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M H Knisely

Publications and source records attributed to M H Knisely.

16 recordsLinked to original sources
PubMed1976

A stochastic model for the transport of oxygen to brain tissue.

Material balances around a small, but finite volume element have formed the basis for previous mathematical models describing the transport of oxygen in the brain microcirculation. Seeking a model which would be both simple and versatile, a stochastic model was proposed based on the assumption that oxygenation of the brain can be described quantitatively by simulating the activity of only one erythrocyte and the oxygen molecules surrounding it. Compared with existing deterministic models, the capillary space-average oxygen partial pressure profiles were in close agreement. Tissue tensions were decidedly different.

Blood Flow Velocity↗
PubMed1971

Effect of microcirculation changes on brain tissue oxygenation.

1. A new, 2 mu tip, oxygen micro-electrode and a constantly circulated Beckman oxygen gas analyser were used to measure tissue and blood P(O) (2) in anaesthetized, curarized cats under positive pressure breathing. As a parameter for the ability of the circulation to oxygenate tissue, the ;reoxygenation time' (defined as the time required to reach the previous P(O) (2) level after a short period of anoxic anoxia) was determined on blood and cerebral cortex.2. First, it was found that haemorrhage (from 15-25 c.c./kg) alone or haemorrhage combined with sludging of the blood (by the I.V. administration of high molecular weight Dextran, 1 g/kg) markedly diminished P(O) (2) levels in blood and tissue.3. Further, the reoxygenation time was significantly affected by these procedures. Sludging markedly prolonged the reoxygenation time, an effect counteracted by the use of an anti-adhesive drug breaking up the red cell aggregates.4. Bleeding prolonged the reoxygenation time up to four times that found in the same animals previous to the bleeding.

Animals↗