Risk Factors and Long-Term Implications of Unplanned Conversion During Laparoscopic Liver Resection for Hepatocellular Carcinoma.

Background: Laparoscopic liver resection (LLR) has become a widely used standardized operation for patients with hepatocellular carcinoma (HCC) in the field of hepatic surgery. However, the risk factors and long-term implications associated with unplanned conversion to an open procedure during the LLR have not been adequately studied. Methods: The study incorporated 96 patients with HCC. Risk factors of conversion and their prognosis were analyzed by comparing patients who successfully underwent LLR with those who required unplanned conversion. Results: In this study, the unplanned conversion rate for laparoscopic hepatectomy was 42.7%. Patients who underwent conversion had longer length of stay (8 versus 7 days, P < .001), longer operation time (297.73 versus 194.03 minutes, P = .000), a higher transfusion rate (29.3% versus 5.5%, P < .001), and more postoperative complications compared with patients who successfully underwent LLR. The two surgical maneuvers did not show substantial disparities in terms of total survival and disease-free survival rates. Risk factors of unplanned conversion contained tumor location (odds ratio [OR], 3.129; 95% confidence interval [CI]: 1.214-8.066; P = 0.018) and tumor size (OR, 2.652; 95% CI: 1.039-6.767; P = 0.041). Conclusions: The unplanned conversion during LLR for HCC was linked to unfavorable short-term prognosis, yet it did not influence long-term oncologic outcomes. Moreover, preoperative evaluation of tumor size and location may effectively reduce the probability of unplanned conversion during LLR.

Delimiting Low Level of Difficulty Scoring System Based on the Extent of Resection Difficulty Scoring System for Laparoscopic Liver Resection.

Background: The difficulty scoring system based on the extent of resection (DSS-ER) is a common tool for assessing the difficulty and risk of laparoscopic liver resection (LLR), but DSS-ER fails to comprehensively and accurately assess low level for beginners. Methods: The 93 cases of LLRs for primary liver cancer in the general surgery department of the Second Affiliated Hospital of Guangxi Medical University from 2017 to 2021 were retrospectively analyzed. The low level of DSS-ER difficulty scoring system was reclassified into three grades. The intraoperative and postoperative complications were compared among different groups. Results: There were significant differences in the operative time, blood loss, intraoperative allogeneic blood transfusion, conversion to laparotomy, and allogeneic blood transfusion among the different groups. Meanwhile, the postoperative complications were mainly pleural effusion and pneumonia, and the incidence of grade III was higher compared with other two grades. No significant difference existed in the postoperative biliary leakage and liver failure among three grades. Conclusions: This reclassified low level of DSS-ER difficulty scoring system has certain clinical value for LLR beginners to complete the corresponding learning curve.

On the evaluation of effective density for plate- and membrane-type acoustic metamaterials without mass attached.

The effective densities of plate- and membrane-type acoustic metamaterials (AMMs) without mass attached are studied theoretically and numerically. Three models, including the analytic model (based on the plate flexural wave equation and the membrane wave equation), approximate model (under the low frequency approximation), and the finite element method (FEM) model, are first used to calculate the acoustic impedance of square and clamped plates or membranes. The effective density is then obtained using the resulting acoustic impedance and a lumped model. Pressure transmission coefficients of the AMMs are computed using the obtained densities. The effect of the loss from the plate is also taken into account. Results from different models are compared and good agreement is found, particularly between the analytic model and the FEM model. The approximate model is less accurate when the frequency of interest is above the first resonance frequency of the plate or membrane. The approximate model, however, provides simple formulae to predict the effective densities of plate- or membrane-type AMMs and is accurate for the negative density frequency region. The methods presented in this paper are useful in designing AMMs for manipulating acoustic waves.

Membrane- and plate-type acoustic metamaterials.

Over the past decade there has been a great amount of research effort devoted to the topic of acoustic metamaterials (AMMs). The recent development of AMMs has enlightened the way of manipulating sound waves. Several potential applications such as low-frequency noise reduction, cloaking, angular filtering, subwavelength imaging, and energy tunneling have been proposed and implemented by the so-called membrane- or plate-type AMMs. This paper aims to offer a thorough overview on the recent development of membrane- or plate-type AMMs. The underlying mechanism of these types of AMMs for tuning the effective density will be examined first. Four different groups of membrane- or plate-type AMMs (membranes with masses attached, plates with masses attached, membranes or plates without masses attached, and active AMMs) will be reviewed. The opportunities, limitations, and challenges of membrane- or plate-type AMMs will be also discussed.