Evaluation of Plasma Volume Using Ultrasound in Disorders of Fluid With Sodium

Overview

Rossi NF \& Schrier RW reported that for having differential diagnosis in hyponatremic state, it is important to have a grasp of extra cellular fluid (ECF) volume. However, recent works showed that it is not easy to estimate the ECF state using by physical findings and by usual laboratory methods. Damaraju SC et al. first demonstrated that measuring central venous pressure (CVP) is significant to evaluate the ECF state in hyponatremic patients with intracranial diseases. Accordingly, it may be useful to measure the CVP in the hyponatremic patients. However, usually it is difficult to measure the CVP in all patients with hyponatremia because that the method is due to invasive procedure. With recently development, it is possible to estimate the CVP calculation using cardiac echogram without invasion. However, it is not clear that an evaluation by using such echogram estimates the state of ECF volume in hyponatremic patients. Therefore, the investigators examine whether the CVP calculation by using cardiac echogram by Marcelino P et al. method without invasion is estimated such condition in hyponatremic patients before and after treatments. As the primary endpoint, the VCI index values is investigated and compared with each group before and after correction of disorders of fluid with sodium. Furthermore, some variables including sodium, potassium, chloride, creatinine, BUN, uric acid, osmolality in blood and urine and plasma vasopressin are investigated and compared with each group before and after correction of disorders of fluid with sodium.

Calculated CVP value as VCI (vena cava inferior) index by Marcelino P et al. method-they reported that VCI index using several echocardiographic parameters measured. A transthoracic echocardiographic study was performed using an Aloka SSD 2200 echocardiograph fitted with 2.5MHz probe with continuous-wave，pulsed and color Doppler (Japan). Using pulsed Doppler，each parameter is measured as following; the deceleration rime of E wave of tricuspid inflow，the gradient between right ventricle (RV) and right atrium (RA) by continuous Doppler，the VCI variation from the corresponding maximum expiratory diameter (measured at 2 cm from the RA and in dorsal decubitus) to its diameter during inspiration. All measurements were taken at the end-expiration in order to standardize the samples. VCI index = \[tricuspid E deceleration (ms)\] x 0.11 + \[RV/RA gradient (mmHg)\] x 0.16 - \[VCI variation (mm)\] (VCI, vena cava inferior; tricuspid E, tricuspid E wave; RV, right ventricle, RA, right atrium). Na, Cl, K, creatinine, BUN and uric acid in serum and urine were measured by the usual methods before and after the correction of plasma volume. Further, osmolality and vasopressin in plasma and osmolality in urine were also measured by the usual methods.