Ultrasound for airway management: An evidence-based review for the emergency clinician.

BACKGROUND: Airway management is a common procedure performed in the Emergency Department with significant potential for complications. Many of the traditional physical examination maneuvers have limitations in the assessment and management of difficult airways. Point-of-care ultrasound (POCUS) has been increasingly studied for the evaluation and management of the airway in a variety of settings. OBJECTIVE: This article summarizes the current literature on POCUS for airway assessment, intubation confirmation, endotracheal tube (ETT) depth assessment, and performing cricothyroidotomy with an emphasis on those components most relevant for the Emergency Medicine clinician. DISCUSSION: POCUS can be a useful tool for identifying difficult airways by measuring the distance from the skin to the thyrohyoid membrane, hyoid bone, or epiglottis. It can also predict ETT size better than age-based formulae. POCUS is highly accurate for confirming ETT placement in adult and pediatric patients. The typical approach involves transtracheal visualization but can also include lung sliding and diaphragmatic elevation. ETT depth can be assessed by visualizing the ETT cuff in the trachea, as well as using lung sliding and the lung pulse sign. Finally, POCUS can identify the cricothyroid membrane more quickly and accurately than the landmark-based approach. CONCLUSION: Airway management is a core skill in the Emergency Department. POCUS can be a valuable tool with applications ranging from airway assessment to dynamic cricothyroidotomy. This paper summarizes the key literature on POCUS for airway management.

Variation in the accuracy of ultrasound for the detection of intubation by endotracheal tube size.

INTRODUCTION: Rapid and accurate confirmation of endotracheal tube (ETT) placement is a fundamental step in definitive airway management. Multiple techniques with different limitations have been reported. Recent studies have evaluated the accuracy, time to performance, and physician confidence for ultrasound in both cadaveric models and live patients. However, no study to date has measured the effect of ETT size. Our study is the first to measure the accuracy of ultrasound for ETT confirmation based on ETT size. METHODS: This study was performed in a cadaver lab using three different cadavers chosen to represent varying neck circumferences. Cadavers were intubated in a random sequence with respect to both the location of intubation (i.e., tracheal vs esophageal) and sizes of ETT. Three ETT sizes were utilized: 6.0-, 7.0-, and 8.0-mm. Blinded sonographers assessed the location of the ETT using the static technique. Accuracy of sonographer identification, time to identification, and operator confidence were assessed. RESULTS: 453 assessments were performed. Overall, ultrasound was 99.1% (95% CI 97.8% to 99.7%) accurate in identification of correct location of intubation. The mean time to placement was 6.45 s (95% CI 5.62 to 7.28). The mean operator confidence level was 4.72/5.0 (95% CI 4.65 to 4.78). There was no significant difference between ETT sizes with respect to any of the outcomes. CONCLUSION: The diagnostic accuracy of ultrasound for ETT confirmation did not vary with the use of different ETT sizes. Further studies are needed to determine if the accuracy would change with more novice providers or in specific patient populations.

Comparison of Static versus Dynamic Ultrasound for the Detection of Endotracheal Intubation.

INTRODUCTION: In the emergency department setting, it is essential to rapidly and accurately confirm correct endotracheal tube (ETT) placement. Ultrasound is an increasingly studied modality for identifying ETT location. However, there has been significant variation in techniques between studies, with some using the dynamic technique, while others use a static approach. This study compared the static and dynamic techniques to determine which was more accurate for ETT identification. METHODS: We performed this study in a cadaver lab using three different cadavers to represent variations in neck circumference. Cadavers were randomized to either tracheal or esophageal intubation in equal proportions. Blinded sonographers then assessed the location of the ETT using either static or dynamic sonography. We assessed accuracy of sonographer identification of ETT location, time to identification, and operator confidence. RESULTS: A total of 120 intubations were performed: 62 tracheal intubations and 58 esophageal intubations. The static technique was 93.6% (95% confidence interval [CI] [84.3% to 98.2%]) sensitive and 98.3% specific (95% CI [90.8% to 99.9%]). The dynamic technique was 92.1% (95% CI [82.4% to 97.4%]) sensitive and 91.2% specific (95% CI [80.7% to 97.1%]). The mean time to identification was 6.72 seconds (95% CI [5.53 to 7.9] seconds) in the static technique and 6.4 seconds (95% CI [5.65 to 7.16] seconds) in the dynamic technique. Operator confidence was 4.9/5.0 (95% CI [4.83 to 4.97]) in the static technique and 4.86/5.0 (95% CI [4.78 to 4.94]) in the dynamic technique. There was no statistically significant difference between groups for any of the outcomes. CONCLUSION: This study demonstrated that both the static and dynamic sonography approaches were rapid and accurate for confirming ETT location with no statistically significant difference between modalities. Further studies are recommended to compare these techniques in ED patients and with more novice sonographers.

Comparison of color flow with standard ultrasound for the detection of endotracheal intubation.

INTRODUCTION: Intubation is a frequently performed procedure in emergency medicine that is associated with significant morbidity and mortality when unrecognized esophageal intubation occurs. However, it may be difficult to visualize the endotracheal tube (ETT) in some patients. This study assessed whether the addition of color Doppler was able to improve the ability to visualize the ETT location. METHODS: This study was performed in a cadaver lab using three different cadavers chosen to represent varying neck circumference. Cadavers were randomized to tracheal or esophageal intubation. Blinded sonographers then assessed the location of the ETT using either grayscale or color Doppler imaging. Accuracy of sonographer identification of ETT location, time to identification, and operator confidence were assessed. RESULTS: One hundred and fifty intubations were performed and each was assessed by both standard and color Doppler techniques. There were 78 tracheal intubations and 72 esophageal intubations. The standard technique was 99.3% (95% CI 96.3 to 99.9%) accurate. The color flow technique was also 99.3% (95% CI 96.3 to 99.9%) accurate. The mean operator time to identification was 3.24s (95% CI 2.97 to 3.51s) in the standard approach and 5.75s (95% CI 5.16 to 6.33s) in the color flow technique. The mean operator confidence was 4.99/5.00 (95% CI 4.98 to 5.00) in the standard approach and 4.94/5.00 (95% CI 4.90 to 4.98) in the color flow technique. CONCLUSION: When added to standard ultrasound imaging, color flow did not improve accuracy or operator confidence for identifying ETT location and resulted in a longer examination time.

Utilization of ultrasound for the evaluation of small bowel obstruction: A systematic review and meta-analysis.

INTRODUCTION: Small bowel obstruction (SBO) is a common presentation to the Emergency Department (ED). While computed tomography (CT) is frequently utilized to confirm the diagnosis, this modality is expensive, exposes patients to radiation, may lead to time delays, and is not universally available. This study aimed to determine the test characteristics of ultrasound for the diagnosis of SBO. METHODS: PubMed, CINAHL, Scopus, the Cochrane Database of Systematic Reviews, and the Cochrane Central Register of Controlled Trials were assessed for prospective trials evaluating the accuracy of ultrasound for the detection of SBO. Data were double extracted into a predefined worksheet and quality analysis was performed using the Quality Assessment of Diagnostic Accuracy Studies (QUADAS-2) tool. RESULTS: This systematic review identified 11 studies comprising 1178 total patients. Overall, ultrasound was found to be 92.4% sensitive (95% CI 89.0% to 94.7%) and 96.6% specific (95% CI 88.4% to 99.1%) with a positive likelihood ratio of 27.5 (95% CI 7.7 to 98.4) and a negative likelihood ratio of 0.08 (95% CI 0.06 to 0.11). DISCUSSION: The existing literature suggests that ultrasound is a valuable tool in the diagnosis of SBO with a sensitivity and specificity comparable to that of CT. Ultrasound may save time and radiation exposure, while also allowing for serial examinations of patients to assess for resolution of the SBO. It may be particularly valuable in settings with limited or no access to CT. Future studies should include more studies in the Emergency Department setting, comparison of probe choices, and inclusion of more pediatric patients.

Ultrasound-Guided Peripheral Intravenous Line Placement: A Narrative Review of Evidence-based Best Practices.

Peripheral intravenous line placement is a common procedure in emergency medicine. Ultrasound guidance has been demonstrated to improve success rates, as well as decrease complications and pain. This paper provides a narrative review of the literature focusing on best practices and techniques to improve performance with this procedure. We provide an evidence-based discussion of preparation for the procedure, vein and catheter selection, multiple techniques for placement, and line confirmation.

Dilated right coronary sinus identified on point-of-care ultrasound.

Point-of-care cardiac ultrasound (POCUS) is a common application in Emergency Medicine. Here we present a case of an incidentally discovered dilated right coronary sinus on ultrasound. This case involved a 55-year-old female who presented with chest pain, shortness of breath, and lightheadedness. Her initial presentation was concerning for congestive heart failure (CHF) exacerbation. A bedside ultrasound was performed to assess cardiac function, where a dilated right coronary sinus was discovered. The right coronary sinus is the vein that serves as the venous return for the coronary system. It is a tubular structure located at the posterior atrioventricular groove and it is generally not visible unless it is pathologically dilated. Identification of a dilated right coronary sinus can assist the clinician in making the diagnoses of CHF exacerbation, as well as alter the approach to specific procedures. To the best of our knowledge, this is the first case report describing the identification of a dilated right coronary sinus using POCUS.

Comparison of Tamsulosin, Nifedipine, and Placebo for Ureteric Colic.

Clinical question Do calcium channel blockers or alpha blockers improve renal stone passage when compared with placebo? Article chosen Pickard R, Starr K, MacLennan G, et al. Medical expulsive therapy in adults with ureteric colic: a multicentre, randomised, placebo-controlled trial. Lancet 2015;386(9991):25-31, doi: 10.1016/S0140-6736(15)60933-3.

Frequency of Fractures Identified on Post-Reduction Radiographs After Shoulder Dislocation.

INTRODUCTION: Most emergency physicians routinely obtain shoulder radiographs before and after shoulder dislocations. However, currently there is limited literature demonstrating how frequently new fractures are identified on post-reduction radiographs. The primary objective of this study was to determine the frequency of new, clinically significant fractures identified on post-reduction radiographs with a secondary outcome assessing total new fractures identified. METHODS: We conducted a retrospective chart review using appropriate International Classification of Diseases, 9(th) Revision (ICD-9) codes to identify all potential shoulder dislocations that were reduced in a single, urban, academic emergency department (ED) over a five-year period. We excluded cases that required operative reduction, had associated proximal humeral head or shaft fractures, or were missing one or more shoulder radiograph reports. All charts were abstracted separately by two study investigators with disagreements settled by consensus among three investigators. Images from indeterminate cases were reviewed by a radiology attending physician with musculoskeletal expertise. The primary outcome was the percentage of new, clinically significant fractures defined as those altering acute ED management. Secondary outcomes included percentage of new fractures of any type. RESULTS: We identified 185 total patients meeting our study criteria. There were no new, clinically significant fractures on post-reduction radiographs. There were 13 (7.0%; 95% CI [3.3%-10.7%]) total new fractures identified, all of which were without clinical significance for acute ED management. CONCLUSION: Post-reduction radiographs do not appear to identify any new, clinically significant fractures. Practitioners should re-consider the use of routine post-reduction radiographs in the ED setting for shoulder dislocations.