A Multicenter Study on the Reliability of Four Ultrasound Measures : the Antero-posterior Diameter , the End-exipratory Area , the Aspect Ratio and the Collapsibility Index of Internal Jugular Vein Evaluated on Patients Admitted to Five Medicine Departments

Introduction Many studies suggest that the ultrasound of Internal Jugular Vein (IJV) is a method valid in predicting volume status and Central Venous Pressure (CVP) among critical patients (1-2).

Because this method is very easy , fast and applicable in several setting , if research will confirm its accuracy in detecting congestion and prognosis , it could have an important role in clinical practice.

The Internal jugular vein changes its size during the respiratory cicle : it enlarges in expiration and reduces in inspiration .

Usually the expiratory (maximum) diameters and area have been used by researchers to test the IJV ultrasound accuracy in predicting Central Venous Pressure and volume status (1,2).

Many ultrasound measures of IJV have been tested (3-8 ) : the antero-posterior , end-expiratory Internal Jugular Vein diameter (AP-IJV max); the end-exipratory IJV area (maximal area in transversal section, CSA-IJV max) ; the ratio between the AP-IJV max and transversal IJV diameter (LL-IJV max) , the Aspect ratio= AP-IJV max/LL-IJV max; the Collapsibility index of IJV , the respiratory variation percentage calculated as [(maximum diameter minus minimum diameter)/maximum diameter].