Background: There is still room for improvement in the modified LEMON (look, evaluate, Mallampati, obstruction, neck mobility) criteria for difficult airway prediction and no prediction tool for first-pass success in the emergency department (ED). Objective: We applied modern machine learning approaches to predict difficult airways and first-pass success. Methods: In a multicenter prospective study that enrolled consecutive patients who underwent tracheal intubation in 13 EDs, we developed 7 machine learning models (eg, random forest model) using routinely collected data (eg, demographics, initial airway assessment). The outcomes were difficult airway and first-pass success. Model performance was evaluated using c-statistics, calibration slopes, and association measures (eg, sensitivity) in the test set (randomly selected 20% of the data). Their performance was compared with the modified LEMON criteria for difficult airway success and a logistic regression model for first-pass success. Results: Of 10,741 patients who underwent intubation, 543 patients (5.1%) had a difficult airway, and 7690 patients (71.6%) had first-pass success. In predicting a difficult airway, machine learning models—except for k-point nearest neighbor and multilayer perceptron—had higher discrimination ability than the modified LEMON criteria (all, P≤.001). For example, the ensemble method had the highest c-statistic (0.74 vs 0.62 with the modified LEMON criteria; P<.001). Machine learning models—except k-point nearest neighbor and random forest models—had higher discrimination ability for first-pass success. In particular, the ensemble model had the highest c-statistic (0.81 vs 0.76 with the reference regression; P<.001). Conclusions: Machine learning models demonstrated greater ability for predicting difficult airway and first-pass success in the ED.

Background and purpose While extracranial carotid artery stenosis is more common among Caucasians and intracranial artery stenosis is more common among Asians, the differences in atherosclerotic plaque characteristics have not yet been extensively examined. We sought to investigate plaque location and characteristics within extracranial carotid and intracranial arteries in symptomatic Caucasians and Chinese using vessel wall MRI. Methods Subjects with recent anterior circulation ischaemic stroke were recruited and imaged at two sites in the USA and China using similar protocols. Both extracranial carotid and intracranial arteries were reviewed to determine plaque location and characteristics. Results The prevalence of extracranial carotid plaque in Caucasians and Chinese was 73.1% and 49.1%, respectively (p=0.055). Prevalence of intracranial plaque was 38.5% and 69.1% in Caucasians and Chinese, respectively (p=0.02). Furthermore, 42% of Caucasians and 16% of Chinese had high-risk plaque (HRP) features (intraplaque haemorrhage, luminal surface disruption) in the extracranial carotid artery (p=0.03). The prevalence of HRP features in intracranial arteries was not significantly different between the two cohorts (4% vs 11%; p=0.42). Conclusions Differences in the location and characteristics of cerebrovascular atherosclerosis were identified by vessel wall MRI in US Caucasian and Chinese subjects with recent anterior circulation ischaemic stroke. Extracranial carotid plaques with HRP features were more common in Caucasians. Intracranial plaques were more common in Chinese subjects, but no significant difference between the two cohorts in intracranial HRP prevalence was found. Larger studies using vessel wall imaging to investigate racial differences in cerebrovascular disease may inform underlying mechanisms of HRP development and may ultimately help guide appropriate therapy.

Background and purpose Atherosclerosis is a very complex process influenced by various systemic and local factors. Therefore, in patients with bilateral carotid plaques (BCPs), there may be differences in carotid plaque vulnerability between the sides. We aimed to investigate the differences in BCP characteristics in patients with BCPs using magnetic resonance vessel wall imaging (MR-VWI). Methods Participants with BCPs were selected for subanalysis from a multicentre study of Chinese Atherosclerosis Risk Evaluation II. We measured carotid plaque burden, identified each plaque component and measured their volume or area bilaterally on MR-VWI. Paired comparisons of the burden and components of BCPs were performed. Results In all, 540 patients with BCPs were eligible for analysis. Compared with the right carotid artery (CA), larger mean lumen area (p<0.001), larger mean wall area (p=0.025), larger mean total vessel area (p<0.001) and smaller normalised wall index (p=0.006) were found in the left CA. Regarding plaque components, only the prevalence of lipid-rich necrotic core (LRNC) in the left CA was higher (p=0.026). For patients with a vulnerable plaque component coexisting on both sides, only the intraplaque haemorrhage (IPH) volume (p=0.011) was significantly greater in the left CA than in the right CA. Conclusions There were asymmetries in plaque growth and evolution between BCPs. The left carotid plaques were more likely to have larger plaque burden, higher prevalence of LRNC and greater IPH volume, which may contribute to the lateralisation of ischaemic stroke in the cerebral hemispheres.

Although airway management with neuromuscular blockade (NMB) alone is discouraged in the emergency department (ED), our previous study demonstrated that many patients were intubated using NMBs alone without sedatives. To refute this practice, we sought to compare the intubation success and adverse event rates between NMBs only and rapid sequence intubation (RSI). This is a secondary analysis of the data from a prospective observational study of ED patients in 13 hospitals who underwent emergency airway management from April 2010 to August 2012. The primary outcome was intubation success rate on first attempt. The secondary outcomes were the intubation success rate in ≤2 attempts and the intubation-related adverse event rate. We compared these outcomes between intubation attempts using NMB alone and RSI. We fit multivariable logistic regression models adjusting for potential confounders (age, sex, weight, primary indication for intubation, and training level of intubators). Overall, 852 patients were eligible for this analysis, with 114 (13%) intubated with NMB alone and 738 (87%) with RSI. Between the NMB-alone and RSI groups, no significant differences were observed in the success rate on the first attempt (70 vs. 73%; P = 0.48) or in ≤2 attempts (89 vs. 91%; P = 0.46), or in the adverse event rate (11 vs. 12%; P = 0.58). Similarly, after adjusting for confounders, no significant differences were observed in any of these outcomes (all P > 0.05). In this analysis of data from a large multicenter study of ED patients, we found no superior effectiveness of intubation with NMB alone when compared to RSI. Our data lend significant support to the concept that intubation with NMB alone should be avoided in the ED.

Objectives Emergency department (ED) visits for asthma exacerbation reflect a failure of longitudinal asthma management. However, little is known about the characteristics of patients with frequent ED visits (≥2 visits in a 1-year period). We aimed to characterise the adult patients who frequently presented to the ED for asthma exacerbation in Japan. Design A multicentre chart review study of 23 EDs across Japan. Participants Adults aged 18–54 years who presented to the ED with asthma exacerbation from 2009 to 2011. Outcome measures Frequency of ED visits for asthma exacerbation in a 1-year period, including the index ED visit. Results Of the 1002 eligible patients, 218 (22%) had frequent ED visits, accounting for 48% of total ED visits for asthma exacerbation in the 1-year period. Specifically, 12% had 2 ED visits and 10% had ≥3 visits. In these patients, guideline-recommended chronic management was suboptimal. For example, among patients with ≥3 ED visits, only 63% were treated with inhaled corticosteroids and 49% were current smokers. In a multinomial logistic regression model, markers of chronic asthma severity (history of hospitalisation for asthma and use of inhaled corticosteroids) were significantly associated with a higher frequency of ED visits (both p<0.05). Conclusions This multicentre study in Japan demonstrated that many patients are frequent ED users for asthma exacerbation. We also found that their asthma control management is suboptimal, most likely contributing to worse chronic severity and more frequent ED visits. Further dissemination and adoption of evidence-based guidelines are required to reduce asthma morbidity in this high-risk population.