Accurate assessment of the patient’s condition in the emergency department (ED) is critical for individuals with acute myocardial infarction (AMI). In this study, point-of-care ultrasound (PoCUS) was utilized to evaluate ventricular wall motion in AMI patients in the ED, aiming to determine its clinical value in early risk stratification and condition assessment. A retrospective cohort study was conducted by systematically collecting clinical data from patients who presented to the ED, were ultimately diagnosed with AMI, and underwent cardiac PoCUS examinations. A total of 143 AMI patients were enrolled in this study. Among them, 108 patients were identified as having regional wall motion abnormalities (RWMA). The proportions of patients with complete occlusion of the culprit artery, culprit artery thrombolysis in myocardial infarction (TIMI) flow ≤ 2, and culprit artery TIMI flow ≤ 1 were significantly higher in the RWMA group compared to the non-RWMA group. Multivariate logistic regression analysis revealed that complete occlusion of the culprit artery and culprit artery located in the left anterior descending artery (LAD) were independent risk factors for RWMA. Patients with RWMA exhibited a markedly reduced left ventricular ejection fraction and were at an elevated risk for the occurrence of new-onset arrhythmias and acute heart failure. RMWA was closely correlated with both the severity of coronary artery lesions and the incidence of adverse complications in AMI patients. Cardiac PoCUS assessment in the ED helps optimize clinical evaluation and management of AMI patients.

Background: University students are a scalable population for strengthening community first-aid capacity, but evaluations beyond CPR/AED outcomes remain limited. We assessed a general-education first-aid course using knowledge, observed skills, self-efficacy, and readiness-to-act outcomes. Methods: We conducted a repeated-cohort, single-group pre-post evaluation of an undergraduate elective course at Sun Yat-sen University (Guangzhou, China) across 10 consecutive semesters (2021-2025). Outcomes included pre/post theoretical knowledge (0-100), end-of-course four-station OSCE performance rated on a DOPS-based 1-5 scale, self-efficacy (five 1-5 Likert items; composite as mean), and willingness/intention (paired yes/no items). Pre/post changes were analyzed using paired tests appropriate to outcome type. Results: Among 446 undergraduates (51.8% men; 28.0% medical-related majors), knowledge increased from 36.9 (SD 6.5) to 80.9 (SD 4.3) (mean difference 44.0, 95% CI 43.3-44.7; p < 0.001), with consistent gains across all five domains (allp < 0.001). Overall observed skills were satisfactory: the composite OSCE score was 3.52 (SD 0.42) and 77.8% passed all four stations. Station competence rates were 71.7%-80.7%, whereas completion of all critical actions was lower (58.3-74.0%). Self-efficacy increased from 2.3 (SD 0.4) to 4.0 (SD 0.3) (mean difference 1.8, 95% CI 1.7-1.8; p < 0.001). Willingness and intention also improved, including willingness to perform CPR on a stranger, use an AED if available, and prepare a home first-aid kit within 1 month (all p < 0.001). Conclusion: This university general-education first-aid course was associated with substantial end-of-course gains in knowledge, satisfactory observed competence, and improved confidence and readiness to act. These findings support embedding multi-domain first-aid training beyond CPR/AED within university general education as a scalable approach to strengthen community emergency preparedness.

Pyroptosis contributes to activation of the innate immunity system and defense against infection by pathogens. Endotoxemia is the host inflammatory storm occurring in response to severe and life-threatening infections caused by endotoxin from gram-negative bacilli. However, whether pyroptosis is involved in intestinal epithelial cell (IEC) or intestinal stem cell (ISC) injury induced by endotoxemia remains unclear. Mice with NF-κB p65 deletion in IECs (p65IEC − KO) were used to investigate the role of NF-κB-mediated pyroptosis in endotoxemia-induced intestinal injury. Morphology, pyroptosis, permeability, inflammation, endoplasmic reticulum stress in the intestine and survival were evaluated in WT and p65IEC − KO mice. Pyroptosis was found in intestinal epithelial cells of mice treated with lipopolysaccharide (LPS), but was significantly reduced in p65IEC − KO mice. Mice with endotoxemia exhibited morphological alterations in intestinal tissue, with a shortened villus length and crypt depth, increased intestinal permeability, increased inflammatory factors, and reduced survival rate, all of which were markedly improved in p65IEC − KO mice. Importantly, ER stress was found to be downregulated in IECs of p65IEC − KO mice with endotoxemia. Furthermore, the ER stress activator tunicamycin markedly enhanced IEC pyroptosis and aggravated intestinal injury in p65IEC − KO mice with endotoxemia. NF-κB p65–mediated pyroptosis participates in IEC injury in response to endotoxemia via regulation of ER stress. It may provide a potential therapeutic target for protecting against endotoxemia-induced intestinal injury.

IntroductionSimultaneous involvement of the peripheral nervous system (PNS) and central nervous system (CNS) during the same period in diffuse large B-cell lymphoma (DLBCL) is rarely documented. In this particular case, the diagnosis of diffuse large B-cell lymphoma was pathologically confirmed, with invasion into the basal ganglia, diencephalon, and several peripheral nerves. The initial clinical manifestations were dyspnoea and hyperventilation.Case presentationThe patient presented to the hospital with fatigue, dyspnoea, and limb pain for over 7 months, accompanied by progressive breathlessness and unconsciousness in the last 6 days. Initial treatment with glucocorticoids for Guillain-Barre syndrome (GBS) proved ineffective in controlling the severe shortness of breath and hyperventilation, necessitating the use of ventilator-assisted ventilation. 18-Fluorodeoxyglucose positron emission tomography/computed tomography (18FDG PET/CT) showed that the basal ganglia, brainstem, and multiple peripheral nerves were thickened and metabolically active. There were atypical cells in the cerebrospinal fluid; the pathology indicated invasive B-cell lymphoma, demonstrating a propensity toward diffuse large B-cell lymphoma (DLBCL). After receiving chemotherapy, the patient regained consciousness and was successfully weaned off ventilator assistance but died of severe pneumonia.DiscussionThe early clinical manifestations of DLBCL lack specificity, and multifocal DLBCL complicates the diagnostic process. When a single primary disease cannot explain multiple symptoms, the possibility of DLBCL should be considered, and nervous system invasion should be considered when nervous system symptoms are present. Once nervous system involvement occurs in DLBCL, whether the central or peripheral nervous system, it indicates a poor prognosis.

Introduction:Nursing knowledge, critical thinking ability, and self-perceived confidence are imperative to nursing skills in professional nursing practice. Therefore, nurse educators are required to use teaching strategies that will help promote their knowledge, critical thinking, and self-confidence in complex contents such as the nursing of acute upper gastrointestinal bleeding (AUGIB).Purpose:This study compares the effect of student-led and instructor-led ward-round training methods on knowledge acquisition, critical thinking ability, and self-perceived confidence during AUGIB sessions.Methods:Forty nursing students in the first year of the Emergency Nursing Residency Program were randomly divided into a student-led ward round training group (SG) and an instructor-led ward round training group (IG) with a ratio of 1:1. A knowledge quiz, critical thinking ability test, and self-perceived confidence questionnaire were performed before and after the ward round training to assess both groups of students for their knowledge acquisition, critical thinking ability, and self-perceived confidence improvement. Feedback questionnaires were conducted after the training to evaluate students' perspectives and interests concerning the teaching module.Results:The scores of the post-training quiz were significantly higher than that of the pre-training quiz in both the SG (44.10±2.92 vs 31.10±4.27, p<0.001) and IG (32.35±2.21 vs 30.55±2.24, p=0.01). In the post-training quiz, scores achieved by the students from the SG (44.10±2.92) were significantly higher than those achieved by the students from the IG (32.35±2.21, p< 0.001). The level of self-perceived confidence improved significantly after ward round training in the SG (p< 0.001). However, there was no statistically significant difference in the IG with respect to the change from pre- to post-training (p=0.43).The students' critical thinking ability improved significantly in the SG (14.95±2.58 vs 7.10±1.79, p<0.001), while no significant improvement was found in the IG (7.91±2.28 vs 6.52±2.21, p=0.07) after ward round training.Conclusion:The teaching method of SWRT improves nursing students' knowledge acquisition, critical thinking ability, and self-perceived confidence in AUGIB.

Sepsis or endotoxemia can induce intestinal dysfunction in the epithelial and immune barrier. Th17 cells, a distinct subset of CD4+ T-helper cells, act as “border patrol” in the intestine under pathological condition and in the previous studies, Th17 cells exhibited an ambiguous function in intestinal inflammation. Our study will explore a specific role of Th17 cells and its relevant mechanism in endotoxemia-induced intestinal injury. Lipopolysaccharide was used to establish mouse model of endotoxemia. miR-681 was analyzed by RT-PCR and northern blot analysis and its regulation by HIF-1α was determined by chromatin immunoprecipitation and luciferase reporter assay. Intestinal Th17 cells isolated from endotoxemic mice were quantitatively evaluated by flow cytometry and its recruitment to the intestine controlled by miR-681/CCR6 pathway was assessed by using anti-miRNA treatment and CCR6 knockout mice. Intestinal histopathology, villus length, intestinal inflammation, intestinal permeability, bacterial translocation and survival were investigated, by histology and TUNEL analysis, ELISA, measurement of diamine oxidase, bacterial culture, with or without anti-miR-681 treatment in endotoxemic wild-type and (or) CCR6 knockout mice. In this study, we found that miR-681 was significantly promoted in intestinal Th17 cells during endotoxemia, which was dependent on hypoxia-inducible factor-1α (HIF-1α). Interestingly, miR-681 could directly suppress CCR6, which was a critical modulator for Th17 cell recruitment to the intestines. In vivo, anti-miR-681 enhanced survival, increased number of intestinal Th17 cells, reduced crypt and villi apoptosis, decreased intestinal inflammation and bacterial translocation, resulting in protection against endotoxemia-induced intestinal injury in mice. However, CCR6 deficiency could neutralize the beneficial effect of anti-miR-681 on the intestine during endotoxemia, suggesting that the increment of intestinal Th17 cells caused by anti-miR-681 relies on CCR6 expression. The results of the study indicate that control of intestinal Th17 cells by regulating novel miR-681/CCR6 signaling attenuates endotoxemia-induced intestinal injury.

Volumetric 3D reconstruction methods have shown great performance in reconstructing indoor scenarios from monocular videos. However, as such approaches utilize discrete feature voxels to encode the observed scenes, the global feature interaction within and across different voxels is ignored, leading to imperfect reconstructions. To solve this problem, we propose a novel volumetric 3D reconstruction method named VolGARecon. The core portion of VolGARecon includes two parts: first, we use an MLP-based weighted fusion module (WFM) to unproject the extracted features to each voxel, which considers the visibility and is capable to reduce the noise caused by occlusion; second, a 3D transformer module (3DTR) is used to perform window-wise global feature interaction in a local sliding window, which strengthens the feature expression in 3D space and benefits estimating more complete and spatially coherent 3D models. In addition, we propose a multi-dimensional hybrid loss (MHL) that incorporates the 3D supervision in classical volumetric methods and the 2D supervision in novel view synthesis works. Extensive experiments show our method achieves superior performance on multiple datasets.

Introduction The flipped classroom (FC) approach and high-fidelity patient simulation (HFPS) training have shown promising effects in short-term acquisition or long-term retention of knowledge in medical education. In this study, we aimed to explore the incorporation of HFPS into the FC and the impact on the long-term (3 months after classes) knowledge retention of medical undergraduate students learning about acute organophosphorus pesticide poisoning (AOPP). Methods Eighty-two fifth-year medical students were randomly divided into an HFPS group (HG, n = 40) and an FC group (FG, n = 42). A postclass quiz and preinternship quiz were performed to assess the short-term knowledge acquisition and long-term (3 months after classes) knowledge retention of both groups of students. Feedback questionnaires were administered immediately after the class and before the internship to assess the students' self-perceived competency. Results In the postclass quiz, the scores achieved by the students from the HG and FG were 15.58 ± 2.69 and 14.62 ± 2.19, respectively. No significant difference was found between the 2 groups (P = 0.19). In the preinternship quiz, the scores achieved by the students from the HG (14.50 ± 2.16) were significantly higher than those achieved by the students from the FG (11.40 ± 2.07, P < 0.001). There was no significant difference between the postclass quiz and preinternship quiz scores achieved by the HG students (P = 0.05). However, scores in the preinternship quiz showed a significant decline compared with the postclass quiz for the FG students (P < 0.001). Students in the HG gave significantly higher scores for self-perceived confidence in dealing with AOPP patients in the forthcoming internship on the postclass and preinternship questionnaires. Conclusions The incorporation of HFPS into the FC approach could improve students' long-term knowledge retention of AOPP and enhance their confidence in caring for these patients in their internship.

Recently, Transformers were shown to enhance the performance of multi-view stereo by enabling long-range feature interaction. In this work, we propose Window-based Transformers (WT) for local feature matching and global feature aggregation in multi-view stereo. We introduce a Window-based Epipolar Transformer (WET) which reduces matching redundancy by using epipolar constraints. Since point-to-line matching is sensitive to erroneous camera pose and calibration, we match windows near the epipolar lines. A second Shifted WT is employed for aggregating global information within cost volume. We present a novel Cost Transformer (CT) to replace 3D convolutions for cost volume regularization. In order to better constrain the estimated depth maps from multiple views, we further design a novel geometric consistency loss (Geo Loss) which punishes unreliable areas where multi-view consistency is not satisfied. Our WT multi-view stereo method (WT-MVSNet) achieves state-of-the-art performance across multiple datasets and ranks 1^st on Tanks and Temples benchmark.

Bird's eye view (BEV) is widely adopted by most of the current point cloud detectors due to the applicability of well-explored 2D detection techniques. However, existing methods obtain BEV features by simply collapsing voxel or point features along the height dimension, which causes the heavy loss of 3D spatial information. To alleviate the information loss, we propose a novel point cloud detection network based on a Multi-level feature dimensionality reduction strategy, called MDRNet. In MDRNet, the Spatial-aware Dimensionality Reduction (SDR) is designed to dynamically focus on the valuable parts of the object during voxel-to-BEV feature transformation. Furthermore, the Multi-level Spatial Residuals (MSR) is proposed to fuse the multi-level spatial information in the BEV feature maps. Extensive experiments on nuScenes show that the proposed method outperforms the state-of-the-art methods. The code will be available upon publication.

目的 探讨改良以团队为基础的教学(team-based learning,TBL)结合模拟教学的方法对低年级医学生早期临床思维能力培养的效果.方法 采用对照试验的方法,选择2020年秋季学期40名选课医学生为试验组,采用改良TBL结合模拟教学的方法,以2017年秋季和2018年秋季两学期选课的各40名医学生分别为对照组1和对照组2,分别已实施传统理论授课教学(lecture-based learning,LBL)和LBL结合案例为基础的教学(case-based learning,CBL),比较三组学生的急诊临床思维模拟演练成绩和问卷调查结果,根据数据类型不同分别使用单因素方差分析和χ2检验分析比较各组的教学效果.结果 试验组在初步诊断正确性方面与对照组2无显著差别,但在急诊处理决策能力、团队合作能力和模拟演练总成绩方面均高于对照组1和对照组2(P<0.05).问卷调查结果显示,在赞同"增强团队合作意识"和"增强沟通能力"两个方面,试验组的正面评价均高于对照组1和对照组2,其差异有统计学意义(P<0.05).试验组和对照组2在赞同"喜欢该教学方式"和"激发学习兴趣"两方面均优于对照组1(P<0.05).结论 改良TBL结合模拟教学的方法可提高已接受过临床理论LBL后的低年级医学生的临床决策能力、团队合作能力和沟通能力,适用于医学生早期临床思维的培养,并值得逐渐应用推广.

Due to Transformer limited by input image resolution, our proposed Window-based Epipolar Transformer (WET) only performs on features of 1/4 raw resolution. Each pixel of reference feature corresponds to an epipolar line throughout the source feature. In inter-attention module, to better divide the corresponding windows of source feature, we iterate at 1/4 resolution twice. The first iteration is to estimate depth map without WET. In the following iteration, we utilize the depth values to warp the center pixels of reference feature windows in order to partition corresponding windows in source features. To train WET with supervision at all stages, we design a transformed feature pathway that interpolates the feature map processed by WET to 1/2 and full resolution and then adds to the corresponding feature map at the next stage.

It has previously been shown that the number of endothelial progenitor cells (EPCs) is negatively correlated with Syntax score in patients with coronary artery disease (CAD). However, the association between alterations in EPC function and Syntax score is still unknown. The present study evaluated the association between the activity of EPCs as well as endothelial function and Syntax score in patients with CAD and investigated the underlying mechanisms. A total of 60 patients with CAD were enrolled in 3 groups according to Syntax score, and 20 healthy subjects were recruited as the control group. The number and migratory, proliferative and adhesive activities of circulating EPCs were studied. The endothelial function was measured by flow-mediated dilatation (FMD) and the levels of nitric oxide (NO) in plasma or secreted by EPCs were detected. The number and activity of circulating EPCs were lower in patients with a high Syntax score, which was similar to the alteration in FMD. The level of NO in plasma or secreted by EPCs also decreased as Syntax score increased. There was a negative association between FMD or circulating EPCs and Syntax score. A similar association was observed between the levels of NO in plasma or secreted by EPCs and Syntax score. Patients with CAD who had a higher Syntax score exhibited lower EPC numbers or activity and weaker endothelial function, which may be associated with attenuated NO production. These findings provide novel surrogate parameters for evaluation of the severity and complexity of CAD.

This study investigates the alteration in function and number of circulating endothelial progenitor cells (EPCs) in patients with aortic dissection (AD), compared with hypertensive patients, and its possible mechanism. Thirty-four patients with acute aortic dissection (AAD) and 20 patients with primary hypertension were involved. Flow cytometry analysis was performed to detect the number of CD34+/KDR+ cells, and acetylated low density lipoprotein (ac-LDL) and lectin fluorescent staining method was applied to test the number of cultured EPCs. In addition, EPC migration and proliferation were measured, and plasma interleukin 6 (IL-6) and interleukin 17 (IL-17) levels were investigated. The number of circulating EPCs in the AAD group was lower than that in the non-AD group, and the proliferation and migration of circulating EPCs in the AAD group were lower than that in the non-AD group. In addition, the number, proliferation, and migration of circulating EPCs were significantly inversely correlated with the aortic dissection detection risk score (ADD-RS). More importantly, increased plasma IL-6 and IL-17 level was found in the AAD group, and the two inflammatory factors were inversely associated with the function and number of circulating EPCs in the AAD group. We first demonstrated that the number and function of circulating EPCs are reduced in the AAD group, which may be partly related to upregulated plasma IL-6 and IL-17. Our study provides novel insight on the underlying mechanism and potential therapeutic target of AAD.

目的:探讨TBL结合情景模拟在全科心肺复苏(CPR)团队急救师资培训中的应用效果及反馈.方法:选取2021年3月在粤北人民医院参加广东省住院医师规范化培训全科普通师资培训班的学员139人为研究对象,采用TBL结合情景模拟教学法进行CPR团队急救培训,培训后进行CPR技能与团队合作的评估.采用问卷星调查培训后学员对不同人数组合CPR团队合作的掌握情况,并评估教学满意度.结果:培训后全科师资对不同人数组合复苏团队急救的掌握程度超过98％.各项课程满意度评价得分均超过94.5分,97.12％的学员认可采用TBL结合情景模拟教学的方法对全科住培学员进行培训,99.28％的学员愿意今后在教学中使用此方法.结论:TBL结合情景模拟教学能有效地提高全科师资对CPR团队急救能力的掌握,调动其采用新型教学方法的积极性,提高全科住院医师CPR团队急救的培训质量.

Out-of-hospital cardiac arrest (OHCA) due to drowning carries high morbidity and mortality. There are a few studies on drowning-related out-of-hospital cardiac arrest (OHCA), in which patients are followed from the scene to hospital discharge. This study aims to compare patient characteristics between the survival group and mortality group of OHCA due to drowning. OHCA due to drowning cases were selected from the North America Termination of Resuscitation Association database between 2011 and 2015. The retrospective analysis of epidemiological characteristics and clinical features of all OHCA patients were performed. Of the 17,094 OHCA cases in the registry, 54 cases of OHCA due to drowning were included in this study. Among the 54 OHCAs due to drowning, 7 (13.0%) survived, while 47 (87.0%) died. Compared to the mortality group, the survival group had a higher bystander witness rate (57.1% versus 17.0%, p < 0.05), higher asystole rate (42.9% versus 78.7%, p < 0.05), and higher mild therapeutic hypothermia rate (28.6% versus 2.1%, p < 0.05). In addition, a large proportion of survivors were children (71.4%) and males (71.4%). Survival among OHCA's due to drowning was found to be improved with a higher bystander rate, higher asystole rate, and higher mild hypothermia rate. In addition, children and males comprised the majority of survivors.

Objective To evaluate the clinical characteristics of acute pancreatitis (AP) concomitant with diabetic ketoacidosis (DKA) in a cohort from South China and identify factors associated with early detection of DKA in AP patients. Methods Inpatient medical records of AP concomitant with DKA were retrospectively reviewed. Results Forty-eight patients with AP concomitant with DKA were enrolled in this study. The results indicated that comorbidity history of diabetes mellitus and mental status of not alert on admission were factors associated with DKA in AP patients. Compared with patients without DKA, patients with DKA showed significantly higher rates of hypertriglyceridemia and lower rates of gallstones than those without DKA. AP patients with concurrent DKA had higher levels of serum triglycerides, longer lengths of hospital stays, and higher complication rates of systemic inflammatory response syndrome and acute kidney injury. Conclusion AP patients might have higher risks of concomitant DKA if presenting as not alert upon admission or if they have past medical histories of diabetes mellitus. Serum triglyceride levels were significantly higher in AP patients with DKA. DKA raised the severity of AP, but did not increase in-hospital mortality.

OBJECTIVE:The aim of this study was to explore the application of the flipped classroom approach in the training of Mass Casualty Triage (MCT) to medical undergraduate students.METHODS:In this study, 103 fourth-year medical students were randomly divided into a Flipped Classroom (FC) group (n = 51) and a Traditional Lecture-based Classroom (TLC) group (n = 52). A post-class quiz, simulated field triage (SFT) and feedback questionnaires were performed to assess both groups of students for their learning of the course.RESULTS:In the post-quiz, the median (IQR) scores achieved by students from the FC and TLC groups were 42(5) and 39(5.5), respectively. Significant differences were found between the two groups. In the SFT, overall triage accuracy was 67.06% for FC, and 64.23% for TLC students. Over-triage and under-triage errors occurred in 18.43% and 14.50% of the FC group, respectively. The TLC group had a similar pattern of 20.77% over-triage and 15.0% under-triage errors. No significant differences were found regarding overall triage accuracy or triage errors between the two groups.CONCLUSIONS:The FC approach could enhance course grades reflected in the post-quiz and improve students' satisfaction with the class. However, there was no significant difference of competency between the two groups demonstrated in the SFT exercise.

Background To this day, the molecular mechanism of endotoxin-induced multi-organ failure has not been completely clarified. This study aimed to construct an miRNA-mRNA regulatory network and identify main pathways and key genes in multi-organ of LPS-mediated endotoxemic mice. Methods Public datasets from six mRNA and three miRNA microarray datasets were downloaded from the GEO website to screen final differentially expressed genes (FDEGs) and hub genes in the heart, lung, liver, and kidney of LPS-mediated endotoxemic mice. Functional and pathway enrichment analysis of FDEGs was used to identify the main pathways in multi-organ damage of LPS-treated mice. Finally, hub genes of each organ were intersected to obtain the key genes of multi-organ. Results Firstly, 158, 358, 299, and 91 FDEGs were identified in the heart, lung, liver, and kidney, respectively. The pathway enrichment analysis of the FDEGs then showed that the TNF signaling pathway, Toll-like receptor signaling pathway, and some viral-infection-related pathways (influenza A, measles, and herpes simplex) were the main pathways in multi-organ damage of LPS-mediated endotoxemic mice. Moreover, miRNA-mRNA or PPI regulatory networks were constructed based on FDEGs. According to these networks, 31, 34, 34, and 31 hub genes were identified in the heart, lung, liver, and kidney, respectively. Among them, nine key genes (Cd274, Cxcl1, Cxcl9, Icam1, Ifit2, Isg15, Stat1, Tlr2, and Usp18) were enriched in Toll-like receptor signaling pathway and chemokine signaling pathway. Finally, seven potential drugs were predicted based on these key genes. Conclusion The shared underlying molecular pathways in endotoxin-induced multi-organ damage that have been identified include Toll-like receptor signaling pathway and TNF signaling pathway. Besides, nine key genes (Cd274, Cxcl1, Cxcl9, Icam1, Ifit2, Isg15, Stat1, Tlr2, and Usp18) and seven potential drugs were identified. Our data provide a new sight and potential target for future therapy in endotoxemia-induced multi-organ failure.

Background. The conversion from a nonshockable rhythm (asystole or pulseless electrical activity (PEA)) to a shockable rhythm (pulseless ventricular tachycardia or ventricular fibrillation) may be associated with better out-of-hospital cardiac arrest (OHCA) outcomes. There are insufficient data on the prognostic significance of such conversions by initial heart rhythm and different rhythm conversion time. Methods. Among 24,849 adult OHCA patients of presumed cardiac etiology with initial asystole or PEA in the Resuscitation Outcomes Consortium Cardiac Epidemiologic Registry (version 3, 2011–2015), we examined the association of shockable rhythm conversion with prehospital return of spontaneous circulation (ROSC), survival, and favorable functional outcome (modified Rankin Scale score ≤3) at hospital discharge by initial rhythm and rhythm conversion time (time from cardiopulmonary resuscitation (CPR) initiation by emergency medical providers to first shock delivery), using logistic regression adjusting for key clinical characteristics. Results. Of 16,516 patients with initial asystole and 8,333 patients with initial PEA, 16% and 20% underwent shockable rhythm conversions; the median rhythm conversion time was 12.0 (IQR: 6.7–18.7) and 13.2 (IQR: 7.0–20.5) min, respectively. No difference was found in odds of prehospital ROSC across rhythm conversion time, regardless of initial heart rhythm. Shockable rhythm conversion was associated with survival and favorable functional outcome at hospital discharge only when occurred during the first 15 min of CPR, for those with initial asystole, or the first 10 min of CPR, for those with initial PEA. The associations between shockable rhythm conversion and outcomes were stronger among those with initial asystole compared with those with initial PEA. Conclusions. The conversion from a nonshockable rhythm to a shockable rhythm was associated with better outcomes only when occurred early in initial nonshockable rhythm OHCA, and it has greater prognostic significance when the initial rhythm was asystole.