Automatic irrigation system with a fiber-optic pressure sensor regulating intrapelvic pressure for flexible ureteroscopy.

Increased intrapelvic pressure (IPP) due to irrigation during flexible ureteroscopy (f-URS) can pose a risk of postoperative severe urinary tract infection associated with pyelovenous backflow. An automatic regulation system for maintaining safe IPP levels could enable surgeons to perform f-URS safely without postoperative complications. This study aimed to assess the measurement accuracy of an ultra-miniature fiber-optic pressure sensor incorporated into a small-caliper ureteroscope for assessing IPP and to develop an automatic irrigation system linked to this sensor. A porcine kidney was used for the ex vivo experiment. The nephrostomy catheter, connected to the conventional pressure transducer, was placed on the renal pelvis to evaluate the actual IPP (a-IPP). For measuring IPP using the fiber-optic pressure sensor (fo-IPP) built into the f-URS, a diaphragm pressure sensor of Φ250 µm was used. To establish an irrigation system, the optimal proportional-integral-derivative (PID) controller was explored to accurately adjust the irrigation pump flow rate. A high correlation between a-IPP and fo-IPP was confirmed across irrigation pressure values of 60-180 mbar (all, r ≥ 0.7, p < 0.001). When performing bolus irrigation, although fo-IPP showed relatively a higher peak value than a-IPP, the response time of fo-IPP was equivalent to that of a-IPP. After PID parameter optimization, our automatic irrigation system based on fo-IPP smoothly and accurately regulated the intended IPP set in the 5-20 mmHg range without overshooting. We successfully developed and demonstrated an automatic irrigation system regulating IPP based on the PID controller for f-URS, utilizing a fiber-optic pressure sensor. Further research, including in vivo studies, will be needed to assess clinical feasibility.

Fusion Assessment of Oblique Lumbar Interbody Fusion Using Demineralized Bone Matrix: A 2-Year Prospective Study.

OBJECTIVE: Although several studies have reported successful fusion rates after oblique lumbar interbody fusion (OLIF) using allografts or dimerized bone matrix (DBM) instead of autografts, whether OLIF can achieve satisfactory solid fusion without the use of autografts remains unclear. This study investigated the real fusion rates after OLIF using allografts and DBM, which were evaluated using both dynamic radiographs and computed tomography scans. METHODS: We enrolled 79 consecutive patients who underwent minimally invasive OLIF followed by percutaneous pedicle screw fixation. All patients were treated with OLIF between L2 and L5 and underwent radiographic and clinical follow-ups at 12, 18, and 24 months after surgery. Radiographic assessment of fusion was performed using the modified BrantigaSteffee-Fraser (mBSF) scale, which was categorized as follows: grades I (radiographic pseudoarthrosis), II (indeterminate fusion), and III (solid radiographic fusion). Other radiologic and clinical outcomes were evaluated using the following parameters: vertebral slippage distance, disc height, subsidence, Oswestry Disability Index (ODI), and visual analogue scale (VAS). RESULTS: Clinical outcomes demonstrated significant improvements in the VAS scores for back pain, leg pain, and ODI after surgery. Subsidence was present in 34 cases (35.4%) at 12 months postoperatively, which increased to 47.9% and reached 50.0% at 1.5 years and 2 years after surgery, respectively. The solid fusion rate after OLIF was 32.3% at 1 year, increased to 58.3% at 1.5 years, and reached 72.9% at 2 years. Radiographic pseudoarthrosis was 24.0% at 1 year, which decreased to 6.3% at 1.5 years and 3.1% at 2 years. CONCLUSION: OLIF is a safe and effective surgical procedure for the treatment of degenerative lumbar diseases. The mBSF scale, which simultaneously evaluates both dynamic angles and bone bridge formation, offers great reliability for the radiological assessment of fusion. Moreover, OLIF using allografts and DBM, which is performed on one or 2 levels at L2-5, can achieve satisfactory fusion rates within 2 years after surgery.

The use of sugammadex in an infant with prolonged neuromuscular blockade - A case report.

BACKGROUND: Residual neuromuscular blockade (RNMB) is a frequent event after general anesthesia, which can lead to serious complications, such as upper airway obstruction. Sugammadex is useful in reversing RNMB. However, its use in infants has not yet been approved by the Food and Drug Administration. Therefore, anesthesiologists can be hesitant use it, even in situations where no other choice is available. CASE: A two-month-old baby presented to the hospital for umbilical polypectomy. At the end of the surgery, neostigmine was administered. Even after waiting for 30 min and injecting an additional dose of neostigmine, neuromuscular blockade was not adequately reversed. Eventually, sugammadex was administered, and spontaneous breathing returned. CONCLUSIONS: If there were no particular causes of delayed return to spontaneous breathing in infants, RNMB should be considered and reversal with sugammadex would be useful.

The principles of presenting statistical results: Table.

General medical journals such as the Korean Journal of Anesthesiology (KJA) receive numerous manuscripts every year. However, reviewers have noticed that the tables presented in various manuscripts have great diversity in their appearance, resulting in difficulties in the review and publication process. It might be due to the lack of clear written instructions regarding reporting of statistical results for authors. Therefore, the present article aims to briefly outline reporting methods for several table types, which are commonly used to present statistical results. We hope this article will serve as a guideline for reviewers as well as for authors, who wish to submit a manuscript to the KJA.

Effect of single dose preoperative intravenous ibuprofen on postoperative pain and opioid consumption: a systematic review and meta-analysis.

BACKGROUND: Ibuprofen, a well-known analgesic, is commonly used as a component of a multimodal analgesic approach for postoperative pain. This systematic review and meta-analysis aimed to investigate whether a single-dose preoperative intravenous ibuprofen can reduce postoperative pain and opioid consumption. METHODS: PubMed/MEDLINE, Embase, Cochrane Library (CENTRAL), and Web of Science databases were searched to identify relevant studies published up to May 2020. Randomized controlled trials comparing preoperative single-dose intravenous ibuprofen effect with the control group on postoperative pain and opioid consumption after surgery under general anesthesia were included. RESULTS: Six studies involving 366 participants were included. Single-dose administration of intravenous ibuprofen preoperatively significantly reduced postoperative pain score on a scale of 0-10 at 1 h (MD: -1.64, 95% CI [-2.56, -0.72], P < 0.001, I2 = 95%), at 4-6 h (MD: -1.17, 95% CI [-2.09, -0.26], P < 0.001, I2 = 94%), and 24 h (MD: -0.58, 95% CI [-0.99, -0.18], P < 0.001, I2 = 90%). Cumulative opioid consumption, presented as fentanyl equivalents, was also reduced significantly in the ibuprofen group compared to placebo group until postoperative 4-6 h (MD: -56.35 µg, 95% CI [-101.10, -11.60], P < 0.001, I2 = 91%) and 24 h (MD: -131.39 µg, 95% CI [-224.56, -38.21], P < 0.001, I2 = 95%). CONCLUSIONS: Preoperative single-dose intravenous ibuprofen can reduce postoperative pain and opioid consumption until 24 h postoperatively. Considering the high heterogeneity and small number of studies included, care should be taken when generalizing these findings.

Prolotherapy for the patients with chronic musculoskeletal pain: systematic review and meta-analysis.

BACKGROUND: Prolotherapy, which stimulates the healing of loosened ligaments and tendons, is a cost-effective and safe treatment modality for chronic musculoskeletal pain. Its benefits may be affected by injection protocols, comparative regimens, and evaluation scales. The aim of this study was to determine the effectiveness of dextrose prolotherapy as a long-term treatment for chronic musculoskeletal pain. METHODS: Medline, Embase, Cochrane Central, KoreaMed, and KMbase databases were searched for studies published up to March 2019. We included randomized controlled trials which compared the effect of dextrose prolotherapy with that of other therapies such as exercise, saline, platelet-rich plasma, and steroid injection. The primary outcome was pain score change during daily life. RESULTS: Ten studies involving 750 participants were included in the final analysis. Pain scores from 6 months to 1 year after dextrose prolotherapy were significantly reduced compared to saline injection (standardized mean difference [SMD] -0.44; 95% confidence interval [CI] -0.76 to -0.11, P = 0.008) and exercise (SMD -0.42; 95% CI -0.77 to -0.07, P = 0.02). Prolotherapy yielded results similar to platelet-rich plasma or steroid injection, that it showed no significant difference in pain score. CONCLUSIONS: Dextrose prolotherapy is more effective in the treatment of chronic pain compared to saline injection or exercise. Its effect was comparable to that of platelet-rich plasma or steroid injection. Adequately powered, homogeneous, and longer-term trials are needed to better elucidate the efficacy of prolotherapy.

An exploratory study of risk factors for pressure injury in patients undergoing spine surgery.

BACKGROUND: Perioperative patients are potentially at risk for pressure injuries due to anesthetic agents and surgical positioning. Pressure injury increases discomfort and pain in patients and causes complications, which lead to an increase in mortality and hospitalization duration. Most previous studies did not focus on specific types of surgery or surgical positioning. We tried to identify the incidence of perioperative pressure injury during spinal surgery and perioperative risk factors that contribute to pressure injury. METHODS: We retrospectively analyzed electronic medical records of 663 patients who underwent spinal surgery between March 2016 and May 2018. The primary outcome was occurrence of pressure injury. Potential risk factors of pressure injury were selected based on previous studies and expert opinion, and divided into two sub-categories: preoperative and intraoperative risk factors. We compared the clinical characteristics of patients in the pressure injury and non-injury groups. Perioperative risk factors for pressure injury were analyzed by logistic regression. RESULTS: Among 663 patients, the incidence of all stages of pressure injury was 5.9%. The face and inguinal regions were the most injured sites (both 28.6%). The pressure injury group showed a 13% longer hospitalization period. Preoperative plasma concentration of protein was associated with 0.5-fold lower pressure injury (OR: 0.50; 95% CI: 0.27 to 0.95; P = 0.034). CONCLUSIONS: The incidence of pressure injury was similar to that previously reported and occurred in the direct weight-bearing areas, which led to longer hospitalization. We found that a lower preoperative serum protein level is significantly associated with intraoperative pressure injury occurrence during spinal surgery.

Effect of preoperative administration of systemic alpha-2 agonists on postoperative pain: a systematic review and meta-analysis.

BACKGROUND: Alpha-2 agonists have sedative, analgesic, and opioid-sparing effects. Moreover, intraoperative or postoperative systemic administration of alpha-2 adrenergic agonists is known to reduce postoperative pain and opioid consumption. This meta-analysis investigated whether preoperative administration of alpha-2 agonists can affect postoperative pain and opioid consumption. METHODS: We searched the MEDLINE, EMBASE, Cochrane Library (CENTRAL), KoreaMed, and KMbase databases through March 2019 to identify relevant randomized controlled trials (RCTs) on the effect of preoperative systemic administration of alpha-2 agonists on postoperative pain and opioid consumption. We conducted a meta-analysis according to the Cochrane Collaboration guidelines. Standardized mean differences (SMDs) of postoperative pain intensity or dose of opioid consumption in the alpha-2 agonist group were extracted and combined using a random-effect model and were compared to those of the control group. RESULTS: Eleven RCTs involving 748 participants were included in this meta-analysis. Preoperative administration of systemic alpha-2 agonists significantly reduced cumulative opioid consumption up to 6 h (SMD, -0.52; 95% confidence interval [-0.90 to -0.14]) and 24 h (SMD, -0.68 [-1.27 to -0.09]) after surgery. Moreover, preoperative administration of alpha-2 agonists significantly reduced postoperative pain intensity at 6 h (SMD, -0.50 [-0.78 to -0.21]) and 24 h (SMD, -0.44 [-0.86 to -0.03]). CONCLUSIONS: In this meta-analysis, high degree of heterogeneity limits the preoperative administration of alpha-2 agonists in reducing postoperative opioid consumption and pain intensity. Future powered large RCTs are required to increase the certainty of evidence on the effect in reducing postoperative opioid consumption and pain intensity.

Risk factors for postoperative delirium in elderly patients after spinal fusion surgery.

BACKGROUND: Postoperative delirium (POD) has an incidence rate of 9% to 41%. It is directly linked to decreasing cognitive function, increasing length of hospitalization and cost, as well as other complications and mortality. We aimed to assess the risk factors for POD among elderly patients by analyzing data from those who underwent spinal surgery. METHODS: This study included 446 patients aged 65 years or older who underwent spinal surgery at our institution between March 2013 and May 2018. Data were collected retrospectively from the patients' electronic medical records, and logistic regression was used to identify the risk factors associated with POD. The diagnosis of POD was based on the Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition, and was made through consultation with a psychiatrist during postoperative hospitalization and before discharge. RESULTS: Seventy-eight (78/446, 17.4%) patients were diagnosed with POD. The most relevant risk factor for POD was preoperative cognitive dysfunction (odds ratio [OR], 4.37; 95% confidence interval [CI], 1.60 to 11.93; P = 0.004), followed by emergency surgery (OR, 2.70; 95% CI, 1.27 to 5.74; P = 0.01), age (OR, 1.19; 95% CI, 1.13 to 1.26; P < 0.001), and anesthesia time (OR, 1.01; 95% CI 1.00 to 1.01; P = 0.002). CONCLUSIONS: Preoperative cognitive dysfunction, emergency surgery, age, and anesthesia time were factors that affected POD occurrence after spinal surgery. Patients with such associated factors may be at a higher risk for POD when undergoing spinal surgery, and hence, careful management may be necessary for these patients.

Micro star tracker with a curved vane for a short baffle length and sharp stray light attenuation.

We present a micro star tracker with curved vanes that offers a short length of the baffle and a sharp cutoff of stray light. The curved vanes are derived mathematically by ray-tracing in such a way that all the stray light from outside of the desired field of view (FOV) is reflected out. The proposed curved vane design allows a smaller number of vanes to completely cut off stray light, leading to a shorter length in baffle design. Furthermore, the capability of a sharp cutoff of stray light eases the sensitivity requirement of image sensors. For the experiment, we fabricated three micro star tracker baffles with curved vanes for 22° FOV, which are required to handle a maximum star magnitude of 5.35 for 100% sky coverage. The sizes of the baffles fabricated are 16mmΦ×16.5mm L with double curved vanes, 24mmΦ×12.1mm L with a single curved vane, and 27mmΦ×14.4mm L with double curved vanes. In comparison, the straight vane baffle designed for 22° FOV requires seven vanes with 18 mm length but results only in mild stray light attenuation with the cutoff at 32°. The proposed star tracker utilizes a 5-megapixel image sensor, 16mm×16mm×39mm in size and weighing 9.2 g with an accuracy of 1.288 arcsecond, a 20.6% improvement over when no baffle is used.

Churros-like Polyvinylidene Fluoride Nanofibers for Enhancing Output Performance of Triboelectric Nanogenerators.

Triboelectric nanogenerators (TENGs) have emerged as a next-generation sustainable power source for Internet of Things technology. Polyvinylidene fluoride (PVDF) nanofibers (NFs) have been investigated widely to enhance the TENG performance by controlling their polarity; however, controlling the surface morphology of the PVDF NFs has rarely been studied. Here, surface-roughened, churros-like PVDF NFs were fabricated by controlling the solvent evaporation kinetics. The solvent evaporation rate was modulated by varying the relative humidity (RH) during the electrospinning process. With increasing RH, the fraction of polar ß-phase in the PVDF NFs increased, the specific surface area of the PVDF NFs increased gradually and the surface morphology changed from smooth to rough, finally resulting in a churros-like structure. Therefore, the output performance of the TENG devices was enhanced with increasing RH, because of the combined effects of the enlarged surface area and the increased fraction of the polar phase in the PVDF NFs. The TENG device with the churros-like PVDF NFs showed an output voltage of 234 V, current of 11 µA, and power density up to 1738 µW/cm2, giving it the capability to turn on 60 series-connected commercial light-emitting diodes without using an external charge storage circuit.

Tips for troublesome sample-size calculation.

Properly set sample size is one of the important factors for scientific and persuasive research. The sample size that can guarantee both clinically significant differences and adequate power in the phenomena of interest to the investigator, without causing excessive financial or medical considerations, will always be the object of concern. In this paper, we reviewed the essential factors for sample size calculation. We described the primary endpoints that are the main concern of the study and the basis for calculating sample size, the statistics used to analyze the primary endpoints, type I error and power, the effect size and the rationale. It also included a method of calculating the adjusted sample size considering the dropout rate inevitably occurring during the research. Finally, examples regarding sample size calculation that are appropriately and incorrectly described in the published papers are presented with explanations.

Flexible Visible-Blind Ultraviolet Photodetectors Based on ZnAl-Layered Double Hydroxide Nanosheet Scroll.

Visible-blind ultraviolet (UV) photodetectors have received a great deal of attention for realizing Internet of Things technologies as well as for monitoring the level of UV exposure to humans. Realizing next-generation flexible and visible-blind UV photodetectors requires development of new functional material systems with easy fabrication, selectively strong UV light absorption, environmental friendliness, and high stability regardless of ambient conditions. Herein, flexible visible-blind UV photodetectors are successfully fabricated on the basis of two-dimensional ZnAl-layered double hydroxide (LDH) nanosheets with scroll structures grown on flexible substrates. The ZnAl-LDH nanosheet scrolls exhibit highly resistive semiconducting properties with a band gap of 3.2 eV and work function of 3.64 eV. The photodetector based on the ZnAl-LDH shows photoresponse in the UV spectral range below 420 nm, indicating visible-blind spectral response. In addition, the UV photodetector shows a maximum responsivity of 17 mA/W under illumination with 365 nm light. Moreover, the flexible photodetector shows reproducible photoresponse even after 1000 bending cycles, which indicates the acceptable stability of the ZnAl-LDH nanosheet scrolls.

Quantitative trait loci analysis of hormone levels in Arabidopsis roots.

Quantitative trait loci (QTL) analyses for five groups of hormones, including cytokinins in Arabidopsis roots were performed using recombinant inbred lines (Ler×Cvi). Significant QTLs were detected for cytokinins, jasmonic acid and salicylic acid. Separate analysis of two sub-populations, viz., vegetative and flowering plants revealed that many of the QTLs were development-specific. Using near-isogenic lines, several significant QTLs were confirmed; three co-localized QTL regions were responsible for determining several cytokinin metabolites. Using a knock-out plant, a functional role of zeatin N-glucosyltransferase gene (UGT76C2) underlying a large-effect QTL for levels of tZ-N-glucosides and tZRMP was evaluated in the metabolism of cytokinins. Pleotropic effects of this gene were found for cytokinin levels in both roots and leaves, but significant changes of morphological traits were observed only in roots. Hormone QTL analysis reveals development-specific and organ-dependent aspects of the regulation of plant hormone content and metabolism.