This was a retrospective pre- and post-study conducted 1 year before and after implementation of a POCUS SSTI training curriculum in a pediatric ED. The study took place at an urban academic pediatric ED with over 60,000 annual visits. It was deemed exempt by the Institutional Review Board.

Pediatric patients (0–17 years of age) who presented to the ED from July 1st, 2016, to June 30th, 2017 (pre-implementation) and July 1st, 2018, to June 30th, 2019 (post-implementation) with an SSTI diagnosis met the inclusion criteria for the study. There was a 12-month washout period from July 1st, 2017, to June 30th, 2018, while the training curriculum was implemented. During this washout period, participants were trained and were able to successfully complete the curriculum while routine SSTI care was provided. Pre and post-assessment groups remained the same during the entire length of the study. Patients were included if they had a final diagnosis of SSTI as identified in the electronic medical record by international classification of diseases (ICD) revision codes, 9th (ICD-9 682.2, 682.3, 682.6, 682.8, 682.9, 685.0, 685.1, 686.8, 686.9, 709.8, and 709.9) and 10th (ICD-10 L03.319, L03.119, L03.11, L03.81, L03.818, L05.01, L05.91, L08.9, L99, L03.221, L03.22, L03.317, L03.312). Patients with a secondary diagnosis, complicated infection including those requiring hospital admission and surgical intervention were excluded (Fig. 1). We collected patient demographic information, diagnostic imaging type including POCUS and radiology ultrasound examinations performed, and patient disposition.

Patient participant flowchart with inclusion and exclusion applied to patient selection pre- and post-intervention of SSTI curriculum

Pediatric emergency medicine faculty and fellows underwent training on soft tissue POCUS to improve knowledge, skill, and comfort to integrate this tool in clinical management of patients. At the time of the study, 14 fellowship-trained pediatric emergency faculty and 8 pediatric emergency fellows took part in training. For the training, faculty were required to complete 1-h didactic sessions, hands-on instruction with supervision by a fellowship-trained POCUS expert, complete 4 h of continuing medical education (CME), successfully pass a competency assessment, and complete 25 quality assured soft tissue POCUS examinations as described previously [3, 5]. Content covered during the didactic sessions included techniques, equipment selection, soft tissue anatomy, image acquisition, differentiating various SSTI and soft tissue edema pathology, differentiating common types of soft tissue foreign body and clinical integration. The hands-on education comprised clinical scans in the emergency department. Faculty obtained CME asynchronously on through institutional and departmental POCUS workshops.

POCUS examinations were completed using a Zonare ZS3 (Mindray, Shenzhen, China) with the linear transducer. Images from the ultrasound system were wirelessly saved to an image archiving and workflow solution (Qpath, Telexy Healthcare, Maple Ridge, BC, Canada) designed to provide immediate feedback and quality assurance.

Radiology ultrasound was conducted in a pediatric radiology department housed adjacent to the main ED with 24-h availability. The ultrasound department is staffed with sonographic technicians who acquire the images and upload them to the institution’s picture archiving and communicating system (PACS) for review and interpretation by a board-certified pediatric radiologist.

Using the corresponding CPT codes for SSTI for POCUS and RUS, data concerning charges toward the patients’ payer were collected via the institutions professional billing services and our hospital system’s finance office. Cost was calculated from these charges which included technical and professional component of the radiology services. POCUS rates were set by payer-negotiated reimbursement through the institution’s finance office which included technical and professional fees billed through a third-party billing service.

For continuous measures, we reported descriptive summary statistics such as mean and standard error of the mean. The Wilcoxon test was used to test for differences over time. For categorical measures, we reported frequency and percentages. The Chi-square test was used to determine differences among proportions of ultrasound examination. P < 0.05 was considered significant. All statistical analysis was performed using SAS 9.4. The study was powered by a sample size of 91 based on a confidence level of 95% and an alpha of 5% assuming a target population 100 which was based on approximately 50% of actual population of estimated patients with SSTI.