The relationship between inferior vena cava diameter measured by bedside ultrasonography and central venous pressure value

Background The exact evaluation of intravascular volume status is an essential parameter for assessing patients in critical conditions in ICUs. It is significant for both primary assessment and response to medical treatment and supportive measures. Objective We are aiming for selecting a method to evaluate patients’ intravascular volume status by measuring inferior vena cava (IVC) diameter noninvasively by using transthoracic sonography and to evaluate if there is a relation between IVC and central venous pressure (CVP). Patients and methods Patients were older than 18 years. All patients with a central venous catheter that was already inserted into internal jugular vein were involved in the study. IVC diameter records were estimated and assessed by the same physician with the help of chest sonography both at the end of inspiration and at the end of expiration. Measurements of CVP were done by water manometer. Results A total of 50 patients were included in our study. The patients were diagnosed as having chronic obstructive pulmonary disease (84%), pneumonia (60%), and pleural effusion (12%). Overall, 48% of patients had spontaneous respiration and 52% required mechanical ventilation. Among respiratory phases of IVC diameter and the IVC caval index, we found an important negative correlation between CVP and caval index. Moreover, we can predict CVP measurement by IVC sonography. Conclusion Measurements of IVC diameter by chest ultrasound can be used for estimation of the intravascular volume status of patients in critical conditions.