Methods and consequences of lowering the blood pressure / by W.D.M. Paton.

  • Paton, William D. M.
Date:
[1957?]
Catalogue details

Licence: In copyright

Credit: Methods and consequences of lowering the blood pressure / by W.D.M. Paton. Source: Wellcome Collection.

    22/24 (page 38)
    and when the infusion stopped the blood pressure returned quietly to normal. Later it has been found that with continued administration of adrenaline a defect of capillary permeability may appear, leading to a loss of plasma to the tissues and there may be haemorrhages in the pericardium and in the intestine (Freeman, et al., 1941). It is clear that this danger of adrenaline shock is more intense with adrenaline than with noradrenaline. On the practical side it seems to be relatively easily avoided by using noradrenaline if an agent of this sort is required, and by seeing that when the infusion is stopped the drug is slowly tapered off and not abruptly removed. But it is significant that the continued administration of these natural substances, a thing which may well be happening during a prolonged sympathoadrenal discharge in “shock,” may in fact be quite deleterious to the body. In fact one wonders whether part of, the so-called irreversible stage of shock may be marked not so much by some new event to do with the shocking process, as by a development of adrenaline shock as a consequence of an overactive and too prolonged reaction to the body to the original damage. To all this we can add a last bit of evidence which seems to be slowly becoming clear. If you subject animals to haemorrhagic or other types of shock, correspond¬ ing to those occurring in man, they seem to survive better if their sympatho-adrenal reaction is blocked. Thus dogs treated with dibenamine may enter the irreversible stage of shock less readily (Remington, et al., 1950; Lotz, et al., 1955). Rats in which tourniquet shock is produced may survive better if treated with hexa- methonium (Spoerel, 1955). There is another rather different example which is interesting; if you poison mice with anticholinesterases you find that after treatment with hexamethonium they may be protected as much as ten-fold against the poison, protection which may in fact considerably exceed that afforded by the conventional antagonist atropine (Parkes and Sacra, 1954). So there is evidence that if you remove this particular response of the body to various stressful situations, then so far from survival being impaired, it may in fact be improved. I think it is not unfair to mention too the interest taken in procedures such as cooling and ganglion block, and the use of central depressants of various sorts to make a patient more fit for various operative procedures, yet with the expressed intention of abolishing the autonomic responses. The Physiological Significance of the Autonomic Nervous System. The conclusions I have just been outlining, if they are followed to a logical conclusion, produce the rather disconcerting result that the autonomic nervous system may be a substantial liability to the body, and it is this last possibility which I would like briefly to examine. The usual teaching about the sympatho¬ adrenal system is based on the work of Cannon and is expressed in the classical statement that it is a system which confers an advantage on the organism when it meets emergency of some sort, resulting in the need for staying to fight, or taking flight, or expressing fright. It is fairly obvious, I think, from several lines of study that the system is not essential for ordinary life. Cannon (1950) himself showed that, after the sympathetic nervous system had been ablated, a cat could still lead a relatively normal life. It is true that he probably did not remove as