PubMed Health⌕ Search

Biomedical subjects

H D Snow

Publications and source records attributed to H D Snow.

32 records · Page 2Linked to original sources
PubMed1971

Determination of arterial blood flow by percutaneously introduced flow sensors in an external magnetic field. II. Implementation of the method in vivo.

Blood flow in a dog's aorta has been measured by percutaneous introduction of a flow sensor. Two types of flow probes have been used in conjunction with an external magnetic field: Loop-shaped probes used as rate of volume-flow meters and L-shaped probes as velometers. Methods of calibration and establishing the base line are discussed, and the performance of the apparatus is illustrated by records of blood flow in the thoracic and abdominal regions of the aorta.

Acetylcholine↗
PubMed1970

Determination of arterial blood flow by percutaneously introduced flow sensors in an external magnetic field. I. The method.

A method for determining the rate of blood flow in arteries without surgical intervention is described. It is shown that a probe capable of securing such information about flow in a blood vessel can be introduced into the vascular tree by means of a needle puncture in the skin made by a no. 18-guage hypodermic needle. A snugly-fitting guide wire is passed through the needle, which is then withdrawn. A Teflon catheter is then passed over the wire and pushed through the skin and subcutaneous tissues into the superficial branch artery from which the wire guides it deep into the aorta to a desired location. The guide wire is then withdrawn and a suitable sensing device of wire-like structure can be passed through the catheter into the major arterial trunk and, if desired, into some of its branches. Two types of sensors are used, loop-shaped ones which are used as volume-flow meters, and L-shaped probes used as volume-flow meters when they fir the artery precisely and as velometers when they do not. The sensors are used in conjunction with an apparatus consisting of a flat coil mounted over the animal and a standard electromagnetic sinusoidal flow meter channel.

Animals↗
PubMedDate not supplied

The harmful effects of aqueous contrast agents on the gastrointestinal tract: a study of mechanism and means of counteraction.

The effect of mildly and strongly hypertonic solutions on intestinal tone and motility was tested with aqueous contrast solutions and with mannitol as a control in 15 dogs. These experiments were repeated in animals premedicated with atropine sulfate and/or methysergide maleate. Intestinal motility was recorded on serial x-ray films. Tone and motility were estimated by variations of intestinal caliber and rate of transit of contrast solution, respectively. The results obtained contradict the currently accepted mechanism of action of iodinated contrast media on the intestinal tract, which assumes that the effect is osmotic like that of a saline laxative. Solutions of different osmolarity produce hyperperistalsis of the same magnitude. This effect begins rapidly after the onset of gastric emptying and much sooner than a significant osmotic fluid shift occurs. Atropine sulfate and methysergide maleate (serotonin blocker), when given individually, are incapable of completely inhibiting hyperperistalsis induced by hypertonic solutions. However, when these agents are given in combination, motility is completely inhibited. The evidence supports a serotonin role in the hyperperistalsis induced by hypertonic solutions, partly by direct action of serotonin on the smooth muscle cells and partly by indirect action on the intramural cholinergic ganglion cells. This concept offers a possible means of eliminating one of the adverse effects of aqueous contrast media on the gastrointestinal tract.

Animals↗