/- SD 61 +/- 20 years), 28 had an in-hospital cardiac arrest and 20 an out-of-hospital onset of arrest. Forty-four patients eventually died; four survived to discharge. The diagnoses made with TEE were cardiac tamponade (n = 6), myocardial infarction (n = 21), pulmonary embolism (n = 6), ruptured aorta (n = 1), aortic dissection (n = 4), papillary muscle rupture (n = 1), other diagnosis (n = 2) and absence of structural cardiac abnormalities (n = 7). A definite diagnosis from a reference standard was available in 31 patients. The TEE diagnosis was confirmed in 27 of the 31-by postmortem examination (n = 19), operation (n = 2), angiography (n = 2) or clinical course (n = 4). In the other four patients the TEE diagnosis proved incorrect by postmortem examination. The sensitivity, specificity and positive predictive value of TEE were 93%, 50% and 87%, respectively. In 15 patients (31%), major therapeutic decisions were based on TEE findings.TEE can reliably establish the cause of a circulatory arrest during cardiopulmonary resuscitation.
Transesophageal echocardiography during cardiopulmonary arrest in the emergency department
DOI:10.1016/j.resuscitation.2008.02.021 URL
Evaluation of out-of-hospital cardiac arrest using transesophageal echocardiography in the emergency department
DOI:10.1016/j.resuscitation.2019.02.013 URL
Association between left ventricular outflow tract opening and successful resuscitation after cardiac arrest
DOI:10.1016/j.resuscitation.2019.02.027 URL
Compression of the left ventricular outflow tract during cardiopulmonary resuscitation
DOI:10.1111/j.1553-2712.2009.00497.x
PMID:19732038
This prospective observational study was performed to investigate if the hand position used for external chest compressions is in an optimal position for compressing the ventricles during standard cardiopulmonary resuscitation (CPR).Transesophageal echocardiography (TEE) was performed during standard CPR in 34 patients with nontraumatic cardiac arrest (24 males, mean +/- standard deviation [SD] age = 56 +/- 12 years). On the recorded image of TEE, an area of maximal compression (AMC) was identified, and the degree of compression at the AMC and the left ventricular stroke volume was calculated.A significant narrowing of the left ventricular outflow tract (LVOT) or the aorta was noted in all patients, with the degree of compression at the AMC ranging from 19% to 83% (mean +/- SD = 49 +/- 19%). The AMC was found at the aorta in 20 patients (59%) and at the LVOT in 14 patients (41%). A significant narrowing of more than 50% of the diameter at the end of the relaxation phase occurred in 15 patients (44%). On linear regression, the left ventricular stroke volume was correlated with the location of the AMC (R(2) = 0.165, p = 0.017).The outflow of the left ventricle is affected during standard CPR, resulting in varying degrees of narrowing in the LVOT and/or the aortic root.
Diagnostic accuracy of transesophageal echocardiography during cardiopulmonary resuscitation
PMID:9283540
[Cited within: 1]
We sought to establish the diagnostic accuracy of transesophageal echocardiography (TEE) during cardiopulmonary resuscitation.Because of its bedside diagnostic capabilities, excellent cardiac images and lack of interference with resuscitation efforts, TEE is ideally suited to determine the cause of a circulatory arrest that is not due to severe arrhythmia. However, the diagnostic accuracy of TEE during resuscitation is unknown.TEE was performed in patients with prolonged circulatory arrest. The TEE diagnoses were compared with diagnoses from autopsy, surgery and clinical follow-up.Of the 48 study patients (29 male, 19 female, mean age +/- SD 61 +/- 20 years), 28 had an in-hospital cardiac arrest and 20 an out-of-hospital onset of arrest. Forty-four patients eventually died; four survived to discharge. The diagnoses made with TEE were cardiac tamponade (n = 6), myocardial infarction (n = 21), pulmonary embolism (n = 6), ruptured aorta (n = 1), aortic dissection (n = 4), papillary muscle rupture (n = 1), other diagnosis (n = 2) and absence of structural cardiac abnormalities (n = 7). A definite diagnosis from a reference standard was available in 31 patients. The TEE diagnosis was confirmed in 27 of the 31-by postmortem examination (n = 19), operation (n = 2), angiography (n = 2) or clinical course (n = 4). In the other four patients the TEE diagnosis proved incorrect by postmortem examination. The sensitivity, specificity and positive predictive value of TEE were 93%, 50% and 87%, respectively. In 15 patients (31%), major therapeutic decisions were based on TEE findings.TEE can reliably establish the cause of a circulatory arrest during cardiopulmonary resuscitation.
Guidelines for the use of transesophageal echocardiography (TEE) in the ED for cardiac arrest
DOI:10.1016/j.annemergmed.2017.06.033 URL [Cited within: 2]
Focused transesophageal echocardiography for emergency physicians-description and results from simulation training of a structured four-view examination
DOI:10.1186/s13089-015-0027-3
PMID:26123608
[Cited within: 3]
Transesophageal echocardiography (TEE) offers several advantages over transthoracic echocardiography (TTE). Despite these advantages, use of TEE by emergency physicians (EPs) remains rare, as no focused TEE protocol for emergency department (ED) use has been defined nor have methods of training been described.This study aims to develop a focused TEE examination tailored for the ED and to evaluate TEE skill acquisition and retention by TEE-naïve EPs following a focused 4-h curriculum.Academic EPs were invited to participate in a 4-h didactic and simulation-based workshop. The seminar emphasized TEE principles and views obtained from four vantage points. Following the training, participants engaged in an assessment of their abilities to carry out a focused TEE on a high-fidelity simulator. A 6-week follow-up session assessed skill retention.Fourteen EPs participated in this study. Immediately following the seminar, 14 (100 %; k = 1.0) and 10 (71.4 %, k = 0.65) successfully obtained an acceptable mid-esophageal four-chamber and mid-esophageal long-axis view. Eleven (78.6 %, k = 1.0) participants were able to successfully obtain an acceptable transgastric short-axis view, and 11 (78.6 %, k = 1.0) EPs successfully obtained a bicaval view. Twelve participants engaged in a 6-week retention assessment, which revealed acceptable images and inter-rater agreement as follows: mid-esophageal four-chamber, 12 (100 %; k = 0.92); mid-esophageal long axis, 12 (100 %, k = 0.67); transgastric short-axis, 11 (91.7 %, k = 1.0); and bicaval view, 11 (91.7 %, k = 1.0).This study has illustrated that EPs can successfully perform this focused TEE protocol after a 4-h workshop with retention of these skills at 6 weeks.
Visually guided TEE probe insertion, making a case based on anatomic variation: a cadaveric study
DOI:10.1111/echo.14129
PMID:30189109
[Cited within: 2]
The variations in upper esophageal anatomy currently are unknown. This study was carried out to evaluate this variation and assess its impact on transesophageal echocardiography probe insertion.We included 9 consecutive cadavers studied at the University of Maryland School of Medicine's Clinical Surgical Laboratory. Each cadaver was first intubated blindly by an echocardiographer (KAA) and then under direct vision with a UE Medical VL 400 video laryngoscope (Newton, MA) by an anesthesiologist (JD).The visually guided method took a shorter average time (19.4 ± 13.4 seconds) and fewer passes (2.4 ± 2.1 passes) than blind insertion (30.3 ± 19.1 seconds, 5.3 ± 3.3 passes). None of the cadavers had the esophagus located directly posterior to the trachea. The esophageal hiatus was posterior and to the right of the trachea in most (n = 6); in these, the traditional "forward" jaw thrust helped to open the esophageal hiatus. Two cadavers had the esophagus and trachea located almost side by side, and in these the "forward" jaw thrust method failed. Instead, the jaw needed to be pulled to the left in order to advance the probe.This is the first study to describe anatomic variations in the location of and relationship between the upper esophageal sphincter and the larynx for the purpose of transesophageal echocardiography probe insertion. Awareness of the side-by-side anatomic variation can help to improve esophageal intubation by prompting the use of a new "pull to the side" technique instead of the traditional "forward" jaw thrust.© 2018 Wiley Periodicals, Inc.
A radiographic comparison of human airway anatomy and airway manikins - implications for manikin-based testing of artificial airways
DOI:10.1016/j.resuscitation.2015.05.001 URL [Cited within: 1]
Evaluation of four manikins as simulators for teaching airway management procedures specified in the Difficult Airway Society guidelines, and other advanced airway skills
PMID:17567347
[Cited within: 1]
Ten volunteers evaluated the performance of four currently available manikins: Airway Management Trainer, Airway Trainer, Airsim and Bill 1 as simulators for the 16 procedures described in the Difficult Airway Society Guidelines (DAS techniques) and eight other advanced airway techniques (non-DAS techniques), by scoring and ranking each manikin and procedure. Manikin performance was unequal (p < 0.0001 for both SCORE and RANK data for both DAS and non-DAS techniques). Post hoc analysis ranked the manikins for DAS techniques as: 1st Laerdal, 2nd Trucorp, 3rd equal VBM and Ambu. For non-DAS techniques, the ranking was: 1st equal Laerdal and Trucorp, 3rd equal VBM and Ambu. The power to discriminate for individual procedures was considerably lower but for 15 of 16 DAS techniques and 6 of 8 non-DAS techniques, manikin performance differed significantly. Post hoc tests showed significant performance differences between individual manikins for 10 DAS procedures, with the Laerdal manikin performing best.
Degrees of reality: airway anatomy of high-fidelity human patient simulators and airway trainers
DOI:10.1097/ALN.0b013e318254cf41
PMID:22481118
[Cited within: 1]
Human patient simulators and airway training manikins are widely used to train airway management skills to medical professionals. Furthermore, these patient simulators are employed as standardized "patients" to evaluate airway devices. However, little is known about how realistic these patient simulators and airway-training manikins really are. This trial aimed to evaluate the upper airway anatomy of four high-fidelity patient simulators and two airway trainers in comparison with actual patients by means of radiographic measurements. The volume of the pharyngeal airspace was the primary outcome parameter.Computed tomography scans of 20 adult trauma patients without head or neck injuries were compared with computed tomography scans of four high-fidelity patient simulators and two airway trainers. By using 14 predefined distances, two cross-sectional areas and three volume parameters of the upper airway, the manikins' similarity to a human patient was assessed.The pharyngeal airspace of all manikins differed significantly from the patients' pharyngeal airspace. The HPS Human Patient Simulator (METI®, Sarasota, FL) was the most realistic high-fidelity patient simulator (6/19 [32%] of all parameters were within the 95% CI of human airway measurements).The airway anatomy of four high-fidelity patient simulators and two airway trainers does not reflect the upper airway anatomy of actual patients. This finding may impact airway training and confound comparative airway device studies.
Safety of transesophageal echocardiography
DOI:10.1016/j.echo.2010.08.013 URL [Cited within: 1]
Hypopharyngeal perforation caused by intraoperative transesophageal echocardiography
DOI:10.1007/s10396-014-0594-0 URL [Cited within: 1]
The mechanical properties of fresh versus fresh/frozen and preserved (Thiel and Formalin) long head of biceps tendons: a cadaveric investigation
DOI:S0940-9602(18)30070-0
PMID:29879483
[Cited within: 1]
Human cadaveric specimens commonly serve as mechanical models and as biological tissue donors in basic biomechanical research. Although these models are used to explain both in vitro and in vivo behavior, the question still remains whether the specimens employed reflect the normal in vivo situation. The mechanical properties of fresh-frozen or preserved cadavers may differ, and whether they can be used to reliably investigate pathology could be debated. The purpose of this study was to therefore examine the mechanical properties of cadaveric long biceps tendons, comparing fresh (n=7) with fresh-frozen (n=8), formalin embalmed (n=15), and Thiel-preserved (n=6) specimens using a Universal Testing Machine. The modulus of elasticity and the ultimate tensile strength to failure was recorded. Tensile failure occurred at an average of 12N/mm in the fresh group, increasing to 40.1N/mm in the fresh-frozen group, 50.3N/mm in the formalin group, and 52N/mm in the Thiel group. The modulus of elasticity/stiffness of the tendon increased from fresh (25.6MPa), to fresh-frozen (55.3MPa), to Thiel (82.5MPa), with the stiffest being formalin (510.6MPa). Thiel-preserved and formalin-embalmed long head of biceps tendons and fresh-frozen tendons have a similar load to failure. Either the Thiel or formalin preserved tendon could therefore be considered as alternatives for load to failure studies. However, the Young's modulus of embalmed tendons were significantly stiffer than fresh or fresh frozen specimens, and these methods might be less suitable alternatives when viscoelastic properties are being investigated.Copyright © 2018 Elsevier GmbH. All rights reserved.
Impact of drying and thiel embalming on mechanical properties of Achilles tendons
DOI:10.1002/ca.22624
PMID:26378610
[Cited within: 1]
Biomechanical research and orthopedic training is regularly carried out on human cadavers. Given the post-mortem decay, these cadavers were usually frozen or embalmed. The embalming method according to Dr. Thiel was often praised for the preservation of natural texture. The main aim of this article was to quantitatively analyze the impact of this embalming technique on the biomechanical properties. To that extent, Achilles tendons (calcaneal tendons) of seven cadavers have been tested. For each cadaver, a first tendon was tested following a fresh-frozen conservation, the other following the Thiel embalming process. The results indicated a significant difference in Young's modulus between both groups (P values = 0.046). The secondary aim of this article was to analyze the impact of exposure to room conditions and associated dehydration on the biomechanical properties of cadaver tissue. Therefore, each tendon was tested before and after 2 hr of exposure to room conditions. The resulting dehydration caused a significant increase of the Young's modulus for the thawed fresh-frozen tendons. The properties of the Thiel embalmed tendons were not significantly altered. In conclusion, this research promoted the use of fresh-frozen specimens for biomechanical testing. Effort should, however, be made to minimize dehydration of the tested specimens.© 2015 Wiley Periodicals, Inc.
