Observations on venous pressures and their relationship to capillary pressures / by W.M. Bayliss and E.H. Starling.

  • Bayliss, William Maddock, Sir, 1860-1924.
Date:
1894
Catalogue details

Licence: Public Domain Mark

Credit: Observations on venous pressures and their relationship to capillary pressures / by W.M. Bayliss and E.H. Starling. Source: Wellcome Collection.

Provider: This material has been provided by The Royal College of Surgeons of England. The original may be consulted at The Royal College of Surgeons of England.

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    Section I. Some effects of the vascular nerves on THE CIRCULATION. Section of the cord. The effect of this procedure is seen by comparing Experiments 10 and 11. At the close of Exp. 10, the pressures were Fern. Art. Portal Vein. Fern. Vein (Inf. Cava). 125 mm. Hgb 97 mm. MgSO^sol.^ 60 mm. MgSO^ sol.^ The cord, which had been previously exposed, was then divided just above 1st dorsal vertebra. The pressures after 10 mins, were then found to be (Exp. 11): Fern. Art. Portal Vein. Fern. Vein. 62 mm. 73 mm. 61 mm. We thus see that the effect of the diminished peripheral resistance, which would tend to raise the venous pressure, is exactly counter- balanced by the increased capacity of the system caused by the vaso-motor paralysis. Hence the pressure in the vena cava (peripheral end) is unaltered, while everywhere else there is a fall of pressure. The “ mean pressure ” of the system is diminished by section of the cord. (In many cases, as in the experiment given in the note at the end of this paper, there is also a distinct fall in the vena cava pressure.) Effect on capillary pressure. There is a simultaneous fall of pressure in aorta and portal vein. This however is accompanied and occasioned by relaxation of the arterioles all over the body, including the splanchnic area. As we have shown above, if this diminution of resistance is so great that the velocity of the blood through the capillaries is increased it is impossible to say with certainty whether the capillary pressure will be diminished, increased, or unaltered. It is necessary then to know how the amount of blood howung through the splanchnic area is affected by section of the cord. We have been unable to find any experiment bearing on this cpiestion, so have performed two experiments on the subject. A cannula was put in the splenic vein, and a ligature on a staff • These of course will be understood in the subsequent quotations of pressure.