Investigating Performance of the SLIM-Based High Resolution Ion Mobility Platform for Separation of Isomeric Phosphatidylcholine Species.

Lipids are structurally diverse molecules that play a pivotal role in a plethora of biological processes. However, deciphering the biological roles of the specific lipids is challenging due to the existence of numerous isomers. This high chemical complexity of the lipidome is one of the major challenges in lipidomics research, as the traditional liquid chromatography-mass spectrometry (LC-MS) based approaches are often not powerful enough to resolve these isomeric and isobaric nuances within complex samples. Thus, lipids are uniquely suited to the benefits provided by multidimensional liquid chromatography-ion mobility-mass spectrometry (LC-IM-MS) analysis. However, many forms of lipid isomerism, including double-bond positional isomers and regioisomers, are structurally similar such that their collision cross section (CCS) differences are unresolvable via conventional IM approaches. Here we evaluate the performance of a high resolution ion mobility (HRIM) system based on structures for lossless ion manipulation (SLIM) technology interfaced to a high resolution quadrupole time-of-flight (QTOF) analyzer to address the noted lipidomic isomerism challenge. SLIM implements the traveling wave ion mobility technique along an ∼13 m ion path, providing longer path lengths to enable improved separation of isomeric features. We demonstrate the power of HRIM-MS to dissect isomeric PC standards differing only in double bond (DB) and stereospecific number (SN) positions. The partial separation of protonated DB isomers is significantly enhanced when they are analyzed as metal adducts. For sodium adducts, we achieve close to baseline separation of three different PC 18:1/18:1 isomers with different cis-double bond locations. Similarly, PC 18:1/18:1 (cis-9) can be resolved from the corresponding PC 18:1/18:1 (trans-9) form. The separation capacity is further enhanced when using silver ion doping, enabling the baseline separation of regioisomers that cannot be resolved when measured as sodium adducts. The sensitivity and reproducibility of the approach were assessed, and the performance for more complex mixtures was benchmarked by identifying PC isomers in total brain and liver lipid extracts.

Delirium and its association with short-term outcomes in younger and older patients with acute heart failure.

Younger patients (18 to 65 years old) are often excluded from delirium outcome studies. We sought to determine if delirium was associated with short-term adverse outcomes in a diverse cohort of younger and older patients with acute heart failure (AHF). We conducted a multi-center prospective cohort study that included adult emergency department patients with confirmed AHF. Delirium was ascertained using the Brief Confusion Assessment Method (bCAM). The primary outcome was a composite outcome of 30-day all-cause death, 30-day all-cause rehospitalization, and prolonged index hospital length of stay. Multivariable logistic regression was performed, adjusting for demographics, cognitive impairment without delirium, and HF risk factors. Older age (≥ 65 years old)*delirium interaction was also incorporated into the model. Odds ratios (OR) with their 95% confidence intervals (95%CI) were reported. A total of 1044 patients with AHF were enrolled; 617 AHF patients were < 65 years old and 427 AHF patients were ≥ 65 years old, and 47 (7.6%) and 40 (9.4%) patients were delirious at enrollment, respectively. Delirium was significantly associated with the composite outcome (adjusted OR = 1.64, 95%CI: 1.02 to 2.64). The older age*delirium interaction p-value was 0.47. In conclusion, delirium was common in both younger and older patients with AHF and was associated with poorer short-term outcomes in both cohorts. Younger patients with acute heart failure should be included in future delirium outcome studies.

Association of Physician Coordination With Interfacility Transfer Acceptance Timeliness.

Objectives: Interfacility transfer for time-sensitive emergencies involves rapid and complex care transitions between facilities. We sought to validate relational coordination, a 7-dimension measure of coordination in which a higher score reflects higher-quality coordination, to examine how the quality of coordination affects timeliness in an emergency care setting. Study Design: Retrospective observational cohort design. Methods: We used a novel method to examine how the quality of coordination between physicians at the time of transfer affects timeliness of physician acceptance. We recorded physician-to-physician conversations from the transfer of patients with ST-segment elevation myocardial infarction (STEMI), a time-sensitive emergency requiring immediate intervention to prevent morbidity and mortality. Results: We identified 81 patients experiencing STEMI who were transferred between August 1, 2016, and March 31, 2018. Descriptive statistics, interrater reliability (Spearman correlation coefficients), and generalized linear models were used to examine the association between relational coordination and the physician time-to-acceptance duration. Median (IQR) relational coordination score was 445 (403-493) of a maximum of 700, and median (IQR) time to acceptance was 90.4 (60.2-140.8) seconds. Agreement between abstractors was high (ρ = 0.76). There was a significant, negative relationship between relational coordination and time to acceptance (ρ = -0.38; P < .001). Every 40-point increase in relational coordination was associated with a 25% reduction in time to acceptance. Conclusions: Relational coordination not only demonstrated high interrater reliability, but we also found that higher-quality coordination was associated with faster physician acceptance during time-sensitive transfers. Use of such measures may provide a mechanism to improve the quality of care and outcomes for patients with STEMI who experience interfacility transfers.

Masked Multiplexed Separations to Enhance Duty Cycle for Structures for Lossless Ion Manipulations.

The experimental paradigm of one ion packet release per spectrum severely hinders throughput in broadband ion mobility spectrometry (IMS) systems (e.g., drift tube and traveling wave systems). Ion trapping marginally mitigates this problem, but the duty cycle deficit is amplified when moving to high resolution, long pathlength systems. As a consequence, new multiplexing strategies that maximize throughput while preserving peak fidelity are essential for high-resolution IMS separations [e.g., structures for lossless ion manipulations (SLIMs) and multi-pass technologies]. Currently, broadly applicable deconvolution strategies for Hadamard-based ion multiplexing are limited to a narrow range of modulation sequences and do not fully maximize the ion signal generated during separation across an extended path length. Compared to prior Hadamard deconvolution errors that rely upon peak picking or discrete error classification, the masked deconvolution matrix technique exploits the knowledge that Hadamard transform artifacts are reflected about the central, primary signal [i.e., the true arrival time distribution (ATD)]. By randomly inducing mathematical artifacts, it is possible to identify spectral artifacts simply by their high degree of variability relative to the core ATD. It is important to note that the deweighting approach using the masked deconvolution matrix does not make any assumptions about the underlying transform and is applicable to any multiplexing strategy employing binary sequences. In addition to demonstrating a 100-fold increase in the total number of ions detected, the effective deconvolution of data from 5, 6, 7, and 8-bit pseudo-random sequences expands the utility and efficiency of the SLIM platform.

Examining the Timeliness of ST-elevation Myocardial Infarction Transfers.

INTRODUCTION: Despite large-scale quality improvement initiatives, substantial proportions of patients with ST-elevation myocardial infarction (STEMI) transferred to percutaneous coronary intervention centers do not receive percutaneous coronary intervention within the recommended 120 minutes. We sought to examine the contributory role of emergency medical services (EMS) activation relative to percutaneous coronary intervention center activation in the timeliness of care for patients transferred with STEMI. METHODS: We conducted a retrospective analysis of interfacility transfers from emergency departments (ED) to a single percutaneous coronary intervention center between 2011-2014. We included emergency department (ED) patients transferred to the percutaneous coronary intervention center and excluded scene transfers and those given fibrinolytics. We calculated descriptive statistics and used multivariable linear regression to model the association of variables with ED time intervals (arrival to electrocardiogram [ECG], ECG-to-EMS activation, and ECG-to-STEMI alert) adjusting for patient age, gender, mode of arrival, weekday hour presentation, facility transfers in the past year, and transferring facility distance. RESULTS: We identified 159 patients who met inclusion criteria. Subjects were a mean of 59 years old (standard deviation 13), 22% female, and 93% White; 59% arrived by private vehicle, and 24% presented after weekday hours. EDs transferred a median of 9 STEMIs (interquartile range [IQR] 3, 15) in the past year and a median of 65 miles (IQR 35, 90) from the percutaneous coronary intervention center. Median ED length of stay was 65 minutes (IQR 51, 85). Among component intervals, arrival to ECG was 6%, ECG-to-EMS activation 32%, and ECG-to-STEMI alert was 49% of overall ED length of stay. Only 18% of transfers had EMS activation earlier than STEMI alert. ECG-to-EMS activation was shorter in EDs achieving length of stay ≤60 minutes compared to those >60 minutes (12 vs 31 minutes, P<0.001). Multivariable modeling showed that after-hours presentation was associated with longer ECG-to-EMS activation (adjusted relative risk [RR] 1.05, P<0.001). Female gender (adjusted RR 0.81, P<0.001), prior facility transfers (adjusted RR 0.84, P<0.001), and initial ambulance presentation (adjusted RR 0.93, P = 0.02) were associated with shorter ECG-to-EMS activation. CONCLUSION: In STEMI transfers, faster EMS activation was more likely to achieve a shorter ED length of stay than a rapid, percutaneous coronary intervention center STEMI alert. Large-scale quality improvement efforts such as the American Heart Association's Mission Lifeline that were designed to regionalize STEMI have improved the timeliness of reperfusion, but major gaps, particularly in interfacility transfers, remain. While the transferring EDs are recognized as the primary source of delay during interfacility STEMI transfers, the contributions to delays at transferring EDs remain poorly understood.

High-Resolution Ion-Mobility-Enabled Peptide Mapping for High-Throughput Critical Quality Attribute Monitoring.

Characterization and monitoring of post-translational modifications (PTMs) by peptide mapping is a ubiquitous assay in biopharmaceutical characterization. Often, this assay is coupled to reversed-phase liquid chromatographic (LC) separations that require long gradients to identify all components of the protein digest and resolve critical modifications for relative quantitation. Incorporating ion mobility (IM) as an orthogonal separation that relies on peptide structure can supplement the LC separation by providing an additional differentiation filter to resolve isobaric peptides, potentially reducing ambiguity in identification through mobility-aligned fragmentation and helping to reduce the run time of peptide mapping assays. A next-generation high-resolution ion mobility (HRIM) technique, based on structures for lossless ion manipulations (SLIM) technology with a 13 m ion path, provides peak capacities and higher resolving power that rivals traditional chromatographic separations and, owing to its ability to resolve isobaric peptides that coelute in faster chromatographic methods, allows for up to 3× shorter run times than conventional peptide mapping methods. In this study, the NIST monoclonal antibody IgG1κ (NIST RM 8671, NISTmAb) was characterized by LC-HRIM-MS and LC-HRIM-MS with collision-induced dissociation (HRIM-CID-MS) using a 20 min analytical method. This approach delivered a sequence coverage of 96.5%. LC-HRIM-CID-MS experiments provided additional confidence in sequence determination. HRIM-MS resolved critical oxidations, deamidations, and isomerizations that coelute with their native counterparts in the chromatographic dimension. Finally, quantitative measurements of % modification were made using only the m/z-extracted HRIM arrival time distributions, showing good agreement with the reference liquid-phase separation. This study shows, for the first time, the analytical capability of HRIM using SLIM technology for enhancing peptide mapping workflows relevant to biopharmaceutical characterization.

Resolving Power and Collision Cross Section Measurement Accuracy of a Prototype High-Resolution Ion Mobility Platform Incorporating Structures for Lossless Ion Manipulation.

A production prototype structures for lossless ion manipulation ion mobility (SLIM IM) platform interfaced to a commercial high-resolution mass spectrometer (MS) is described. The SLIM IM implements the traveling wave ion mobility technique across a ∼13m path length for high-resolution IM (HRIM) separations. The resolving power (CCS/ΔCCS) of the SLIM IM stage was benchmarked across various parameters (traveling wave speeds, amplitudes, and waveforms), and results indicated that resolving powers in excess of 200 can be accessed for a broad range of masses. For several cases, resolving powers greater than 300 were achieved, notably under wave conditions where ions transition from a nonselective "surfing" motion to a mobility-selective ion drift, that corresponded to ion speeds approximately 30-70% of the traveling wave speed. The separation capabilities were evaluated on a series of isomeric and isobaric compounds that cannot be resolved by MS alone, including reversed-sequence peptides (SDGRG and GRGDS), triglyceride double-bond positional isomers (TG 3, 6, 9 and TG 6, 9, 12), trisaccharides (melezitose, raffinose, isomaltotriose, and maltotriose), and ganglioside lipids (GD1b and GD1a). The SLIM IM platform resolved the corresponding isomeric mixtures, which were unresolvable using the standard resolution of a drift-tube instrument (∼50). In general, the SLIM IM-MS platform is capable of resolving peaks separated by as little as ∼0.6% without the need to target a specific separation window or drift time. Low CCS measurement biases <0.5% were obtained under high resolving power conditions. Importantly, all the analytes surveyed are able to access high-resolution conditions (>200), demonstrating that this instrument is well-suited for broadband HRIM separations important in global untargeted applications.

High-defined quantitative snapshots of the ganglioside lipidome using high resolution ion mobility SLIM assisted shotgun lipidomics.

Defects in sphingolipid metabolism have emerged as a common link across neurodegenerative disorders, and a deeper understanding of the lipid content in preclinical models and patient specimens offers opportunities for development of new therapeutic targets and biomarkers. Sphingolipid metabolic pathways include the formation of glycosphingolipid species that branch into staggeringly complex structural heterogeneity within the globoside and ganglioside sub-lipidomes. Characterization of these sub-lipidomes has typically relied on liquid chromatography-mass spectrometry-based (LC-MS) approaches, but such assays are challenging and resource intensive due to the close structural heterogeneity, the presence of isobaric and isomeric species, and broad dynamic range of endogenous glycosphingolipids. Here, we apply Structures for Lossless Ion Manipulations (SLIM)-based High Resolution Ion Mobility (HRIM)-MS to enable rapid, repeatable, quantitative assays with deep structural information sufficient to resolve endogenous brain gangliosides at the level of individual molecular species. Analyses were performed using a prototype SLIM-MS instrument equipped with a 13-m serpentine path which enabled resolution of closely related isomeric analytes such as GD1a d36:1 and GD1b d36:1 based on recorded mass-to-charge (m/z) and arrival times. To demonstrate the power of our methodology, brain extracts derived from wild-type mice hemi-brains were analyzed by HRIM-MS using flow injection analyses (FIA) without the need for additional separation by liquid chromatography. Endogenous ganglioside species were readily resolved, identified, and quantified by FIA-SLIM-MS analyses within 2 min per sample. Thus, the FIA-SLIM-MS platform enables robust quantification across a broad range of lipid species in biological specimens in a standardized assay format that is readily scalable to support studies with large sample numbers.

Effect of a Self-care Intervention on 90-Day Outcomes in Patients With Acute Heart Failure Discharged From the Emergency Department: A Randomized Clinical Trial.

Importance: Up to 20% of patients who present to the emergency department (ED) with acute heart failure (AHF) are discharged without hospitalization. Compared with rates in hospitalized patients, readmission and mortality are worse for ED patients. Objective: To assess the impact of a self-care intervention on 90-day outcomes in patients with AHF who are discharged from the ED. Design, Setting, and Participants: Get With the Guidelines in Emergency Department Patients With Heart Failure was an unblinded, parallel-group, multicenter randomized trial. Patients were randomized 1:1 to usual care vs a tailored self-care intervention. Patients with AHF discharged after ED-based management at 15 geographically diverse EDs were included. The trial was conducted from October 28, 2015, to September 5, 2019. Interventions: Home visit within 7 days of discharge and twice-monthly telephone-based self-care coaching for 3 months. Main Outcomes and Measures: The primary outcome was a global rank of cardiovascular death, HF-related events (unscheduled clinic visit due to HF, ED revisit, or hospitalization), and changes in the Kansas City Cardiomyopathy Questionnaire-12 (KCCQ-12) summary score (SS) at 90 days. Key secondary outcomes included the global rank outcome at 30 days and changes in the KCCQ-12 SS score at 30 and 90 days. Intention-to-treat analysis was performed for the primary, secondary, and safety outcomes. Per-protocol analysis was conducted including patients who completed a home visit and had scheduled outpatient follow-up in the intervention arm. Results: Owing to slow enrollment, 479 of a planned 700 patients were randomized: 235 to the intervention arm and 244 to the usual care arm. The median age was 63.0 years (interquartile range, 54.7-70.2), 302 patients (63%) were African American, 305 patients (64%) were men, and 178 patients (37%) had a previous ejection fraction greater than 50%. There was no significant difference in the primary outcome between patients in the intervention vs usual care arm (hazard ratio [HR], 0.89; 95% CI, 0.73-1.10; P = .28). At day 30, patients in the intervention arm had significantly better global rank (HR, 0.80; 95% CI, 0.64-0.99; P = .04) and a 5.5-point higher KCCQ-12 SS (95% CI, 1.3-9.7; P = .01), while at day 90, the KCCQ-12 SS was 2.7 points higher (95% CI, -1.9 to 7.2; P = .25). Conclusions and Relevance: The self-care intervention did not improve the primary global rank outcome at 90 days in this trial. However, benefit was observed in the global rank and KCCQ-12 SS at 30 days, suggesting that an early benefit of a tailored self-care program initiated at an ED visit for AHF was not sustained through 90 days. Trial Registration: ClinicalTrials.gov Identifier: NCT02519283.

Breaking down walls: a qualitative evaluation of perceived emergency department delays for patients transferred with ST-elevation myocardial infarction.

BACKGROUND: Despite regionalization efforts, delays at transferring hospitals for patients transferred with ST-elevation myocardial infarction (STEMI) for primary percutaneous coronary intervention (PCI) persist. These delays primarily occur in the emergency department (ED), and are associated with increased mortality. We sought to use qualitative methods to understand staff and clinician perceptions underlying these delays. METHODS: We conducted semi-structured interviews at 3 EDs that routinely transfer STEMI patients to identify staff perceptions of delays and potential interventions. Interviews were recorded, transcribed, coded, and analyzed using an iterative inductive-deductive approach to build and refine a list of themes and subthemes, and identify supporting quotes. RESULTS: We interviewed 43 ED staff (staff, nurses, and physicians) and identified 3 major themes influencing inter-facility transfers of STEMI patients: 1) Processes, 2) Communication; and 3) Resources. Standardized processes (i.e., protocols) reduce uncertainty and can mobilize resources. Use of performance benchmarks can motivate staff but are frequently focused on internal, not inter-organizational performance. Direct use ofcommunication between ORGANIZATIONS can process uncertainty and expedite care. Record sharing and regular post-transfer communication could provide opportunities to discuss and learn from delays and increase professional satisfaction. Finally, characteristics of resources that enhanced their capacity, clarity, experience, and reliability were identified as contributing to timely transfers. CONCLUSIONS: Processes, communication, and resources were identified as modifying inter-facility transfer timeliness. Potential quality improvement strategies include ongoing updates of protocols within and between organizations to account for changes, enhanced post-transfer feedback between organizations, shared medical records, and designated roles for coordination.

The AFFORD clinical decision aid to identify emergency department patients with atrial fibrillation at low risk for 30-day adverse events.

There is wide variation in the management of patients with atrial fibrillation (AF) in the emergency department (ED). We aimed to derive and internally validate the first prospective, ED-based clinical decision aid to identify patients with AF at low risk for 30-day adverse events. We performed a prospective cohort study at a university-affiliated tertiary-care ED. Patients were enrolled from June 9, 2010, to February 28, 2013, and followed for 30 days. We enrolled a convenience sample of patients in ED presenting with symptomatic AF. Candidate predictors were based on ED data available in the first 2 hours. The decision aid was derived using model approximation (preconditioning) followed by strong bootstrap internal validation. We used an ordinal outcome hierarchy defined as the incidence of the most severe adverse event within 30 days of the ED evaluation. Of 497 patients enrolled, stroke and AF-related death occurred in 13 (3%) and 4 (<1%) patients, respectively. The decision aid included the following: age, triage vitals (systolic blood pressure, temperature, respiratory rate, oxygen saturation, supplemental oxygen requirement), medical history (heart failure, home sotalol use, previous percutaneous coronary intervention, electrical cardioversion, cardiac ablation, frequency of AF symptoms), and ED data (2 hours heart rate, chest radiograph results, hemoglobin, creatinine, and brain natriuretic peptide). The decision aid's c-statistic in predicting any 30-day adverse event was 0.7 (95% confidence interval 0.65, 0.76). In conclusion, in patients with AF in the ED, Atrial Fibrillation and Flutter Outcome Risk Determination provides the first evidence-based decision aid for identifying patients who are at low risk for 30-day adverse events and candidates for safe discharge.

Atrial fibrillation and flutter outcomes and risk determination (AFFORD): design and rationale.

BACKGROUND: Atrial fibrillation (AF) is the most common sustained arrhythmia affecting over 700,000 individuals in Japan and 2.2 million in the USA. The proper management of patients with AF is critical due to the well-documented association with heart failure and stroke. A strategy to better define the emergency department (ED) management, admission decisions, and spectrum of risk from low to high is needed. METHODS AND SUBJECTS: The atrial fibrillation and flutter outcomes and risk determination investigation is a prospective, observational cohort study to develop a multivariable clinical prediction rule that accurately estimates risk for adverse outcomes in patients presenting to the ED with symptomatic AF. We will enroll 430 patients at 2 sites who present to the ED with symptomatic AF defined as a new or established diagnosis of AF or atrial flutter that require ED evaluation for a complaint thought related to their rhythm disturbance. The study's endpoint is to develop an accurate, objective, internally validated, reliable clinical prediction rule to risk-stratify ED patients presenting with AF exacerbations. The rule will incorporate patient history and examination findings and laboratory studies obtained upon ED presentation, as well as trends over the first 2 h of care. This investigation's primary outcome is the incidence of any AF-related adverse event at 5 days and 30 days. We expect to complete the study by the end of 2014. The study was registered at Clinicaltrials.gov NCT01138644.