Echocardiographic assessment of LVEFThe tested US was a new generation (VScan?, General Electrics Healthcare) miniaturized (size: 135 �� 73 �� 28 mm; weight: 390 g), battery-operated (total scan time of one hour) device with a broad-band width (1.7 to 3.8 MHz) phased array probe (120 �� 33 �� 26 mm). This Vorinostat HDAC3 system can store digital still-frames or image loops, uses a color-coded overlay for real-time blood flow imaging, and allows distance measurements using integrated electronic calipers, but has neither spectral nor tissue Doppler capability (Figure (Figure1).1). TTE studies were performed with a full-feature system (CX50, Philips Healthcare).Figure 1New generation miniaturized ultrasound system the size of a smartphone used in the current study.

The two echocardiographic examinations were performed independently, and randomly according to the availability of investigators and ultrasound systems, but within the same hour. Operators were experienced intensivists highly trained in critical care echocardiography [13]. The following TTE views were systematically screened in each patient: parasternal short-axis view, apical four- and two-chamber views and subcostal four-chamber view. In each TTE view, imaging quality was graded as 0 (no image), 1 (less than 50 percent of endocardial border well delineated), 2 (more than 50 percent of endocardial border well delineated) and 3 (entire endocardial border well delineated) [7]. An overall quality score was calculated by adding imaging quality grades of all four studied TTE views (range: 0 to 12).

Three digital loops were recorded during TTE at end-expiration in the apical four- and two-chamber views for further analysis. The time required to perform the examination purposely focused on the visual estimation of LVEF (from the first image obtained to the end of examination) was recorded.The investigators assessed semi-quantitatively LVEF using TTE or the US in the apical four- and two-chamber views, with the same four-subset classification than that used for the clinical evaluation. The echocardiographers and the front-line intensivists who clinically assessed LVEF had access to the same information but were not allowed to communicate until individual clinical research forms had been independently fulfilled at the patient’s bedside. LVEF was then measured off-line by two independent intensivists with an ASE level 3 competence in echocardiography [14].

LV end-diastolic volume (LVEDV) and LV end-systolic volume (LVESV) were measured in the apical four- and two-chamber views using the Simpson’s method, according to current recommendations Cilengitide [15]. LV volumes were measured on three non-consecutive cardiac cycles and averaged. LVEF was conventionally calculated as the stroke volume (LVEDV-LVESV) normalized by LVEDV [5].