Continuous cardiac output estimation using a new modified Fick method during off-pump coronary artery bypass graft surgery: a retrospective observational study.

PURPOSE: Several technical aspects of the Fick method limit its use intraoperatively. A data-driven modification of the Fick method may enable its use in intraoperative settings. METHODS: This two-center retrospective observational study included 57 (28 and 29 in each center) patients who underwent off-pump coronary artery bypass graft (OPCAB) surgery. Intraoperative recordings of physiological data were obtained and divided into training and test datasets. The Fick equation was used to calculate cardiac output (CO-Fick) using ventilator-determined variables, intraoperative hemoglobin level, and SvO2, with continuous thermodilution cardiac output (CCO) used as a reference. A modification CO-Fick was derived and validated: CO-Fick-AD, which adjusts the denominator of the original equation. RESULTS: Increased deviation between CO-Fick and CCO was observed when oxygen extraction was low. The root mean square error of CO-Fick was decreased from 6.07 L/min to 0.70 L/min after the modification. CO-Fick-AD showed a mean bias of 0.17 (95% CI 0.00-0.34) L/min, with a 36.4% (95% CI 30.6-44.4%) error. The concordance rates of CO-Fick-AD ranged from 73.3 to 87.1% depending on the time interval and exclusion zone. CONCLUSIONS: The original Fick method is not reliable when oxygen extraction is low, but a modification using data-driven approach could enable continuous estimation of cardiac output during the dynamic intraoperative period with minimal bias. However, further improvements in precision and trending ability are needed.

Optimal view detection for ultrasound-guided supraclavicular block using deep learning approaches.

Successful ultrasound-guided supraclavicular block (SCB) requires the understanding of sonoanatomy and identification of the optimal view. Segmentation using a convolutional neural network (CNN) is limited in clearly determining the optimal view. The present study describes the development of a computer-aided diagnosis (CADx) system using a CNN that can determine the optimal view for complete SCB in real time. The aim of this study was the development of computer-aided diagnosis system that aid non-expert to determine the optimal view for complete supraclavicular block in real time. Ultrasound videos were retrospectively collected from 881 patients to develop the CADx system (600 to the training and validation set and 281 to the test set). The CADx system included classification and segmentation approaches, with Residual neural network (ResNet) and U-Net, respectively, applied as backbone networks. In the classification approach, an ablation study was performed to determine the optimal architecture and improve the performance of the model. In the segmentation approach, a cascade structure, in which U-Net is connected to ResNet, was implemented. The performance of the two approaches was evaluated based on a confusion matrix. Using the classification approach, ResNet34 and gated recurrent units with augmentation showed the highest performance, with average accuracy 0.901, precision 0.613, recall 0.757, f1-score 0.677 and AUROC 0.936. Using the segmentation approach, U-Net combined with ResNet34 and augmentation showed poorer performance than the classification approach. The CADx system described in this study showed high performance in determining the optimal view for SCB. This system could be expanded to include many anatomical regions and may have potential to aid clinicians in real-time settings.Trial registration The protocol was registered with the Clinical Trial Registry of Korea (KCT0005822, https://cris.nih.go.kr ).

Comparison between costotransverse foramen block and thoracic paravertebral block for VATS pulmonary resection: A randomized noninferiority trial.

STUDY OBJECTIVE: The present study assessed whether costotransverse foramen block (CTFB) is noninferior to thoracic paravertebral block (TPVB) for postoperative analgesia in video-assisted thoracoscopic surgery (VATS) pulmonary resection. DESIGN: Single-center, double-blinded, randomized, non-inferiority trial. SETTING: Operating room and intensive care unit or ward in a tertiary hospital. PATIENTS: Patients aged 20 to 80 years with American Society of Anesthesiology physical status 1 to 3 scheduled for elective VATS pulmonary resection. INTERVENTIONS: Sixty patients were randomly allocated 1:1 to receive CTFB or TPVB using 15 mL aliquots of 0.5% ropivacaine at the T4-5 and T6-7 intercostal levels immediately after the induction of general anesthesia. MEASUREMENTS: The primary outcome was the area under the curve (AUC) of numeric rating scale (NRS, 0 to 10) during 24 h postoperatively (noninferiority limit was 24; NRS 1 per hour). The secondary outcomes included postoperative opioid consumption, rescue analgesic use, postoperative nausea and vomiting, pulmonary function, dermatomal spread of the blockade, and quality of recovery. MAIN RESULTS: Forty-seven patients were included for final analysis. The difference between the mean 24-h AUCs of NRS in the CTFB (34.25 ± 16.30, n = 24) and TPVB (39.52 ± 17.13, n = 23) groups was -5.27 (95% confidence interval [CI], -15.09 to 4.55), with the upper limit of 95% CI being far below the predefined noninferiority margin of 24. There was no significant difference in the dermatomal spread of the blockades between the groups, as both reached the upper and lower most levels of T3 and T7 (median). Additionally, there were no significant differences in other secondary outcomes between the two groups. CONCLUSIONS: The analgesic effect of CTFB was noninferior to that of TPVB during 24 h postoperatively in VATS pulmonary resection. Moreover, CTFB may offer potential safety benefits by keeping the tip of the needle far from the pleura and vascular structure.

3D Printing of CNT- and YSZ-Added Dental Resin-Based Composites by Digital Light Processing and Their Mechanical Properties.

This study demonstrates the successful 3D printing of dental resin-based composites (DRCs) containing ceramic particles using the digital light processing (DLP) technique. The mechanical properties and oral rinsing stability of the printed composites were evaluated. DRCs have been extensively studied for restorative and prosthetic dentistry due to their clinical performance and aesthetic quality. They are often subjected to periodic environmental stress, and thus can easily undergo undesirable premature failure. Here, we investigated the effects of two different high-strength and biocompatible ceramic additives, carbon nanotube (CNT) and yttria-stabilized zirconia (YSZ), on the mechanical properties and oral rinsing stabilities of DRCs. Dental resin matrices containing different wt.% of CNT or YSZ were printed using the DLP technique after analyzing the rheological behavior of slurries. Mechanical properties such as Rockwell hardness and flexural strength, as well as the oral rinsing stability of the 3D-printed composites, were systematically investigated. The results indicated that a DRC with 0.5 wt.% YSZ exhibits the highest hardness of 19.8 ± 0.6 HRB and a flexural strength flexural strength of 50.6 ± 6 MPa, as well as reasonable oral rinsing steadiness. This study provides a fundamental perspective for designing advanced dental materials containing biocompatible ceramic particles.