Feasibility of transhepatic ultrasonic evaluation of inferior vena cava diameter to guide fluid management in comparison with anterior approach

Non-invasive estimation of right atrial pressure from the inspiratory collapse of the inferior vena cava using ultrasound machines is nowadays promising with the increasing availability of these machines in emergency departments, critical care units and in operating theaters. The learning curve of these tools is steep and they are becoming less expensive and give quick, non-invasive, dynamic clue to the preload status. The aim of this study is to evaluate the transhepatic inferior vena cava (IVC) diameter by non-invasive sonographic imaging and compare it with that measured by subxiphoid approach to reveal the degree of agreement between them. This is a prospective study, done in a tertiary care referral hospital at intensive care unit in Al-Sadr Teaching Hospital over a period of four months from 1st February 2017 to 5th of June 2017. Eighty shocked patients were included for assessment of volume status. Bedside ultrasound images were obtained with the patient in supine position to determine the dimensions and collapsibility of IVC. Evaluation of each patient included the standard anterior subxiphoid IVC assessment and lateral transhepatic assessment of IVC by ultrasound using liver as an acoustic window in mid-axillary line. The IVC diameter was measured 2 cm caudal to the hepatic vein-IVC junction, or approximately 3-4 cm caudal to the junction of IVC and the right atrium. Then IVC maximal diameter, IVC minimal diameter and collapsibility index were calculated for both approaches. A comparison between these data was made. A total of eighty patients were included, 31 (37.5%) were females and 49 (62.5%) were males. Mean age was 45.81±14.89 years. The results showed that there is no statistically significant difference between transhepatic and subxiphoid approaches in regard to IVC diameter and its collapsibility. In conclusion, transhepatic lateral view of IVC provides a good alternative when subxiphoid anterior view cannot be obtained to guide fluid management in shocked patients.