Fluid-responsiveness Assessment Simplified by Electric Cardiometry in Children

Volume expansion is the cornerstone of acute circulatory failure treatment in children. However, inappropriate administration can lead to fluid overload, which is associated with poor outcome. Thus, the search for indicators to predict fluid responsiveness is a major issue in pediatric intensive care unit. In such an emergency context, this assessment must be as simple and fast as possible, and ideally non-invasive. In children, respiratory variability of peak aortic velocity is the most studied test and has an excellent diagnostic accuracy but is only validated in the absence of any spontaneous respiratory movement, a rare situation in practice. Recently, the abdominal compression maneuver has been investigated. This classical clinical maneuver induces a transient and reversible preload increase by increasing the venous return via the mobilization of the hepato-splanchnic venous reservoir. The echocardiographic evaluation of this maneuver can accurately predict fluid responsiveness. However, this echocardiographic assessment is a pitfall, as it is an operator-dependent, discontinuous and time-consuming examination. Therefore, electrical cardiometry could be interesting. This continuous and non-invasive cardiac output monitor could be an interesting alternative to evaluate the hemodynamic effects of the abdominal compression maneuver in order to predict fluid responsiveness.

Therefore, the investigators will evaluate the diagnostic accuracy of an abdominal compression maneuver for the diagnosis of fluid responsiveness in critically ill children, for whom the physician in charge prescribed a 10ml/kg volume expansion for circulatory failure. The index test will be the SV variation induced by an abdominal compression maneuver, with SV being measured with electrical cardiometry. Fluid responsiveness will be defined as a > 15% increase in echocardiographically-measured SV between baseline and within one hour after fluid expansion (gold standard test).

In this non-interventional, prospective, multi-center study of diagnostic accuracy, children requiring a 10ml/kg volume expansion will be included. After a prescription of 10 ml/kg volume expansion by the physician in charge, screening for inclusion and exclusion criteria will be performed by an investigator physician. If the patient is included, volume expansion will be delayed for a few minutes (<3 min) while an echocardiography and the index test are performed, but no supplemental blood test or invasive parameters will be collected. Another echocardiographic evaluation will be conducted within one hour after volume expansion, to assess response to fluid expansion (gold-standard test). Patients will be follow-up until PICU discharge (28 days maximum).

The index test is the ΔSV-ACICON: percentage of SV variation between baseline and during a standardized abdominal compression. Stroke volume will be assessed by electrical cardiometry, a noninvasive cardiac output monitoring.

The abdominal compression maneuver, a common clinical test in critically ill children, will be standardized as follow: a sphygmomanometer will be inflated with 80ml of air and will be applied to the center of the patient's abdomen. Then, the operator's hand will be placed on the sphygmomanometer (which is thus interposed between the patient's abdomen and the operator's hand) and a gentle manual anteroposterior compression will be performed, calibrated at 30 cmH2O according to the sphygmomanometer. Parameters of interest will be collected 30 seconds after the start of the compression.