Blood flow

About: Blood flow is a research topic. Over the lifetime, 27604 publications have been published within this topic receiving 735527 citations.

Real-Time Two-Dimensional Blood Flow Imaging Using an Autocorrelation Technique

Abstract: A new blood Row imaging system is described that com- bines a conventional pulsed Doppler device and a newly developed au- tocorrelator. In the system blood flow within a given cross section of a live organ is displayed in real time. The direction of blood Row and its variance are expressed by means of a difference in color and its hue, respectively. Experiments were conducted with a mechanical and an electrical scanner using phantoms, and good agreement with the theory was obtained. Studies on clinical significance have also been carried out for normal and diseased hearts, and successful results have been found.

Measurement of Coronary Sinus Blood Flow by Continuous Thermodilution in Man

Abstract: A technique was developed for measurement of blood flow in the coronary sinus in man by continuous thermodilution. For single determinations, 5% dextrose at room temperature is injected at a constant rate of 35 ml/min for a period of about 20 sec. In 14 subjects with normal coronary arteries the mean coronary sinus blood flow was 122 ± 25 ml/min (range, 83 to 159 ml/min). The blood flow computed per 100 g of left ventricle was 82 ± 16 ml/min, which is in the range of values obtained by nitrous oxide and coincidence counting methods. In 35 patients with arteriographically confirmed coronary artery disease the mean flow was similar (128 ± 20 ml/min; range, 92 to 167 ml/min). A special catheter was used for simultaneous measurement of blood flow in the coronary sinus and great cardiac vein. In eight normal subjects the mean great cardiac vein flow was 68 ± 11 ml/min (range, 51 to 78 ml/min) or 65 ± 10% of the coronary sinus blood flow. The method allowed continuous measurement of flow over a period of severa...

The determination of cerebral blood flow in man by the use of nitrous oxide in low concentrations

Abstract: Quantitative measurements of the total blood flow to the brain of man have not previously been reported and the few procedures which have been used for the purpose of obtaining relative or qualitative values have recently been subjected to considerable criticism (1). The method to be described is based on the principle that the rate at which the cerebral venous blood content of an inert gas approaches the arterial blood content depends upon the volume of blood flowing through the brain. Certain aspects of this principle were recognized by Haggard (2) who postulated that the rate at which an anesthetic gas is taken up by the brain depends in part on the rate of blood flow to that organ, and similarly by Ferris, Molle a,nd Ryder (3) who stated that the clearance of nitrogen from the brain during the inhalation of 100 per cent oxygen may be markedly influenced by the magnitude of cerebral blood flow. As far as we are aware, however, the principle has not previously been subjected to mathematical analysis and applied to actual measurements of cerebral blood flow in animals or man. The experiments described in the preceding report (4) a,fforded an opportunity for calibrating this procedure against direct measurements of cerebral blood flow and thus for refining the technical and theoretical fact,ors to a degree that would not otherwise have been possible. METHODS. The specific substance which is employed is not of consequence provided that it is physiologically inert in the concentrations employed, capable of diffusing rapidly across the blood-brain barrier, and susceptible of accurate analysis in the blood. It need not$ even be a gas if it meets all these requirements. In the present experimentIs nitrous oxide has been employed although ot#her gases may be found to be more suittable. Radioact,ive gases offer certain unique advantages and their use is being considered. In the animal experiments t,he inhaled gas consisted of 40 per cent! nitrous oxide in oxygen which was inhaled through the inspiratory valve attached to the tracheal cannula. In the early experiments on man 15 per cent nitrous oxide and 85 per cent oxygen was employed and was inhaled tlhrough the inlet, t,ube of an anesthesia mask. Because the presence of nit,rogen in t/he blood imroduces cer-

Cardiac nucleotides in hypoxia: possible role in regulation of coronary blood flow.

Abstract: Experiments were performed on isolated cat hearts perfused with Tyrode's solution and intact hearts of open-chest dogs. Cardiac hypoxia resulted in a decrease in coronary vascular resistance and a ...

Distribution of blood flow in isolated lung; relation to vascular and alveolar pressures.

Abstract: The left lung from a dog was removed, ventilated with negative pressure, and perfused with venous blood. Pulmonary arterial, venous, and alveolar pressures could be varied over a large range. The d...