RESUMO
OBJECTIVE: Emerging evidence suggests that chest radiography (CXR) following central venous catheter (CVC) placement is unnecessary when point-of-care ultrasound (POCUS) is used to confirm catheter position and exclude pneumothorax. However, few providers have adopted this practice, and it is unknown what contributing factors may play a role in this lack of adoption, such as ultrasound experience. The objective of this study was to evaluate the diagnostic accuracy of POCUS to confirm CVC position and exclude a pneumothorax after brief education and training of nonexperts. METHODS: We performed a prospective cohort study in a single academic medical center to determine the diagnostic characteristics of a POCUS-guided CVC confirmation protocol after brief training performed by POCUS nonexperts. POCUS nonexperts (emergency medicine senior residents and critical care fellows) independently performed a POCUS-guided CVC confirmation protocol after a 30-minute didactic training. The primary outcome was the diagnostic accuracy of the POCUS-guided CVC confirmation protocol for malposition and pneumothorax detection. Secondary outcomes were efficiency and feasibility of adequate image acquisition, adjudicated by POCUS experts. RESULTS: Twenty-six POCUS nonexperts collected data on 190 patients in the final analysis. There were five (2.5%) CVC malpositions and six (3%) pneumothoraxes on CXR. The positive likelihood ratios of POCUS for malposition detection and pneumothorax were 12.33 (95% confidence interval [CI] = 3.26 to 46.69) and 3.41 (95% CI = 0.51 to 22.76), respectively. The accuracy of POCUS for pneumothorax detection compared to CXR was 0.93 (95% CI = 0.88 to 0.96) and the sensitivity was 0.17 (95% CI = 0.00 to 0.64). The median (interquartile range) time for CVC confirmation was lower for POCUS (9 minutes [8.5-9.5 minutes]) compared to CXR (29 minutes [1-269 minutes]; Mann-Whitney U, p < 0.01). Adequate protocol image acquisition was achieved in 76% of the patients. CONCLUSION: Thirty-minute training of POCUS in nonexperts demonstrates adequate diagnostic accuracy, efficiency, and feasibility of POCUS-guided CVC position confirmation, but not exclusion of pneumothorax.
RESUMO
This work first overviews a novel design, and prototype implementation, of a virtually transparent epidermal imagery (VTEI) system for laparo-endoscopic single-site (LESS) surgery. The system uses a network of multiple, micro-cameras and multiview mosaicking to obtain a panoramic view of the surgery area. The prototype VTEI system also projects the generated panoramic view on the abdomen area to create a transparent display effect that mimics equivalent, but higher risk, open-cavity surgeries. The specific research focus of this paper is on two important aspects of a VTEI system: 1) in vivo wireless high-definition (HD) video transmission and 2) multi-image processing-both of which play key roles in next-generation systems. For transmission and reception, this paper proposes a theoretical wireless communication scheme for high-definition video in situations that require extremely small-footprint image sensors and in zero-latency applications. In such situations the typical optimized metrics in communication schemes, such as power and data rate, are far less important than latency and hardware footprint that absolutely preclude their use if not satisfied. This work proposes the use of a novel Frequency-Modulated Voltage-Division Multiplexing (FM-VDM) scheme where sensor data is kept analog and transmitted via "voltage-multiplexed" signals that are also frequency-modulated. Once images are received, a novel Homographic Image Mosaicking and Morphing (HIMM) algorithm is proposed to stitch images from respective cameras, that also compensates for irregular surfaces in real-time, into a single cohesive view of the surgical area. In VTEI, this view is then visible to the surgeon directly on the patient to give an "open cavity" feel to laparoscopic procedures.