Echocardiographic diagnosis and clinical implications of wide-open tricuspid regurgitation for evaluating right ventricular dysfunction in the emergency department.

The tricuspid regurgitation pressure gradient (TRPG) reflects the difference in pressure between the right ventricle and right atrium (ΔPRV-RA). Its estimation by echocardiography correlates well with that obtained using right-heart catheterization. An elevated TRPG is an important marker for identifying right ventricular dysfunction in both the acute and chronic settings. However, in the "wide-open" variant of TR, the TRPG counterintuitively falls. Failure to recognize this potential pitfall and underlying pathophysiology can cause underestimation of the severity of right ventricular dysfunction. This could lead to erroneous fluid tolerance assessments, and potentially harmful resuscitative and airway management strategies. In this manuscript, we illustrate the pathophysiology and potential pitfall of wide-open TR through a series of cases in which emergency physicians made the diagnosis using cardiac point-of-care ultrasound. To our knowledge, this clinical series is the first to demonstrate recognition of the paradoxically-low TRPG of wide-open TR, which guided appropriate management of critically ill patients in the emergency department.

Is pulmonary hypertension protective against cardiac tamponade? A systematic review.

The presence of pulmonary hypertension (PH) may affect whether cardiac tamponade physiology develops from a pericardial effusion. Specifically, the increased intracardiac pressure and right ventricular hypertrophy associated with PH would seemingly increase the intrapericardial pressure threshold at which the right-sided chambers collapse. In this systematic review, we examined the impact of PH on the incidence, in-hospital and long-term mortality, and echocardiographic findings of patients with cardiac tamponade. Using the PRISMA guideline, a systematic search was conducted in PubMed, Academic Search Premier, Web of Science, Google Scholar, and the Cochrane Database for studies investigating PH and cardiac tamponade. The Newcastle-Ottawa Scale was used to analyze the quality of returned studies. Primary outcomes included the incidence of cardiac tamponade, as well as in-hospital and long-term mortality rates. Secondary outcomes were the presence or absence of echocardiographic findings of cardiac tamponade in patients with PH. Forty-three studies (9 cohort studies and 34 case reports) with 1054 patients were included. The incidence of cardiac tamponade was significantly higher in patients with PH compared to those without PH, 2.0% (95% CI 1.2-3.2%) vs. 0.05% (95% CI 0.05-0.05%), p < 0.0001, OR 40.76 (95% CI 24.8-66.9). The incidence of tamponade in patients with a known pericardial effusion was similar in those with and without PH, 20.3% (95% CI 12.0-32.3%) and 20.9% (95% CI 18.0-24.1%), p = 0.9267, OR 0.97 (95% CI 0.50-1.87). In patients with tamponade, those with PH demonstrated a significantly higher in-hospital mortality than those without PH, 38.8% (95% CI 26.4-52.8%) vs. 14.4% (95% CI 14.2-14.6%), p < 0.0001, OR 3.77 (95% CI 2.12-6.70). Long-term mortality in patients with tamponade was significantly lower in those with PH than in those without PH, 45.5% (95% CI 33.0-58.5%) vs. 59.1% (95% CI 54.7-63.4%), p = 0.0258, OR 0.576 (95% CI 0.33-1.01). However, after stratifying by non-malignant etiologies, the long-term mortality benefit for those with PH disappeared. In the studies that described specific echocardiographic findings of cardiac tamponade, only 10.5% of patients with PH and tamponade showed right atrial and right ventricular collapse. When evaluating patients with pericardial effusions, physicians must recognize the effects of underlying PH on the incidence, in-hospital and long-term mortality rates, and potentially atypical echocardiographic presentation of cardiac tamponade.

Point of Care Ultrasound Diagnosis of Maxillary Artery Pseudoaneurysm in the Emergency Department.

A pseudoaneurysm results from a tear in a vessel wall. This leads to extravasation of blood into adjacent tissue and eventual formation of a fibrous sac that maintains continuity with the lumen. These vascular injuries very rarely occur in deeper vessels of the face (e.g. maxillary artery) due to protection from structures like the bony mandible and parotid gland. If left untreated, these pseudoaneurysms can lead to infection, thromboembolism, hemorrhage, and compression of surrounding structures such as facial nerve branches. Pseudoaneurysms are typically diagnosed by advanced imaging techniques including computed tomography angiography and magnetic resonance angiography. However, these tests require time to perform and interpret, are costly, and take place outside the patient care area. Computed tomography also confers ionizing radiation. Fortunately, point of care ultrasound (POCUS) is a readily available, dynamic imaging tool that can be performed at the bedside. Here we present the first known case report of a maxillary artery pseudoaneurysm diagnosed by POCUS in the emergency department. Early differentiation from a typical hematoma led to rapid management in the form of a compression bandage, as well as expedited consultation to the appropriate services.

Invasive Fungus Balls Diagnosed by Point-of-Care Ultrasound in the Emergency Department.

BACKGROUND: Genitourinary tract fungus balls are a rare complication of urinary tract infections (UTI). They arise from dense aggregations of hyphae that combine with surrounding urothelial cells and debris. Symptoms can progress to urosepsis and systemic dissemination. Unfortunately, fungus balls may remain unrecognized. Even with computed tomography (CT) and magnetic resonance imaging, fungus balls can be mistaken for malignancies, urinary calculi, or blood clots. CASE REPORT: A 54-year-old man with past medical history of type 2 diabetes mellitus presented to the Emergency Department (ED) reporting urinary retention for one week. He had undergone Foley catheter insertion three separate times for this symptom over the past five weeks. The emergency physicians expected that point-of-care ultrasound (POCUS) would show a distended, anechoic bladder. Instead, there were multiple discrete, gravitationally-dependent, circular echogenic masses without posterior acoustic shadowing, floating freely within a mosaic-like background of mixed echogenicity urine. These findings, together with the CT scan subsequently ordered, raised concern for fungus balls. Instead of being discharged with antibiotics for UTI, the patient was admitted for antifungal coverage, with contingency plans for bladder irrigation and antifungal instillation as needed. WHY SHOULD AN EMERGENCY PHYSICIAN BE AWARE OF THIS?: This is the first known case report in which emergency physicians used POCUS to diagnose invasive fungus balls in the ED. POCUS findings led to further CT imaging and specialist consultation that otherwise would not have occurred. Rather than discharge with antibiotics, goal-directed management and appropriate disposition mitigated the risk of systemic decompensation in an immunocompromised patient.

A Prospective Comparison of Standard Technique, Doppler Ultrasonography, and Pressure Waveform Analysis for Confirming Intraosseous Catheter Placement.

Purpose: Intraosseous (IO) catheters allow healthcare workers to rapidly administer fluids and medications to critically ill patients when intravenous access is inadequate or unable to be obtained. An improperly placed IO catheter can lead to delays in care, as well as serious complications such as limb necrosis. Methods: In this single-center, prospective, observational study, we compared 2 established methods of confirming proper IO catheter placement to a novel pressure waveform analysis technique in which the IO catheter is attached to a standard pressure transducer. Attaching a pressure transducer to a properly placed IO catheter produces a pulsatile waveform. Misplacement of the IO catheter produces a flatline waveform. Results: Of 42 IO catheters, 8 (19%) were incorrectly placed per the waveform analysis technique. Compared to the pressure waveform analysis technique, the standard method and the power Doppler method incorrectly classified 4/8 (50%) and 5/8 (62.5%) of the misplaced catheters, respectively. The standard method had a higher positive predictive value for detecting incorrectly placed IO catheters than the power Doppler method (100% vs 63%, respectively). Blinded reviewers demonstrated better agreement using the pressure waveform analysis technique than using power Doppler (k = 0.77 vs k = 0.58, respectively). Conclusion: The standard and power Doppler ultrasonography techniques identify incorrectly placed IO catheters sub-optimally. The pressure waveform analysis technique is more accurate than the standard of care and has superior interrater agreement compared to the ultrasound method of confirmation. With more than 500 000 IO catheters placed in the United States each year, this novel technique may improve overall IO safety. Trial Registration Number: NCT03908879.

What echocardiographic findings differentiate acute pulmonary embolism and chronic pulmonary hypertension?

BACKGROUND: Pulmonary embolism (PE) and pulmonary hypertension (PH) are potentially fatal disease states. Early diagnosis and goal-directed management improve outcomes and survival. Both conditions share several echocardiographic findings of right ventricular dysfunction. This can inadvertently lead to incorrect diagnosis, inappropriate and potentially harmful management, and delay in time-sensitive therapies. Fortunately, bedside echocardiography imparts a few critical distinctions. OBJECTIVE: This narrative review describes eight physiologically interdependent echocardiographic parameters that help distinguish acute PE and chronic PH. The manuscript details each finding along with associated pathophysiology and summarization of the literature evaluating diagnostic utility. This guide then provides pearls and pitfalls with high-quality media for the bedside evaluation. DISCUSSION: The echocardiographic parameters suggesting acute or chronic right ventricular dysfunction (best used in combination) are: 1. Right heart thrombus (acute PE) 2. Right ventricular free wall thickness (acute ≤ 5 mm, chronic > 5 mm) 3. Tricuspid regurgitation pressure gradient (acute ≤ 46 mmHg, chronic > 46 mmHg, corresponding to tricuspid regurgitation maximal velocity ≤ 3.4 m/sec and > 3.4 m/sec, respectively) 4. Pulmonary artery acceleration time (acute ≤ 60-80 msec, chronic < 105 msec) 5. 60/60 sign (acute) 6. Pulmonary artery early-systolic notching (proximally-located, higher-risk PE) 7. McConnell's sign (acute) 8. Right atrial enlargement (equal to left atrial size suggests acute, greater than left atrial size suggests chronic). CONCLUSIONS: Emergency physicians must appreciate the echocardiographic findings and associated pathophysiology that help distinguish acute and chronic right ventricular dysfunction. In the proper clinical context, these findings can point towards PE or PH, thereby leading to earlier goal-directed management.

Delayed Iatrogenic Bladder Rupture Diagnosed by POCUS in the Emergency Department.

Bladder rupture is an uncommon injury that leads to significant morbidity and mortality. Though occurring mostly due to trauma, this life-threatening pathology may also occur spontaneously or after a procedure such as transurethral resection of bladder tumor (TURBT). Computed tomography (CT) cystography is the standard imaging modality for diagnosis. However, this test is unlikely to be ordered in a patient with undifferentiated abdominal pain unless there is specific suspicion for this diagnosis. In our emergency department, a 48 year-old male with history of bladder cancer and TURBT two weeks prior to arrival presented with severe abdominal pain and difficulty urinating for 3 days. Point of care ultrasound (POCUS) revealed an irregularly shaped bladder, likely site of bladder rupture, and large amount of abdominal free fluid with sediment. These findings prompted an expedited diagnostic CT scan with cystography. Emergent exploratory laparotomy ultimately confirmed a small bladder defect with 2.5 L of urinary ascites. The diagnosis of non-traumatic bladder rupture can be overlooked in patients presenting with a peritonitic abdominen. The typically ordered test for such patients is standard CT, which carries a high false-negative rate for bladder rupture. This case highlights the utility of POCUS in facilitating a rapid diagnosis.

Pericardial tamponade: A comprehensive emergency medicine and echocardiography review.

INTRODUCTION: Pericardial tamponade requires timely diagnosis and management. It carries a high mortality rate. OBJECTIVE: This review incorporates available evidence to clarify misconceptions regarding the clinical presentation, while providing an in-depth expert guide on bedside echocardiography. It also details the decision-making strategy for emergency management including pericardiocentesis, along with pre- and peri-procedural pearls and pitfalls. DISCUSSION: Pericardial effusions causing tamponade arise from diverse etiologies across acute and sub-acute time courses. The most frequently reported symptom is dyspnea. The classically taught Beck's triad (which includes hypotension) does not appear commonly. Echocardiographic findings include: a pericardial effusion (larger size associated with tamponade), diastolic right ventricular collapse (specific), systolic right atrial collapse (sensitive), a plethoric non-collapsible inferior vena cava (sensitive), and sonographic pulsus paradoxus. Emergent pericardiocentesis is warranted by hemodynamic instability, impending deterioration, or cardiac arrest. Emergent surgical indications include type A aortic dissection causing hemopericardium, ventricular free wall rupture after acute myocardial infarction, severe chest trauma, and iatrogenic hemopericardium when bleeding cannot be controlled percutaneously. Pre-procedure management includes blood products for patients with traumatic hemopericardium; gentle intravenous fluids to hypotensive, hypovolemic patients with consideration for vasoactive medications; treatment of anticoagulation, coagulopathies, and anemia. Positive-pressure ventilation and intravenous sedation can lower cardiac output and should be avoided if possible. Optimal location for echocardiography-guided pericardiocentesis is the largest, shallowest fluid pocket with no intervening vital structures. Patient positioning to prevent hypoxia and liberal amounts of local anesthesia can facilitate patients remaining still. Safe needle guidance and confirmation of catheter placement is achieved using low-depth sonographic views, injection of agitated saline, and evaluation of initial aspirate for hemorrhage. Pericardial fluid should be drained slowly to avoid pericardial decompression syndrome. CONCLUSION: An understanding of the pathophysiology, clinical presentation, echocardiographic findings, and time-sensitive management of pericardial tamponade is essential for emergency physicians.

Teaching Module on Ultrasound-Guided Venous Access Using a Homemade Gel Model for Fourth-Year Medical Students.

INTRODUCTION: Evidence supports an ultrasound-guided approach in patients with difficult vascular access. Prior research on teaching ultrasound-guided intravenous access has included only small groups of first- and second-year medical students. METHODS: We enrolled fourth-year medical students in our teaching module. The module featured a 6-minute prelearning narrated lecture and 5-minute orientation, followed by ultrasound-guided IV placement on homemade gel models. Facilitators were emergency medicine (EM) residents with a prespecified level of procedural ultrasound skills according to EM milestones. Students completed pre- and postmodule surveys. Facilitators completed the Directly Observed Procedural Skills Evaluation. Primary outcomes included global rating, proficiency on six procedural skills, and perceived learning. RESULTS: Our module was completed by 150 fourth-year medical students (94% of the class); 84% cannulated the vein in one attempt. We used a global rating scale to describe the students' cannulation abilities; 59% were trusted to perform this procedure with direct supervision and coaching, 29% with indirect supervision, and 8% without supervision. There was no association between a student's order of attempting IV access within the group and global rating (p = .41). Students reported increased understanding of indications, antecubital anatomy, sonographic anatomy, and procedural comfort (12%, 29%, 38%, and 65% improvement pre- vs. postmodule, respectively; p < .001). DISCUSSION: Our module enabled more than one-third of fourth-year medical students to achieve an indirect supervision or better level of proficiency in ultrasound-guided IV access, with significant improvements in perceived knowledge. This module may be useful for other educators facilitating the transition to residency.

A Multicenter, Prospective Study Comparing Subxiphoid and Parasternal Views During Brief Echocardiography: Effect on Image Quality, Acquisition Time, and Visualized Anatomy.

BACKGROUND: Recent literature has suggested echocardiography (echo) may prolong pauses in chest compressions during cardiac arrest. OBJECTVES: We sought to determine the impact of the sonographic approach (subxiphoid [SX] vs. parasternal long [PSL]) on time to image completion, image quality, and visualization of cardiac anatomy during echo, as performed during Advanced Cardiac Life Support. METHODS: This was a multicenter, randomized controlled trial conducted at 29 emergency departments (EDs) assessing the time to image acquisition and image quality between SX and PSL views for echo. Patients were enrolled in the ED and imaged in a simulated cardiac arrest scenario. Clinicians experienced in echo performed both SX and PSL views, first view in random order. Image quality and time to image acquisition were recorded. Echos were evaluated for identification of cardiac landmarks. Data are presented as percentages or medians with interquartile ranges (IQRs). RESULTS: We obtained 6247 echo images, comprising 3124 SX views and 3123 PSL. Overall time to image acquisition was 9.0 s (IQR 6.7-14.1 s). Image acquisition was shorter using PSL (8.8 s, IQR 6.5-13.5 s) compared with SX (9.3 s, IQR 6.7-15.0 s). The image quality was better with the PSL view (3.86 vs. 3.54; p < 0.0001), twice as many SX images scoring in the worst quality category compared with PSL (8.6% vs. 3.7%). Imaging of the pericardium, cardiac chambers, and other anatomic landmarks was superior with PSL imaging. CONCLUSIONS: Echo was performed in < 10 s in > 50% of patients using either imaging technique. Imaging using PSL demonstrated improved image quality and improved identification of cardiac landmarks.

Cardiac Ultrasound for Pediatric Emergencies.

Cardiac point-of-care ultrasound (POCUS) provides real-time views of the heart to answer specific questions in a timely manner. This is a valuable tool for managing pediatric patients, from those with congenital heart disease to those who are critically ill. The main echocardiographic findings of pericardial tamponade consist of a pericardial effusion, diastolic right ventricular collapse, systolic right atrial collapse, and a plethoric inferior vena cava with minimal respiratory variation. The main echocardiographic findings of hypertrophic cardiomyopathy consist of increased wall thickness (concentric or eccentric), systolic anterior motion of the anterior mitral leaflet, and a dynamic sub-aortic left ventricular outflow tract obstruction. Additional uses of cardiac POCUS include assessment of dilated cardiomyopathy and the detection of pediatric congenital heart disease, including detection of a patent ductus arteriosus. The use of POCUS in the pediatric population is supported by societal position statements and is expected to develop further with increasingly robust education and training. [Pediatr Ann. 2021;50(10):e424-e431.].

National Survey of Point-of-Care Ultrasound Scholarly Tracks in Emergency Medicine Residency Programs.

INTRODUCTION: Residency scholarly tracks are educational programs, designed to help trainees develop an area of expertise. Although the breadth of residency point-of-care ultrasound (POCUS) education has developed considerably in recent years, there is no literature to date describing scholarly tracks specifically in POCUS. In this study we sought to determine the prevalence, characteristics, and outcomes of POCUS scholarly tracks in emergency medicine (EM). METHODS: This was a cross-sectional survey of EM residency programs accredited by the Accreditation Council for Graduate Medical Education. Surveys were distributed between March-August 2020 using a listserv followed by targeted emails to residency and ultrasound leadership. We summarized data using descriptive statistics, and performed logistic regression to identify factors associated with a POCUS scholarly track. RESULTS: Of 267 residency programs 199 (74.5%) completed the survey. Fifty-seven (28.6%) had a POCUS scholarly track as of the 2019-2020 academic year. Scholarly tracks in POCUS were more common in university-based/academic sites and larger residency programs. Of the 57 programs with POCUS scholarly tracks, 48 (84.2%) required residents to present at least one POCUS lecture, 45 (78.9%) required residents to serve as instructor at a hands-on workshop, and 42 (73.7%) required residents to participate in quality assurance of departmental POCUS scans. Only 28 (49.1%) tracks had a structured curriculum, and 26 (45.6%) required POCUS research. In total, 300 EM residents completed a POCUS scholarly track over the past three academic years, with a median of 4 (2-9) per program. Seventy-five (25.0%) proceeded to a clinical ultrasound fellowship after residency graduation, with a median of 1 (interquartile range 0-2) per program. A total of 139 POCUS-specific abstracts (median 2 [0-3]) and 80 peer-reviewed manuscripts (median 1 [0-2]) were published by scholarly track residents over the past three years. CONCLUSION: This survey study describes the current prevalence, characteristics, and outcomes of POCUS scholarly tracks across EM residency programs. The results may inform the decisions of residency programs to create these tracks.

What are the echocardiographic findings of acute right ventricular strain that suggest pulmonary embolism?

INTRODUCTION: Pulmonary embolism (PE) is a potentially fatal disease encountered in the hospital setting. Prompt diagnosis and management can improve outcomes and survival. Unfortunately, a PE may be difficult to diagnose in a timely manner. Point-of-care ultrasound (POCUS) can assist in the evaluation for suspected PE by assessing for acute right ventricular strain. Physicians should thus be aware of these echocardiographic findings. OBJECTIVE: This manuscript will review ten echocardiographic findings of right ventricular strain that may suggest a diagnosis of PE. It will provide a description of each finding along with the associated pathophysiology. It will also summarize the literature for the diagnostic utility of echocardiography for this indication, while providing reference parameters where applicable. Along with labeled images and video clips, the review will then illustrate how to evaluate for each of the ten findings, while offering pearls and pitfalls in this bedside evaluation. DISCUSSION: The ten echocardiographic findings of right ventricular strain are: increased right ventricle: left ventricle size ratio, abnormal septal motion, McConnell's sign, tricuspid regurgitation, elevated pulmonary artery systolic pressure, decreased tricuspid annular plane systolic excursion, decreased S', pulmonary artery mid-systolic notching, 60/60 sign, and speckle tracking demonstrating decreased right ventricular free wall strain. CONCLUSIONS: Physicians must recognize and understand the echocardiographic findings and associated pathophysiology of right ventricular strain. In the proper clinical context, these findings can point toward a diagnosis of PE and thereby lead to earlier initiation of directed management.

Milestone Approach to Designing a Point-of-Care Ultrasound Curriculum for Transition-to-Residency Programs in the United States.

Phenomenon: Point-of-care ultrasound is fast becoming standard clinical bedside practice for diverse specialties. Medical schools are responding by adding ultrasound education, though the majority use it to supplement the learning of basic sciences. Point-of-care ultrasound practice-based clinical skills education is rare. There also is a lack of standardization across curricula, leading to much variability in the ultrasound skills that medical students from different schools bring to residency. To best inform a point-of-care ultrasound curriculum for our Transition-to Residency program, we investigated literature on 1) how medical students are being prepared for use of point-of-care ultrasound in clinical practice, 2) what skills are being taught, 3) what point-of-care ultrasound skills residency programs expect from incoming residents. Approach: We reviewed literature to identify curricula in U.S. medical schools that teach the concepts, knowledge, and skills related to point-of-care ultrasound. We also mapped point-of-care ultrasound expectations set forth by the Entrustable Professional Activities for undergraduate medical education to the specialty-specific milestones identified by the Accreditation Council for Graduate Medical Education. Additionally, we reviewed specialty-specific professional organizations for position statements and guidelines describing the point-of-care ultrasound skills expected for practicing physicians in their respective specialties. The goal was to identify any needs and gaps in education regarding point-of-care ultrasound across the undergraduate to graduate medical education continuum to practice. Findings: We found seven published point-of-care ultrasound curricula for medical students. There was wide variability in these curricula regarding what point-of-care ultrasound content is being taught, as well as when and how this skill is taught. No Entrustable Professional Activity listed point-of-care ultrasound as a skill requirement for graduating medical students. For graduate medical education, there was wide variability across specialties in residency milestones related to point-of-care ultrasound; some (e.g., emergency medicine) listed extensive milestones while others (e.g., internal medicine) listed none. However, we found that many specialty-specific professional organizations do list detailed point-of-care ultrasound expectations for their practicing physicians. Insights: As point-of-care ultrasound is fast becoming common practice across many specialties, standardization of education and related competencies-similar to other clinical skills training-is necessary across medical schools. Mapping point-of-care ultrasound expectations to current teaching across the continuum from undergraduate to graduate medical education may allow schools to tailor point-of-care ultrasound training for Transition-to-Residency programs. We provide a sample pilot point-of-care ultrasound curriculum that we designed for our Transition-to-Residency course.

Integrating Basic and Clinical Sciences Using Point-of-Care Renal Ultrasound for Preclerkship Education.

Introduction: Point-of-care ultrasound (POCUS) is a valuable asset in bedside clinical care. Undergraduate medical education is increasingly using POCUS as an adjunct tool for teaching anatomy, pathophysiology, and physical exam in an integrated manner. Many medical schools teach content in an organ systems-based format in the preclerkship years. POCUS teaching can be very effectively tailored to specific organ systems. Though pilot curricula for generalized ultrasound education exist, few teach organ systems-based content using POCUS. To address this gap, we designed and implemented an integrated POCUS module to supplement anatomy, pathophysiology, and physical exam teaching in the renal course. Methods: The module consisted of (1) a 30-minute didactic lecture introducing students to renal ultrasound technique and image interpretation and (2) a practical hands-on skills session. Pre- and postmodule surveys assessed the efficacy and impact of the curriculum. Results: A total of 31 first-year medical students completed the POCUS renal curriculum. A majority reported that the module positively affected their understanding of renal pathophysiology and the physical exam. They also reported increased confidence in using POCUS to detect renal pathology and make clinical decisions. Discussion: It was feasible to implement a POCUS curriculum to supplement integrated teaching of renal system concepts in the first year of medical school, and students found POCUS teaching valuable. POCUS provides educators with another tool to integrate basic and clinical sciences with hands-on relevant clinical skills practice in early medical school years.

Point-of-care echocardiography for the evaluation of right-to-left cardiopulmonary shunts: a narrative review.

Right-to-left pulmonary and cardiac shunts (RLS) are important causes of refractory hypoxia in the critically-ill perioperative patient. Using a point-of-care ultrasound (POCUS) agitated saline bubble study for an early diagnosis allows patients with clinically significant RLSs to receive expedited therapy. This narrative review discusses the principles of agitated saline ultrasonography as well as the role of POCUS in detecting the most common RLS types seen in the intensive care unit, including patent foramen ovale, atrial septal defects, and pulmonary arterio-venous malformations. An illustrated discussion of the procedure, as well as shunt-enhancing maneuvers (Valsalva or lung recruitment maneuver with subsequent rapid release) is provided. With the wide dissemination of bedside ultrasound within the perioperative and critical care arena, POCUS practitioners should be knowledgeable of the potential pitfalls leading to both false-positive and false-negative studies. False-positive studies may be due to congenital abnormalities, mischaracterization of intrapulmonary shunts as intracardiac shunts (and vice versa), or evidence of the Valsalva effect. False negatives are typically due to respiratory-phasic variation, performing an inadequate shunt-enhancing maneuver, inadequate injection of agitated saline, or pathophysiologic states of elevated left atrial pressure. Finally, alternative POCUS methods for determining presence of an RLS in patients with poor echocardiographic windows are discussed, with a focus on pulsed-wave Doppler interrogation of arterial signals.

RéSUMé: Les shunts pulmonaires et cardiaques de droite à-gauche sont d'importantes causes d'hypoxie réfractaire chez le patient périopératoire en état critique. En réalisant un test aux bulles sous échographie au chevet, un diagnostic rapide de shunt de droite à-gauche peut être posé, favorisant le traitement rapide des patients présentant un shunt de droite à-gauche significatif d'un point de vue clinique. Ce compte rendu narratif présente les principes de l'échographie avec test aux bulles ainsi que le rôle de l'échographie au chevet pour détecter les types les plus répandus de shunts de droite à-gauche à l'unité de soins intensifs, notamment les communications interauriculaires, les foramens ovales perméables et les malformations artérioveineuses pulmonaires. Nous présentons également une discussion illustrée de l'intervention, ainsi que des manœuvres augmentant le shunt (manœuvre de Valsalva ou de recrutement pulmonaire avec cessation rapide subséquente). Étant donné l'utilisation répandue de l'échographie dans le domaine des soins périopératoires et critiques, les praticiens de l'échographie au chevet devraient être conscients des écueils potentiels menant à des résultats faux positifs ou faux négatifs. Les résultats faux positifs peuvent être dus à des anomalies congénitales, à la caractérisation erronée de shunts intrapulmonaires en tant que shunts intracardiaques (et vice versa) ou à l'efficacité de l'effet Valsalva. Les résultats faux négatifs sont fréquemment dus à des variations des phases respiratoires, à la réalisation d'une manœuvre inadéquate d'amélioration du shunt, à l'injection inadéquate de solution saline agitée, ou à des états physiopathologiques de pression auriculaire gauche élevée. Enfin, les méthodes alternatives d'échographie au chevet visant à déterminer la présence d'un shunt de droite à-gauche chez les patients présentant des fenêtres échocardiographiques sous-optimales sont discutées, avec une emphase sur l'interrogation des signaux artériels par Doppler pulsé.

Point-of-Care Ultrasound for Intubation Confirmation of COVID-19 Patients.

The novel coronavirus disease of 2019 (COVID-19) is associated with significant morbidity and mortality, as well as large numbers of patients requiring endotracheal intubation. While much of the literature has focused on the intubation technique, there is scant discussion of intubation confirmation. Herein, we discuss the limitations of traditional confirmatory approaches, summarize the literature supporting a role for point-of-care ultrasound in this application, and propose an algorithm for intubation confirmation among COVID-19 patients.