Administration and clearance of amphotericin B during high-efficiency or high-efficiency/high-flux dialysis.

Administration and clearance of amphotericin B infused during high-efficiency or high-efficiency/high-flux dialysis were studied in two end-stage renal disease patients requiring systemic antimycotic treatment for fungal peritonitis. Amphotericin B concentrations were measured in the arterial and venous dialysis ports as well as in the ultrafiltrate. Amphotericin B is poorly dialyzable while administered during hemodialysis sessions with high-efficiency (CA 210) or high-efficiency/high-flux (CT 190 G) membranes. Amphotericin B infusion during hemodialysis was well tolerated and can be administered conveniently in an outpatient dialysis setting, avoiding prolonged hospitalization for parenteral antifungal therapy.

Cyclic variation of integrated backscatter: dependence of time delay on the echocardiographic view used and the myocardial segment analyzed.

To determine the influence of myocardial anisotropy in ultrasonic tissue characterization, we measured the time delay (and magnitude) of the cyclic variation of myocardial integrated backscatter from specific segments visualized in the 4 standard transthoracic echocardiographic views. The cyclic variation data in 10 myocardial regions were obtained from analyses of 2-dimensional integrated backscatter images from 23 healthy subjects. Resultant values (mean +/- SD) for the time delay were as follows: parasternal long-axis view: 1.08 +/- 0.17 (septum) and 1.00 +/- 0.14 (posterior wall); parasternal short-axis view: 1.03 +/- 0.16 (anterior septum), 1.03 +/- 0.14 (posterior wall), 2.22 +/- 0.71 (lateral wall), and 1.65 +/- 0.66 (posterior septum); apical 4-chamber view: 1.08 +/- 0.31 (septum) and 2.20 +/- 0.79 (lateral wall); and apical 2-chamber view: 1.68 +/- 0.62 (inferior wall) and 2.04 +/- 0.72 (anterior wall). Hence, results of this study indicate that myocardial ultrasonic characterization that uses the cyclic variation is influenced by the echocardiographic view and the specific segment of the left ventricle.

Dependence of "apparent" magnitude on the time delay of cyclic variation of myocardial backscatter.

The goal of this study was to determine if the "apparent" magnitude of the cyclic variation, defined as the difference between the values of integrated backscatter at end-diastole and end-systole, was dependent on the corresponding time delay. We measured the cyclic variation in four myocardial segments of the parasternal short-axis view in 23 healthy subjects. The "apparent" magnitude, actual magnitude, and time delay were compared for each segment. Measured time delays were: 2.22+/-0.71 (lateral wall); 1.65+/-0.66 (inferior septum); and approximately 1.0 for the anterior septum and posterior wall. Segments exhibiting large time delays (> 1.0) resulted in a reversal in sign of the "apparent" magnitude of cyclic variation in one instance, and underestimated the true magnitude in both cases. Thus, estimates of the "apparent" magnitude of the cyclic variation are dependent on the associated time delay, whereas a properly defined magnitude is not.

Dissociation between wall thickening of normal myocardium and cyclic variation of backscatter during inotropic stimulation.

The purpose of this study was to determine the relation between increased myocardial wall thickening during inotropic stimulation and quantitative acoustic properties of normal myocardium in humans. We first validated a new 2-dimensional ultrasonic backscatter imaging approach for measurement of cyclic variation in the parasternal long-axis view against conventional M-mode integrated backscatter technique in 41 patients and controls (group A). We then performed 2-dimensional ultrasonic integrated backscatter imaging in 18 patients (group B) with normal segmental function at baseline to determine the magnitude of the cyclic variation of the septum and the posterior wall before and during infusion of dobutamine (10 and 20 microgram/kg/min). Group A patients showed a close correlation of the cyclic variation obtained by the new 2-dimensional ultrasonic integrated backscatter imaging approach and the conventional M-mode technique. Group B patients had mean values of cyclic variation that remained unchanged in the septum (4.4 +/- 1.4, 4.3 +/- 1.7, and 4.8 +/- 1.6 dB at baseline and at each dobutamine stage, respectively, p = NS) and in the posterior wall (6.4 +/- 1.7, 6.4 +/- 1.8 and 6.1 +/- 1.9 dB, respectively, p = NS) despite progressive dobutamine-induced increases in percent wall thickening (septum: 38 +/- 10% to 57 +/- 17% and 68 +/- 19%, respectively, and posterior wall 42 +/- 13% to 72 +/- 20% and 77 +/- 18%, respectively; both p <0.001 vs baseline for both walls). Thus, physical properties of normal myocardium remain unchanged during inotropic stimulation.