CJEM Articles: ultrasonography

Objective:
To determine whether novices can distinguish between properly and improperly placed guidewires in a vascular access model after only minimal training.
Methods:
This was a prospective study involving trainees with no previous training in sonographic guidewire visualization. A vascular access model was created with guidewires positioned inside or adjacent to simulated veins. Subjects were taught to scan each wire to determine its location. Afterward, participants scanned a test model of five vein-wire pairs and recorded their answers as “inside,” “outside,” or “unsure.” The test characteristics of sonographic guidewire localization were determined using actual wire location as the criterion standard.
Results:
Forty trainees (21 emergency medicine residents, 19 medical students) participated, and each examined five simulated veins. There were 156 true positives (intravascular wire correctly identified), 38 true negatives (extravascular wire correctly identified), 2 false negatives, 2 false positives, and 2 cases in which the participant marked “not sure,” which were reclassified as false negatives. Test characteristics were sensitivity 97.5% (95% CI 93.3–99.2) and specificity 95.0% (95% CI 81.8–99.1). The overall accuracy was 97.0%.
Conclusions:
Sonographic guidewire visualization, a step recommended for ensuring proper vessel cannulation during central venous access, can be accomplished by novices with a high degree of accuracy.

Objectives:

To quantify the current availability and use of bedside emergency department ultrasonography (EDUS) for blunt trauma at Canadian pediatric centres and to identify any perceived barriers to the use of bedside EDUS in such centres.

Methods:

An electronic survey was sent to 162 pediatric emergency physicians and 12 site directors from the 12 pediatric emergency departments across Canada.

Results:

Ninety-two percent (11 of 12) of centres completed the survey. The individual physician response rate was 65% (106 of 162), with 100% of site directors responding. Ultrasound machines were available in 45% (5 of 11) of centres. Forty-two percent (32 of 77) of emergency physicians working in equipped pediatric centres used bedside EDUS to evaluate blunt abdominal trauma (BAT). In the subgroup of staff who also worked at adults sites, the frequency of ultrasonography use for the evaluation of pediatric BAT was 75%. In the 55% (6 of 11) of centres without ultrasonography, 88% of staff intend to incorporate its use in the future and 81% indicated that they believed the incorporation of ultrasonography would have a positive impact on patient care. The main perceived barriers to the use of ultrasonography in the evaluation of BAT were a lack of training (41%) and a lack of equipment (26%).

Conclusion:

Bedside EDUS is currently used in almost half of pediatric trauma centres, a frequency that is significantly lower than adult centres. Physicians in pediatric centres who use ultrasonography report that it has a high utility, and a great majority of physicians at pediatric centres without EDUS plan to incorporate it in the future. The main reported barriers to its use are a lack of training and a lack of equipment availability.

Objective: Our goal was to gain a better understanding of the femoral vessel anatomy as it relates to central venous cannulation. The primary objective of this study was to use bedside ultrasonography to determine the amount of exposed femoral vein at three sites corresponding to surface anatomy of the landmark-based procedure.
Methods: This cross-sectional study enrolled a random sample of 180 adult patients presenting to a large urban academic emergency department. Subjects underwent standardized ultrasonography to identify and measure the depth and diameter of the femoral vessels and amount of exposed femoral vein at the level of the inguinal ligament (0 cm) 2 cm and 4 cm below. Repeated measures analysis of variance was used to determine significant relationships between vessel measurements and distance from the inguinal ligament.
Results: The median age was 44.5 (range 19–90) years; 101 patients were male. The mean (± SD) percentage of exposed vein at the inguinal ligament was 83% (± 21). This decreased significantly (p < 0.01) with increasing distance from the inguinal ligament: 65% (± 25) at 2 cm and 56% (± 30) at 4 cm. At every distance away from the inguinal ligament, there were some subjects with no vein exposed.
Conclusion: This study demonstrates significant overlap of the femoral vessels at sites where landmark-based femoral vein cannulation is often attempted. Our results suggest that ultrasound guidance would be beneficial as femoral vein cannulation may be difficult or impossible in certain individuals owing to anatomic variations.