Factors Increasing The Blood Pressure


Categories: Uncategorized
Sources: Disturbances Of The Heart

With normal heart and arteries, exertion and exercise should

increase the systolic pressure, and generally somewhat increase the

diastolic pressure. The pressure pulse should therefore be greater.

When there is circulatory defect or abnormal blood pressure,

exercise may not increase the systolic pressure, and the pressure

pulse may grow smaller. As a working rule it should be noted that

the diastolic pressure is not as much influenced by physiologic

factors or the varying conditions of normal life as is the systolic

pressure.



In an irregularly acting heart the systolic pressure may vary

greatly, from 10 to 20 mm. or more, and a ventricular contraction

may not be of sufficient power to open the semilunar valves. Such

beats will show an intermittency in the blood pressure reading as

well as in the radial pulse. The succeeding heart beats after

abortive beats or after a contraction of less power have increased

force, and consequently give the highest blood pressure. Kilgore

urges that these highest pressures should not be taken as the true

systolic blood pressure, but the average of a series of these

varying blood pressures. In irregularly acting hearts it is best to

compress the arm at a point above which the systolic pressure is

heard, then gradually reduce the pressure until the first systolic

pressure is recorded, and then keep the pressure of the cuff at this

point and record the number of beats of the heart which are heard

during the minute. Then reduce the pressure 5 mm. and read again for

a minute, and so on down the scale until the varying systolic

pressures are recorded. The average of these pressures should be

read as the true systolic blood pressure. During an intermittency of

the pulse from a weak or intermittently acting ventricle, the

diastolic pressure will reach its lowest point, and in auricular

fibrillation the pressure pulse from the highest systolic to the

lowest diastolic may be very great.



In arteriosclerosis the systolic may be high, and the diastolic low,

and hence a large pressure pulse. When the heart begins to fail in

this condition, the systolic pressure drops and the pressure pulse

shortens, and of course any improvement in this condition will be

shown by an increase in the systolic pressure. The same is true with

aortic regurgitation and a high systolic pressure.



If the systolic pressure is low and the diastolic very low, or when

the heart is rapid, circulation through the coronary vessels of the

heart is more or less imperfect. Any increase in arterial pressure

will therefore help the coronary circulation. The compression of a

tight bandage around the abdomen, or the infusion of blood or saline

solutions, especially when combined with minute amounts of

epinephrin, will raise the blood pressure and increase the coronary

circulation and therefore the nutrition of the heart.



MacKenzie [Footnote: MacKenzie: Med Rec., New York, Dec. 18, 1915.],

from a large number of insurance examinations in normal subjects,

finds that for each increase of 5 pulse beats the pressure rises 1

mm. He also finds that the effect of height on blood pressure in

adults seems to be negligible. On the other hand, it is now

generally proved that persons with overweight have a systolic

pressure greater than is normal for individuals of the same age. He

believes that diastolic pressure may range anywhere from 60 mm. of

mercury to 105, and the person still be normal. A figure much below

60 certainly shows dangerous loss of pressure, and one far below

this, except in profound heart weakness, is almost pathognomonic of

aortic regurgitation. While the systolic range from youth to over 60

years of age gradually increases, at the younger age anything below

105 mm. of mercury should be considered abnormally low, and although

150 mm. at anything over 40 has been considered a safe blood

pressure as long as the diastolic was below 105, such pressures are

certainly a subject for investigation, and if the systolic pressure

is persistently above 150, insurance companies dislike to take the

risk. However, it should be again urged in making insurance

examinations that psychic disturbance or mental tensity very readily

raises the systolic pressure. MacKenzie believes that a diastolic

pressure over 100 under the age of 40 is abnormal, and anything over

the 110 mark above that age is certainly abnormal.



It has been shown, notably by Barach and Marks, [Footnote: Barach,

J. H., and Marks, W. L.: Effect of Change of Posture--Without Active

Muscular Exertion--on the Arterial and Venous Pressures, Arch. Int.

Med., May, 1913, p 485.] that posture changes the blood pressure.

When a normal person reclines, with the muscular system relaxed,

there is an increase in the systolic pressure and a decrease in the

diastolic pressure, with an increase in the pressure pulse from the

figures found when the person is standing. When, after some minutes

of repose, he assumes the erect posture again, the systolic pressure

will diminish and the diastolic pressure increase, and the pressure

pulse shortens.



Excitement can raise the blood pressure from 20 to 30 mm., and if

such excitement occurs in high tension cases there is often a

systolic blow in the second intercostal space at the right of the

sternum. This may not be due to narrowing of the aortic orifice; it

may be due to a sclerosis of the aorta. On the other hand, it may be

due entirely to the hastened blood stream from the nervous

excitability. This is probably the case if this sound disappears

when the patient reclines. If it increases when the heart becomes

slower and the patient is lying down, the cause is probably organic.



This psychic influence on blood pressure is stated by Maloney and

Sorapure [Footnote: Maloney and Sorapure: New York Med. Jour., May

23, 1914, p. 1021.] "to be greater than that from posture, than that

arising from carbonic acid gas control of the blood, than that

arising from mechanical action of deep breathing upon the

circulation, and than that arising from removal of spasm from the

musculature."



Weysse and Lutz [Footnote: Weysse and Lutz: Am. Jour. Physiol., May,

1915.] find that the systolic pressure varies during the day in

normal persons, and is increased by the taking of food, on an

average of 8 mm. The diastolic pressure is not much affected by

food. This increased systolic pressure is the greatest about half an

hour after a meal, and then gradually declines until the next meal.



Any active, hustling man, or a man under strain, has a rise of blood

pressure during that strain, especially notable with surgeons during

operation, or with brokers or persons under high nervous tension.

Daland [Footnote: Daland: Pennsylvania Med Jour., July, 1913.]

states that a man driving an automobile through a crowded street may

have an increase of systolic pressure of 30 mm., and an increase of

15 mm. in his diastolic pressure, while the same man driving through

the country where there is little traffic will increase but 10 mm.

systolic and 5 mm. diastolic. Fear always increases the blood

pressure. This is probably largely due to the peripheral

contractions of the blood vessels and nervous chilling of the body.





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