Is there an association between central venous pressure measurement and ultrasound assessment of the inferior vena cava?

Introduction:Early assessment of volume status is paramount in critically ill patients. Central venous pressure (CVP) measurement and ultrasound assessment of the inferior vena cava (IVC) are both used for volume assessment in the emergency centre. Recent data is conflicting over whether there is a correlation between CVP and ultrasound assessment of the IVC.Methods:This was a retrospective review of an audit previously performed in the Emergency Unit of Ngwelezane Hospital in Kwazulu-Natal. The audit involved measuring inferior vena cava collapsibility index (IVC-CI) within 5 min of CVP measurement. In this retrospective study, audit data were analysed to determine if an association exists.Results:Twenty-four patients were included. The median age of participants was 36 (IQR 42) years (95% CI 33­56). The median time to ultrasound was 18.6 (52.5) h (95% CI 7.5­36.2). The mean CVP was 13.7 ±â€¯7.7 cm H2O and mean IVC-CI was 39.4 ±â€¯17.8%. Based on a Pearson correlation test, there was a weak negative correlation between CVP and IVC-CI, which was not statistically significant (r = −0.05, n = 24, p = 0.81, 95% CI −0.5 to 0.4) for all participants. However, among females there was a moderate negative correlation between CVP and IVC-CI, which was not statistically significant (r = −0.43, n = 7, p = 0.34, 95% CI −0.9 to 0.5), while among males there was a weak positive correlation, which was not statistically significant (r = 0.16, n = 17, p = 0.53, 95% CI −0.3 to 0.6).Discussion:There is no significant correlation between CVP and IVC-CI. Further validation research is required to support our preliminary findings of no significant correlation between CVP measurement and ultrasound assessment of the IVC. CVP and IVC ultrasound should be used as clinical adjuncts, and not as stand-alone measures of volume assessment

Ultrasound reference values for inferior vena cava diameter and collapsibility index among adult Nigerians

Background: Correct estimation of intravascular volume is crucial in critically ill and traumatized patients. Measurement of the central venous pressure (CVP) is invasive and time consuming. Studies have shown that inferior vena cava diameter (IVCD) correlates with CVP. Sonographic assessment of IVCD and its respirophasic changes (collapsibility index; CI) is a non-invasive, quick and reliable means of estimating CVP and hence, intravascular fluid volume. Data on such studies are scanty among adult Nigerians. Aim: To establish normograms of IVCD and CI for healthy adults in Benin City, Nigeria as well as determine the relationship of IVCD and CI with height, weight, body mass index (BMI), age and gender. Method: Four hundred apparently healthy adult volunteers were prospectively studied by means of ultrasound. Demographic data and BMI were obtained. The IVCD was measured during inspiration, expiration and sniff. The CI was subsequently calculated for each subject. Statistical Package for the Social Sciences (SPSS) version 17.0 was used for data analysis including tests of significance. Probability values less than or equal to 0.05 were considered significant. Results: The mean IVCD in this study was 6.1±2.2mm and 13.0±4.0 mm for inspiration and expiration respectively. The mean CI was 49.7±0.5%. There was no statistically significant correlation between IVCD and CI with height and BMI. Conclusion: This study has determined normal IVCD and CI reference range for healthy Nigerian adults. The CI is independent of height, weight, BMI and gender. Since the CI is not dependent on physical attributes and gender, it may serve as an objective tool for monitoring the fluid status of patient