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At least 145 records · Page 8Linked to original sources
PubMed1997

Flow measurement at the pump head of centrifugal pumps: comparison of ultrasonic transit time and ultrasonic Doppler systems.

Determination of blood flow is essential for monitoring rotary blood pumps. However, accurate measurement directly adjacent to the pump housing is difficult because of the highly irregular flow profiles near the fast spinning rotor. Therefore, a specially adapted flow probe based on the ultrasound transit time (USTT) principle was designed to evaluate the flow in centrifugal blood pumps. The probe can be directly mounted at the housing and creates 2 crossed measuring ultrasound beams. The mean value, Qm, of the 2 output signals corresponds to the blood flow and the difference, Qd, correlates to the vorticity of the flow profile in the pump outflow tract. In vitro measurements obtained an accuracy for mean flow values of better than +/-0.6 L/min in extreme working points and for vorticity values even as high as Qd = 3.5 L/min. Because of vorticity, however, the output signal contained considerable noise, and that required the application of a 10 Hz filter. Positioning of the ultrasound (US) beams parallel to the axial direction of the pump was superior to radial positioning. Additional measurement of the flow profile demonstrated that a large vorticity occurred (up to Qd equal to 3.5 L/min), and this vorticity was highly dependent upon the afterload of the pump. In vivo experiments demonstrated the reliability of the method. We concluded that USTT flow measurement can determine blood flow immediately adjacent to the pump housing with sufficient accuracy, and these measurements are superior to those from US-Doppler systems (which cannot handle the vorticity accurately enough) and electromagnetic devices (which lack zero stability).

Blood Flow Velocity↗
PubMed1993

Peripheral pulmonary lesions: ultrasonic features and ultrasonically guided fine needle aspiration biopsy.

When transthoracic biopsy is required for diagnosing lung diseases, radiographic procedures are the methods of choice, sonographic application being still limited. Sixty-four consecutive patients with pulmonary lesions adjacent to the chest wall underwent sonography. Findings showed hypoechoic homogeneous lesions (56 cases) with posterior regular margin (57 cases). Increasing echoes deep to the mass and sonographic interruption of hyperechoic surface were seen in all patients. In two cases, chest wall invasion had been diagnosed. Histologic diagnosis was made in 55 of the 64 patients (85.9%). Two pneumothoraces occurred. Sonography is a useful, accurate, and safe technique for diagnosing selected pulmonary lesions.

Adult↗