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.

Dexamethasone concentration affecting rocuronium-induced neuromuscular blockade and sugammadex reversal in a rat phrenic nerve-hemidiaphragm model: An ex vivo study.

BACKGROUND: The concentration range of dexamethasone that inhibits neuromuscular blockade (NMB) and sugammadex reversal remains unclear. OBJECTIVE: To evaluate the effects of dexamethasone on rocuronium-induced NMB and sugammadex reversal. DESIGN: Ex vivo study. SETTING: Asan Institute for Life Sciences, Asan Medical Center, Korea, from July 2015 to November 2015. ANIMALS: One hundred sixty male Sprague-Dawley rats. INTERVENTIONS: We assessed the effect of four concentrations of dexamethasone [0, 0.5, 5 (clinical concentrations) and 50 µg ml (experimental concentration)] on partial NMB on 40 phrenic nerve-hemidiaphragm preparations (n=10 per concentration). Once the first twitch of train-of-four (TOF) had been depressed by 50% with rocuronium, dexamethasone was administered. To assess the effect of dexamethasone on sugammadex reversal, 120 phrenic nerve-hemidiaphragm preparations were used in three subexperiments (n=40 per experiment), using three administration regimens of rocuronium-equimolar sugammadex: a single dose, a split-dose (split and ) and a reduced split-dose (split and ). After complete NMB was achieved, dexamethasone and sugammadex were administered. MAIN OUTCOME MEASURES: The change in the first twitch height, the recovery time to a TOF ratio at least 0.9, and the TOF ratio at 30 min were evaluated. RESULTS: There were no significant differences in the first twitch height among groups (P = 0.532). With a single dose of sugammadex, dexamethasone did not affect the recovery time to a TOF ratio at least 0.9 (P = 0.070). After using a split-dose of sugammadex, the recovery time to a TOF ratio at least 0.9 was delayed only at a concentration of 50 µg ml of dexamethasone. With a reduced split-dose of sugammadex, the TOF ratio at 30 min was lowered only by a concentration of 50 µg ml of dexamethasone (P < 0.010). CONCLUSION: Acute bolus administration of dexamethasone at clinical concentrations had no effect on NMB or on sugammadex reversal.

Natural variation of hormone levels in Arabidopsis roots and correlations with complex root architecture.

Studies on natural variation are an important tool to unravel the genetic basis of quantitative traits in plants. Despite the significant roles of phytohormones in plant development, including root architecture, hardly any studies have been done to investigate natural variation in endogenous hormone levels in plants. Therefore, in the present study a range of hormones were quantified in root extracts of thirteen Arabidopsis thaliana accessions using a ultra performance liquid chromatography triple quadrupole mass spectrometer. Root system architecture of the set of accessions was quantified, using a new parameter (mature root unit) for complex root systems, and correlated with the phytohormone data. Significant variations in phytohormone levels among the accessions were detected, but were remarkably small, namely less than three-fold difference between extremes. For cytokinins, relatively larger variations were found for ribosides and glucosides, as compared to the free bases. For root phenotyping, length-related traits-lateral root length and total root length-showed larger variations than lateral root number-related ones. For root architecture, antagonistic interactions between hormones, for example, indole-3-acetic acid to trans-zeatin were detected in correlation analysis. These findings provide conclusive evidence for the presence of natural variation in phytohormone levels in Arabidopsis roots, suggesting that quantitative genetic analyses are feasible.

A Co-Opted Hormonal Cascade Activates Dormant Adventitious Root Primordia upon Flooding in Solanum dulcamara.

Soil flooding is a common stress factor affecting plants. To sustain root function in the hypoxic environment, flooding-tolerant plants may form new, aerenchymatous adventitious roots (ARs), originating from preformed, dormant primordia on the stem. We investigated the signaling pathway behind AR primordium reactivation in the dicot species Solanum dulcamara Transcriptome analysis indicated that flooding imposes a state of quiescence on the stem tissue, while increasing cellular activity in the AR primordia. Flooding led to ethylene accumulation in the lower stem region and subsequently to a drop in abscisic acid (ABA) level in both stem and AR primordia tissue. Whereas ABA treatment prevented activation of AR primordia by flooding, inhibition of ABA synthesis was sufficient to activate them in absence of flooding. Together, this reveals that there is a highly tissue-specific response to reduced ABA levels. The central role for ABA in the response differentiates the pathway identified here from the AR emergence pathway known from rice (Oryza sativa). Flooding and ethylene treatment also induced expression of the polar auxin transporter PIN2, and silencing of this gene or chemical inhibition of auxin transport inhibited primordium activation, even though ABA levels were reduced. Auxin treatment, however, was not sufficient for AR emergence, indicating that the auxin pathway acts in parallel with the requirement for ABA reduction. In conclusion, adaptation of S. dulcamara to wet habitats involved co-option of a hormonal signaling cascade well known to regulate shoot growth responses, to direct a root developmental program upon soil flooding.

Pain after single-incision versus conventional laparoscopic appendectomy: a propensity-matched analysis.

BACKGROUND: The aim of this study was to compare postoperative pain outcomes between single-incision laparoscopic appendectomy (SILA) and conventional laparoscopic appendectomy (CLA) using a propensity score matching analysis. MATERIALS AND METHODS: Adult patients who underwent SILA or CLA for acute appendicitis between January 2010 and December 2015 at a single center were identified retrospectively from a prospectively collected database. All patients had used an intravenous patient-controlled analgesia (PCA) device for postoperative pain control. As potential confounding variables, patient characteristics and surgery-related, anesthesia-related, and PCA-related factors were collected from the database. The primary outcome was the postoperative pain score, and secondary outcomes were nausea, vomiting, rescue analgesic use, rescue antiemetic use, and PCA-related complications. These outcomes were compared between the SILA and CLA groups before and after 1:1 propensity score matching. RESULTS: From a total of 915 patients, 753 were selected: 116 in the SILA group and 637 in the CLA group. After propensity score matching, two comparable groups with 111 patients each were obtained. Pain score (P = 0.007) and rescue analgesic use (P = 0.043) on the day of surgery were significantly lower in the SILA group than in the CLA group. The other outcomes were similar between the two groups. CONCLUSIONS: SILA is a beneficial surgical procedure for postoperative pain management.

Effects of presynaptic muscarinic cholinoreceptor blockade on neuromuscular transmission as assessed by the train-of-four and the tetanic fade response to rocuronium.

This study investigated the effect of muscarinic M1 and M2 receptor antagonists on the rocuronium-induced train of four (TOF) fade and tetanic fade, respectively. Ex-vivo phrenic nerves and diaphragms were obtained from adult Sprague-Dawley rats and stabilized in Krebs buffer; the nerve-stimulated muscle TOF fade was observed at 20 s intervals. For the TOF study, phrenic nerves and diaphragms were incubated with pirenzepine (an M1 blocker) at concentrations of 0 nmol L-1 (control), 10 nmol L-1 (PZP10), or 100 nmol L-1 (PZP100). Rocuronium was then administered incrementally until the first twitch tension had depressed by >95% during TOF stimulation. The mean TOF ratios were compared when the first twitch tensions were depressed by 40%-50%. For the tetanic fade study, 50 Hz/5 s tetani was applied initially, 30 min after the administration of a loading dose of rocuronium and methoctramine (an M2 receptor blocker, loaded at 0 µmol L-1 [control], 1 µmol L-1 [MET1], or 10 µmol L-1 [MET10]). The EC95 of rocuronium was significantly lower in the PZP10 group than in the control group. In the PZP10 group, the TOF ratios at 50% and first twitch tension depression were significantly lower than those in the control group (P=.02). During tetanic stimulation, the tetanic fade was significantly enhanced in the MET10 group compared to the other groups. This study shows that antagonists of muscarinic M1 and M2 receptors affect the rocuronium-induced neuromuscular block as demonstrated by the reduced EC95 and TOF ratios (M1 antagonist, pirenzepine) or the enhanced 50-Hz tetanic fade (M2 antagonist, methoctramine).

The neuromuscular effects of rocuronium under sevoflurane-remifentanil or propofol-remifentanil anesthesia: a randomized clinical comparative study in an Asian population.

BACKGROUND: We conducted a prospective, randomized, multicenter study to evaluate the differences in the blocking effect of different doses of rocuronium between sevoflurane- or propofol-remifentanil anesthesia in an Asian population. METHODS: A total of 368 ASA I-II patients was enrolled. Anesthesia was induced with 2.0 mg/kg propofol and 0.1 µg/kg/min remifentanil (TIVA) or 5.0 vol.% sevoflurane with 0.1 µg/kg/min remifentanil (SEVO). Tracheal intubation was facilitated at 180 s after the administration of rocuronium at 0.3, 0.6, or 0.9 mg/kg and then intubation condition was evaluated. The time to maximum block and recovery profile were monitored by TOF stimulation of the ulnar nerve and by recording the adductor pollicis response using acceleromyography. RESULTS: The numbers of patients with clinically acceptable intubation conditions were 41, 82, and 97 % (TIVA) and 34, 85, and 90 % (SEVO) at each dose of rocuronium, respectively. There were no significant differences in the time to maximum block between groups at each rocuronium dose. There were significant differences in the recovery to a train-of-four ratio of 90 % between the groups: 42.7 (19.5), 74.8 (29.9), and 118.4 (35.1) min (TIVA) and 66.5 (39.3), 110.2 (43.5), and 144.4 (57.5) min (SEVO) at 0.3, 0.6, and 0.9 mg/kg, respectively (P < 0.001). CONCLUSIONS: There are no significant differences in intubation conditions between propofol-remifentanil and sevoflurane-remifentanil anesthesia at the same dose of rocuronium. The type of anesthetic does not significantly influence the time to maximum block by rocuronium. Rocuronium at a dose of 0.9 mg/kg should be used for better intubation conditions with both anesthesia regimens in an Asian population. TRIAL REGISTRATION: UMIN-CTR Clinical Trial ( http://www.umin.ac.jp/ctr/index.htm ; UMIN#000007289 ; date of registration 14(th) February 2012).

Immobilization with atrophy induces de novo expression of neuronal nicotinic α7 acetylcholine receptors in muscle contributing to neurotransmission.

BACKGROUND: Mature acetylcholine receptor (AChR) isoform normally mediates muscle contraction. The hypothesis that α7AChRs up-regulate during immobilization and contribute to neurotransmission was tested pharmacologically using specific blockers to mature (waglerin-1), immature (αA-OIVA), and α7AChRs (methyllycaconitine), and nonspecific muscle AChR antagonist, α-bungarotoxin. METHODS: Mice were immobilized; contralateral limbs were controls. Fourteen days later, anesthetized mice were mechanically ventilated. Nerve-stimulated tibialis muscle contractions on both sides were recorded, and blockers enumerated above sequentially administered via jugular vein. Data are mean ± standard error. RESULTS: Immobilization (N = 7) induced tibialis muscle atrophy (40.6 ± 2.8 vs. 52.1 ± 2.0 mg; P < 0.01) and decrease of twitch tension (34.8 ± 1.1 vs. 42.9 ± 1.5 g; P < 0.01). Waglerin-1 (0.3 ± 0.05 µg/g) significantly (P = 0.001; N = 9) depressed twitch tension on contralateral (≥97%) versus immobilized side (approximately 45%). Additional waglerin-1 (total dose 1.06 ± 0.12 µg/g or approximately 15.0 × ED50 in normals) could not depress twitch of 80% or greater on immobilized side. Immature AChR blocker, αA-OIVA (17.0 ± 0.25 µg/g) did not change tension bilaterally. Administration of α-bungarotoxin (N = 4) or methyllycaconitine (N = 3) caused 96% or greater suppression of the remaining twitch tension on immobilized side. Methyllycaconitine, administered first (N = 3), caused equipotent inhibition by waglerin-1 on both sides. Protein expression of α7AChRs was significantly (N = 3; P < 0.01) increased on the immobilized side. CONCLUSIONS: Ineffectiveness of waglerin-1 suggests that the twitch tension during immobilization is maintained by receptors other than mature AChRs. Because αA-OIVA caused no neuromuscular changes, it can be concluded that immature AChRs contribute minimally to neurotransmission. During immobilization approximately 20% of twitch tension is maintained by up-regulation of α-bungarotoxin- and methyllycaconitine-sensitive α7AChRs.

Nonsurgically induced disuse muscle atrophy and neuromuscular dysfunction upregulates alpha7 acetylcholine receptors.

Previous models of muscle disuse have invariably used surgical methods that require the repetitive application of plaster casts. A method of disuse atrophy that does not require such repetitive applications is described herein. Modified plastic pipette tubing was applied to a single hindlimb (mouse), from thigh to foot, resulting in immobilization of the knee in the extension position, and the ankle in the plantar flexion position. This method resulted in the loss of soleus muscle to 11%, 22%, 39%, and 45% of its original mass at 3, 7, 14, and 21 days, respectively, in association with a significant decrease of tibialis twitch (25%) and tetanic tensions (26%) at 21 days, compared with the contralateral side and (or) sham-immobilized controls. Immunohistochemical analysis of the soleus using fluorescent α-bungarotoxin revealed a significant increase in the number of synapses per unit area (818 + 31 compared with 433 + 16/mm(2)) and an increase in muscle fibers per unit area (117 compared with 83/mm(2)), most likely related to the atrophy of muscle fibers bringing synapses closer. A 3-fold increase in alpha7 acetylcholine receptor (α7AChR) protein expression, along with increased expression of α1AChR subunit in the immobilized side compared with the contralateral side was observed. The physiology and pharmacology of the novel finding of upregulation of α7AChRs with disuse requires further study.

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.

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 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.

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 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.

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.