Extracorporeal Carbon Dioxide Removal to De-escalate Venovenous Extracorporeal Membrane Oxygenation in Severe COVID-19 Acute Respiratory Distress Syndrome.

OBJECTIVES: In a subset of patients with COVID-19 acute respiratory distress syndrome (ARDS), there is a need for extracorporeal membrane oxygenation (ECMO) for pulmonary support. The primary extracorporeal support tool for severe COVID-19 ARDS is venovenous (VV) ECMO; however, after hypoxemic respiratory failure resolves, many patients experience refractory residual hypercarbic respiratory failure. Extracorporeal carbon dioxide removal (ECCO2R) for isolated hypercarbic type II respiratory failure can be used in select cases to deescalate patients from VV ECMO while the lung recovers the ability to exchange CO2. The objective of this study was to describe the authors' experience in using ECCO2R as a bridge from VV ECMO. DESIGN: Hemolung Respiratory Assist System (RAS) is a commercially available (ECCO2R) device, and the United States Food and Drug Administration accelerated its use under its Emergency Use Authorization for the treatment of refractory hypercarbic respiratory failure in COVID-19-induced ARDS. This created an environment in which selected and targeted mechanical circulatory support therapy for refractory hypercarbic respiratory failure could be addressed. This retrospective study describes the application of Hemolung RAS as a VV ECMO deescalation platform to treat refractory hypercarbic respiratory failure after the resolution of hypoxemic COVID-19 ARDS. SETTING: A quaternary-care academic medical center, single institution. PARTICIPANTS: Patients with refractory hypercarbic respiratory failure after COVID-19 ARDS who were previously supported with VV ECMO. MEASUREMENTS AND MAIN RESULTS: Twenty-one patients were placed on ECCO2R after VV ECMO for COVID-19 ARDS. Seventeen patients successfully were transitioned to ECCO2R and then decannulated; 3 patients required reescalation to VV ECMO secondary to hypercapnic respiratory failure, and 1 patient died while on ECCO2R. Five (23.8%) of the 21 patients were transitioned off of VV ECMO to ECCO2R, with a compliance of <20 (mL/cmH2O). Of these patients, 3 with low compliance were reescalated to VV ECMO. CONCLUSIONS: Extracorporeal carbon dioxide removal can be used to continue supportive methods for patients with refractory type 2 hypercarbic respiratory failure after COVID-19 ARDS for patients previously on VV ECMO. Patients with low compliance have a higher rate of reescalation to VV ECMO.

Pragmatic Evaluation of a Deep-Learning Algorithm to Automate Ejection Fraction on Hand-Held, Point-of-Care Echocardiography in a Cardiac Surgical Operating Room.

OBJECTIVE: To test the correlation of ejection fraction (EF) estimated by a deep-learning-based, automated algorithm (Auto EF) versus an EF estimated by Simpson's method. DESIGN: A prospective observational study. SETTING: A single-center study at the Hospital of the University of Pennsylvania. PARTICIPANTS: Study participants were ≥18 years of age and scheduled to undergo valve, aortic, coronary artery bypass graft, heart, or lung transplant surgery. INTERVENTIONS: This noninterventional study involved acquiring apical 4-chamber transthoracic echocardiographic clips using the Philips hand-held ultrasound device, Lumify. MEASUREMENTS AND MAIN RESULTS: In the primary analysis of 54 clips, compared to Simpson's method for EF estimation, bias was similar for Auto EF (-10.17%) and the experienced reader-estimated EF (-9.82%), but the correlation was lower for Auto EF (r = 0.56) than the experienced reader-estimated EF (r = 0.80). In the secondary analyses, the correlation between EF estimated by Simpson's method and Auto EF increased when applied to 27 acquisitions classified as adequate (r = 0.86), but decreased when applied to 27 acquisitions classified as inadequate (r = 0.46). CONCLUSIONS: Applied to acquisitions of adequate image quality, Auto EF produced a numerical EF estimate equivalent to Simpson's method. However, when applied to acquisitions of inadequate image quality, discrepancies arose between EF estimated by Auto EF and Simpson's method. Visual EF estimates by experienced readers correlated highly with Simpson's method in both variable and inadequate imaging conditions, emphasizing its enduring clinical utility.

The Society of Thoracic Surgeons Adult Cardiac Surgery Database: Intraoperative Echocardiography Reporting.

OBJECTIVES: To identify trends in the reporting of intraoperative transesophageal echocardiographic (TEE) data in the Society of Thoracic Surgeons (STS) Adult Cardiac Surgery Database (ACSD) and the Adult Cardiac Anesthesiology (ACA) module by period, practice type, and geographic distribution, and to elucidate ongoing areas for practice improvement. DESIGN: A retrospective study. SETTING: STS ACSD. PARTICIPANTS: Procedures reported in the STS ACSD between July 2017 and December 2021 in participating programs in the United States. INTERVENTIONS: None MEASUREMENTS AND MAIN RESULTS: Intraoperative TEE is reported for 73% of all procedures in ACSD. Although the intraoperative TEE data reporting rate increased from 2017 to 2021 for isolated coronary artery bypass graft surgery, it remained low at 62.2%. The reporting of relevant echocardiographic variables across a wide range of procedures has steadily increased over the study period but also remained low. The reporting in the ACA module is high for most variables and across all anesthesia care models; however, the overall contribution of the ACA module to the ACSD remains low. CONCLUSIONS: This progress report suggests a continued need to raise awareness regarding current practices of reporting intraoperative TEE in the ACSD and the ACA, and highlights opportunities for improving reporting and data abstraction.

Evolution in the treatment of gastroesophageal reflux disease over the last century: from a crural-centered to a lower esophageal sphincter-centered approach and back.

The surgical management of gastroesophageal reflux disease (GERD) has evolved significantly over the past century, driven by increased understanding of the physiology of the reflux barrier, its anatomic components, and surgical innovation. Initially, emphasis was on reduction of hiatal hernias and crural closure as the etiology behind GERD was felt to be solely related to the anatomic alterations caused by hiatal hernias. With persistence of reflux-related changes in some patients despite crural closure, along with the development of what is now modern manometry and the discovery of a high-pressure zone at the distal esophagus, focus evolved to surgical augmentation of the lower esophageal sphincter (LES). With this transition to an LES-centric approach, attention shifted to reconstruction of the angle of His, ensuring sufficient intra-abdominal esophageal length, development of the now commonly employed Nissen fundoplication, and creation of devices that directly augment the LES such as magnetic sphincter augmentation. More recently, the role of crural closure in antireflux and hiatal hernia surgery has again received renewed attention due to the persistence of postoperative complications including wrap herniation and high rates of recurrences. Rather than simply preventing transthoracic herniation of the fundoplication as was originally thought, diaphragmatic crural closure has been documented to have a key role in re-establishing intra-abdominal esophageal length and contributing to the restoration of normal LES pressures. This progression from a crural-centric to a LES-centric approach and back has evolved along with our understanding of the reflux barrier and will continue to do so as more advances are made in the field. In this review, we will discuss the evolution of surgical techniques over the past century, highlighting key historical contributions that have shaped our management of GERD today.

Bridging preference-based instrumental variable studies and cluster-randomized encouragement experiments: Study design, noncompliance, and average cluster effect ratio.

Instrumental variable (IV) methods are widely used in medical research to draw causal conclusions when the treatment and outcome are confounded by unmeasured confounding variables. One important feature of such studies is that the IV is often applied at the cluster level, for example, hospitals' or physicians' preference for a certain treatment where each hospital or physician naturally defines a cluster. This paper proposes to embed such observational IV data into a cluster-randomized encouragement experiment using nonbipartite matching. Potential outcomes and causal assumptions underpinning the design are formalized and examined. Testing procedures for two commonly used estimands, Fisher's sharp null hypothesis and the pooled effect ratio (PER), are extended to the current setting. We then introduce a novel cluster-heterogeneous proportional treatment effect model and the relevant estimand: the average cluster effect ratio. This new estimand is advantageous over the structural parameter in a constant proportional treatment effect model in that it allows treatment heterogeneity, and is advantageous over the PER estimand in that it does not suffer from Simpson's paradox. We develop an asymptotically valid randomization-based testing procedure for this new estimand based on solving a mixed-integer quadratically constrained optimization problem. The proposed design and inferential methods are applied to a study of the effect of using transesophageal echocardiography during coronary artery bypass graft surgery on patients' 30-day mortality rate. R package ivdesign implements the proposed method.

Impact of Hospital Practice and Staffing Differences on Transesophageal Echocardiography Use in Cardiac Valve or Coronary Artery Bypass Graft Surgery.

OBJECTIVES: To identify and quantify the predictors of intraoperative transesophageal echocardiography (TEE) use among the patients undergoing cardiac valve or isolated coronary artery bypass graft (CABG) surgery. DESIGN: An observational cohort study. SETTING: This study used the Centers for Medicare and Medicaid Services administrative claims dataset of the beneficiaries undergoing valve or isolated CABG surgery between 2013 to 2015. PARTICIPANTS: Adults aged ≥65 years of age undergoing cardiac valve or isolated CABG surgery. INTERVENTIONS: Generalized linear mixed-model (GLMM) analyses were used to examine the relationship between the TEE and patient characteristics, hospital factors, and staffing differences, while accounting for clustering within hospitals. The proportion of variation in TEE use attributable to patient-level characteristics was quantified using odds ratios. Hospital-level factors and staffing differences were quantified using the median odds ratios (MOR) and interval odds ratios (IOR). MEASUREMENTS AND MAIN RESULTS: Among 261,860 patients (123,702 valve procedures and 138,158 isolated CABG), the GLMM analysis demonstrated that the strongest predictor for intraoperative TEE use was the hospital where the surgery occurred (MOR for TEE of 2.57 in valve and 4.16 in isolated CABG). The TEE staffing variable reduced the previously unexplained across-hospital variability by 9% in valve and 21% in isolated CABG, and hospitals with anesthesiologist TEE staffing (versus mixed) were more likely to use TEE in both valve and CABG (MOR for TEE of 1.21 in valve and 1.84 in isolated CABG). CONCLUSION: Hospital practice was the strongest predictor for TEE use overall. In isolated CABG surgery, hospitals with anesthesiologist TEE staffing were a primary predictor for TEE use.

Validation of Claims Data for the Identification of Intraoperative Transesophageal Echocardiography During Cardiac Surgery.

OBJECTIVE: The goal of this study was to assess the validity of Current Procedural Terminology (CPT) claims data for the identification of intraoperative transesophageal echocardiography (TEE) during cardiac surgery. DESIGN: This study was a retrospective, cohort analysis. SETTING: This study used data from electronic medical records (EMRs), in combination with CPT billing claims data, from two hospitals within the Penn Medicine Health System-Penn Presbyterian Medical Center and the Hospital of the University of Pennsylvania. PARTICIPANTS: The cohort consisted of adult patients, aged ≥18 years, undergoing open cardiac valve surgery (repair or replacement), coronary artery bypass graft surgery, or aortic surgery between April 1 and October 31, 2019. INTERVENTIONS: Agreement between TEE identified using CPT billing code(s) (93312-8 with or without 93320-1 or 93325) and TEE identified by manual EMR review. MEASUREMENTS AND MAIN RESULTS: As identified by a reference standard (ie, EMR review) of the 873 cases that met inclusion criteria, 867 (99.31%) cases were performed with TEE and six cases were performed without TEE (<1%). Of the 867 cases performed with TEE, CPT code(s) correctly identified 866 cases, as indicated by having at least one of the CPT codes (93312-8 with or without 93320-1 or 93325). These CPT codes identified intraoperative TEE with a 99.88% sensitivity, 100.00% specificity, 100.00% positive predictive value, and 85.71% negative predictive value. When billing claims for TEE were restricted to the CPT code 93312 alone, the results were identical. CONCLUSIONS: Billing claims using CPT code(s) identified true intraoperative TEE with a high sensitivity, specificity, excellent positive predictive value, and moderate negative predictive value. These results demonstrated that claims data are a valuable data source from which to study the effect of TEE in cardiac surgical patients.

Base-Promoted C-C Bond Activation Enables Radical Allylation with Homoallylic Alcohols.

The Cα-Cß bond in homoallylic alcohols can be activated under basic conditions, qualifying these nonstrained acyclic systems as radical allylation reagents. This reactivity is exemplified by photoinitiated (with visible light and/or blue LEDs) allylation of perfluoroalkyl and alkyl radicals generated from perfluoroalkyl iodides and alkylpyridinium salts, respectively, with homoallylic alcohols. C-radical addition to the double bond of the title reagents and subsequent base-promoted homolytic Cα-Cß cleavage leads to the formation of the corresponding allylated products along with ketyl radicals that act as single electron reductants to sustain the chain reactions. Substrate scope is documented and the role of base in the C-C bond activation is studied by computation.

Pilot Study Suggests Smartphone Application Knowledge Improves Resident Transesophageal Echocardiography Knowledge: A Randomized Controlled Trial.

OBJECTIVE: The objective of this study was to determine whether an asynchronous smartphone-based application with image-based questions would improve anesthesiology resident transesophageal echocardiography (TEE) knowledge compared with standard intraoperative teaching alone. DESIGN: Prospective, single-blinded, pilot, randomized controlled trial. SETTING: Large university teaching hospital. PARTICIPANTS: Participants were anesthesiology residents on their cardiac anesthesiology rotation. INTERVENTIONS: EchoEducator, a TEE image-based smartphone application of learning content through questions, was developed. Content was derived from the Examination of Special Competence in Basic Perioperative Transesophageal Echocardiography and the Objective Structured Clinical Examination portion of the APPLIED Examination and focused on identification of basic TEE views, cardiac structures, and pathology. Residents were randomly assigned to receive access to either the application or to standard intraoperative teaching. Thirty residents met inclusion criteria, and 18 residents completed the study. A pre-intervention assessment was given at the beginning of the rotation, and a post-intervention assessment was given after 2 weeks. MEASUREMENTS: The primary outcome was the difference between the post-test score and the pre-test score. Standard bivariate statistics and the chi-square test were used for categorical variables, and the Student t test was used for continuous variables. Tests were 2-sided, and statistical significance was set at p < 0.05. The intervention group demonstrated a greater increase in score; (+19.19% [95% confidence interval 4.14%-34.24%]; p = 0.02) compared with the control group. CONCLUSIONS: This study supports the hypothesis that use of a smartphone-based asynchronous educational application improves TEE knowledge compared with traditional modalities alone. This supports an opportunity to improve medical education by expanding the role of web-based asynchronous learning.

Transesophageal Echocardiography, Acute Kidney Injury, and Length of Hospitalization Among Adults Undergoing Coronary Artery Bypass Graft Surgery.

OBJECTIVE: To test the association between transesophageal echocardiography (TEE) and incidence of acute kidney injury and length of hospitalization among United States adults undergoing isolated coronary artery bypass graft (CABG) surgery. DESIGN: This was an observational, retrospective cohort analysis. SETTING: This study used a multicenter claims dataset from a commercially insured population undergoing CABG surgery in the United States between 2004 and 2016. PARTICIPANTS: Adults aged 18 years or older with continuous insurance enrollment and an absence of renal-related diagnoses before the index CABG surgery. INTERVENTIONS: Receipt of TEE within 1 calendar day of the index CABG surgery date. MEASUREMENTS AND MAIN RESULTS: Of 51,487 CABG surgeries, 5,361 (10.4%; [95% confidence interval [CI]: 10.1-10.7%]) developed acute kidney injury and the mean length of hospitalization was 8.8 days (95% CI: 8.7-8.8). The TEE group demonstrated a greater absolute risk difference (RD) for acute kidney injury by multiple linear regression, overall, (RD=+1.0; [95% CI: 0.4-1.5%]; p < 0.001) and among a low-risk subgroup (RD=+1.0; [95% CI: 0.4-1.6; p = 0.002), but not by instrumental variable analysis (RD=+0.9 [95% CI: -1.1 to 2.9%]; p = 0.362). The TEE group demonstrated a longer length of hospitalization by multiple linear regression, overall (+2.0%; [95% CI: 1.1-2.9%]; p < 0.001), among a low-risk subgroup (+2.2%; [95% CI: 1.2-3.2%]; p < 0.001), and by instrumental variable analysis (+10.3%; [95% CI: 7.0-13.7%]; p < 0.001). CONCLUSIONS: TEE monitoring in CABG surgery was not associated with a lower incidence of acute kidney injury or decreased length of hospitalization. These findings highlight the importance of additional work to study the clinical effectiveness of TEE in CABG surgery.

The Effect of Sedation on Long-Term Psychological Impairment After Extracorporeal Life Support.

OBJECTIVE: This retrospective study aimed to identify the association between long-term psychological impairment and total sedation received during venovenous extracorporeal life support (VV-ECLS) for acute respiratory failure (ARF). DESIGN: This observational retrospective study compared characteristics between patients with and without long-term psychological morbidity at long-term follow-up after VV-ECLS for ARF. SETTING: A single institutional experience in a quaternary referral academic medical center in the United States. PATIENTS: Patients who received VV-ECLS for ARF between January 1, 2015, and April 1, 2017, were identified for selection. Presence of psychiatric morbidity (anxiety and/or depression) was determined with the Hospital Anxiety and Depression Subscale battery at long-term follow-up. INTERVENTIONS: No interventions were made during this retrospective observational study. MEASUREMENTS AND MAIN RESULTS: A total of 42 patients (21 male, 21 female, median age 49 [interquartile range {IQR} 36-57]) completed a telephone interview a median of 14.6 (IQR 7.7-21.1) months after ECLS decannulation. Cohorts were defined as possessing any psychiatric morbidity (anxiety and/or depression) as defined by the Hospital Anxiety and Depression Subscale battery (n = 22 [52%]) versus no psychiatric morbidity (n = 20 [48%]) at long-term follow-up. Patients who had clinically significant psychiatric morbidity received a median of 15.0 (IQR 11.0-17.0) days of continuous intravenous sedation compared with patients who had no psychiatric morbidity, who received a median of 10.0 (IQR 6.5-13.5) days of intravenous sedation; (p = 0.02). CONCLUSIONS: This retrospective analysis identified a significant association between the presence of long-term post-VV-ECLS psychiatric symptoms and the total number of days of intravenous sedation.

A Case Series of Devastating Intracranial Hemorrhage During Venovenous Extracorporeal Membrane Oxygenation for COVID-19.

OBJECTIVE: Anticoagulation may be a challenge in coronavirus disease 2019 (COVID-19) extracorporeal membrane oxygenation due to endothelial injury and dysregulation of coagulation, which may increase the risk of thrombotic and bleeding complications. This report was created to describe the authors' single institutional experience, with emphasis on the high rate of intracranial hemorrhage for the first 10 patients with COVID-19 placed on venovenous extracorporeal membrane oxygenation (VV ECMO). DESIGN: Case series, retrospective analysis. SETTING: Single institution. PARTICIPANTS: Ten patients. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: Patient characteristics, mortality, stroke rate, and length of stay data were collected in all patients. In addition, laboratory values of D-dimer and C-reactive protein and standard measurements of prothrombin and activated partial thromboplastin time were collected on all patients. Ten patients, each confirmed with COVID-19 via reverse transcription-polymerase chain reaction, were supported on VV ECMO for acute respiratory distress syndrome (ARDS) for a mean duration of 9.4 ± 7 days. Four of 10 patients had hemorrhagic strokes, 3 of which resulted in death. At 30 days after initiation of VV ECMO, a total of 7 survivors included 6 patients discharged from the hospital and 1 patient who remained in the intensive care unit. CONCLUSIONS: In this small study of 10 patients, intracranial hemorrhage was a common complication, resulting in a high rate of death. The authors urge caution in the anticoagulation management of VV ECMO for patients with severe ARDS and COVID-19 patients. Close monitoring of all hematologic parameters is recommended during ECMO support while awaiting larger, multicenter studies to examine the best practice.

Surgical training in the midst of a pandemic: a distributed general surgery residency program's response to COVID-19.

Summary: The coronavirus disease 2019 (COVID-19) pandemic has had a substantial impact on surgical training. We describe some of the challenges brought on by the pandemic and our program's province-wide response to them. We focus specifically on residents' provision of service, education and wellness.

Acute Respiratory Failure Managed via Inter-Facility Transport for Extracorporeal Life Support: A 3-Year Experience.

OBJECTIVES: The objectives of this study were as follows: (1) to describe a successful design for a mobile lung rescue program, focusing on challenges and resources required to support such a program, and (2) report short-term outcomes for patients placed on venovenous extracorporeal life support (VV-ECLS) by a transferring team before inter-facility transport to a specialized extracorporeal life support (ECLS) center. DESIGN: This retrospective review and analysis used patient chart review to collect outcomes data and resource demand. SETTING: A single institutional experience in an academic center in the United States. PARTICIPANTS: Patient selection targeted the 75 patients who were placed on VV-ECLS for acute respiratory failure at an outside institution by the authors' team before transport from January 1, 2015, through December 31, 2017. INTERVENTIONS: No intervention was made. MEASUREMENTS AND MAIN RESULTS: Average time for dispatch and transfer was 4 hours and 10 minutes for ground and 3 hours and 30 minutes for air transport (p = 0.029). Demand was highest in winter, with 61% (46/75) of patients presenting from November through April, and daytime, with 73% (55/75) occurring from 8 am to 8 pm. Demand increased during the study period, with 21 patients in 2015, 24 in 2016, and 30 in 2017. Mortality was low, with 72% of patients surviving to discharge. CONCLUSIONS: Herein a successful mobile lung rescue program for transfer to a regional ECLS center is described. These findings demonstrate bed availability during high census and presence of a physician for duration of transport. These challenges can be overcome and successful implementation can be made with low mortality, supporting the development of regional ECLS centers.

Practice Pattern Variation in the Use of Transesophageal Echocardiography for Open Valve Cardiac Surgery.

OBJECTIVE: The authors sought to assess for the presence of practice variation in the use of intraoperative transesophageal echocardiography (TEE) for open cardiac valve surgery. DESIGN: This study was a retrospective cohort analysis. SETTING: The administrative claims data used for this investigation were multi-institutional and a representative sample of commercially insured patients in the United States between 2010 and 2015. PARTICIPANTS: The cohort consisted of adult patients, aged 18 years or older, undergoing open mitral valve (MV) or aortic valve (AV) surgery. INTERVENTIONS: This was an observational analysis without interventions. MEASUREMENTS AND MAIN RESULTS: Of 19,386 valve surgeries, 12,313 (64%) underwent AV replacement, 6,192 (32%) underwent MV repair or replacement, and 881 (<5%) underwent both MV and AV surgery. The overall rate of intraoperative TEE was 82% (95% confidence interval [CI]: 81%-82%), less frequently observed in AV procedures compared to MV or combined MV-AV procedures (80% v 85%, p < 0.001). Rates of intraoperative TEE claims varied markedly across U.S. states. After adjustment, the relative odds of an intraoperative TEE claim ranged across states from 0.26 (Louisiana, 95% CI: 0.18-0.36; p < 0.001) to 2.10 (North Carolina, 95% CI: 1.57-2.82; p < 0.001). CONCLUSION: Among adult patients undergoing open AV or MV surgery in the United States, 82% had a claim for an intraoperative TEE with marked variability across U.S. states. Increasing adherence to intraoperative TEE guidelines for valve surgery may represent an unrecognized opportunity to improve the quality of cardiac surgical care.

Venovenous Extracorporeal Membrane Oxygenation for Patients With Return of Spontaneous Circulation After Cardiac Arrest Owing to Acute Respiratory Distress Syndrome.

OBJECTIVE: The primary objective of this study was to determine the survival to hospital discharge of patients who were treated with venovenous (VV) extracorporeal membrane oxygenation (ECMO) for respiratory failure after cardiac arrest. DESIGN: Retrospective chart review. SETTING: University-affiliated tertiary care hospitals. PARTICIPANTS: The study comprised 21 patients. INTERVENTIONS: Implementation of VV ECMO in patients with return of spontaneous circulation after cardiac arrest owing to respiratory insufficiency. MEASUREMENTS AND MAIN RESULTS: The most common etiology of arrest was pneumonia-associated acute respiratory distress syndrome (8/21 [38%]). Overall, 12/21(57%) patients survived to hospital discharge. Two of 12 (17%) patients required hemodialysis upon discharge. CONCLUSION: VV ECMO may be an appropriate alternative to venoarterial ECMO in select patients with return of spontaneous circulation after cardiac arrest owing to profound respiratory failure.

Aortic Regurgitation in Acute Type-A Aortic Dissection: A Clinical Classification for the Perioperative Echocardiographer in the Era of the Functional Aortic Annulus.

The functional aortic annulus offers a clinical approach for the perioperative echocardiographer to classify the mechanisms of aortic regurgitation in acute type-A dissection. Comprehensive examination of the functional aortic annulus in this setting using transesophageal echocardiography can guide surgical therapy for the aortic root by considering the following important aspects: severity and mechanism of aortic regurgitation, extent of root dissection, and the pattern of coronary artery involvement. The final choice of surgical therapy also should take into account factors, such as patient presentation and surgical experience, to limit mortality and morbidity from this challenging acute aortic syndrome. This review explores these concepts in detail within the framework of the functional aortic annulus, detailed anatomic considerations, and the latest literature.

Abnormal Calcium Levels During Trauma Resuscitation Are Associated With Increased Mortality, Increased Blood Product Use, and Greater Hospital Resource Consumption: A Pilot Investigation.

BACKGROUND: Admission hypocalcemia predicts both massive transfusion and mortality in severely injured patients. However, the effect of calcium derangements during resuscitation remains unexplored. We hypothesize that any hypocalcemia or hypercalcemia (either primary or from overcorrection) in the first 24 hours after severe injury is associated with increased mortality. METHODS: All patients at our institution with massive transfusion protocol activation from January 2013 through December 2014 were identified. Patients transferred from another hospital, those not transfused, those with no ionized calcium (Ca) measured, and those who expired in the trauma bay were excluded. Hypocalcemia and hypercalcemia were defined as any level outside the normal range of Ca at our institution (1-1.25 mmol/L). Receiver operator curve analysis was also used to further examine significant thresholds for both hypocalcemia and hypercalcemia. Hospital mortality was compared between groups. Secondary outcomes included advanced cardiovascular life support, damage control surgery, ventilator days, and intensive care unit days. RESULTS: The massive transfusion protocol was activated for 77 patients of whom 36 were excluded leaving 41 for analysis. Hypocalcemia occurred in 35 (85%) patients and hypercalcemia occurred in 9 (22%). Mortality was no different in hypocalcemia versus no hypocalcemia (29% vs 0%; P = .13) but was greater in hypercalcemia versus no hypercalcemia (78% vs 9%; P < .01). Receiver operator curve analysis identified inflection points in mortality outside a Ca range of 0.84 to 1.30 mmol/L. Using these extreme values, 15 (37%) had hypocalcemia with a 60% mortality (vs 4%; P < .01) and 9 (22%) had hypercalcemia with a 78% mortality (vs 9%; P < .01). Patients with extreme hypocalcemia and hypercalcemia also received more red blood cells, plasma, platelets, and calcium repletion. CONCLUSIONS: Hypocalcemia and hypercalcemia occur commonly during the initial resuscitation of severely injured patients. Mild hypocalcemia may be tolerable, but more extreme hypocalcemia and any hypercalcemia should be avoided. Further assessment to define best practice for calcium management during resuscitation is warranted.

Electron-Catalyzed Fluoroalkylation of Vinyl Azides.

The transition-metal free fluoroalkylation of vinyl azides is herein reported. This operationally simple reaction employs the Togni reagent as a CF3 source, Bu4 NI as an initiator, and occurs under electron catalysis. A range of readily prepared starting materials are functionalized using this approach to produce both phenanthridines and quinoxalin-2-ones.