OBJECTIVE It is known from animal experiments that blood flow through the ductus venosus changes with fetal strain. Therefore the ratio of umbilical vein to ductus venosus flow rate in human intrauterine growth retardation and multifetal pregnancies was investigated and compared with that in control subjects. STUDY DESIGN Blood flow rates in the umbilical vein and in the ductus venosus, as we...

It is obvious that a noninvasive technique that can provide continuous measurements of blood flow through a cerebral artery would be very valuable for clinical and investigative purposes. The most promising approach to the development of such a technique involves the use of ultrasound for the measurement of blood flow velocity. Since blood flow through a vessel is equal to the instantaneous ave...

We present a three-dimensional mathematical model for the study of radiofrequency ablation (RFA) with blood flow for varicose vein. The model designed to analyze temperature distribution heated by radiofrequency energy and cooled by blood flow includes a cylindrically symmetric blood vessel with a homogeneous vein wall. The simulated blood velocity conditions are U = 0, 1, 2.5, 5, 10, 20, and 4...

PURPOSE Our purpose was to evaluate intraaneurysmal blood velocity by using time-density curve analysis and digital subtraction angiography. METHODS In 31 aneurysms, aneurysmal blood velocity was examined with digital subtraction angiography to determine mean transit time (MTF), peak density time (time to peak opacification) (PDT), and time to half-peak opacification (T1/2). Thirty frames per...

Little is known about the effects of hyperoxia on the cerebral circulation of human infants. Using duplex Doppler we measured the changes in cerebral blood flow velocity in a group of full term (n = 15) and premature infants (n = 17, median gestational age 31 weeks) in response to a transient threefold increase in oxygen tension. Measurements of blood gas tensions as well as blood pressure and ...

To evaluate the capacity of different metabolic indices to predict performance in middle distance swimming, 15 competitive swimmers performed a submaximal and a maximal 400 metres freestyle swimming event. Expired gases were collected in Douglas bags immediately after the events for the determination of VO2 max. Arterialized blood samples were collected for the determination of maximal blood la...

The aims of the present study were to assess critical velocity using the swimmer curriculum in front crawl events and to compare critical velocity to the velocity corresponding to a 4 mmol·l(-1) of blood lactate concentration and to the velocity of a 30 min test. The sample included 24 high level male swimmers ranged between 14 and 16 years old. For each subject the critical velocity, the veloc...

Biophysical behavior of blood in the vasculature is of importance in microcirculation researches. Especially, rheological properties of blood flow have been studied using in vivo and in vitro experiments. This paper describes flow characteristics of in vitro blood flow. In order to obtain velocity distributions with high spatial resolution, a micro PIV technique, which consists of a fluorescent...