Impedance cardiographic waveforms in children: Involvement in left ventricular ejection time determination during anesthesia

[What non invasive haemodynamic assessment in paediatric intensive care unit in 2009?]

The haemodynamic assessment of the patients is a daily activity in paediatric intensive care unit. It completes and is guided by the clinical examination. The will to develop the least invasive possible coverage of the patients is a constant concern. The haemodynamic monitoring, all the more if it is invasive, ceaselessly has to put in balance the profit and the risk of beginning this technique at a fragile patient. In the last three decades, numerous non-invasive haemodynamic tools were developed. The ideal one must be reliable, reproducible, with a time of fast, easily useful answer, with a total harmlessness, cheap and allowing a monitoring continues. Among all the existing tools (oesophageal Doppler ultrasound method, transthoracic echocardiography, NICO, thoracic impedancemetry, plethysmography, sublingual capnography), no one allies all these qualities. We can consider that the transthoracic echocardiography gets closer to most of these objectives. We shall blame it for its cost and for the fact that it is an intermittent monitoring but both in the diagnosis and in the survey, it has no equal among the non-invasive tools of haemodynamic assessment from part the quality and the quantity of the obtained information. The learning of the basic functions (contractility evaluation, cardiac output, cardiac and the vascular filling) useful for the start of a treatment is relatively well-to-do. We shall miss the absence of training in this tool in France in its paediatric and neonatal specificity within the university or interuniversity framework.

Comparison of computational algorithms applied on transthoracic impedance waveforms to predict head-up tilt table testing outcome

The goal of the present study was to develop and evaluate new algorithms for the prediction of the outcome of a head-upright tilt test (HUTT). Using transthoracic impedance and its first derivative, we attempted to determine if indexes computed on these waveforms could detect a positive outcome to a 70 degrees -45min HUTT with reliable sensitivity and specificity. The methods were evaluated retrospectively in a group of 70 patients and validated prospectively in a group of 59 patients. The best detector obtained used a neural network. It compares very favorably with published results for other syncope detectors.