Ten Influential Point-of-Care Ultrasound Papers: 2023 in Review.

In an effort to help keep busy clinicians up to date with the latest ultrasound research, our group of experts has selected 10 influential papers from the past 12 months and provided a short summary of each. We hope to provide emergency physicians, intensivists, and other acute care providers with a succinct update concerning some key areas of ultrasound interest.

Agitated Saline Contrast Injection in Patients with Severe Hypoxemia.

The use of agitated saline contrast (ASC) during echocardiographic examinations is a well-established practice, most commonly performed to identify atrial septal abnormalities in the context of stroke. In the intensive care unit, this technique may be employed to identify anatomic right-to-left shunts (either intracardiac or transpulmonary) that may be contributing to hypoxemic respiratory failure. This narrative review will describe the technique of ASC injection, summarize clinical scenarios where it may be useful, and review the strengths and limitations of the tool.

Ten Influential Point-of-Care Ultrasound Papers: 2022 in Review.

Keeping up with the latest developments in the point-of-care ultrasound (POCUS) literature is challenging, as with any area of medicine. Our group of POCUS experts has selected 10 influential papers from the past 12 months and provided a short summary of each. We hope to provide emergency physicians, intensivists, and other acute care providers with a succinct update concerning some key areas of ultrasound interest.

Association of age with death and withdrawal of life-sustaining therapy after severe traumatic brain injury.

BACKGROUND: Compared to younger age, older age (≥ 65 yr) is associated with worse outcomes after severe traumatic brain injury (TBI). We sought to describe the association of older age with in-hospital death and aggressiveness of intervention. METHODS: We conducted a retrospective cohort study of adult (age ≥ 16 yr) patients with severe TBI admitted to a single academic tertiary care neurotrauma centre between January 2014 and December 2015. We collected data through chart review as well as from our institutional administrative database. We provided descriptive statistics and used multivariable logistic regression to evaluate the independent association of age with the primary outcome, in-hospital death. The secondary outcome was early withdrawal of life-sustaining therapy. RESULTS: There were 126 adult patients (median age 67 yr [Q1-Q3, 33-80 yr]) with severe TBI during the study period who met our eligibility criteria. The most common mechanism was high-velocity blunt injury (55 patients [43.6%]). The median Marshall score was 4 (Q1-Q3, 2-6), and the median Injury Severity Score was 26 (Q1-Q3, 25-35). After controlling for confounders including clinical frailty, pre-existing comorbidity, injury severity, Marshall score and neurologic examination at admission, we observed that older patients were more likely than younger patients to die in hospital (odds ratio 5.10, 95% confidence interval 1.65-15.78). Older patients were also more likely to experience early withdrawal of life-sustaining therapy and less likely to receive invasive interventions. CONCLUSION: After controlling for confounding factors relevant to older patients, we observed that age was an important and independent predictor of in-hospital death and early withdrawal of life-sustaining therapy. The mechanism by which age influences clinical decision-making independent of global and neurologic injury severity, clinical frailty and comorbidities remains unclear.

Ten Influential Point-of-Care Ultrasound Papers: 2021 in Review.

The ongoing rapid expansion of point-of-care ultrasound (POCUS) and its corresponding supporting literature leaves the frontline clinician in a difficult position when trying to keep abreast of the latest developments. Our group of POCUS experts has selected ten influential POCUS-related papers from the past twelve months and provided a short summary of each. Our aim is to give to emergency physicians, intensivists, and other acute care providers key information, helping them to keep up to date on rapidly evolving POCUS literature.

Ultrasound Assessment of the Inferior Vena Cava for Fluid Responsiveness: Making the Case for Skepticism.

Determining whether a patient in shock is in a state of fluid responsiveness (FR) has long been the Holy Grail for clinicians who care for acutely ill patients. While various tools have been put forth as solutions to this important problem, ultrasound assessment of the inferior vena cava has received particular attention of late. Dozens of studies have examined its ability to determine whether a patient should receive volume expansion, and general enthusiasm has been strengthened by the fact that it is easy to perform and non-invasive, unlike many competing FR tests. A deeper examination of the technique, however, reveals important concerns regarding inaccuracies in measurement and a high prevalence of confounding factors. Furthermore, a detailed review of the evidence (small individual studies, multiple meta-analyses, and a single large trial) reveals that the tool performs poorly in general and is unlikely to be helpful at the bedside in circumstances where genuine clinical uncertainty exists.

Comparative Accuracy of Focused Cardiac Ultrasonography and Clinical Examination for Left Ventricular Dysfunction and Valvular Heart Disease: A Systematic Review and Meta-analysis.

Background: Incorporating focused cardiac ultrasonography (FoCUS) into clinical examination could improve the diagnostic yield of bedside patient evaluation. Purpose: To compare the accuracy of FoCUS-assisted clinical assessment versus clinical assessment alone for diagnosing left ventricular dysfunction or valvular disease in adults having cardiovascular evaluation. Data Sources: English-language searches of MEDLINE, Embase, and Web of Science from 1 January 1990 to 23 May 2019 and review of reference citations. Study Selection: Eligible studies were done in patients having cardiovascular evaluation; compared FoCUS-assisted clinical assessment versus clinical assessment alone for the diagnosis of left ventricular systolic dysfunction, aortic or mitral valve disease, or pericardial effusion; and used transthoracic echocardiography as the reference standard. Data Extraction: Three study investigators independently abstracted data and assessed study quality. Data Synthesis: Nine studies were included in the meta-analysis. The sensitivity of clinical assessment for diagnosing left ventricular dysfunction (left ventricular ejection fraction <50%) was 43% (95% CI, 33% to 54%), whereas that of FoCUS-assisted examination was 84% (CI, 74% to 91%). The specificity of clinical assessment was 81% (CI, 65% to 90%), and that of FoCUS-assisted examination was 89% (CI, 85% to 91%). The sensitivities of clinical assessment and FoCUS-assisted examination for diagnosing aortic or mitral valve disease (of at least moderate severity) were 46% (CI, 35% to 58%) and 71% (CI, 63% to 79%), respectively. Both the clinical assessment and the FoCUS-assisted examination had a specificity of 94% (CI, 91% to 96%). Limitation: Evidence was scant, persons doing ultrasonography had variable skill levels, and most studies had unclear or high risk of bias. Conclusion: Clinical examination assisted by FoCUS has greater sensitivity, but not greater specificity, than clinical assessment alone for identifying left ventricular dysfunction and aortic or mitral valve disease; FoCUS-assisted examination may help rule out cardiovascular pathology in some patients, but it may not be sufficient for definitive confirmation of cardiovascular disease suspected on physical examination. Primary Funding Source: None. (PROSPERO: CRD42019124318).

Subjective awareness of ultrasound expertise development: individual experience as a determinant of overconfidence.

Medical decision-making requires years of experience in order to develop an adequate level of competence to successfully engage in safe practice. While diagnostic and technical skills are essential, an awareness of the extent and limits of our own knowledge and skills is critical. The present study examines clinicians' subjective awareness in a diagnostic cardiac ultrasound task. Clinicians answered diagnostic and treatment related questions for a range of pathologies. Following these questions, clinicians indicated their level of confidence in their response. A comparison of response accuracy and confidence revealed that clinicians were generally overconfident in their responses. Critically, we observed that a clinician's overconfidence was negatively correlated with prior experience: clinicians that had more prior experience expressed less overconfidence in their performance such that some clinicians were in fact underconfident. We discuss the implications for training in medical education and decision-making.

Expert Agreement in the Interpretation of Lung Ultrasound Studies Performed on Mechanically Ventilated Patients.

OBJECTIVES: Although lung ultrasound (US) has been shown to have high diagnostic accuracy in patients presenting with acute dyspnea, its precision in critically ill patients is unknown. We investigated common areas of agreement and disagreement by studying 6 experts as they interpreted lung US studies in a cohort of intensive care unit (ICU) patients. METHODS: A previous study by our group asked experts to rate the quality of 150 lung US studies performed by 10 novices in a population of mechanically ventilated patients. For this study, experts were asked to interpret them without the clinical context, reporting the presence of pneumothorax, interstitial syndrome, consolidation, atelectasis, or pleural effusion. RESULTS: The rate of expert agreement depended on how it was defined, ranging from 51% (with a strict definition of agreement) to 57% (with a more liberal definition). Removing cases involving lung consolidation (the most common source of disagreement) improved the rates of agreement to 69% and 86%, respectively. CONCLUSIONS: The frequency of agreement was lower than might have been expected in this study. Several potential reasons are identified, chief among them the fact that ICU patients often develop multiple pulmonary insults, making agreement on a specific primary diagnosis challenging. This finding suggests that the utility of lung US in identifying the main contributing lung condition in ICU patients may be lower than in dyspneic patients encountered in the emergency department. It also raises the possibility that the clinical context is more important for lung US than other imaging modalities.

Defining Competencies for Ultrasound-Guided Bedside Procedures: Consensus Opinions From Canadian Physicians.

OBJECTIVES: This study sought to define the competencies in ultrasound knowledge and skills that are essential for medical trainees to master to perform ultrasound-guided central venous catheterization, thoracentesis, and paracentesis. METHODS: Experts in the 3 procedures were identified by a snowball technique through 3 Canadian tertiary academic health centers. Experts completed 2 rounds of surveys, including an 88-item central venous catheterization survey, a 96-item thoracentesis survey, and an 89-item paracentesis survey. For each item, experts were asked to determine whether the knowledge/skill described was essential, important, or marginal. Consensus on an item was defined as agreement by at least 80% of the experts. For items on which consensus was not reached during the first round of surveys, a second survey was created in which the experts were asked to rate the item in a binary fashion (essential/important versus marginal/unimportant). RESULTS: Of the 27 experts invited to complete each survey, 25 (93%) completed the central venous catheterization survey; 22 (81%) completed the thoracentesis survey; and 23 (85%) completed the paracentesis survey. The experts represented 8 specialties from 8 cities within Canada. A total of 22, 32, and 28 items were determined to be essential competencies for central venous catheterization, thoracentesis, and paracentesis, respectively, whereas 47, 38, and 42 competencies were determined to be important, and 8, 13, and 10 were determined to be marginal. The ability to perform real-time direct ultrasound guidance was considered essential only for the performance of central venous catheterization insertion. CONCLUSIONS: Our study presents expert consensus-derived ultrasound competencies that should be considered during the design and implementation of procedural skills training for learners.

The Rapid Assessment of Competency in Echocardiography Scale: Validation of a Tool for Point-of-Care Ultrasound.

OBJECTIVES: Increased use of point-of-care ultrasound (US) requires the development of assessment tools that measure the competency of learners. In this study, we developed and tested a tool to assess the quality of point-of-care cardiac US studies performed by novices. METHODS: In phase 1, the Rapid Assessment of Competency in Echocardiography (RACE) scale was developed on the basis of structured interviews with subject matter experts; the tool was then piloted on a small series of US studies in phase 2. In phase 3, the tool was applied to a sample of 154 point-of-care US studies performed by 12 learners; each study was independently rated by 2 experts, with quantitative analysis subsequently performed. RESULTS: Evidence of the content validity of the RACE scale was supported by a consensus exercise, wherein experts agreed on the assessment dimensions and specific items that made up the RACE scale. The tool showed good inter-rater reliability. An analysis of inter-item correlations provided support for the internal structure of the scale, and the tool was able to discriminate between learners early in their point-of-care US learning and those who were more advanced in their training. CONCLUSIONS: The RACE scale provides a straightforward means to assess learner performance with minimal requirements for evaluator training. Our results support the conclusion that the tool is an effective means of making valid judgments regarding competency in point-of-care cardiac US.

High and intermediate risk pulmonary embolism in the ICU.

Pulmonary embolism (PE) is a common and important medical emergency, encountered by clinicians across all acute care specialties. PE is a relatively uncommon cause of direct admission to the intensive care unit (ICU), but these patients are at high risk of death. More commonly, patients admitted to ICU develop PE as a complication of an unrelated acute illness. This paper reviews the epidemiology, diagnosis, risk stratification, and particularly the management of PE from a critical care perspective. Issues around prevention, anticoagulation, fibrinolysis, catheter-based techniques, surgical embolectomy, and extracorporeal support are discussed.

Setting and Titrating Positive End-Expiratory Pressure.

Although maintaining some amount of positive end-expiratory pressure (PEEP) seems essential, selecting and titrating a specific level for patients with ARDS remains challenging despite extensive research on the subject. Although an "open lung" approach to ventilation is popular and has some degree of biological plausibility, it is not without risk. Furthermore, there is no clear evidence-based guidance regarding initial PEEP settings or how to titrate them early in the course of the illness. Many busy clinicians use a "one-size-fits-all" approach based on local medical culture, but an individualized approach has the potential to offer significant benefit. Here we present a pragmatic approach based on simple measurements available on all ventilators, focused on achieving balance between the potential risks and benefits of PEEP. Acknowledging "best PEEP" as an impossible goal, we aim for a straightforward method to achieve "better PEEP."