Background-Therapeutic hypothermia (TH) improves survival and confers neuroprotection in out-of-hospital cardiac arrest (OHCA), but TH is underutilized, and regional systems of care for OHCA that include TH are needed. Methods and Results-The Cool It protocol has established TH as the standard of care for OHCA across a regional network of hospitals transferring patients to a central TH-capable hospital. Between February 2006 and August 2009, 140 OHCA patients who remained unresponsive after return of spontaneous circulation were cooled and rewarmed with the use of an automated, noninvasive cooling device. Three quarters of the patients (nϭ107) were transferred to the TH-capable hospital from referring network hospitals. Positive neurological outcome was defined as Cerebral Performance Category 1 or 2 at discharge. Patients with non-ventricular fibrillation arrest or cardiogenic shock were included, and patients with concurrent ST-segment elevation myocardial infarction (nϭ68) received cardiac intervention and cooling simultaneously. Overall survival to hospital discharge was 56%, and 92% of survivors were discharged with a positive neurological outcome. Survival was similar in transferred and nontransferred patients. Non-ventricular fibrillation arrest and presence of cardiogenic shock were associated strongly with mortality, but survivors with these event characteristics had high rates of positive neurological recovery (100% and 89%, respectively). A 20% increase in the risk of death (95% confidence interval, 4% to 39%) was observed for every hour of delay to initiation of cooling. Conclusions-A comprehensive TH protocol can be integrated into a regional ST-segment elevation myocardial infarction network and achieves broad dispersion of this essential therapy for OHCA. (Circulation. 2011;124:206-214.)
Background
Although left ventricular (LV) ejection fraction (EF) and global longitudinal strain (GLS) are recommended by the current echocardiographic chamber quantification guidelines, these measurements are not performed routinely. Because EF measurements rely on manual tracing of LV boundaries, and are subject to inter‐reader variability and experience dependence, we hypothesized that semiautomated GLS measurements using speckle tracking would be more reproducible and less experience‐dependent.
Methods
Images from 30 patients were analyzed to obtain biplane EF using manual tracing. GLS was measured in three long‐axis views using EchoInsight software (Epsilon Imaging) that automatically detects LV endocardial boundary, which is edited manually as necessary and is then automatically tracked throughout the cardiac cycle. All measurements were performed by an expert echocardiographer and three first‐year cardiology fellows.
Results
Semiautomated GLS analysis showed excellent correlation (r=.98) and small bias (−1.0±13% of measured value) between the experienced and less experienced readers, superior to EF (r=.91, bias 7.3±16%). Also, in repeated measurements, GLS showed higher intra‐class correlation (ICC=.98) than EF (ICC=.89). Additionally, GLS analysis required ~1 minute per patient, while biplane EF measurements took twice as long.
Conclusions
Semiautomated GLS measurements are fast, less experience‐dependent, and more reproducible than conventional EF measurements. This is probably because, irrespective of experience, the readers' choice of boundary position varies less when asked to refine the automated detection than to draw borders without initial clues. This technique may facilitate the workflow of a busy laboratory and make a step forward toward incorporating quantitative analysis into everyday echocardiography practice.
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