BLOOD PRESSURE AND EFFORT

Press, Volume LXXXIII, Issue 25307, 6 October 1947, Page 6

BLOOD PRESSURE AND EFFORT

SUPPLY OF OXYGEN TO MUSCLES

. MEDICAL OPINIONS

Medical witnesses for the defence gave their opinions on the effect of effort on blood pressure when they fave evidence in a case heard by Mr ustice Ongley in the Compensation Court. i . “I believe that ordinary effort produces very little variation and very little change in the blood pressure within the arteries. I think it could be taken that the pressure within the cerebral arteries is more or less the same as the pressure, say, in the arteries of the arm where the blood pressure is usually taken,” said Dr. P. P. Lynch, pathologist, Wellington. “During effort there* is a great demand made by the muscles for a supply of oxygen. That increase in supply is made up by an increase in the blood flow. That is achieved by an increase in the -flow in the, veins, which is brought about by an increase in respiratiori; it is made up also by acceleration of the pulse rate, the blood flows quicker; it is made up by dilatation of some of the surface vessels so that resistance to the blood flow is diminished; and lastly, the increase in the blood flow is made up by an increase jn the arterial blood pressure. “The effect of effort 7 in my opinion, even where the effort is severe, is not to cause more than a slight increase in the arterial blood pressure. At the end of the effort the blood pressure would go back quite quickly. “The extent to which blood pressure is increased by exertion would depend on the nature of the effort and whether it was an effort to which the person was accustomed. The range of arterial blood pressure that might occur, say, in the arteries of a practised and experienced shearer would be very much less than in a person not accustomed to the work and found it laborious.

Special Mechanisms “There are some ways by which the blood volume to the muscles can be increased without great increase in the blood pressure. Some of the physiologists say there are special mechanisms affecting the cerebral circulation as opposed to the circulation m the muscles. Most of the differences between the needs of the brain anc 1 the needs of the muscles are got over by factors other than those that lead to the actual increases in the arteries.” “It is suggested that stooping would have a definite influence in raising the blood pressure. I don’t know, it might by a very few points; but surely it is such a temporary effort that the few points it could raise the pressure m that time would be very small,” - A - B - Pearson, director of the Pathological Department at the Christchurch Public Hospital. “Mr Bennett referred to fainting and to lowering the patient to restore the blood pressure in the cerebral arteries. I would think that fainting is not only a question of blood pressure, but largely one of blood volume, and it is the restoration of volume which is just as important as pressure. “I agree with Dr. Lynch that ordinary work produces very little variation in the blood pressure within the arteries.”