Correlation Between Intravascular Injection Rate, Pain Intensity, and Degree of Cervical Neural Foraminal Stenosis During a Cervical Transforaminal Epidural Block.

PURPOSE: Cervical transforaminal epidural blocks (CTEBs) are useful for the treatment of cervical radicular pain. However, during CTEBs, inadvertent intravascular injection can introduce particulate steroids into the bloodstream, thus leading to serious complications. Moreover, the risk factors associated with intravascular injection during CTEBs have not been identified. Cervical neural foraminal stenosis (CNFS) is a form of neural foraminal narrowing and a common cause of cervical radicular pain. In this study, we aimed to identify whether there is a correlation between the incidence of intravascular injection during CTEB, pain intensity, and the degree of CNFS. PATIENTS AND METHODS: A total of 126 patients were recruited. The patients were classified into two subgroups (group M and group S) based on the routine cervical T2-weighted axial magnetic resonance imaging (MRI) findings. Group M (n = 63) consisted of moderate CNFS patients, while group S (n = 63) consisted of severe CNFS patients. The occurrence of intravascular injection during CTEB was established using real-time fluoroscopy. The intravascular injection was determined by the spreading of the contrast medium through the vascular channel during the injection. Additionally, pain intensity was scored using a Numeric Rating Scale (NRS) before the procedure and 1 month after the procedure. RESULTS: There was no significant difference in the incidence of intravascular injection during CTEB between group M and group S (41.3% vs 39.7%, respectively; p = 0.99) and in the NRS scores before and 1 month after CTEB. However, both groups showed a significant decrease in the NRS scores at 1 month after the procedure compared with that before the procedure. CONCLUSION: The degree of CNFS does not affect the incidence of intravascular injection during CTEB. Regardless of whether patients have moderate or severe CNFS, caution should be exercised during CTEB procedures.

Data-driven experimental design and model development using Gaussian process with active learning.

Interest in computational modeling of cognition and behavior continues to grow. To be most productive, modelers should be equipped with tools that ensure optimal efficiency in data collection and in the integrity of inference about the phenomenon of interest. Traditionally, models in cognitive science have been parametric, which are particularly susceptible to model misspecification because their strong assumptions (e.g. parameterization, functional form) may introduce unjustified biases in data collection and inference. To address this issue, we propose a data-driven nonparametric framework for model development, one that also includes optimal experimental design as a goal. It combines Gaussian Processes, a stochastic process often used for regression and classification, with active learning, from machine learning, to iteratively fit the model and use it to optimize the design selection throughout the experiment. The approach, dubbed Gaussian process with active learning (GPAL), is an extension of the parametric, adaptive design optimization (ADO) framework (Cavagnaro, Myung, Pitt, & Kujala, 2010). We demonstrate the application and features of GPAL in a delay discounting task and compare its performance to ADO in two experiments. The results show that GPAL is a viable modeling framework that is noteworthy for its high sensitivity to individual differences, identifying novel patterns in the data that were missed by the model-constrained ADO. This investigation represents a first step towards the development of a data-driven cognitive modeling framework that serves as a middle ground between raw data, which can be difficult to interpret, and parametric models, which rely on strong assumptions.

Comparison of the intraoperative analgesic efficacy between ultrasound-guided deep and superficial serratus anterior plane block during video-assisted thoracoscopic lobectomy: A prospective randomized clinical trial.

BACKGROUND: The serratus anterior plane block (SAPB) is a novel method that provides lateral chest wall analgesia. There are 2 methods of SAPB; deep and superficial SAPB. Each of these methods has been demonstrated to provide effective perioperative analgesia in thoracic surgery. The aim of this study was to compare the intraoperative hemodynamic and analgesic benefits of deep versus superficial SAPB during video-assisted thoracic surgery (VATS) lobectomy. METHODS: We performed a prospective, randomized, patient/assessor-blinded trial. We included patients who were 20 to 75 years of age and scheduled to undergo VATS lobectomy with American Society of Anesthesiologists physical status 1 or 2. Patients were randomly allocated to receive either ultrasound-guided deep SAPB (Group D) or superficial SAPB (Group S). The primary outcome was intraoperative remifentanil consumption. We also recorded intraoperative systolic blood pressure (SBP), heart rate (HR), emergence time, and doses of rescue drugs used to manage hemodynamic instability. RESULTS: Data for 50 patients undergoing 3-port VATS lobectomy were analyzed. Intraoperative remifentanil consumption did not differ significantly between Group D (n = 25, 715.62 ±â€Š320.36 µg) and group S (n = 25, 721.08 ±â€Š294.48 µg) (P = .97). Additionally, there were no significant differences between the 2 groups in SBP and HR at any time point, emergence time, or amount of rescue drugs used. CONCLUSION: Our study suggests that the intraoperative analgesic efficacy is similar for deep and superficial SAPB during VATS lobectomy.

The Effect of Different Posture on Normal Saline Injection in Optic Nerve Sheath Diameter in Thoracic Epidural Anesthesia.

BACKGROUND: Thoracolumbar or caudal epidural anesthesia affects intracranial pressure (ICP) in both animals and humans. Epidural injection increases ICP at least transiently. Measurement of the optic nerve sheath diameter (ONSD) using ultrasonography is one of the noninvasive methods for ICP assessment. OBJECTIVES: The purpose of this study was to investigate the effect of the different posture during epidural saline injection to the ONSD under awake conditions. STUDY DESIGN: Prospective, randomized trial. SETTING: An interventional pain management practice in South Korea. METHODS: This study included 44 patients receiving thoracic epidural catheterization for pain management after upper abdominal or thoracic surgery. Following successful epidural space confirmation, patients were randomized to receive epidural saline while supine (A group) or in sitting position (B group), respectively. Transorbital sonography was performed for the measurement of the ONSD, and the ONSD was measured at 3 mm posterior to the optic nerve head. RESULTS: Both A and B groups showed significant increases of ONSD according to time. Mean ONSD values measured at T10, T20, and T40 significantly increased from the baseline value (T0) (*P < 0.05 vs. T0, †P < 0.001 vs. T0, ‡P < 0.005 vs. T0). The mean ONSD values measured at any of the time points and degrees of changes (T10-T0, T20-T0, and T40-T0) between groups A and B did not show any significant changes. LIMITATIONS: Epidural pressure and ONSD measurement can make this study more reliable. Further study showing changes of epidural pressure with ONSD measurement is required. CONCLUSIONS: Thoracic epidural injection of 10 mL of normal saline resulted in a significant increase of ONSD compared with the baseline. However, the different posture did not affect the increase of ONSD.

Efficient Closed-loop Maximization of Carbon Nanotube Growth Rate using Bayesian Optimization.

A major technological challenge in materials research is the large and complex parameter space, which hinders experimental throughput and ultimately slows down development and implementation. In single-walled carbon nanotube (CNT) synthesis, for instance, the poor yield obtained from conventional catalysts is a result of limited understanding of input-to-output correlations. Autonomous closed-loop experimentation combined with advances in machine learning (ML) is uniquely suited for high-throughput research. Among the ML algorithms available, Bayesian optimization (BO) is especially apt for exploration and optimization within such high-dimensional and complex parameter space. BO is an adaptive sequential design algorithm for finding the global optimum of a black-box objective function with the fewest possible measurements. Here, we demonstrate a promising application of BO in CNT synthesis as an efficient and robust algorithm which can (1) improve the growth rate of CNT in the BO-planner experiments over the seed experiments up to a factor 8; (2) rapidly improve its predictive power (or learning); (3) Consistently achieve good performance regardless of the number or origin of seed experiments; (4) exploit a high-dimensional, complex parameter space, and (5) achieve the former 4 tasks in just over 100 hundred experiments (~8 experimental hours) - a factor of 5× faster than our previously reported results.

Comparison of Epidural Pressure Decrease Pattern According to Different Lumbar Epidural Approaches.

BACKGROUND: During lumbar epidural injection (LEI) using a midline approach, we might encounter failure of identifying the epidural space owing to an equivocal or absent loss of resistance (LOR) sensation. The reason for such absence of LOR sensation has been suggested as paucity of midline ligamentum flavum, paravertebral muscle, and cyst in the interspinous ligament of the lumbar spine. Despite its low specificity, LOR is the most commonly used method to identify the epidural space. OBJECTIVES: The purpose of this study was to analyze lumbar epidural pressure decrease patterns and identify factors contributing to this pressure decrease. STUDY DESIGN: Prospective randomized trial. SETTING: An interventional pain management practice in South Korea. METHODS: This prospective study included 104 patients receiving LEI due to lumbar radiculopathy. A midline or paramedian approach of LEI was determined with randomization. Among various factors, gender, age, body mass index (BMI), and diagnosis were analyzed using a subgroup that included 60 cases of only a paramedian approach. RESULTS: Grades I, II (abrupt decrease), and III (gradual decrease) were found as patterns of epidural pressure decrease. Abrupt pressure decrease was more frequently observed in the paramedian group (P < 0.001). Age, gender, BMI, and diagnosis did not show any significant difference in frequencies between abrupt and gradual pressure decrease. LIMITATIONS: We could not match LOR sensation with epidural pressure decrease shown in the monitor. CONCLUSIONS: This study demonstrates that abrupt pressure decrease occurs more frequently with the paramedian approach. However, age, gender, BMI, or diagnosis did not affect the incidence of epidural pressure decrease. KEY WORDS: Epidural, paramedian, midline, pressure decrease.

Effect of tranexamic acid on reducing postoperative blood loss in combined hypotensive epidural anesthesia and general anesthesia for total hip replacement.

STUDY OBJECTIVE: To determine whether the use of tranexamic acid in the setting of hypotension induced by hypotensive epidural anesthesia (HEA) has any additional beneficial effects in reducing perioperative blood loss and transfusion requirements in total hip replacement. DESIGN: Prospective, randomized, double-blinded trial. SETTING: University-affiliated hospital. PATIENTS: 68 adult, ASA physical status 1 and 2 patients undergoing primary unilateral cementless total hip replacement with general anesthesia and HEA. INTERVENTIONS: The HEATA group received a bolus dose of 15 mg/kg of tranexamic acid before surgical incision, followed by a continuous 15 mg/kg infusion until skin closure. The HEA group received normal saline instead of tranexamic acid in the same manner. MEASUREMENTS: Intraoperative blood loss was measured using the difference between the weights of used gauze and the original unused gauze, in addition to the blood volume accumulated in suction bottles. Postoperative blood loss was considered to be the amount of blood accumulated in drainage bags. MAIN RESULTS: There was no significant difference in intraoperative blood loss between the HEA and HEATA groups (251.8 ± 109.9 mL vs. 234.9 ± 93.9 mL), but postoperative blood loss was significantly less in the HEATA group than the HEA group (439.3 ± 171. 6 mL vs. 1074.4 ± 287.1 mL), as was total cumulative blood loss (674.2 ± 216.4 mL vs. 1326.2 ± 347.8 mL). There was no significant difference in intraoperative transfusion incidences, but postoperative transfusion was greater in the HEA group than the HEATA group. CONCLUSIONS: Administration of tranexamic acid combined with hypotensive epidural anesthesia reduced postoperative and total accumulative blood loss and transfusion requirements more than did hypotensive epidural anesthesia alone.