Abstract:
Respiratory changes in the retrohepatic inferior vena cava size (DIVC) assessed by transthoracic echocardiography has been proposed to assess preload dependency. However, its relevance may be impaired by the occurrence of an increase in intra abdominal pressure (IAP). In an experimental model, we investigated the effects of a gradual IAP increase on the disappearance of respiratory IVC flow fluctuations and its related DIVC. In the present experimental study nine pigs were anesthetized, mechanically ventilated and instrumented. IAP was gradually increased from 0 to 30 mmHg by step of 15 mmHg during normovolemia and hypovolemia generated by blood withdrawal of 30% of total blood volume. At each step, cardiac output, IVC flow and area were assessed by flowmeters and transesophageal echocardiography, respectively. We found that at high IAP, neither DIVC nor modulations of IVC flow were observed whatever the volemic status. At normal IAP, even in presence of respiratory changes of IVC flows, no DIVC sizes were observed in the two groups of animals and the majority of animals exhibiting an expiratory IVC area less than 0.65 cm² showed evidence of IAP greater than right atrial pressure (RAP) values. These results suggest that IVC flows are not associated to DIVC sizes in mechanically ventilated pigs regardless the volemic state or IAP value. However, IVC area less than 0.65 cm² is associated with the presence of IAP values higher than RAP suggesting that IVC dimensions could anticipate this pathophysiologic state.

Brief Biography of the Speaker:
Karim Bendjelid, MD, PhD is a Cardiologist-Intensivist attending physician at the Geneva University Hospitals (Intensive Care Division) and a Privat Docent at Geneva Medical University. He has also a Master of Science (MSc) in Cardiovascular Pharmacology at University of Pierre-Marie Curie-Paris VI (France) and a PhD in Physiology at University of Claude Bernard-Lyon I (France). Dr Bendjelid succeeds to the Gold Decoration Competition (“Gold Medal awards”) of the Lyon University Hospitals. His main research interests concern hemodynamic monitoring (macrocirculation-microcirculation) and reliability of static and dynamic markers to predict fluid responsiveness in critically ill patients. In these fields, he authored or co-authored over 60 scientific papers published in peer reviewed journals or presented at international conferences. He co-authored over 5 Review & Chapters papers books edited by Springer-Verlag, Distribuna Editorial and Elsevier. He was a chairman or keynote lecturer in a number of international conferences organized by different prestigious societies. He is a regular Member of The French Society of Cardiology (echocardiography), the French Cardio-Vasculaire Research Group, the European Society of Cardiology, the American Physiological Society and the European Society of Intensive Care. He is a technical reviewer for the following international journals: IEEE Transactions on Biomedical Engineering, Critical Care Medicine, Intensive Care Medicine, Anesthesia Analgesia, Circulation, Chest, Acta Anaesthesiologica Scandinavica, Anesthesiology, European Journal of Echocardiography, Pulmonary Pharmacology and Therapeutics, the American Journal of Respiratory Critical Care Medicine, Stroke, Critical Care, European Journal of clinical investigation, Journal of Surgical Research, and British medical journal. He is also, member of the editorial board of Current Drug Therapy, Annals of Thoracic Medicine and Open Critical Care Medicine Journal.