Can emergency medicine residents detect acute deep venous thrombosis with a limited, two-site ultrasound examination?

Deep venous thrombosis (DVT) diagnostics: gleaning insights from point-of-care ultrasound (PoCUS) techniques in emergencies: a systematic review and meta-analysis

BACKGROUND

The assessment of deep venous thrombosis (DVT) is clinically difficult diagnosis. The "gold standard test" for DVT diagnosis is venography; however, various point-of-care ultrasound (POCUS) protocols have been suggested for DVT evaluation in the emergency department.

AIMS

This review evaluated the role of different POCUS protocols in diagnosing DVT in the emergency department.

METHODS

A systematic review and meta-analysis was conducted based of PRISMA guideline and registered on PROSEPRO (CRD42023398871). An electronic database search in Embase, PubMed, ScienceDirect, and Google scholar and a manual search were performed to identify eligible studies till February 2023. Quality Assessment of Diagnostic Accuracy Studies tool (QUADAS-2) was used to assess the risk of bias in included studies. Quantitative analysis was carried out using STATA 16 and Review Manager software (RevMan 5.4.1). Sensitivity, specificity of POCUS protocols for DVT diagnosis compared to reference standard test was calculated.

RESULTS

Heterogeneity was identified between 26 included studies for review. The pooled sensitivity, specificity, PPV, and NPV for the 2-point POCUS protocol were 92.32% (95% CI: 87.58-97.06), 96.86% (95% CI: 95.09-98.64), 88.41% (95% CI: 82.24-94.58) and 97.25% (95% CI: 95.51-98.99), respectively. Similarly, the pooled sensitivity, specificity, PPV, and NPV for 3-point POCUS were 89.15% (95% CI: 83.24-95.07), 92.71% (95% CI: 89.59-95.83), 81.27% (95% CI: 73.79-88.75), and 95.47% (95% CI: 92.93-98). The data pooled for complete compression ultrasound, and whole-leg duplex ultrasound also resulted in a sensitivity and specificity of 100% (95% CI: 98.21-100) and 97.05% (95% CI: 92.25-100), respectively. On the other hand, the time from triage to DVT diagnosis was significantly shorter for emergency physician-performed POCUS than diagnostic tests performed by radiologists.

CONCLUSION

The diagnostic performance of POCUS protocols performed by emergency physicians was excellent. Combined with the significant reduction in time to diagnosis. POCUS can be used as the first-line imaging tool for DVT diagnosis in the emergency department. We also recommended that attending emergency physicians with POCUS training are present during DVT diagnosis to improve diagnostic performance even though high diagnostic performance is observed even with the minimum training.

EFSUMB Clinical Practice Guidelines for Point-of-Care Ultrasound: Part One (Common Heart and Pulmonary Applications) LONG VERSION

AIMS

 To evaluate the evidence and produce a summary and recommendations for the most common heart and lung applications of point-of-care ultrasound (PoCUS).

METHODS

 We reviewed 10 clinical domains/questions related to common heart and lung applications of PoCUS. Following review of the evidence, a summary and recommendation were produced, including assignment of levels of evidence (LoE) and grading of the recommendation, assessment, development, and evaluation (GRADE). 38 international experts, the expert review group (ERG), were invited to review the evidence presented for each question. A level of agreement of over 75 % was required to progress to the next section. The ERG then reviewed and indicated their level of agreement regarding the summary and recommendation for each question (using a 5-point Likert scale), which was approved if a level of agreement of greater than 75 % was reached. A level of agreement was defined as a summary of "strongly agree" and "agree" on the Likert scale responses.

FINDINGS AND RECOMMENDATIONS

 One question achieved a strong consensus for an assigned LoE of 3 and a weak GRADE recommendation (question 1). The remaining 9 questions achieved broad agreement with one assigned an LoE of 4 and weak GRADE recommendation (question 2), three achieving an LoE of 3 with a weak GRADE recommendation (questions 3-5), three achieved an LoE of 3 with a strong GRADE recommendation (questions 6-8), and the remaining two were assigned an LoE of 2 with a strong GRADE recommendation (questions 9 and 10).

CONCLUSION

 These consensus-derived recommendations should aid clinical practice and highlight areas of further research for PoCUS in acute settings.

The Use of Point-of-Care Ultrasound (POCUS) in the Diagnosis of Deep Vein Thrombosis

Acute lower extremity proximal deep venous thrombosis (DVT) requires accurate diagnosis and treatment in order to prevent embolization and other complications. Point-of-care ultrasound (POCUS), a clinician performed, and clinician interpreted bedside ultrasound examination has been increasingly used for DVT evaluation mainly in the urgent and critical care setting, but also in the ambulatory clinics and the medical wards. Studies have demonstrated that POCUS has excellent diagnostic accuracy for acute proximal DVT when performed by well-trained users. However, there is significant heterogeneity among studies on the necessary extent of training and universally acceptable standardized education protocols are needed. In this review, we summarize the evidence that supports the use of POCUS to diagnose acute proximal DVT and focus on methodology and current technology, sensitivity and specificity, pre-test probability and the role of D-dimer, time and resources, education, limitations, and future directions.

Agreement between emergency physicians and radiologists for the diagnosis of deep venous thrombosis with compression ultrasound: a prospective study

INTRODUCTION

The time factor in diagnosis and management of a deep vein thrombosis of the lower extremities (LE DVT) is of increasing importance in the era of crowding of emergency departments (ED). Current techniques used to detect LE DVT include a two-point regional compression ultrasound (rCUS), yet assessments are usually performed only during office hours. Outside office hours ultrasonography is postponed and low molecular weight heparin (LMWH) prescribed.

OBJECTIVES

Primary outcome of the study was to assess the level of agreement in rCUS for LE DVT when performed by Dutch emergency physicians compared to rCUS by a radiologist. Secondary outcome was time to diagnosis.

METHOD

We performed a single-blind cohort study. All consecutive patients aged 18 years and older attending the ED with clinical suspicion of LE DVT were considered eligible for study enrolment. rCUS was ordered at the radiology department; subsequently, the bedside rCUS examination was also performed in the ED by the emergency physicians or ED residents.

RESULTS

A total of 138 patients were included, of whom 28 patients were diagnosed with DVT by a radiologist. Emergency physicians and radiologists showed comparable agreement [absolute agreement 94% (P < 0.001), Cohen's Kappa 0.87]. Emergency physicians decreased overall time to diagnosis by 01:04 h, ED residents showed comparable results. During out-of-office hours, time benefit was 16:39 h on weekdays and 18:40 h during weekends.

CONCLUSION

Emergency physicians show comparable agreement in diagnosing LE DVT using rCUS when compared to radiologists. Average time benefit is over an hour, thereby reducing unnecessary waiting and improving time to disposition. ED residents demonstrated similar results in both agreement and time-saving.

Analysis of lawsuits related to diagnostic errors from point-of-care ultrasound in internal medicine, paediatrics, family medicine and critical care in the USA

PURPOSE

The purpose of this study is to identify the extent of diagnostic error lawsuits related to point-of-care ultrasound (POCUS) in internal medicine, paediatrics, family medicine and critical care, of which little is known.

METHODS

We conducted a retrospective review of the Westlaw legal database for indexed state and federal lawsuits involving the diagnostic use of POCUS in internal medicine, paediatrics, family medicine and critical care. Retrieved cases were reviewed independently by three physicians to identify cases relevant to our study objective. A lawyer secondarily reviewed any cases with discrepancies between the three reviewers.

RESULTS

Our search criteria returned 131 total cases. Ultrasound was mentioned in relation to the lawsuit claim in 70 of the cases returned. In these cases, the majority were formal ultrasounds performed and reviewed by the radiology department, echocardiography studies performed by cardiologists or obstetrical ultrasounds. There were no cases of internal medicine, paediatrics, family medicine or critical care physicians being subjected to adverse legal action for their diagnostic use of POCUS.

CONCLUSION

Our results suggest that concerns regarding the potential for lawsuits related to POCUS in the fields of internal medicine, paediatrics, family medicine and critical care are not substantiated by indexed state and federal filed lawsuits.

Evaluation of short training session for venous limited compression ultrasonography: prospective multicenter study

BACKGROUND

Venous limited compression ultrasonography (VLCU) is recommended in case of suspicion of deep venous thrombosis (DVT). Current training pathways are rather long and include experiential phase. This aim of this study was to investigate the efficacy of a short training session for VLCU without experiential phase. The training session was applied in residents without previous ultrasound skills. Program included operation of ultrasound device and interpretation of venous images. Included patients were older than 18 years and had a suspicion of DVT. After realization of VLCU using usual technique, residents reported the dynamic compressibility of the femoral and popliteal veins, the presence or not of a visible thrombus, self-reported difficulty and duration. Patients then underwent a whole leg ultrasonography (WLCU) in the local laboratory which was blinded to VLCU results. The main criterion was the negative-predictive value (NPV) of VLCU for the absence of proximal DVT diagnosed with WLCU. Secondary criteria were VLCU diagnostic performances, rate of inability to conclude, difficulty and duration. For a NPV of 95 ± 6%, the needed number of patients was 96. This study was approved by the ethical committee.

RESULTS

102 patients were analyzed. 46 residents were trained. A DVT was diagnosed by WLCU in 18 patients (prevalence of 17.6% [95% CI 11-26%]). VLCU detected 15 DVT (NPV of 96% [95% CI 89-99%]). The positive likelihood ratio was 9.9, the negative likelihood ratio 0.19 and Cohen's Kappa 0.62 [95% CI 0.52-0.71]. The sensitivity was 83% [CI 95% 60-94%] and specificity 88% [CI 95% 79-93%]. The mean number of VLCU by residents was 2.3 ± 2.1, median 2 (minimum 1, maximum 8). Mean duration was 3.4 min, difficulty was 3.7 ± 2.

CONCLUSION

The principal objective, NPV 96% [95% CI 89-99%], was achieved. However, this short training session was inadequate to allow ruling-out a DVT with sufficient security. Thus, the experiential phase seems to be essential.

Accuracy of three-point compression ultrasound for the diagnosis of proximal deep-vein thrombosis in emergency department

Background:

This study aimed to assess the accuracy of three-point compression ultrasonography (3PCUS) performed for the diagnosis of proximal deep-vein thrombosis (DVT) in Emergency Department (ED) compared with the results of duplex US (DUS) (whole-leg compression ultrasound).

Materials and Methods:

The current prospective cross-sectional study with diagnostic test assessment was conducted on adult patients who were referred to the ED of a general teaching hospital in Shiraz, southern part of Iran (September 2016–May 2017), suspected of lower-extremity DVT, using a convenience sampling. The results of 3PCUS performed by ED residents were compared with the results of DUS performed by the radiology residents, which was considered as a criterion standard.

Results:

A total of 240 patients were enrolled, with a mean (standard deviation) age of 59.46 (16.58). 3PCUS has a sensitivity and a specificity of 100% (95% confidence interval [CI], 96.55%–100%) and 93.33% (95% CI, 87.72%–96.91%), respectively, in comparison with DUS (whole-leg compression ultrasound). Negative predictive value and positive predictive value were 100% and 92.11% (95% CI, 86.12%–95.64%), respectively, with an accuracy of 96.25% (95% CI, 93%–98.27%).

Conclusion:

The results of this study showed that 3PCUS of the lower extremities with a portable US machine, performed by the ED's residents, can accurately identify the presence or absence of lower-extremity DVT.

Diagnostic Accuracy of a Three-point Compression Ultrasonography Performed by Emergency Medicine Resident for the Diagnosis of Deep Vein Thrombosis: a Prospective Diagnostic Study

Introduction:

Deep vein thrombosis (DVT) is a common cause of admission to the emergency departments (ED). Doppler ultrasonography of the entire lower limb is the first-line imaging modality. But most EDs do not access to full-time radiologists which can lead to delayed diagnosis.

Aim:

The aim of this study was to evaluate the diagnostic accuracy of three-point compression ultrasonography performed by emergency medicine resident for diagnosis of DVT.

Methods:

This prospective diagnostic study was carried out at Imam Khomeini Hospital in Sari from March 2018 to November 2018. For all patients with suspected lower extremity DVT, first bedside 3-point compression ultrasound were performed by a third year emergency medicine resident at ED. Then Doppler ultrasonography were performed by a radiologist in the radiology department, as a reference test. Sensitivity, specificity, and positive predictive value of the three-point compression ultrasound performed by emergency medicine resident was calculated.

Results:

Of the 72 patients enrolled in our study, 50% of the patients were male, with an average age of 36±19 years. The mean of patient admission time to perform ultrasonography by an emergency medicine resident and radiologist were 14.05±19 and 216±140.1 minutes, respectively. The two groups had a statistically significant difference (P<0.0001). In ultrasonography performed by emergency medicine resident and doper ultrasonography by radiologist, 91.67% and 36.1% of patients were diagnosed with DVT, respectively. Although the ultrasonography performed by emergency medicine resident has a relatively low sensitivity (53.8%), it has a good specificity (85.7%). The positive and negative predictive value was 70 and 75%, respectively.

Conclusion:

Although the results of this study indicate insufficient sensitivity of bedside three-point compression ultrasound performed by emergency medicine resident in diagnosis of lower limb DVT, the specificity, positive and negative predictive values and positive likelihood ratio were almost appropriate.

Prevalence and Scope of Point-of-Care Ultrasound Education in Internal Medicine, Pediatric, and Medicine-Pediatric Residency Programs in the United States

OBJECTIVES

The purpose of this study was to determine the prevalence and scope of point-of-care ultrasound (US) education in internal medicine, pediatric, and medicine-pediatric residency programs nationwide.

METHODS

Program directors were surveyed between January and June 2016 with a 15-item online questionnaire to assess the state of point-of-care US training in their programs. The survey aimed to identify whether programs had an established point-of-care US curriculum and, if not, what reasons may have existed for a lack of point-of-care US training in their programs.

RESULTS

The survey was distributed to 685 program directors, and the response rate was 19.2%. Only 31.5% of respondents reported having a formal point-of-care US curriculum in their program, and in 12.4% of programs, there was no US training at all. The presence of point-of-care US training as reported by internal medicine (n = 64) and medicine-pediatric (n = 24) respondents showed formal point-of-care US curriculum rates of 37.5% and 43.5%, respectively. Pediatric programs (n = 24) reported limited point-of-care US training, with formal curriculum in only 12.4% of programs and 27.3% having no point-of-care US training at all. The most common reasons for lack of a point-of-care US curriculum among program directors were lack of trained faculty/instructors (70.4%), lack of guidelines/standards by governing societies (44.4%), and lack of the necessary technology (33.3%).

CONCLUSIONS

Less than half of residents with internal medicine training will have trained at a program with a point-of-care US curriculum, and point-of-care US training in pediatrics is even more limited. The major reason for the lack of point-of-care US education is a lack of trained faculty or instructors.

Comparison of 2-point and 3-point point-of-care ultrasound techniques for deep vein thrombosis at the emergency department: A meta-analysis

BACKGROUND

To our knowledge, so far, no studies have comprehensively examined the performance of 2-point and 3-point point-of-care compression ultrasound (POCUS) in the diagnosis of lower extremity deep vein thrombosis (DVT). The aim of this meta-analysis was to compare the performance of 2-point and 3-point POCUS techniques for the diagnosis of DVT and evaluate the false-negative rate of each POCUS method.

METHODS

A computerized search of the PubMed, EMBASE, and Cochrane library databases was performed to identify relevant original articles. Bivariate modeling and hierarchical summary receiver operating characteristic modeling were performed to compare the diagnostic performance of 2-point and 3-point POCUS. The pooled proportions of the false-negative rate for each POCUS method were assessed using a DerSimonian-Laird random-effects model. Meta-regression analyses were performed according to the patient and study characteristics.

RESULTS

Seventeen studies from 16 original articles were included (2-point, 1337 patients in 9 studies; 3-point, 1035 patients in 8 studies). Overall, 2-point POCUS had similar pooled sensitivity [0.91; 95% confidence interval (95% CI), 0.68-0.98; P = .86) and specificity (0.98; 95% CI, 0.96-0.99; P = .60) as 3-point POCUS (sensitivity, 0.90; 95% CI, 0.83-0.95 and specificity, 0.95; 95% CI, 0.83-0.99). The false-negative rates of 2-point (4.0%) and 3-point POCUS (4.1%) were almost similar. Meta-regression analysis showed that high sensitivity and specificity tended to be associated with an initial POCUS performer (including attending emergency physician > only resident) and separate POCUS training for DVT (trained > not reported), respectively.

CONCLUSION

Both 2-point and 3-point POCUS techniques showed excellent performance for the diagnosis of DVT. We recommend that POCUS-trained attending emergency physicians perform the initial 2-point POCUS to effectively and accurately diagnose DVT.

Point-of-Care Ultrasound in the Intensive Care Unit

Spreading beyond the realm of tertiary academic medical centers, point-of-care ultrasound in the intensive care unit is an important diagnostic tool. The real-time feedback garnered can lead to critical and clinically relevant changes in management and decrease potential complications. Bedside ultrasound evaluation in the intensive care setting with a small, portable equipment is well-suited for placement of central lines, lumbar puncture, thoracentesis or other bedside ICU procedures and in the evaluation of cardiac activity, pleural and abdominal cavity and the overall fluid volume. Formalized curriculums centering on point-of-care ultrasound are emerging that will enhance its applicability and relevance.

Current State of Point-of-care Ultrasound Usage in Canadian Emergency Departments

Background Point-of-care ultrasound (POCUS) has many applications in emergency medicine, which have been proven to improve patient outcomes. Training programs and well-established guidelines for its use are available, but Canadian adoption rates and attitudes toward this technology have not been recently assessed. Objectives This study aimed to provide a national assessment of the current use of POCUS in Canadian emergency departments (ED) including patterns of use, attitudes towards its role, descriptors of training experience, as well as barriers to increased utilization. Methods An electronic survey was sent to physician members of the Canadian Association of Emergency Physicians. The survey included questions related to demographics, attitudes towards POCUS, POCUS utilization, and barriers to POCUS use. Responses were statistically analyzed to identify significant associations. Results Responses demonstrated a strong association between POCUS training and amount of POCUS usage. Neither hospital type nor community type was associated with the degree of POCUS usage. POCUS was most widely adopted for Canadian Point of Care Ultrasound Society (CPOCUS) core applications and has increased since the last national survey. The most commonly reported barrier to increased POCUS adoption was the lack of training. Most physicians have formal POCUS training in core applications, and approximately one third have advanced training. Conclusions POCUS training and utilization appear to have increased since the last national assessment. This provides a foundation for future POCUS research.

The utility of superb microvascular imaging for the detection of deep vein thrombosis

Superb microvascular imaging (SMI) reduces motion artifacts significantly and allows visualization of low-velocity blood flow in vessels; thus, thrombi are clearly demonstrated compared to conventional B-mode and color Doppler imaging. Ultrasonographic images of the lower extremities of a 69-year-old woman with acute ischemic stroke complicated with deep vein thrombosis (DVT) are presented. Because SMI allows visualization of low-velocity blood flow, echo contrast between the thrombus and the surrounding flow makes it possible to clearly visualize the thrombus. SMI is a useful method to evaluate DVT, especially early after thrombus formation when it is difficult to delineate size and length because of echolucency.

Ultrasound Vein and Artery Mapping by General Surgery Residents During Initial Consult Can Decrease Time to Dialysis Access Creation

BACKGROUND

Formal preoperative ultrasound (US) mapping of vascular anatomy by radiology is recommended before hemodialysis access surgery. We hypothesized that US performed by general surgery residents in place of formal US would decrease the time from initial consult to creation of dialysis access without affecting patient outcomes.

METHODS

This is a retrospective review of all patients who underwent dialysis access surgery from November 2014 to July 2016 and received preoperative upper extremity US vein and artery evaluation by either radiology or general surgery residents. The primary endpoints were days from initial consult to dialysis access creation, rate of arteriovenous fistula (AVF) creation, fistula maturation, and 1-year primary assisted patency.

RESULTS

Of 242 patients, 167 (69%) had formal US, and 75 (31%) had only a resident US. The resident US group had 100% AVF creation compared with the formal US group with 92.2% AVF creation (P = 0.01). There was no difference between the groups in rate of fistula maturation (P = 0.1) and 1-year assisted patency (P = 0.9). Of the resident US 90.7% occurred in the outpatient setting. On multivariable analysis controlling for outpatient consult, the average time to the operating room was 13.7 days longer for the formal US group in the outpatient setting (P = 0.0006).

CONCLUSIONS

Ultrasound vein and artery evaluation at the time of the initial consult by general surgery residents can decrease the time to dialysis access creation by bypassing the need for formal US with a higher rate of AVF creation and no difference in fistula maturation or 1-year primary assisted patency.

Management of Suspected Deep Venous Thrombosis in an Emergency Medicine Ward in Hong Kong

Introduction

Clinical signs and symptoms can vary for patients with deep venous thrombosis (DVT). DVT is an important diagnosis to recognise as it can lead to proximal embolism into the pulmonary circulation resulting in sudden collapse and death. The objective of this study is to describe the management of patients with suspected DVT in the emergency medicine ward (EMW) setting in Hong Kong using a standardised clinical pathway.

Methods

A retrospective review was conducted for patients with suspected DVT admitted to the EMW from April to December 2008 using a standardised protocol. The use of a clinical prediction rule and diagnostic tests (including the modified Well's score, D-dimer and ultrasound examination) and outcomes (including the length of stay and secondary admission rate) were investigated.

Results

A total of 100 patients with suspected DVT were admitted to the EMW in the nine-month study period. DVT was confirmed in 30% using ultrasonography. Fifty-two percent of patients were in the high-risk category according to the modified Well's score. Seventy-six percent of patients had positive D-dimer results. Ten percent of patients were safely discharged without an ultrasound examination. Mean length of stay in the EMW was 1.99 days. Thirteen percent of patients required second admission to other specialties.

Conclusions

This study suggests that a standardised clinical pathway based in the EMW can be used for patients with suspected DVT to reduce hospital admission.

Accuracy of emergency physician–performed ultrasonography in the diagnosis of deep-vein thrombosis

Duplex ultrasound is the first-line diagnostic test for detecting lower limb deep-vein thrombosis (DVT) but it is time consuming, requires patient transport, and cannot be interpreted by most physicians. The accuracy of emergency physician–performed ultrasound (EPPU) for the diagnosis of DVT, when performed at the bedside, is unclear. We did a systematic review and meta-analysis of the literature, aiming to provide reliable data on the accuracy of EPPU in the diagnosis of DVT. The MEDLINE and EMBASE databases (up to August 2012) were systematically searched for studies evaluating the accuracy of EPPU compared to either colour-flow duplex ultrasound performed by a radiology department or vascular laboratory, or to angiography, in the diagnosis of DVT. Weighted mean sensitivity and specificity and associated 95% confidence intervals (CIs) were calculated using a bivariate random-effects regression approach. There were 16 studies included, with 2,379 patients. The pooled prevalence of DVT was 23.1% (498 in 2,379 patients), ranging from 7.4% to 47.3%. Using the bivariate approach, the weighted mean sensitivity of EPPU compared to the reference imaging test was 96.1% (95%CI 90.6–98.5%), and with a weighted mean specificity of 96.8% (95%CI:94.6–98.1%). Our findings suggest that EPPU may be useful in the management of patients with suspected DVT. Future prospective studies are warranted to confirm these findings.

Hospital Medicine Point of Care Ultrasound Credentialing: An Example Protocol

Though the use of point-of-care ultrasound (POCUS) has increased over the last decade, formal hospital credentialing for POCUS may still be a challenge for hospitalists. This document details the Hospital Medicine Department Ultrasound Credentialing Policy from Regions Hospital, which is part of the HealthPartners organization in Saint Paul, Minnesota. National organizations from internal medicine and hospital medicine (HM) have not published recommended guidelines for POCUS credentialing. Revised guidelines for POCUS have been published by the American College of Emergency Physicians, though these are not likely intended to guide hospitalists when working with credentialing committees and medical boards. This document describes the scope of ultrasound in HM and our training, credentialing, and quality assurance program. This report is intended to be used as a guide for hospitalists as they work with their own credentialing committees and will require modification for each institution. However, the overall process described here should assist in the establishment of POCUS at various institutions.

Phelgmasia Cerulea Dolens Diagnosed by Point-of-Care Ultrasound

Phlegmasia cerulea dolens (PCD) is a rare entity that is associated with significant morbidity and mortality, including limb ischemia and pulmonary embolism. Point-of-care ultrasound (POCUS) can expedite the diagnosis, leading to earlier life- and limb-saving treatment. Although primarily used for assessing for the presence of deep venous thrombosis, in the appropriate clinical setting POCUS can also be used to diagnosis PCD as well as to distinguish between venous and arterial occlusion, which can lead to a difference in management. We present a case of phlegmasia cerulea dolens after mild trauma in a patient with an underlying hypercoagulability disorder diagnosed by an emergency physician using POCUS, which expedited treatment with catheter-directed thrombolytic therapy.

The path to ultrasound proficiency: A systematic review of ultrasound education and training programmes for junior medical practitioners

Background

Point-of-care ultrasound (POCUS) is a form of diagnostic ultrasonography, which has a defined role as a clinical adjunct in patient assessment and management. If it is to continue to develop as a core clinical skill, junior medical practitioners and trainees may benefit from dedicated ultrasound education and familiarisation early in their training. Controversy endures, however, as inappropriate use of this highly technical and operator-dependent imaging modality has negative clinical implications.

Aims

A systematic review was performed to assess the ability of doctors in training to perform clinically appropriate and beneficial diagnostic ultrasound after undergoing a formal training programme.

Methods

Studies meeting pre-defined inclusion criteria were identified in electronic databases MEDLINE, EMBASE, CINAHL, PUBMED and through Google Scholar. Methodological quality was assessed using an established series of indicators.

Results

Fifteen studies were included in the review. Ten of these were performed in the United States, and eight focused on emergency medicine trainees. After the teaching intervention, ten studies assessed overall ultrasound capacity by calculating the collective sensitivity and specificity of trainee-performed ultrasound. Five studies used a standardised objective assessment tool to evaluate ultrasound skills and technique. Studies varied in terms of the specific ultrasound use investigated, teaching programmes used and methodological quality. Consistently identified areas for further research included the definition of the trainee learning curve and what constitutes competency in ultrasound.

Conclusions

Ultrasound can feasibly be incorporated into junior medical practitioner training, but more research is required to assess its effectiveness and appropriateness.

Teaching the internist to see: effectiveness of a 1-day workshop in bedside ultrasound for internal medicine residents

Background

A growing body of evidence supports the use of bedside ultrasound for core Internal Medicine procedures and increasingly as augmentation of the physical exam. The literature also supports that trainees, both medical students and residents, can acquire these skills. However, there is no consensus on training approach.

Aim

To implement and study the effectiveness of a high-yield and expedited curriculum to train internal medicine interns to use bedside ultrasound for physical examination and procedures.

Setting

The study was conducted at a metropolitan, academic medical center and included 33 Internal Medicine interns.

Program description

This was a prospective cohort study of a new educational intervention consisting of a single-day intensive bedside ultrasound workshop followed by two optional hour-long workshops later in the year. The investigation was conducted at Oregon Health & Science University in Portland, Oregon. The intensive day consisted of alternating didactic sessions with small group hands-on ultrasound practice sessions and ultrasound simulations. A 30-question assessment was used to assess ultrasound interpretation knowledge prior to, immediately post, and 6 months post intervention.

Results

Thirty-three interns served as their own historical controls. Assessment performance significantly increased after the intervention from a mean pre-test score of 18.3 (60.9 % correct) to a mean post-test score 25.5 (85.0 % correct), P value of <0.0001. This performance remained significantly better at 6 months with a mean score of 23.8 (79.3 % correct), P value <0.0001. There was significant knowledge attrition compared to the immediate post-assessment, P value 0.0099.

Conclusions

A single-day ultrasound training session followed by two optional noon conference sessions yielded significantly improved ultrasound interpretation skills in internal medicine interns.

Mistakes and Pitfalls Associated with Two-Point Compression Ultrasound for Deep Vein Thrombosis

Introduction

Two-point compression ultrasound is purportedly a simple and accurate means to diagnose proximal lower extremity deep vein thrombosis (DVT), but the pitfalls of this technique have not been fully elucidated. The objective of this study is to determine the accuracy of emergency medicine resident-performed two-point compression ultrasound, and to determine what technical errors are commonly made by novice ultrasonographers using this technique.

Methods

This was a prospective diagnostic test assessment of a convenience sample of adult emergency department (ED) patients suspected of having a lower extremity DVT. After brief training on the technique, residents performed two-point compression ultrasounds on enrolled patients. Subsequently a radiology department ultrasound was performed and used as the gold standard. Residents were instructed to save videos of their ultrasounds for technical analysis.

Results

Overall, 288 two-point compression ultrasound studies were performed. There were 28 cases that were deemed to be positive for DVT by radiology ultrasound. Among these 28, 16 were identified by the residents with two-point compression. Among the 260 cases deemed to be negative for DVT by radiology ultrasound, 10 were thought to be positive by the residents using two-point compression. This led to a sensitivity of 57.1% (95% CI [38.8–75.5]) and a specificity of 96.1% (95% CI [93.8–98.5]) for resident-performed two-point compression ultrasound. This corresponds to a positive predictive value of 61.5% (95% CI [42.8–80.2]) and a negative predictive value of 95.4% (95% CI [92.9–98.0]). The positive likelihood ratio is 14.9 (95% CI [7.5–29.5]) and the negative likelihood ratio is 0.45 (95% CI [0.29–0.68]). Video analysis revealed that in four cases the resident did not identify a DVT because the thrombus was isolated to the superior femoral vein (SFV), which is not evaluated by two-point compression. Moreover, the video analysis revealed that the most common mistake made by the residents was inadequate visualization of the popliteal vein.

Conclusion

Two-point compression ultrasound does not identify isolated SFV thrombi, which reduces its sensitivity. Moreover, this technique may be more difficult than previously reported, in part because novice ultrasonographers have difficulty properly assessing the popliteal vein.

Longitudinal Ultrasound Curriculum Improves Long-Term Retention Among Internal Medicine Residents

BACKGROUND

Point-of-care ultrasound is a rapidly evolving component of internal medicine (IM) residency training. The optimal approach for teaching this skill remains unclear.

OBJECTIVE

We sought to determine whether the addition of a longitudinal ultrasound curriculum to a stand-alone workshop for ultrasound training improved knowledge retention in IM residents.

METHODS

We conducted an observational cohort study from July to December 2013. All postgraduate year (PGY)-1 IM residents attended an ultrasound workshop during orientation. Ability to identify static images of ascites, kidney, thyroid, pleural fluid, inferior vena cava, and internal jugular vein was assessed immediately after the workshop. An ultrasound curriculum, including morning report and ultrasound rounds, was initiated during the inpatient medicine rotation. PGY-1 residents were randomly assigned to participate in the longitudinal curriculum. Six months later, we conducted a follow-up survey with all PGY-1 residents.

RESULTS

Forty-eight PGY-1 residents (67%) completed the postworkshop test and the 6-month follow-up test. Of these, 50% (24 of 48) had participated in the ultrasound curriculum. Residents not exposed to the curriculum showed a decline in the identification of ascites, pleural effusion, and internal jugular vein at 6 months (P < .05), whereas those who participated in the curriculum maintained their performance (P < .05).

CONCLUSIONS

Six months after exposure to a longitudinal ultrasound curriculum, residents were more likely to correctly identify ultrasound images of ascites, kidney, and pleural effusion. The addition of a longitudinal ultrasound curriculum may result in improved knowledge retention in IM residents.

Point-of-Care Ultrasound for a Deep Venous Thrombosis

Patients presenting to the emergency department with lower extremity symptoms suggestive of venous thromboembolic disease require a diagnostic evaluation. Although contrast venography was the diagnostic standard, this has largely been replaced by duplex ultrasound as the first-line imaging modality. This review presents a summary of the literature on the evolution and performance of B-mode point-of-care compression ultrasound as an alternative to duplex ultrasound evaluation. The 2-point compression and 2-region compression techniques are described. The limitations of point-of-care ultrasound of the lower extremity as a diagnostic modality for this disease entity, the role of a D-dimer assay in the emergency department evaluation and future directions for this diagnostic modality are discussed.

Estimated effect of an integrated approach to suspected deep venous thrombosis using limited-compression ultrasound

OBJECTIVES

Deep vein thrombosis (DVT) is both common and serious, yet the desire to never miss the diagnosis, coupled with the low specificity of D-dimer testing, results in high imaging rates, return visits, and empirical anticoagulation. The objective of this study was to evaluate a new approach incorporating bedside limited-compression ultrasound (LC US) by emergency physicians (EPs) into the workup strategy for DVT.

METHODS

This was a cross-sectional observational study of emergency department (ED) patients with suspected DVT. Patients on anticoagulants; those with chronic DVT, leg cast, or amputation; or when the results of comprehensive imaging were already known were excluded. All patients were treated in the usual fashion based on the protocol in use at the center, including comprehensive imaging based on the modified Wells score and serum D-dimer testing. Seventeen physicians were trained and performed LC US in all subjects. The authors identified a priori an alternate workup strategy in which DVT would be ruled out in "DVT unlikely" (Wells score < 2) patients if the LC US was negative and in "DVT likely" (Wells score ≥ 2) patients if both the LC US and the D-dimer were negative. The criterion standard was based on comprehensive imaging interpreted by radiologists blinded to LC US findings and by structured medical record review at 6 months in patients without comprehensive imaging.

RESULTS

A total of 227 patients were enrolled (47% DVT likely), of whom 24 had DVT. The LC US was positive in 27 cases (21 actually DVT positive), indeterminate in 28 (one DVT positive), and negative in 172 (two DVT positive). Of 130 patients deemed DVT negative by the new strategy, one had confirmed DVT (miss rate = 0.8%; 95% confidence interval [CI] = 0.1% to 4.0%), but this patient had been misclassified by the treating physician as low risk by Wells criteria. The stand-alone sensitivity and specificity of LC US were 91% (95% CI = 70% to 98%) and 97% (95% CI = 92% to 99%), respectively. Incorporating LC US into the diagnostic approach would have reduced the rate of comprehensive imaging from 70% to 43%, D-dimer testing from 100% to 33%, and the mean time to diagnostic certainty by 5.0 hours and avoided 24 (11%) return visits for imaging and 10 (4.4%) cases of unnecessary anticoagulation. In 19% of cases, the treating and scanning physician disagreed whether the patient was DVT likely or DVT unlikely based on Wells score (κ = 0.62; 95% CI = 0.48 to 0.77).

CONCLUSIONS

Limited-compression US holds promise as one component of the diagnostic approach to DVT, but should not be used as a stand-alone test due to imperfect sensitivity. Tradeoffs in diagnostic efficiency for the sake of perfect sensitivity remain a difficult issue collectively in emergency medicine (EM), but need to be scrutinized carefully in light of the costs of overinvestigation, delays in diagnosis, and risks of empirical anticoagulation.

Bedside ultrasonography-Applications in critical care: Part II

Point of care ultrasonography, performed by acute care physicians, has developed into an invaluable bedside tool providing important clinical information with a major impact on patient care. In Part II of this narrative review, we describe ultrasound guided central venous cannulation, which has become standard of care with internal jugular vein cannulation. Besides improving success rates, real-time guidance also significantly reduces the incidence of complications. We also discuss compression ultrasonography - a quick and effective bedside screening tool for deep vein thrombosis of the lower extremity. Abdominal ultrasound offers vital clues in the emergency setting; in the unstable trauma victim, a focused examination may provide immediate answers and has largely superseded diagnostic peritoneal lavage in diagnosing intraperitoneal bleed. From estimation of intracranial pressure to transcranial Doppler studies, ultrasound is becoming increasingly relevant to neurocritical care. Ultrasound may also help with airway management in several situations, including percutaneous tracheostomy. Clearly, bedside ultrasonography has become an indispensable part of intensive care practice – in the rapid assessment of critically ill-patients as well as in enhancing the safety of invasive procedures.

Early diagnosis of iliofemoral DVT in pregnancy in the emergency department

The case of a 26-year-old woman who was 23 weeks pregnant is described; the patient presented, on a weekend, to the emergency department (ED) with left groin pain. There were few clinical signs of deep venous thrombosis (DVT) but ED ultrasound (US) showed a left external iliac vein thrombus. This is a new technique in the ED. Not only does this case show the importance of using this technique in the ED, but it also shows the importance of correct training in how to examine for thrombus in the external iliac vein in the pregnant patient. The patient was admitted to the hospital and started on low-molecular-weight heparin. A formal radiology department US performed the next week confirmed the diagnosis of DVT.

Effectiveness of an ultrasound training module for internal medicine residents

BACKGROUND

Few internal medicine residency programs provide formal ultrasound training. This study sought to assess the feasibility of simulation based ultrasound training among first year internal medicine residents and measure their comfort at effectively using ultrasound to perform invasive procedures before and after this innovative model of ultrasound training.

METHODS

A simulation based ultrasound training module was implemented during intern orientation that incorporated didactic and practical experiences in a simulation and cadaver laboratory. Participants completed anonymous pre and post surveys in which they reported their level of confidence in the use of ultrasound technology and their comfort in identifying anatomic structures including: lung, pleural effusion, bowel, peritoneal cavity, ascites, thyroid, and internal jugular vein. Survey items were structured on a 5-point Likert scales (1 = extremely unconfident, 5 = extremely confident).

RESULTS

Seventy-five out of seventy-six interns completed the pre-intervention survey and 55 completed the post-survey. The mean confidence score (SD) increased to 4.00 (0.47) (p < 0.0001). The mean (SD) comfort ranged from 3.61 (0.84) for peritoneal cavity to 4.48 (0.62) for internal jugular vein. Confidence in identifying all anatomic structures showed an increase over the pre-intervention means (p < 0.002).

CONCLUSION

A simulation based ultrasound learning module can improve the self-reported confidence with which residents identify structures important in performing invasive ultrasound guided procedures. Incorporating an ultrasound module into residents' education may address perceived need for ultrasound training, improve procedural skills, and enhance patient safety.

The efficacy and value of emergency medicine: a supportive literature review

Study objectives

The goal of this study was to identify publications in the medical literature that support the efficacy or value of Emergency Medicine (EM) as a medical specialty and of clinical care delivered by trained emergency physicians. In this study we use the term "value" to refer both to the "efficacy of clinical care" in terms of achieving desired patient outcomes, as well as "efficiency" in terms of effective and/or cost-effective utilization of healthcare resources in delivering emergency care. A comprehensive listing of publications describing the efficacy or value of EM has not been previously published. It is anticipated that the accumulated reference list generated by this study will serve to help promote awareness of the value of EM as a medical specialty, and acceptance and development of the specialty of EM in countries where EM is new or not yet fully established.

Methods

The January 1995 to October 2010 issues of selected journals, including the EM journals with the highest article impact factors, were reviewed to identify articles of studies or commentaries that evaluated efficacy, effectiveness, and/or value related to EM as a specialty or to clinical care delivered by EM practitioners. Articles were included if they found a positive or beneficial effect of EM or of EM physician-provided medical care. Additional articles that had been published prior to 1995 or in other non-EM journals already known to the authors were also included.

Results

A total of 282 articles were identified, and each was categorized into one of the following topics: efficacy of EM for critical care and procedures (31 articles), efficacy of EM for efficiency or cost of care (30 articles), efficacy of EM for public health or preventive medicine (34 articles), efficacy of EM for radiology (11 articles), efficacy of EM for trauma or airway management (27 articles), efficacy of EM for using ultrasound (56 articles), efficacy of EM faculty (34 articles), efficacy of EM residencies (24 articles), and overviews and editorials of EM efficacy and value (35 articles).

Conclusion

There is extensive medical literature that supports the efficacy and value for both EM as a medical specialty and for emergency patient care delivered by trained EM physicians.

Cost-effectiveness of lower extremity compression ultrasound in emergency department patients with a high risk of hemodynamically stable pulmonary embolism

BACKGROUND

Computed tomography angiograms (CTAs) for patients with suspected pulmonary embolism (PE) are being ordered with increasing frequency from the emergency department (ED). Strategies are needed to safely decrease the utilization of CTs to control rising health care costs and minimize the associated risks of anaphylaxis, contrast-induced nephropathy, and radiation-induced carcinogenesis. The use of compression ultrasonography (US) to identify deep vein thromboses (DVTs) in hemodynamically stable patients with signs and symptoms suggestive of PE is highly specific for the diagnosis of PE and may represent a cost-effective alternative to CT imaging.

OBJECTIVES

  The objective was to analyze the cost-effectiveness of a selective CT strategy incorporating the use of compression US to diagnose and treat DVT in patients with a high pretest probability of PE.

METHODS

The authors constructed a decision analytic model to evaluate the scenario of an otherwise healthy 59-year-old female in whom PE was being considered as a diagnosis. Two strategies were used. The selective CT strategy began with a screening compression US. Negative studies were followed up with a CTA, while patients with positive studies identifying a DVT were treated as though they had a PE and were anticoagulated. The universal CT strategy used CTA as the initial test, and anticoagulation was based on the CT result. Costs were estimated from the 2009 Medicare data for hospital reimbursement, and professional fees were obtained from the 2009 National Physician Fee Schedule. Clinical probabilities were obtained from existing published data, and sensitivity analyses were performed across plausible ranges for all clinical variables.

RESULTS

In the base case, the selective CT strategy cost $1,457.70 less than the universal CT strategy and resulted in a gain of 0.0213 quality-adjusted life-years (QALYs). Sensitivity analyses confirm that the selective CT strategy is dominant above both a pretest probability for PE of 8.3% and a compression US specificity of 87.4%.

CONCLUSIONS

A selective CT strategy using compression US is cost-effective for patients provided they have a high pretest probability of PE. This may reduce the need for, and decrease the adverse events associated with, CTAs.

Systematic review of emergency physician-performed ultrasonography for lower-extremity deep vein thrombosis

OBJECTIVES

The authors performed a systematic review to evaluate published literature on diagnostic performance of emergency physician-performed ultrasonography (EPPU) for the diagnosis and exclusion of deep venous thrombosis (DVT).

METHODS

Structured search criteria were used to query MEDLINE and EMBASE, followed by a hand search of published bibliographies. Relevance and inclusion criteria required prospective investigation of emergency department (ED) outpatients with suspected DVT; diagnostic evaluations had to consist of EPPU followed by criterion standard (radiology-performed) imaging. Two authors independently extracted data from included studies; study quality was assessed utilizing a validated tool for quality assessment of diagnostic accuracy studies (QUADAS). Pooled data were analyzed using an unweighted summary receiver-operating-characteristic (SROC) curve; sensitivity and specificity were estimated using a random effects model.

RESULTS

The initial search yielded 1,162 publications. Relevance screening and selection yielded six articles including 936 patients. Four of the six studies reported adequate blinding but a number of other methodologic flaws were identified. A random effects model yielded an overall sensitivity of 0.95 (95% confidence interval [CI] = 0.87 to 0.99) and specificity of 0.96 (95% CI = 0.87 to 0.99).

CONCLUSIONS

Systematic review of six studies suggests that EPPU may be accurate for the diagnosis of DVT compared with radiology-performed ultrasound (US). However, given the methodologic limitations identified among the primary studies, the estimates of diagnostic test performance may be overly optimistic. Further research into EPPU for suspected DVT is needed before it can be adopted into routine clinical practice.