Acute circulatory failure is frequent, affecting up to one-third of patients admitted to intensive care units (ICU). Monitoring hemodynamics and cardiac function is therefore a major concern. Analysis of respiratory diameter variations of the superior vena cava (SVC) is easily obtained with transesophageal echocardiography (TEE) and is helpful to assess fluid responsiveness. Transthoracic echocardiography (TTE) exploration of the SVC is not used in routine. Recently, micro-convex ultrasound transducers have been marketed and these may be of use for non-invasive SVC flow examination. However, analysis of diameter variations of the SVC with TTE does not seem to be possible since the approach from the supraclavicular fossa does not allow for a good visualization of the SVC walls. It was recently demonstrated in a short pilot study that TTE examination of the SVC flow with a micro-convex ultrasound transducer (GE 8C-RS) seems both easy to learn and to use (feasibility = 84.9%), and is reproducible in most ventilated ICU patients with an intraclass correlation coefficient for the systolic fraction of the superior vena cava flow of 0.90 (95% confidence interval \[0.86-0.93\]). The hypothesis is that cardio-respiratory interactions in intubated-ventilated patients are responsible of SVC flow variations and that the analysis of the SVC flow respiratory variations could be a new predictive tool of fluid responsiveness.
Study Type
INTERVENTIONAL
Allocation
NA
Purpose
DIAGNOSTIC
Masking
NONE
Enrollment
188
PLR is a test that predicts whether cardiac output will increase with volume expansion. By transferring a volume of around 300 mL of venous blood from the lower body toward the right heart, PLR mimics a fluid challenge. However, no fluid is infused and the hemodynamic effects are rapidly reversible, thereby avoiding the risks of fluid overload. PLR starts from the semi-recumbent and not the supine position. PLR is performed by adjusting the bed and not by manually raising the patient's legs
Echo-Doppler measurements are performed with Vivid S6 model (GE Healthcare France, Lyon, France). All measurements are recorded at the end of expiration. Echo-Doppler measurements are performed in the upper part of the SVC, approximately 1 to 2 cm below the brachiocephalic vein. From this view, pulse Doppler is performed. Pulse Doppler waves obtained in the SVC are used to obtain velocity time integrals (VTI). Expiratory VTI is named VTImax and inspiratory VTI is named VTImin. These values will allow the calculation of Respiratory variations of the superior vena cava flow (ΔSVCf). ΔSVCf is calculated as (VTImax- VTImin )/(1/2(VTImax+ VTImin)).
Département d'Anesthésie-Réanimation, Hôpital Edouard Herriot,
Lyon, France
RECRUITINGventricular outflow tract velocity time index (LVOT TVI)
Echo-Doppler measurements are performed with Vivid S6 model (GE Healthcare France, Lyon, France). All measurements are recorded at the end of expiration. Echo-Doppler measurements are performed in the upper part of the SVC, approximately 1 to 2 cm below the brachiocephalic vein. From this view, pulse Doppler is performed. Pulse Doppler waves obtained in the SVC are used to obtain velocity time integrals (VTI). Expiratory VTI is named VTImax and inspiratory VTI is named VTImin. These values will allow the calculation of Respiratory variations of the superior vena cava flow (ΔSVCf). ΔSVCf is calculated as(VTImax- VTImin )/(1/2(VTImax+ VTImin))
Time frame: The day of inclusion
optimal cut-off value of ΔSVCf to predict fluid-responsiveness
Time frame: The day of inclusion
proportion of patients in which measurement of ΔSVCf is not possible
Time frame: The day of inclusion
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