OBJECTIVE To assess the impact of respiratory therapy with the expiratory flow increase technique on cerebral hemodynamics of premature newborns. METHODS This is an intervention study, which included 40 preterm infants (≤34 weeks) aged 8-15 days of life, clinically stable in ambient air or oxygen catheter use. Children with heart defects, diagnosis of brain lesion and/or those using vasoactiv...

Background. Orthostatic hypotension (OH) is an important nonmotor manifestation of Parkinson's disease (PD). Changes in cerebrovascular reactivity may contribute to this manifestation and can be monitored using transcranial Doppler. Objective. To identify possible changes in cerebrovascular reactivity in patients with OH. Methods. Twenty-two individuals were selected and divided into three grou...

Fifteen preterm infants suffering from respiratory distress syndrome were randomly allocated to receive either high-dose (200 mg/kg) or low-dose (100 mg/kg) surfactant treatment. Retreatments were done with the low dose. Blood pressure, blood gases and cerebral blood flow velocities were determined before and after 24 bolus instillations. With the high dose mean blood pressure and mean cerebral...

A chronic animal model is described which permits for the first time the continuous measurement of uterine artery blood flow velocity in the pregnant guinea-pig by using a miniaturized Doppler flow probe. Preliminary validation revealed that alterations in actual blood flow are directly and proportionally related to the change in the Doppler shift (r = 0.984) from 0 to 100 ml/h. The velocity si...

In order to identify left ventricular diastolic function in patients with betathalassemia major and normal systolic function by noninvasive M-mode and Doppler echocardiography, an analytic study was designed in a university hospital in Sari. We have studied 44 patients (23 men and 21 women), mean age 15.48±2.16 (range 12 to 20) and 43 age and sex matched control subjects. Peak flow velocit...

The paper presents an application of the FSI technique to determine hemodynamics in the abdominal aorta (AA). To establish boundary conditions for the FSI study, MR anatomical data and 4D MRI velocity-mapping data (in three blood flow velocity directions and time) were collected to acquire realistic geometry of the AA and blood velocity. The mechanical parameters of the patient-specific aortic ...

PURPOSE To evaluate and model the risk of in vivo thrombosis in each hepatic vessel type during hepatic microwave ablation as a function of vessel diameter, velocity, and vessel-antenna spacing. MATERIALS AND METHODS A single microwave ablation antenna was inserted into a single porcine lobe (n = 15 total) adjacent to a hepatic artery, hepatic vein, or portal vein branch. Conventional ultraso...

In cremaster muscle of pentobarbital-anesthetized rats, temporary occlusion of an arteriole increased red blood cell velocity (mean increase, 8.2 +/- 1.0 mm/sec from a control velocity of 7.9 +/- 0.7 mm/sec) in proximal parallel arteriolar branches (mean control diameter, 19.4 +/- 0.6 microns). Increases in flow velocity were consistently followed by proportional delayed (6-15 seconds) increase...

Blood resistivity is an important quantity whose value influences the results of various methods used in the study of heart and circulation. In this paper, the relationship between blood resistivity and velocity of blood flow was evaluated and analyzed based upon a probe using six-ring electrodes and a circulatory model. The experimental results indicated that the change in blood resistivity wa...

To understand better the relationship between blood velocity measured by transcranial Doppler and cerebral blood flow measured by the 133Xe inhalation method, we examined 23 patients undergoing evaluation in the Comprehensive Sickle Cell Center at Columbia University. Blood velocity in the middle cerebral artery was directly related to cerebral flow (r = 0.77; p less than 0.05). A multivariate ...