Search

Binocular mechanisms for visual processing are thought to enhance spatial acuity by combining matched input from the two eyes. Studies in the primary visual cortex of carnivores and primates have confirmed that eye-specific neuronal response properties are largely matched. In recent years, the mouse has emerged as a prominent model for binocular visual processing, yet little is known about the spatial frequency tuning of binocular responses in mouse visual cortex. Using calcium imaging in awake mice of both sexes, we show that the spatial frequency preference of cortical responses to the contralateral eye is ∼35% higher than responses to the ipsilateral eye. Furthermore, we find that neurons in binocular visual cortex that respond only to the contralateral eye are tuned to higher spatial frequencies. Binocular neurons that are well matched in spatial frequency preference are also matched in orientation preference. In contrast, we observe that binocularly mismatched cells are more mismatched in orientation tuning. Furthermore, we find that contralateral responses are more direction-selective than ipsilateral responses and are strongly biased to the cardinal directions. The contralateral bias of high spatial frequency tuning was found in both awake and anesthetized recordings. The distinct properties of contralateral cortical responses may reflect the functional segregation of direction-selective, high spatial frequency-preferring neurons in earlier stages of the central visual pathway. Moreover, these results suggest that the development of binocularity and visual acuity may engage distinct circuits in the mouse visual system.SIGNIFICANCE STATEMENT Seeing through two eyes is thought to improve visual acuity by enhancing sensitivity to fine edges. Using calcium imaging of cellular responses in awake mice, we find surprising asymmetries in the spatial processing of eye-specific visual input in binocular primary visual cortex. The contralateral visual pathway is tuned to higher spatial frequencies than the ipsilateral pathway. At the highest spatial frequencies, the contralateral pathway strongly prefers to respond to visual stimuli along the cardinal (horizontal and vertical) axes. These results suggest that monocular, and not binocular, mechanisms set the limit of spatial acuity in mice. Furthermore, they suggest that the development of visual acuity and binocularity in mice involves different circuits.

Background and Objectives: Reducing opioid exposure in common pediatric surgeries is of paramount importance. This study aimed to assess the efficacy of regional nerve blocks in reducing opioid exposure while preserving high success rates. Materials and Methods: We conducted a retrospective matched cohort study (1:1) including patients with elbow fractures < 12 years old who underwent treatment with percutaneous pinning. Patients were divided into general-anesthesia (GA) and GA-followed-by-supraclavicular-brachial-plexus-block (GA-SCB) groups. The primary outcome was the number of patients administered postoperative rescue opioids. The secondary outcomes included intraoperative and postoperative opioid administration, the time to first request for rescue analgesia, pain scores, block success rate, block performing time, and block-related complications. Results: In a total of 478 patients, 363 underwent percutaneous pinning, and 86 were cohort-matched (GA: n = 43, GA-SCB: n = 43). On the first postoperative day, 34 (79.0%) patients in the GA group were administered postoperative rescue opioids, compared with 12 (27.9%) in the GA-SCB group (p < 0.001). All the patients in the GA-SCB group were opioid-free during the intraoperative period. No SCB-associated complications were observed. Total opioid consumption was significantly lower in the GA-SCB group than in the GA group until the first postoperative day (GA vs. GA-SCB, 3.2 ± 3.0 mg vs. 0.9 ± 1.8 mg, p < 0.001). Conclusions: SCB application in pediatric patients who underwent elbow fracture surgery significantly reduced opioid exposure and had a high success rate when performed using ultrasound guidance by an expert. Furthermore, the complication risk and surgical delay were minimal. [ABSTRACT FROM AUTHOR]

Background and Objectives: Remimazolam offers advantages over propofol in terms of hemodynamic stability. However, it remains unclear whether remimazolam-based total intravenous anesthesia (TIVA) can reduce intraoperative hypotension compared to propofol-based TIVA, especially after prone positioning. In this study, we compared the effects of remimazolam- and propofol-based TIVA on intraoperative hemodynamic stability in patients undergoing surgery in the prone position. Materials and Methods: This study randomly assigned patients undergoing major spinal surgery in the prone position to the propofol or remimazolam group. Target-controlled infusion (2–3.5 μg/mL for induction and 2–3 μg/mL for maintenance) was used in the propofol group and continuous infusion (6 mg/kg/h for induction and 1–2 mg/kg/h for maintenance) was used in the remimazolam group; target-controlled infusion (3–5 ng/mL) of remifentanil was performed in both groups. The primary outcomes were the incidence of hypotensive episodes during the first hour after prone positioning. The secondary outcomes included the incidence of severe hypotension and the total amount of inotropic or vasopressor medication. Systolic and mean arterial pressure, heart rate, cardiac index and output, stroke volume, stroke volume variation, and pleth variability index were also evaluated. These variables were recorded per minute for the first 10 min after prone positioning, and every 10 min thereafter. Results: The study enrolled 94 patients (47 patients in each group). The incidence of hypotension or severe hypotension did not differ significantly between the two groups during the first hour after prone positioning. The total amount of ephedrine administered during the first hour after prone positioning was lesser (p = 0.020) and the mean arterial pressure during the initial 10 min after prone positioning was higher in the remimazolam group (p = 0.003). Conclusions: Our study uncovered no significant differences in the incidence of hypotension between remimazolam- and propofol-based TIVA in patients undergoing major spine surgery in prone position. [ABSTRACT FROM AUTHOR]

Background: Lung herniation is a rare complication of heart–lung transplantation that can be fatal owing to vascular compromise and airway obstruction. To date, only five cases of lung herniation related to heart–lung transplantation have been reported in the literature; however, to the best of our knowledge, this is the first worldwide report of heart–lung transplantation‐related lung herniation in an infant. Methods: We describe the case of lung herniation as a rare heart–lung transplantation‐related complication in an infant. A 12‐month‐old female baby developed severe bronchopulmonary dysplasia with severe pulmonary hypertension, and she underwent extracorporeal membrane oxygenation for cardiac collapse and lung support. Then, we performed heart–lung transplantation to manage the irreversible deterioration of her lung function. After the heart‐lung transplantation, we found the radiological abnormalities persisted on follow‐up chest radiographs until the 13th postoperative day diagnosed as lung herniation of the right lower lobe on chest computed tomography. Results: After the relocation of the herniated lung, the clinical condition of the patient improved, and the patient is currently growing without any respiratory symptoms. Conclusions: In this case report, we emphasize that clinical awareness and high suspicion of this rare complication are needed for early diagnosis and proper treatment to prevent post‐transplantation morbidity and mortality related to potential ischemic injury. [ABSTRACT FROM AUTHOR]

Background: This systematic review and meta-analysis with trial sequential analysis (TSA) aimed to compare perioperative outcomes of peripheral nerve blocks (PNBs) and spinal anesthesia (SA) in elective foot and ankle surgery. Methods: The study protocol was registered in PROSPERO (CRD42021229597). Researchers independently searched PubMed, EMBASE, and the Cochrane Central Register of Controlled Trials for relevant randomized controlled trials (RCTs). Results: Analysis of nine RCTs (n = 802; 399 PNBs, 403 SA) revealed significantly shorter block performance times (WMD: 7.470; 95% CI 6.072 to 8.868), the onset of sensory (WMD: 7.483; 95% CI 2.837 to 12.130) and motor blocks (WMD: 9.071; 95% CI 4.049 to 14.094), durations of sensory (WMD: 458.53; 95% CI 328.296 to 588.765) and motor blocks (WMD: 247.416; 95% CI 95.625 to 399.208), and significantly higher postoperative analgesic requirements (SMD: −1.091; 95% CI −1.634 to −0.549) in the SA group. Additionally, systolic blood pressure (SBP) at 30 min (WMD: 13.950; 95% CI 4.603 to 23.298) was lower in the SA group. Conclusions: The SA demonstrated shorter block performance time, faster onset and shorter duration of sensory and motor blocks, higher postoperative analgesic requirements, and lower SBP at 30 min compared to PNBs in elective foot and ankle surgery. [ABSTRACT FROM AUTHOR]

The recently introduced pectoral nerve (Pecs) block is a simple alterative to the conventional thoracic paravertebral block or epidural block for breast surgery. It produces excellent analgesia and can be used to provide balanced anesthesia and as a rescue block in cases where performing a neuraxial blockade is not possible. In the thoracic region, a neuraxial blockade is often used to manage zoster-associated pain. However, this can be challenging for physicians due to the increased risk of hemodynamic instability in the upper thoracic level, and comorbid and contraindicated medical conditions such as coagulopathy. Here, we introduce an ultrasound-guided Pecs block for the management of herpes zoster-associated pain, which could be an effective alternative to other interventional options in the thoracic region., Author(s): Yeon-Dong Kim [sup.1] , Seon-Jeong Park [sup.1] , Junho Shim [sup.2] , Hyungtae Kim [sup.2] Author Affiliations: (Aff1) 0000 0004 0533 4755, grid.410899.d, Department of Anesthesiology and Pain Medicine, [...]

Background and objectives: Anesthesia maintenance agents affect the incidence of postoperative shivering (PS) after general anesthesia. This study compared the effects of remimazolam with sevoflurane on PS in patients undergoing laparoscopic gynecologic surgery under general anesthesia. Materials and methods: Seventy-four patients were allocated into one of two groups. In anesthesia maintenance, group S received sevoflurane and remifentanil, and group R received remimazolam and remifentanil. Results: The incidence and severity of postoperative shivering, mean arterial pressure (MAP), heart rate (HR), core body temperature, and the association of PS with hypothermia, MAP, or HR in the post-anesthesia care unit (PACU) were measured. Group R had significantly lower rates of perioperative hypothermia (58.8 vs. 27.8%, p = 0.009) and postoperative shivering (41.2 vs. 19.4%, p = 0.047). The severity of PS was also lower in group R than in group S (p = 0.034). Core body temperature was significantly higher in group R than in group S from 10 min after induction (p = 0.047) to the PACU (p = 0.009). MAP and HR were significantly higher in group R than in group S from 20 min after induction (p = 0.047) to the PACU (p = 0.009). In group S, the correlation between the severity of PS and the incidence of hypothermia (φc = 0.414, p = 0.121) was moderate but not significant. In group R, the correlation between PS severity and hypothermia (φc = 0.418, p = 0.043) was moderate and significant. Conclusions: Remimazolam showed better results than sevoflurane in anesthesia maintenance regarding hypothermia and PS. [ABSTRACT FROM AUTHOR]

Background and Objectives: Although epidural steroid injections are used as an effective treatment, this technique is associated with rare but serious ischemic complications, especially when particulate steroids are used. However, recent studies have reported that even if non-particulate steroids are used, particulates are formed by the interaction with some local anesthetics (LA), causing ischemic complications. This observational study evaluated commonly used combinations of non-particulate steroids and LA with contrast media via microscopic analysis and analyzed the chemical properties of each mixture to identify the correlation of particulate formation. Materials and Methods: Commonly used clinical non-particulate and particulate steroids, contrast media, and LA agent combinations were evaluated macroscopically and microscopically. The pH values were also measured at both room temperature (26 °C) and body temperature (36 °C). Where particulates were observed, the particulate size was measured. Results: Macroscopically, the mixture of non-particulate steroid and ropivacaine had a slightly cloudy appearance at all concentrations, but there was no visible particulate. However, when observed under a microscope, the pH-dependent particulate formation was observed at all concentration combinations tested. (0.1% ropivacaine: from 19 μm to 70 μm, and 0.2% ropivacaine: from 37 μm to 108 μm at room temperature (26 °C)). When contrast media was mixed or the temperature was raised to body temperature (36 °C), the number and size of the particulates decreased or dissolved. Conclusions: The combination of ropivacaine and dexamethasone, a non-particulate steroid, mainly used in epidural injections, forms particulates. However, when mixed with contrast media, particulates are dissolved because of changes in pH and factors affecting particulate formation. In fluoroscopy-guided injections, the use of contrast media could resolve particulate formation. [ABSTRACT FROM AUTHOR]

Background: To determine the effectiveness of ethanol (EtOH) washing on porcine pulmonary artery (PA) wall decellularization using sodium dodecyl sulfate (SDS), we compared three different washing methods (phosphate‐buffered saline [PBS], pH 9 alkali, and EtOH washing). Methods: Fresh porcine PA walls were decellularized using 0.5% SDS and 0.5% sodium deoxycholate (SDC). The decellularized tissues were rinsed using three different washing techniques. Histological, biochemical, and mechanical analyses were conducted. Implantation into the subcutaneous tissue of rats and patch implantation into the carotid artery of dogs were performed as preliminary in vivo studies. Results: The decellularization protocol based on SDS and SDC effectively removed the cells. The major extracellular matrix (ECM) structures (collagen, elastic fiber, and glycosaminoglycan) were properly preserved with the 75% EtOH‐washing method. Significantly reduced residual SDS content was identified in EtOH‐washed tissues compared to that in the other methods. No significant difference in the mechanical strength test was observed between the washing methods, and the EtOH‐washing method showed better results in the metabolic activity test compared to the PBS‐washing method. In the rat study model, no acute rejection or massive calcification was observed. The in vivo preliminary canine study showed better cell repopulation in the EtOH‐washed group. Conclusion: EtOH washing of SDS‐based decellularized porcine PA wall can reduce the residual SDS content and preserve ECM structures, especially the elastin content, and could also enhance cell repopulation after re‐implantation. [ABSTRACT FROM AUTHOR]

A continuous interscalene brachial plexus block (CIBPB) is usually administered before surgery in awake patients. However, the use of CIBPB before surgery could hinder the identification of nerve injuries after total shoulder arthroplasty (TSA). This study aimed to compare the analgesic effects of preoperatively and postoperatively initiated CIBPBs in patients undergoing TSA. The medical records of patients who underwent TSA between January 2016 and August 2020 were retrospectively reviewed. The following analgesic phases were used: intravenous (IV) patient-controlled analgesia (PCA) phase (IV PCA group, n = 40), preoperative block phase (PreBlock group, n = 44), and postoperative block phase (PostBlock group, n = 33). The postoperative initiation of CIBPB after a neurologic exam provided better analgesia than IV PCA and had no differences with the preoperative initiation of CIBPB, except for the worst pain at the postanesthetic care unit. Opioid consumption was significantly greater in the IV PCA group, but there were no differences between the PreBlock and PostBlock groups on operation day after the transfer to the general ward. The initiation of CIBPB after a patient's emergence from general anesthesia had comparable analgesic efficacy with preoperative CIBPB but offered the chance of a postoperative neurologic exam. [ABSTRACT FROM AUTHOR]

Background and Objectives: Staggered bilateral total knee arthroplasty, two procedures performed 4–7 days apart during a single hospitalization, has an increased risk of blood transfusion. This observational study aimed to evaluate whether immediate post‐operative single, high‐dose intravenous iron supplementation could reduce transfusion requirements and facilitate anaemia recovery in patients. Materials and Methods: We retrospectively analysed 131 patients who underwent staggered bilateral total knee arthroplasty. The ferric carboxymaltose (FCM) group received 1000 mg of FCM after the first operation. The non‐FCM group did not receive intravenous iron. The transfusion rate and post‐operative complications were compared between the groups. The anaemia rate was evaluated pre‐operatively, during hospitalization, and 5 weeks after the second total knee arthroplasty. Results: The FCM group comprised 78 patients (59.5%). The rate (21.8% vs. 47.2%, p = 0.004) and amount of transfusion (0 [0–2] vs. 0 [0–0], p = 0.001) was significantly lower in the FCM group than in the non‐FCM group. Although both groups' pre‐operative haemoglobin concentrations were not significantly different, the FCM group demonstrated higher haemoglobin values 5 weeks post surgery (12.25 ± 0.83 mg/dl vs. 11.48 ± 1.36 mg/dl, p < 0.001). More non‐FCM patients developed moderate to severe anaemia at 5 weeks post surgery (p < 0.001). The mortality and complication rates were not significantly different. Conclusions: Immediate post‐operative, high‐dose, intravenous iron treatment may contribute to reduced transfusion rates, facilitate haemoglobin recovery after staggered bilateral total knee arthroplasty, and minimize the development of moderate to severe anaemia. [ABSTRACT FROM AUTHOR]