Vena cava diameter measurement for estimation of dry weight in haemodialysis patients

Abstract

A correct estimation of volume status and so-called dry weight in dialysis patients remains a difficult clinical problem. Clinical status and chest X-ray are not sensitive enough, while invasively measured central venous pressures are not routinely available. Recently, the sonographic determination of the diameter and collapse of the inferior vena cava (IVC) has been proposed as a noninvasive method for estimating intravascular volume. We tried to evaluate the clinical relevance of this method in dialysis patients by comparing it with central venous pressures (CVP) and atrial natriuretic peptide (ANP). To establish a normal range and to control for confounding variables, we examined a large number of healthy controls. Furthermore, the influence of tricuspid insufficiency was examined echocardiographically. Measurements of the IVC diameters were well reproducible, with a coefficient of variation for interobserver error of 2.2%, and a coefficient of variation of 1.4% for intraobserver error. The collapse index was less well reproducible and therefore not used for further analysis. In 86 normal controls (age 18 to 76 years), IVC diameters showed a wide variation, and they were not correlated to age, height, weight, or body surface area. However, there was a significant correlation of IVCex to heart rate (r = 0.63, P < 0.001). Therefore, we calculated percentiles of the heart rate-IVCex relation in normals, and compared the results in patients to these. In 10 overhydrated haemodialysis patients, CVP was closely correlated to IVCex (r = 0.72, P < 0.001), but there was a wide interindividual variation of the slope of this relation. An IVCex above the 95th percentile of normal was a good predictor of an elevated CVP (i.e. > 12 cmH2O). In another 39 stable, chronic haemodialysis patients, there was a significant correlation of the intradialytic decrease of ANP and IVCex (r = 0.69, P < 0.001). However, this correlation existed only in patients without tricuspid insufficiency. In summary, sonography of the inferior vena cava is a valuable tool for estimating dry weight in dialysis patients, provided that some caveats are kept in mind: (i) there is a wide variation of IVC diameters in normals, and single measurements are not helpful in individual patients; (ii) there is a significant, inverse correlation between IVC diameters and heart rate, and the precision of intravascular volume assessment is enhanced by interpreting heart rate corrected diameters; (iii) the presence of tricuspid insufficiency leads to unreliable results, as it influences IVC diameters per se. Intravascular volume changes are reflected by IVC measurements, as shown by the correlation to other indices of intravascular volume, such as CVP and alpha-hANP. IVC sonography is noninvasive and easily available; serial measurements allow an estimation of changes of intravascular volume in patients without cardiac filling impairment. However, unlike with body impedance, interstitial volume is not reflected by IVC diameters.

Changes of the Cardiac Architectures and Functions for Chronic Hemodialysis Patients with Dry Weight Determined by Echocardiography

“…Chang/Chen/Chen/Cheng/Chung/Yang Meanwhile, the DW for the control group patients was monitored using traditional methods. Many works have demonstrated that estimating IVCD by echocardiography offers a simple, non-invasive and reliable tool for DW determination, and correlates well with other methods such as multifrequency bioimpedance and plasma volume detected by radioiodinated serum albumin method for estimating fluid volume for chronic hemodialysis patients [10,12,23]. Besides, an experienced echocardiographic operator at the bedside can obtain this measurement more quickly and easily.…”

Bioimpedance for assessing volume status in children with nephrotic syndrome

“…As such, the usage of these biomarkers is restricted, but echocardiography and the inferior vena cava collapsibility index (IVCCI) and inferior vena cava index (IVCI) are commonly used to determine intravascular volume, especially for hemodialysis patients (8)(9)(10). It is difficult to perform these techniques with pediatric patients as these measures often vary depending on the individual performing the test, and sometimes these tests do not accurately indicate the severity of the volume loss, which greatly reduces the utility of these methods (11,12).…”

Interactions between respiration and systemic hemodynamics. Part II: practical implications in critical care

“…Thus, one would expect that phasic changes in transmural pressure would more readily translate into respiratory variations in cross-sectional size when imposed on a partially empty vessel (hypovolemia), as opposed to a fully repleted one (normo or hypervolemia). Based on this rationale, the phasic changes in caval diameters, as evaluated from echocardiography, have been proposed as non-invasive indices of intravascular volume status [44][45][46][47][48][49][50].…”

“…The latter, however, only causes the IVC diameter to shrink if the vessel is not fully repleted (i.e., if it operates on the steep part rather than the plateau of its transmural pressure/ diameter relationship). Quantified in various ways with transthoracic echocardiography, the inspiratory decrease of IVC diameter has been used to characterize volume status in the course of hemodialysis for end-stage renal disease [45,46]. In the ICU, we are aware of no similar application in spontaneously breathing subjects.…”