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

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

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

INTRODUCTION

Evidence supports an ultrasound-guided approach in patients with difficult vascular access. Prior research on teaching ultrasound-guided intravenous access has included only small groups of first- and second-year medical students.

METHODS

We enrolled fourth-year medical students in our teaching module. The module featured a 6-minute prelearning narrated lecture and 5-minute orientation, followed by ultrasound-guided IV placement on homemade gel models. Facilitators were emergency medicine (EM) residents with a prespecified level of procedural ultrasound skills according to EM milestones. Students completed pre- and postmodule surveys. Facilitators completed the Directly Observed Procedural Skills Evaluation. Primary outcomes included global rating, proficiency on six procedural skills, and perceived learning.

RESULTS

Our module was completed by 150 fourth-year medical students (94% of the class); 84% cannulated the vein in one attempt. We used a global rating scale to describe the students' cannulation abilities; 59% were trusted to perform this procedure with direct supervision and coaching, 29% with indirect supervision, and 8% without supervision. There was no association between a student's order of attempting IV access within the group and global rating (p = .41). Students reported increased understanding of indications, antecubital anatomy, sonographic anatomy, and procedural comfort (12%, 29%, 38%, and 65% improvement pre- vs. postmodule, respectively; p < .001).

DISCUSSION

Our module enabled more than one-third of fourth-year medical students to achieve an indirect supervision or better level of proficiency in ultrasound-guided IV access, with significant improvements in perceived knowledge. This module may be useful for other educators facilitating the transition to residency.

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

INTRODUCTION

Point-of-care ultrasound (POCUS) is a valuable asset in bedside clinical care. Undergraduate medical education is increasingly using POCUS as an adjunct tool for teaching anatomy, pathophysiology, and physical exam in an integrated manner. Many medical schools teach content in an organ systems-based format in the preclerkship years. POCUS teaching can be very effectively tailored to specific organ systems. Though pilot curricula for generalized ultrasound education exist, few teach organ systems-based content using POCUS. To address this gap, we designed and implemented an integrated POCUS module to supplement anatomy, pathophysiology, and physical exam teaching in the renal course.

METHODS

The module consisted of (1) a 30-minute didactic lecture introducing students to renal ultrasound technique and image interpretation and (2) a practical hands-on skills session. Pre- and postmodule surveys assessed the efficacy and impact of the curriculum.

RESULTS

A total of 31 first-year medical students completed the POCUS renal curriculum. A majority reported that the module positively affected their understanding of renal pathophysiology and the physical exam. They also reported increased confidence in using POCUS to detect renal pathology and make clinical decisions.

DISCUSSION

It was feasible to implement a POCUS curriculum to supplement integrated teaching of renal system concepts in the first year of medical school, and students found POCUS teaching valuable. POCUS provides educators with another tool to integrate basic and clinical sciences with hands-on relevant clinical skills practice in early medical school years.

Discovery and quantification of a widespread methane ebullition event in a coastal inlet (Baltic Sea) using a novel sonar strategy

How much of the greenhouse gas methane is transported from the seafloor to the atmosphere is unclear. Here, we present data describing an extensive ebullition event that occurred in Eckernförde Bay, a shallow gas-hosting coastal inlet in the Baltic Sea, in the fall of 2014. A weak storm induced hydrostatic pressure fluctuations that in turn stimulated gas ebullition from the seabed. In a finely tuned sonar survey of the bay, we obtained a hydroacoustic dataset with exceptionally high sensitivity for bubble detection. This allowed us to identify 2849 bubble seeps rising within 28 h from the seafloor across the 90 km² study site. Based on our calculations, the estimated bubble-driven episodic methane flux from the seafloor across the bay is 1,900 μMol m⁻² d⁻¹. Our study demonstrates that storm-associated fluctuations of hydrostatic pressure induce bulk gas-driven ebullitions. Given the extensive occurrence of shallow gas-hosting sediments in coastal seas, similar ebullition events probably take place in many parts of the Western Baltic Sea. However, these are likely to be missed during field investigations, due to the lack of high-quality data acquisition during storms, such that atmospheric inputs of marine-derived methane will be highly underestimated.

The Impact of Interdisciplinary Education on Skills and Attitudes of Surgery and Emergency Medicine Residents

Background  Interdisciplinary education (IDE) has been proposed as a means to improve patient safety by enhancing the performance of diverse health care teams. The improved camaraderie between members of different specialties may enhance communication and can foster a more supportive and positive work environment.

Objective  This study was aimed to assess the effect of IDE on the procedural skills of general surgery (GS) and emergency medicine (EM), as well as the perceptions that GS and EM residents have of one another.

Methods  EM and GS residents participated in two separate IDE sessions (4 months apart) designed to teach extended focused assessment with sonography in trauma (e-FAST), tube thoracostomy, and complex wound closure. Surveys were administered to determine the effects that IDE had on confidence in performing bedside procedures, perceptions of IDE, and perceptions of one another's specialty. Survey responses were recorded using a 5-point Likert's scale.

Results  Nine GS residents and 10 EM residents participated in the entire study. Significant improvements in the confidence levels of performing bedside procedures were noted among both groups of residents. We also report a significant improvement in the perceived respect and communication between EM and GS residents.

Conclusions  Although further studies with a larger sample size are required, we have shown that IDE can improve the confidence levels of EM and GS residents in performing tube thoracostomy, e-FAST, and complex wound closure. These IDE sessions also improve the perceptions that the residents have of one another. IDE is a useful tool and may translate into improved consultation, collaboration, and patient care.

Size does matter: importance of large bubbles and small-scale hot spots for methane transport

Ebullition (bubbling) is an important mechanism for the transfer of methane (CH4) from shallow waters to the atmosphere. Because of their stochastic nature, however, ebullition fluxes are difficult to accurately resolve. Hydroacoustic surveys have the potential to significantly improve the spatiotemporal observation of emission fluxes, but knowledge of bubble size distribution is also necessary to accurately assess local, regional, and global water body CH4 emission estimates. Therefore, we explore the importance of bubble size and small-scale flux variability on CH4 transport in and emissions from a reservoir with a bubble-size-calibrated echosounder that can efficiently and economically survey greater areas while still resolving individual bubbles. Using a postprocessing method that resolves bubble density, we found that the largest 10% of the >6700 observed bubbles were responsible for more than 65% of the total CH4 transport. Furthermore, the asymmetry of CH4 ebullition flux distribution and the high spatial heterogeneity of those fluxes suggests that inadvertently omitting emission hot spots (i.e., areas of high flux) could lead to significant underestimations of CH4 emissions from localized areas and potentially from entire water bodies. While the bubble sizes resolved by the hydroacoustic method may provide insight into the factors controlling ebullition (e.g., sediment type, carbon sedimentation), the better resolution of small-scale CH4 emission hot spots afforded by hydroacoustics will bring us closer to the true CH4 emission estimates from all shallow waters, be them lakes, reservoirs, or coastal oceans and seas.