Single injection, ultrasound-guided planar nerve blocks: An essential skill for any clinician caring for patients with rib fractures.

In patients with acute rib fractures, regional anesthesia has the potential to reduce suffering, decrease opiate use, lower rates of in-hospital delirium, and improve pulmonary function. While many regional anesthesia techniques are complex and time consuming, two single injection nerve blocks, the serratus anterior plane block and erector spinae plane block, are particularly fast, safe, and simple methods to anesthetize the chest wall. Herein we describe two cases in which the serratus anterior plane block and erector spinae plane block were each used with great success in achieving improved pain control in trauma patients with multiple rib fractures. We believe that any provider who routinely cares for patients with rib fractures (emergency physicians and trauma surgeons alike) can and should learn to use these straightforward nerve blocks.

The Use of Critical Care Services After Orthopedic Surgery at a High-Volume Orthopedic Medical Center: A Retrospective Study.

Background: With an aging population, orthopedics has become one of the largest and fastest growing surgical fields. However, data on the use of critical care services (CCS) in patients undergoing orthopedic procedures remain sparse. Purpose: We sought to elucidate the prevalence and characteristics of patients requiring CCS and intermediate levels of care after orthopedic surgeries at a high-volume orthopedic medical center. Methods: We retrospectively reviewed inpatient electronic medical record data (2016-2020) at a high-volume orthopedic hospital. Patients who required CCS and intermediate levels of care, including step-down unit (SDU) and telemetry services, were identified. We described characteristics related to patients, procedures, and outcomes, including type of advanced services required and surgery type. Results: Of the 50,387 patients who underwent orthopedic inpatient surgery, 1.6% required CCS and 21.6% were admitted to an SDU. Additionally, 482 (1.0%) patients required postoperative mechanical ventilation and 3602 (7.1%) patients required continuous positive airway pressure therapy. Spine surgery patients were the most likely to require any form of advanced care (45.7%). Conclusions: This retrospective review found that approximately one-fourth of orthopedic surgery patients were admitted to units that provided critical and intermediate levels of care. These results may prove useful to hospitals in estimating needs and allocating resources for advanced and critical care services after orthopedic surgery.

Binding Sites and the Mechanism of Action of Propofol and a Photoreactive Analogue in Prokaryotic Voltage-Gated Sodium Channels.

Propofol, one of the most commonly used intravenous general anesthetics, modulates neuronal function by interacting with ion channels. The mechanisms that link propofol binding to the modulation of distinct ion channel states, however, are not understood. To tackle this problem, we investigated the prokaryotic ancestors of eukaryotic voltage-gated Na+ channels (Navs) using unbiased photoaffinity labeling (PAL) with a diazirine derivative of propofol (AziPm), electrophysiological methods, and mutagenesis. AziPm inhibits Nav function in a manner that is indistinguishable from that of the parent compound by promoting activation-coupled inactivation. In several replicates (8/9) involving NaChBac and NavMs, we found adducts at residues located at the C-terminal end of the S4 voltage sensor, the S4-S5 linker, and the N-terminal end of the S5 segment. However, the non-inactivating mutant NaChBac-T220A yielded adducts that were different from those found in the wild-type counterpart, which suggested state-dependent changes at the binding site. Then, using molecular dynamics simulations to further elucidate the structural basis of Nav modulation by propofol, we show that the S4 voltage sensors and the S4-S5 linkers shape two distinct propofol binding sites in a conformation-dependent manner. Supporting the PAL and MD simulation results, we also found that Ala mutations of a subset of adducted residues have distinct effects on gating modulation of NaChBac and NavMs by propofol. The results of this study provide direct insights into the structural basis of the mechanism through which propofol binding promotes activation-coupled inactivation to inhibit Nav channel function.

Solo dining in Chinese restaurants: A mixed-method study in Macao.

Given the emergence of solo dining resulting from the changing family structure and increasingly individualised lifestyle in contemporary Chinese society, this study investigates solo dining in the setting of Chinese restaurants in Macao, including the solo dining motivations, behavioural characteristics, and experiences, taking into considerations the underlying social and cultural factors. Adopting a sequential exploratory mixed-method design, 18 interviews were conducted, followed by a survey with 493 local diners. Findings show that freedom of choice and satisfying hunger are the main motivations for solo dining, and some solo-friendly attributes, food-related attributes, and restaurant characteristics are considered as important elements. Solo dining is perceived positively, partly because its perceptions and experiences are shaped by the diners' socio-cultural backgrounds and unique regional characteristics, in which solo dining is considered relatively common in Macao as opposed to extant literature that has suggested an essentialised assumption about Chinese group-oriented dining preference. Sociocultural insights and managerial implications are provided in catering to the growing solo diner market.

Trends in total knee and hip arthroplasty recipients: a retrospective cohort study.

BACKGROUND: Arthroplasty is one of the most commonly performed procedures in the USA with projections of continuous growth. As this field undergoes continuous changes, the goal of this study was to provide an analysis of patient-related and healthcare system-related trends. This is important as it allows practitioners, administrators and policy makers to allocate needed resources appropriately. METHODS: The study included total knee arthroplasty (TKA) and total hip arthroplasty (THA) procedures from 2006 to 2016. Demographic information, comorbidities and complications were extracted and analyzed from the Premier Healthcare database. RESULTS: The surgical volume increased annually over the observation period by an average of 5.54% for TKA and 7.02% for THA, respectively. The average age of the patient population and the types of anesthesia used remained relatively consistent over time. Comorbidity burden increased, especially for obesity (16.52% in 2006 and 29.77% in 2016 for TKA, 11.15% in 2006 and 20.92% in 2016 for THA), obstructive sleep apnea (OSA) (6.82% in 2006 and 17.03% in 2016 for TKA, 4.69% in 2006 and 12.72% in 2016 for THA) and renal insufficiency (2.81% in 2006 and 7.01% in 2016 for TKA, 2.78% in 2006 and 6.43% in 2016 for THA). Minor trends of increases were also observed in the prevalence of liver disease, depression and hypothyroidism. All postoperative complications were trending lower except for acute renal failure, where an increase was noted (4.39% in 2006 and 8.10% in 2016 for TKA, 4.99% in 2006 and 8.42% in 2016 for THA). DISCUSSION: Significant trends in the care of patients who undergo TKA and THA were identified. Individuals undergoing these procedures presented with a higher prevalence of comorbidities. Despite these trajectories, complications declined over time. These data can be used to inform future research and to allocate resources to address changes in populations cared for and complications encountered.

Teaching a Point-of-Care Ultrasound Curriculum to Anesthesiology Trainees With Traditional Didactic Lectures or an Online E-Learning Platform: A Pilot Study.

BACKGROUND: Point-of-care ultrasonography (PoCUS) provides real-time, dynamic clinical evidence for providers to make potentially lifesaving medical decisions; however, these tools cannot be used effectively without appropriate training. Although there is always the option of traditional didactic methods, there has been a recent trend toward a "reverse classroom" web-based model using online e-learning modules. Our objective was to collect pilot data that would justify a future randomized controlled trial, comparing traditional didactics to an e-learning PoCUS curriculum for lung ultrasonography (LUS) and the focused assessment with sonography in trauma (FAST) exam. METHODS: Anesthesiology interns, residents (CA 1-3), and fellow trainees enrolled in a LUS and FAST exam course and were randomized to receive didactic lectures or e-learning. Trainees completed knowledge pre- and posttests. Surveys were administered to gauge learning satisfaction. All trainees completed a hands-on-training (HOT) workshop. Image acquisition was assessed through practical tests before HOT, immediately after HOT, and 5 months later. RESULTS: Eighteen trainees completed the study. There was no evidence of a difference in change in LUS knowledge test score from baseline to posttest between the e-learning and didactic groups (difference in median percentage point change [95 % CI]: 6.6 [-10.0, 23.2]; P = .411). There was no evidence of a difference in LUS knowledge posttest scores (difference in median percentage points [95% CI]: -0.9 [-4.8, 3.0]; P = .629), FAST knowledge posttest score (0 [incalculable]; P = .999), or post-HOT practical test score (-4.2 [-24.6, 16.3]; P = .672) between groups. There was no evidence of a difference in degree of satisfaction with learning experience between groups (odds ratios [95% CI]: 1.75 [0.31, 9.94]; P = .528). CONCLUSIONS: There was no evidence of a difference between the e-learning and traditional didactic groups in learning or satisfaction outcomes. These results justify establishing an adequately powered, randomized controlled trial assessing the noninferiority of e-learning to traditional didactics for teaching LUS and FAST.

Infective Endocarditis.

Infective endocarditis (IE) is an uncommon infection of cardiac valves associated with bacteremia. It increasingly affects elderly patients with chronic disease and artificial cardiac devices. The presentation, however, remains subtle and varied, with nonspecific symptoms ranging from those resembling a mild viral infection to septic shock and multiorgan failure. IE carries potential to cause significant morbidity and mortality through its impact on cardiac function and from embolic complications. Blood cultures prior to antibiotics and obtaining prompt echocardiography are key diagnostic steps, followed by proper selection of empiric antibiotics and, in many cases, collaboration with infectious disease, cardiology, and cardiothoracic surgery specialists.

Propofol inhibits prokaryotic voltage-gated Na+ channels by promoting activation-coupled inactivation.

Propofol is widely used in the clinic for the induction and maintenance of general anesthesia. As with most general anesthetics, however, our understanding of its mechanism of action remains incomplete. Local and general anesthetics largely inhibit voltage-gated Na+ channels (Navs) by inducing an apparent stabilization of the inactivated state, associated in some instances with pore block. To determine the biophysical and molecular basis of propofol action in Navs, we investigated NaChBac and NavMs, two prokaryotic Navs with distinct voltage dependencies and gating kinetics, by whole-cell patch clamp electrophysiology in the absence and presence of propofol at clinically relevant concentrations (2-10 µM). In both Navs, propofol induced a hyperpolarizing shift of the pre-pulse inactivation curve without any significant effects on recovery from inactivation at strongly hyperpolarized voltages, demonstrating that propofol does not stabilize the inactivated state. Moreover, there was no evidence of fast or slow pore block by propofol in a non-inactivating NaChBac mutant (T220A). Propofol also induced hyperpolarizing shifts of the conductance-voltage relationships with negligible effects on the time constants of deactivation at hyperpolarized voltages, indicating that propofol does not stabilize the open state. Instead, propofol decreases the time constants of macroscopic activation and inactivation. Adopting a kinetic scheme of Nav gating that assumes preferential closed-state recovery from inactivation, a 1.7-fold acceleration of the rate constant of activation and a 1.4-fold acceleration of the rate constant of inactivation were sufficient to reproduce experimental observations with computer simulations. In addition, molecular dynamics simulations and molecular docking suggest that propofol binding involves interactions with gating machinery in the S4-S5 linker and external pore regions. Our findings show that propofol is primarily a positive gating modulator of prokaryotic Navs, which ultimately inhibits the channels by promoting activation-coupled inactivation.

Propofol inhibits the voltage-gated sodium channel NaChBac at multiple sites.

Voltage-gated sodium (NaV) channels are important targets of general anesthetics, including the intravenous anesthetic propofol. Electrophysiology studies on the prokaryotic NaV channel NaChBac have demonstrated that propofol promotes channel activation and accelerates activation-coupled inactivation, but the molecular mechanisms of these effects are unclear. Here, guided by computational docking and molecular dynamics simulations, we predict several propofol-binding sites in NaChBac. We then strategically place small fluorinated probes at these putative binding sites and experimentally quantify the interaction strengths with a fluorinated propofol analogue, 4-fluoropropofol. In vitro and in vivo measurements show that 4-fluoropropofol and propofol have similar effects on NaChBac function and nearly identical anesthetizing effects on tadpole mobility. Using quantitative analysis by 19F-NMR saturation transfer difference spectroscopy, we reveal strong intermolecular cross-relaxation rate constants between 4-fluoropropofol and four different regions of NaChBac, including the activation gate and selectivity filter in the pore, the voltage sensing domain, and the S4-S5 linker. Unlike volatile anesthetics, 4-fluoropropofol does not bind to the extracellular interface of the pore domain. Collectively, our results show that propofol inhibits NaChBac at multiple sites, likely with distinct modes of action. This study provides a molecular basis for understanding the net inhibitory action of propofol on NaV channels.

Electrophysiological Analysis of Voltage-Gated Ion Channel Modulation by General Anesthetics.

Voltage-gated ion channels (VGICs) of excitable tissues are emerging as targets likely involved in both the therapeutic and toxic effects of inhaled and intravenous general anesthetics. Whereas sevoflurane and propofol inhibit voltage-gated Na+ channels (Navs), sevoflurane potentiates certain voltage-gated K+ channels (Kvs). The combination of these effects would dampen neural excitability and, therefore, might contribute to the clinical endpoints of general anesthesia. As the body of work regarding the interaction of general anesthetics with VGICs continues to grow, a multidisciplinary approach involving functional, biochemical, structural, and computational techniques, many of which are detailed in other chapters, has increasingly become necessary to solve the molecular mechanism of general anesthetic action on VGICs. Here, we focus on electrophysiological and modeling approaches and methodologies to describe how our work has elucidated the biophysical basis of the inhibition Navs by propofol and the potentiation of Kvs by sevoflurane.

Happier Healers: Randomized Controlled Trial of Mobile Mindfulness for Stress Management.

PURPOSE: Medical students have higher rates of depression and psychologic distress than the general population, which may negatively impact academic performance and professional conduct. This study assessed whether 10-20 min of daily mindfulness meditation for 30 days, using a mobile phone application, could decrease perceived stress and improve well-being for medical students. METHODS: Eighty-eight medical students were stratified by class year and randomized to either intervention or control groups to use the mobile application Headspace, an audio-guided mindfulness meditation program, for 30 days. All participants completed the Perceived Stress Scale (PSS), Five-Facet Mindfulness Questionnaire (FFMQ), and General Well-Being Schedule (GWBS) at baseline (T1), 30 days (T2), and 60 days (T3). Repeated measures analysis of variance (rANOVA) was conducted for intervention versus control groups across T1, T2, and T3 to examine differences in stress, mindfulness, and well-being. RESULTS: There was a significant interaction between time and treatment group for perceived stress and well-being. Perceived stress significantly decreased for the intervention group from T1 to T3 (F[2,142] = 3.98, p < 0.05). General well-being significantly increased for the intervention group compared to the control group from T1 to T2, and the increase was sustained through T3 (F[2,144] = 3.36, p < 0.05). CONCLUSIONS: These results highlight that a mobile audio-guided mindfulness meditation program is an effective means to decrease perceived stress in medical students, which may have implications on patient care. Integrating mindfulness training into medical school curricula for management of school- and work-related stress may lead to fewer negative physician outcomes (e.g., burnout, anxiety, and depression) and improved physician and patient outcomes. This has implications for a broad group of therapists and healthcare providers, ultimately improving quality of healing and patient care.

Trends in Inpatient Resource Utilization and Complications Among Total Joint Arthroplasty Recipients: A Retrospective Cohort Study.

INTRODUCTION: Joint arthroplasty practice is highly dynamic to adapt to economic changes and advances in medicine. This study provides updates of the current perioperative practice on healthcare resource utilization. METHODS: The study included total knee arthroplasty, total hip arthroplasty, and total shoulder arthroplasty within the healthcare cost and utilization project New York State database from 2007 to 2013 (ie, 202,100, 127,872, and 8858 cases, respectively). RESULTS: A higher proportion of sicker patients were prevalent over time. The length of stay decreased continuously. However, total hospital charges increased after adjusting for inflation. The incidence of wound infection and transfusion decreased steadily over time, whereas acute renal failure has been on the rise. There was an increased utilization of echocardiography, while decreased among other resources. DISCUSSION: Total knee arthroplasty, total hip arthroplasty, and total shoulder arthroplasty changed toward sicker patients with shorter length of stay, fewer complications, and less resource utilization. However, overall costs increased over time.

Perioperative management of patients with pulmonary hypertension for non-cardiac surgery.

Pulmonary hypertension (PH) is associated with significant morbidity and mortality. While the advent of disease-modifying therapies in the treatment of PH has dramatically increased the life expectancy of these patients, they remain at high risk for perioperative complications. Outcome studies suggest that patients with PH undergoing non-cardiac surgery have higher morbidity and mortality than those without, independent of severity. Despite these risks, more and more of these patients are presenting for non-cardiac surgery. Patients with rheumatologic disorders in particular often have pulmonary arterial hypertension (PAH), a group that is associated with a poorer prognosis. Yet, these patients invariably develop debilitating joint diseases and not uncommonly present for elective surgery. Preoperatively, patients with PH should be appropriately risk stratified based on functional class, etiology, exercise capacity, pulmonary hemodynamics, and the risk of surgery. If the risks and benefits assessment proves favorable, they should undergo optimization prior to surgery, with any chronic therapy continuing without cessation through the perioperative period. A multidisciplinary approach involving all intraoperative physicians is imperative to forming a safe intraoperative plan based on the inherent physiology underlying the patient's disease. Finally, because complications in this patient population often occur postoperatively, patients should be monitored in an appropriate setting with a goal of preventing right ventricular dysfunction. In this review article, we focus on the evaluation, risk stratification, and optimization of patients with PH undergoing non-cardiac surgery.

Spatially oriented, temporally sequential smooth muscle cell-endothelial progenitor cell bi-level cell sheet neovascularizes ischemic myocardium.

BACKGROUND: Endothelial progenitor cells (EPCs) possess robust therapeutic angiogenic potential, yet may be limited in the capacity to develop into fully mature vasculature. This problem might be exacerbated by the absence of a neovascular foundation, namely pericytes, with simple EPC injection. We hypothesized that coculturing EPCs with smooth muscle cells (SMCs), components of the surrounding vascular wall, in a cell sheet will mimic the native spatial orientation and interaction between EPCs and SMCs to create a supratherapeutic angiogenic construct in a model of ischemic cardiomyopathy. METHODS AND RESULTS: Primary EPCs and SMCs were isolated from Wistar rats. Confluent SMCs topped with confluent EPCs were spontaneously detached from the Upcell dish to create an SMC-EPC bi-level cell sheet. A rodent ischemic cardiomyopathy model was created by ligating the left anterior descending coronary artery. Rats were then immediately divided into 3 groups: cell-sheet transplantation (n=14), cell injection (n=12), and no treatment (n=13). Cocultured EPCs and SMCs stimulated an abundant release of multiple cytokines in vitro. Increased capillary density and improved blood perfusion in the borderzone elucidated the significant in vivo angiogenic potential of this technology. Most interestingly, however, cell fate-tracking experiments demonstrated that the cell-sheet EPCs and SMCs directly migrated into the myocardium and differentiated into elements of newly formed functional vasculature. The robust angiogenic effect of this cell sheet translated to enhanced ventricular function as demonstrated by echocardiography. CONCLUSIONS: Spatially arranged EPC-SMC bi-level cell-sheet technology facilitated the natural interaction between EPCs and SMCs, thereby creating structurally mature, functional microvasculature in a rodent ischemic cardiomyopathy model, leading to improved myocardial function.

Sustained release of engineered stromal cell-derived factor 1-α from injectable hydrogels effectively recruits endothelial progenitor cells and preserves ventricular function after myocardial infarction.

BACKGROUND: Exogenously delivered chemokines have enabled neovasculogenic myocardial repair in models of ischemic cardiomyopathy; however, these molecules have short half-lives in vivo. In this study, we hypothesized that the sustained delivery of a synthetic analog of stromal cell-derived factor 1-α (engineered stromal cell-derived factor analog [ESA]) induces continuous homing of endothelial progenitor cells and improves left ventricular function in a rat model of myocardial infarction. METHODS AND RESULTS: Our previously designed ESA peptide was synthesized by the addition of a fluorophore tag for tracking. Hyaluronic acid was chemically modified with hydroxyethyl methacrylate to form hydrolytically degradable hydrogels through free-radical-initiated crosslinking. ESA was encapsulated in hyaluronic acid hydrogels during gel formation, and then ESA release, along with gel degradation, was monitored for more than 4 weeks in vitro. Chemotactic properties of the eluted ESA were assessed at multiple time points using rat endothelial progenitor cells in a transwell migration assay. Finally, adult male Wistar rats (n=33) underwent permanent ligation of the left anterior descending (LAD) coronary artery, and 100 µL of saline, hydrogel alone, or hydrogel+25 µg ESA was injected into the borderzone. ESA fluorescence was monitored in animals for more than 4 weeks, after which vasculogenic, geometric, and functional parameters were assessed to determine the therapeutic benefit of each treatment group. ESA release was sustained for 4 weeks in vitro, remained active, and enhanced endothelial progenitor cell chemotaxis. In addition, ESA was detected in the rat heart >3 weeks when delivered within the hydrogels and significantly improved vascularity, ventricular geometry, ejection fraction, cardiac output, and contractility compared with controls. CONCLUSIONS: We have developed a hydrogel delivery system that sustains the release of a bioactive endothelial progenitor cell chemokine during a 4-week period that preserves ventricular function in a rat model of myocardial infarction.

Ascending aortic cannulation in acute type a dissection repair.

Femoral and axillary cannulation for arterial inflow in acute type A aortic dissection are the most commonly used cannulation strategies in current practice. More recently, our group and others have successfully used a central cannulation technique with excellent results. Although this approach has been described, specific technical details have not been clearly defined. In addition, the ideal anatomic characteristics of different types of aortic dissections amenable to central cannulation have not been delineated. The purpose of this brief communication is to describe the technical and procedural details specific to cannulation of the dissected ascending aorta and to propose a classification scheme of ascending aortic dissection anatomy based on difficulty of central cannulation.

Mathematically engineered stromal cell-derived factor-1α stem cell cytokine analog enhances mechanical properties of infarcted myocardium.

OBJECTIVE: The biomechanical response to a myocardial infarction consists of ventricular remodeling that leads to dilatation, loss of contractile function, abnormal stress patterns, and ultimately heart failure. We hypothesized that intramyocardial injection of our previously designed pro-angiogenic chemokine, an engineered stromal cell-derived factor-1α analog (ESA), improves mechanical properties of the heart after infarction. METHODS: Male rats (n = 54) underwent either sham surgery (n = 17) with no coronary artery ligation or ligation of the left anterior descending artery (n = 37). The rats in the myocardial infarction group were then randomized to receive either saline (0.1 mL, n = 18) or ESA (6 µg/kg, n = 19) injected into the myocardium at 4 predetermined spots around the border zone. Echocardiograms were performed preoperatively and before the terminal surgery. After 4 weeks, the hearts were explanted and longitudinally sectioned. Uniaxial tensile testing was completed using an Instron 5543 Microtester. Optical strain was evaluated using custom image acquisition software, Digi-Velpo, and analyzed in MATLAB. RESULTS: Compared with the saline control group at 4 weeks, the ESA-injected hearts had a greater ejection fraction (71.8% ± 9.0% vs 55.3% ± 12.6%, P = .0004), smaller end-diastolic left ventricular internal dimension (0.686 ± 0.110 cm vs 0.763 ± 0.160 cm, P = .04), greater cardiac output (36 ± 11.6 mL/min vs 26.9 ± 7.3 mL/min, P = .05), and a lower tensile modulus (251 ± 56 kPa vs 301 ± 81 kPa, P = .04). The tensile modulus for the sham group was 195 ± 56 kPa, indicating ESA injection results in a less stiff ventricle. CONCLUSIONS: Direct injection of ESA alters the biomechanical response to myocardial infarction, improving the mechanical properties in the postinfarct heart.

Hyaluronic acid-binding scaffold for articular cartilage repair.

Hyaluronic acid (HA) is an extracellular matrix molecule with multiple physical and biological functions found in many tissues, including cartilage. HA has been incorporated in a number of biomaterial and scaffold systems. However, HA in the material may be difficult to control if it is not chemically modified and chemical modification of HA may negatively impact biological function. In this study, we developed a poly(ethylene glycol) hydrogel with noncovalent HA-binding capabilities and evaluated its ability to support cartilage formation in vitro and in an articular defect model. Chondrogenic differentiation of mesenchymal stem cells encapsulated in the HA-interactive scaffolds containing various amounts of exogenous HA was evaluated. The HA-binding hydrogel without exogenous HA produced the best cartilage as determined by biochemical content (glysocaminoglycan and collagen), histology (Safranin O and type II collagen staining), and gene expression analysis for aggrecan, type I collagen, type II collagen, and sox-9. This HA-binding formulation was then translated to an osteochondral defect model in the rat knee. After 6 weeks, histological analysis demonstrated improved cartilage tissue production in defects treated with the HA-interactive hydrogel compared to noninteractive control scaffolds and untreated defects. In addition to the tissue repair in the defect space, the Safranin O staining in cartilage tissue surrounding the defect was greater in treatment groups where the HA-binding scaffold was applied. In sum, incorporation of a noncovalent HA-binding functionality into biomaterials provides an ability to interact with local or exogenous HA, which can then impact tissue remodeling and ultimately new tissue production.