A Narrative Review of Point of Care Ultrasound Assessment of the Optic Nerve in Emergency Medicine.

Point of care ultrasound (POCUS) of the optic nerve is easy to learn and has great diagnostic potential. Within emergency medicine, research has primarily focused on its use for the assessment of increased intracranial pressure, but many other applications exist, though the literature is heterogeneous and largely observational. This narrative review describes the principles of POCUS of the optic nerve including anatomy and scanning technique, as well as a summary of its best studied clinical applications of relevance in emergency medicine: increased intracranial pressure, idiopathic intracranial hypertension, optic neuritis, acute mountain sickness, and pediatric intracranial pressure assessment. In many of these applications, sonographic optic nerve sheath diameter (ONSD) has moderately high sensitivity and specificity, but the supporting studies are heterogeneous. Further studies should focus on standardization of the measurement of ONSD, establishment of consistent diagnostic thresholds for elevated intracranial pressure, and automation of ONSD measurement.

Test characteristics of ultrasound for the diagnosis of peritonsillar abscess: A systematic review and meta-analysis.

BACKGROUND: Distinguishing peritonsillar abscess (PTA) from peritonsillar cellulitis using clinical assessment is challenging as many features overlap for both conditions, and physical examination is only about 75% sensitive and 50% specific for diagnosing PTA. The primary objective of this systematic review was to determine the test characteristics of ultrasound for diagnosing PTA when compared to a reference standard of computed tomography or acquisition of pus via needle aspiration or incision and drainage. METHODS: This systematic review was performed in accordance with the Preferred Reporting Items for a Systematic Review and Meta-analysis of Diagnostic Test Accuracy (PRISMA-DTA) guidelines. We searched seven databases from 1960 to November 2022. Two independent reviewers completed study selection, data extraction, and QUADAS-2 risk-of-bias assessment. We used a bivariate random-effects model to calculate pooled sensitivity, specificity, positive likelihood ratio (LR+), and negative likelihood ratio (LR-). We also conducted subgroup analyses on radiology ultrasound compared to point-of-care ultrasound (POCUS) and intraoral compared to transcervical scanning techniques. RESULTS: From 339 citations, we identified 18 studies for inclusion. Because one study only reported positive cases of PTA (thereby preventing the calculation of specificity), it was excluded from the analysis, so the analysis included a total of 17 studies with 812 patients, of whom 541 had PTA. Pooled bivariate sensitivity was 86% (95% confidence interval [CI] 78%-91%), specificity 76% (95% CI 67%-82%), LR+ 3.51 (95% CI 2.59-4.89), and LR- 0.19 (95% CI 0.12-0.30). On subgroup analysis, radiology-performed ultrasound had a sensitivity and specificity of 89% and 71%, compared to POCUS, which had a sensitivity and specificity of 74% and 79%. Comparing the two different techniques, intraoral had a sensitivity and specificity of 91% and 75% while transcervical had a sensitivity and specificity of 80% and 81%. CONCLUSIONS: Ultrasound demonstrates high sensitivity for ruling out PTA, but it only has moderate specificity for ruling in the diagnosis.

Multi-Institutional Variation in Performance of Low-Dose Computed Tomography for the Evaluation of Suspected Nephrolithiasis.

Introduction and Objective: Guidelines from the American Urological Association (AUA) and American College of Radiology (ACR) recommend that patients with suspected nephrolithiasis undergo low-dose CT of the kidney, ureter, and bladder (LD CT KUB) as opposed to higher dose conventional imaging. We hypothesized that even at institutions with established LD protocols, higher dose imaging is common. Materials and Methods: We identified four academic medical centers where LD CT KUB protocols were implemented to yield an effective dose (EDose) consistent with national guidelines. Fifty consecutive adult patients who underwent CT KUB specifically for the evaluation of nephrolithiasis were retrospectively reviewed at each site. Patient age, sex, body mass index (BMI), imaging location, and EDose (millisieverts [mSv]) were recorded. Results: Two hundred patients with a mean age of 54 years were identified. Forty-six patients (23%) underwent CT KUB with an EDose ≤4 mSv, accounting for 10% to 48% of each institution's cohort. One hundred sixteen patients had a BMI <30, and would have been expected to receive LD CTs by the AUA criteria for LD CT KUB. Within this subset, only 37 patients (32%) actually underwent LD CT KUB. The highest dose CT KUB at each institution resulted in an EDose of 33.8 to 44.6 mSv, exceeding the recommended exposure of LD CT KUB by 10-fold. Conclusions: At academic institutions where LD CT KUB was implemented for the evaluation of nephrolithiasis, a minority of patients with BMI <30 received guideline-concordant imaging. Differences in patient BMI did not account for the variation in radiation exposure. Further research is necessary to elucidate barriers to LD CT implementation.

The physical examination is unreliable in determining the location of the distal fibular physis.

OBJECTIVES: Salter-Harris type 1 (SH1) fractures of the distal fibula are acute orthopedic injuries with tenderness over the physis without radiographic evidence of fracture. Our primary objective was to establish the accuracy of the physical examination performed by pediatric emergency medicine (PEM) physicians in determining the location of the distal fibular physis compared to a criterion standard of ultrasound. METHODS: This was a prospective, observational study at an urban academic pediatric emergency department of a convenience sample of children aged 4 to 10 years old between March 2019 and March 2020. A PEM physician or fellow examined the patient's distal fibula and marked the location of the physis with a marker. A study investigator scanned the distal fibula to establish the location of the physis on ultrasound and measured the distance between the clinician's estimated position and the actual sonographic position. We a priori defined a clinically accurate position as a distance of ≤5 mm. We compared the accuracy rate of physical examination to ultrasound landmarking using proportions with 95% confidence intervals (CI). RESULTS: We enrolled 71 patients, of whom 52 (73%) were male. The mean age was 6.7 years and the mean weight was 25.5 kg. Participating PEM physicians included 18 attending physicians and 2 fellows. The distal fibular physis was correctly identified in 24 patients, yielding an accuracy rate of 34% (95% CI 23%-46%). The mean distance between the physician's estimated position and the sonographic position was 7.4 mm (95% CI 6.4-8.4 mm). CONCLUSIONS: PEM physicians were unable to accurately identify the distal fibular physis on physical examination.

Adjunctive Use of Point of Care Ultrasound to Diagnose Compartment Syndrome of the Thigh.

Compartment syndrome is a medical emergency and must be considered in patients who present with severe limb pain. Compartment syndrome is a clinical diagnosis, classically described as presenting with the 5 'P's (pain, pulselessness, pallor, paraesthesia, and paralysis). Apart from pain, the other findings signify acute arterial obstruction and would be late findings. We present a case of a 31-year-old male in which point of care ultrasound (POCUS) expedited this diagnosis by demonstrating a large thigh hematoma in the anterior compartment. This prompted emergent orthopedic surgery consultation, and the diagnosis of compartment syndrome was confirmed both at the bedside and in the operating room. Compartment syndrome can be a challenging diagnosis, especially early in the course of illness. While POCUS should not be used in isolation in the assessment of possible compartment syndrome, it can be used as an adjunct in the workup, especially if it identifies an underlying cause.

Combined Burst Wave Lithotripsy and Ultrasonic Propulsion for Improved Urinary Stone Fragmentation.

PURPOSE: Burst wave lithotripsy (BWL) is a new technology in development to fragment urinary stones. Ultrasonic propulsion (UP) is a separate technology under investigation for displacing stones. We measure the effect of propulsion pulses on stone fragmentation from BWL. MATERIALS AND METHODS: Two artificial stone models (crystalline calcite, BegoStone plaster) and human calcium oxalate monohydrate (COM) stones measuring 5 to 8 mm were subjected to ultrasound exposures in a polyvinyl chloride tissue phantom within a water bath. Stones were exposed to BWL with and without propulsion pulses interleaved for set time intervals depending on stone type. Fragmentation was measured as a fraction of the initial stone mass fragmented to pieces smaller than 2 mm. RESULTS: BegoStone model comminution improved from 6% to 35% (p < 0.001) between BWL and BWL with interleaved propulsion in a 10-minute exposure. Propulsion alone did not fragment stones, whereas addition of propulsion after BWL slightly improved BegoStone model comminution from 6% to 11% (p < 0.001). BegoStone model fragmentation increased with rate of propulsion pulses. Calcite stone fragmentation improved from 24% to 39% in 5 minutes (p = 0.047) and COM stones improved from 17% to 36% (p = 0.01) with interleaved propulsion. CONCLUSIONS: BWL with UP improved stone fragmentation compared with BWL alone in vitro. The improvement was greatest when propulsion pulses are interleaved with BWL treatment and when propulsion pulses are applied at a higher rate. Thus, UP may be a useful adjunct to enhance fragmentation in lithotripsy in vivo.

National Imaging Trends after Percutaneous Nephrolithotomy.

PURPOSE: Followup imaging after percutaneous nephrolithotomy serves to detect postoperative complications, residual fragments and silent hydronephrosis. However, the timing and optimal imaging modality remain poorly defined. We describe imaging use patterns after percutaneous nephrolithotomy. MATERIALS AND METHODS: In the MarketScan® database we identified patients 17 to 64 years old who underwent percutaneous nephrolithotomy between 2007 and 2014. Imaging modalities were identified by CPT, and ICD-9 and 10 codes, and tracked for 1 year after percutaneous nephrolithotomy. The modalities included computerized tomography, renal ultrasound, abdominal x-ray and intravenous pyelogram. Cumulative longitudinal use patterns were characterized and the association with demographic factors was assessed by the chi-square test. RESULTS: Of the 6,495 patients included in analysis 29% and 15% had undergone no postoperative imaging by 3 and 12 months, respectively. While abdominal x-ray was the most common modality at 3, 6 and 12 months, performed in 46%, 53% and 62% patients, respectively, nearly 50% underwent computerized tomography by 1 year. Of these patients 34% underwent computerized tomography within 3 months, which was done within the first 3 days in 69%. During the study period renal ultrasound use increased by 13% while computerized tomography and abdominal x-ray use remained relatively stable. Female gender, residence in the Northeast, no health maintenance organization status and treatment in a metropolitan statistical area were independently associated with higher rates of renal ultrasound on multivariate analyses (p <0.05). CONCLUSIONS: Among insured adults national imaging patterns vary following percutaneous nephrolithotomy. Many patients do not receive any followup imaging while approximately half undergo computerized tomography within a year. Imaging patterns may be evolving with the increased use of ultrasound.

Acute Ischemic Priapism Management: An Educational and Simulation Curriculum.

Introduction: Ischemic priapism is a urologic emergency managed by both urologic and nonurologic providers in the community. Given ischemic priapism's rare occurrence and the time-sensitive nature of treatment, effective provider education on management of this entity is imperative. We sought to develop a low-cost effective simulation model and curriculum to enhance trainee education. Methods: A comprehensive didactic curriculum based on national urologic guidelines was developed, along with a low-cost, easily reproducible priapism simulator using hot dogs and Red Vines candy. The simulators cost $1.25 each, and assembly took 10 minutes. All materials were reviewed by three urology faculty members. The curriculum was piloted with two andrology fellowship-trained urology faculty among eight urology residents (PGY2-PGY4/U1-U2) and one medical student. Participants provided feedback regarding the overall course as well as the face and content validity of the simulator. Results: Cognitive test scores significantly improved on average by 15.0% (p = .002), and confidence improved from baseline somewhat or very much among 88.9% of participants after completion of the curriculum. The task trainer was rated easy to use (average score: 4.78 out of 5), and 77.8% of participants though it was somewhat or very useful for training (average score: 4.00 out of 5). Additionally, 77.8% recommended its incorporation into resident training (average score: 4.00 out of 5). Discussion: This simulation curriculum is effective, inexpensive, and easily reproducible, making it ideal for groups with limited resources. Expanding access to simulation-based curricula on priapism management may improve education of both urologic and nonurologic trainees.

National Imaging Trends after Ureteroscopic or Shock Wave Lithotripsy for Nephrolithiasis.

PURPOSE: The study of diagnostic imaging after procedural intervention for nephrolithiasis is limited. We sought to characterize actual national imaging patterns and longitudinal trends after ureteroscopic or shock wave lithotripsy. MATERIALS AND METHODS: We analyzed the MarketScan® database and identified a nationally representative sample of insured, employed patients, 17 to 64 years old who underwent ureteroscopic or shock wave lithotripsy for nephrolithiasis between 2007 and 2014. Patients were excluded from study if they lacked at least 1 year of postoperative database enrollment or underwent a repeat nephrolithiasis procedure of any type within 90 days after the initial procedure. We identified and tracked postoperative imaging modalities by medical billing codes. RESULTS: We identified 101,554 patients treated with ureteroscopy, of whom 55% and 39% underwent no postoperative imaging within 3 and 12 months, respectively. Of the 101,590 patients treated with shock wave lithotripsy 23% and 16% underwent no postoperative imaging within 3 and 12 months, respectively. Abdominal x-ray was the most common imaging modality after either procedure type. Ultrasound use increased with time while computerized tomography decreased. In about 25% of ureteroscopy and shock wave lithotripsy cases at least 1 postoperative computerized tomography was done within a year. Female gender and older age were associated with higher imaging rates. Ultrasound was more commonly performed in the northeast region and in more densely populated areas. CONCLUSIONS: A notable portion of patients treated with ureteroscopy and a smaller percent treated with shock wave lithotripsy do not undergo any followup imaging within 1 year. In the majority who undergo imaging abdominal x-ray is done, precluding the ability to screen for hydronephrosis or silent obstruction in almost 75% of patients treated with ureteroscopy.

Asteroid Hyalosis: A Mimic of Vitreous Hemorrhage on Point of Care Ultrasound.

Point of care ultrasound in the emergency department (ED) is increasingly being used to diagnose time-sensitive, vision-threatening conditions. We present a case of a 64-year-old female who presented to the ED with a three-day history of worsening left eye floaters. Point of care ocular ultrasound demonstrated a posterior chamber containing many echogenic opacities of varying size without acoustic shadowing. Movement of the eye resulted in significant after-movement of these opacities, giving the classic "washing machine" appearance seen with vitreous hemorrhage (VH). Based on these ultrasound findings, the patient was diagnosed with a VH and was referred to ophthalmology. The consulting ophthalmologist ultimately diagnosed the patient with asteroid hyalosis without VH. Asteroid hyalosis is a benign condition of the vitreous resulting in calcium phosphate and lipid deposits that can mimic more serious VH on point of care ultrasound. Knowledge of this mimic is helpful for communication with specialists and for awareness of the potential for misdiagnosis with ocular ultrasound.

Using Ultrasound to Enhance Medical Students' Femoral Vascular Physical Examination Skills.

OBJECTIVES: To determine whether the addition of ultrasound to traditional physical examination instruction improves junior medical students' abilities to locate the femoral pulse. METHODS: Initially, 150 second-year medical students were taught the femoral pulse examination using traditional bedside teaching on standardized patients and online didactic videos. Students were then randomized into 2 groups: group 1 received ultrasound training first and then completed the standardized examination; and group 2 performed the standardized examination first and then received ultrasound training. On the standardized patients, the femoral artery was marked with invisible ink before the sessions using ultrasound. Compared to these markers, students were then evaluated on the accuracy of femoral artery pulse palpation and the estimated location of the femoral vein. All students completed a self-assessment survey after the ultrasound sessions. RESULTS: Ultrasound training improved the students' ability to palpate the femoral pulse (P= .02). However, ultrasound did not facilitate correct estimation of the femoral vein's anatomic location (P = .09). Confidence levels in localizing the femoral artery and vein were equal between groups at baseline, and both increased after the ultrasound sessions. CONCLUSIONS: The addition of ultrasound teaching to traditional physical examination instruction enhanced medical student competency and confidence with the femoral vascular examination. However, understanding of anatomy may require emphasis on precourse didactic material, but further study is required.

Familiarity with radiation exposure dose from diagnostic imaging for acute pulmonary embolism and current patterns of practice.

OBJECTIVE: To assess the current level of knowledge and practice patterns of emergency physicians regarding radiation exposure from diagnostic imaging modalities for investigating acute pulmonary embolism (PE). METHODS: An online survey was sent to adult emergency physicians working at two academic tertiary care adult emergency departments (EDs) to determine imaging choices for investigating PE in various patient populations and to assess their current knowledge of radiation doses and risks. A retrospective chart review was performed for all adult patients who underwent computed tomographic pulmonary angiography (CTPA) and/or ventilation-perfusion (V/Q) scanning in the same EDs. RESULTS: The survey response rate was 72.1% (31 of 43 physicians). For patients < 30 years old, 83.9% of physicians chose V/Q scanning as their test of choice, regardless of gender. Although only a third of respondents knew the estimated radiation dose of a V/Q scan (37.5%) and a CTPA (32%), the majority were aware that V/Q scans involved less ionizing radiation than CTPAs. In the retrospective review, 663 charts were reviewed, including 201 CTPAs and 462 V/Q scans. V/Q scanning was the preferred modality in female patients (75.9% v. CTPA 24.1% [OR 2.1; 95% CI 1.5-2.9]) and in patients < 30 years old (87.9% v. CTPA 12.1% [OR 4.8; 95% CI 2.4-9.4]). CONCLUSIONS: Although surveyed physicians possessed limited knowledge of radiation doses of CTPA and V/Q scans, they preferentially used the lower radiation V/Q scans in younger patients, particularly females, in both the survey vignettes and in clinical practice. This may reflect efforts to reduce radiation exposures at our institution.

Training peer instructors for a combined ultrasound/physical exam curriculum.

BACKGROUND: The integration of bedside ultrasound into medical school curricula is limited by the availability of skilled faculty instructors. Peer mentors have been utilized successfully to teach clinical and procedural skills and may serve as a valuable resource for potential ultrasound instructors. We describe a method to train senior medical students as peer instructors for a combined ultrasound/physical exam curriculum and assessed junior medical students' perceptions of peer instruction relative to faculty. DESCRIPTION: The University of Colorado has incorporated ultrasound into ocular, abdominal, musculoskeletal, cardiac, vascular, and pulmonary physical exam instruction for 1st-year (n=155) and 2nd-year (n=155) medical students. Fourth-year medical students who completed a 2- or 4-week bedside ultrasound elective were recruited as peer instructors. Both peer and faculty instructors received similar session training and were assigned to random groups of junior medical students. Instructor evaluation scores completed by students were collected after every session. EVALUATION: Twenty students and 29 faculty served as instructors for the curriculum. Comparisons of evaluation scores between faculty and student teachers were equivalent (α>.05) in 5 out of 6 sessions. In addition, students who taught more than 1 session showed improvement in their instructor scores and had higher average scores than students who taught only 1 session. Student instructors who completed the 4-week elective had higher average scores than students who completed the 2-week elective. CONCLUSIONS: Students' perception of peer instructors' teaching competency was equivalent to faculty instructors for the majority of sessions. Senior students who have completed an elective ultrasound rotation may serve as a useful resource for circumstances where the availability of skilled instructors is limited. However, further research is required to evaluate their effectiveness.

Spontaneous low cerebrospinal fluid pressure headache: an emergency medicine perspective.

Spontaneous low cerebrospinal fluid pressure headaches are a rare but treatable cause of debilitating headaches. The condition is characterized by a postural headache in the absence of any recent spinal procedures and is exacerbated when upright and relieved when supine. Diagnosis and treatment are often delayed, however, due to a lack of recognition and awareness, as illustrated by this case report of a patient who had multiple emergency department visits before further investigations were sought.