Hypotension


Categories: Uncategorized
Sources: Disturbances Of The Heart

A low systolic pressure and a low diastolic pressure may not cause

any symptoms or give any cause for anxiety. It does show, especially

if the systolic pressure is below normal for the age of the person,

a lack of reserve power, and such patients will not well stand

serious illnesses, operations, injuries or serious physical and

mental strains. If there is a low systolic pressure and a high

diastolic pressure, this shows impairment of the heart, whether or

not any other organic lesion is present.



Generally speaking, a low systolic pressure shows a weak acting

heart muscle, and a very low diastolic pressure shows a dilated

condition of the arterioles. In aortic regurgitation this low

diastolic pressure is constantly in evidence, and, if the systolic

pressure is not below normal, does not signify that the circulation

is insufficient. If the systolic pressure is not very low but the

diastolic is high, vasodilator drugs, by lowering the diastolic and

increasing the pulse pressure, are often of benefit. If there is

increased venous congestion and increased venous pressure and a high

diastolic pressure with a low systolic pressure, digitalis not only

will often raise the systolic pressure, but also will lower

diastolic by improving the general circulation and removing venous

congestion.



While intestinal indigestion and absorption of toxins often tend to

raise the blood pressure, some toxins thus absorbed, especially of

the ptomain variety, lower blood pressure and cause shock, perhaps

by weakening the muscle of the heart or by acting on the vasodilator

vessels; or they may cause dilation of the vessels of the abdomen

and in this manner lower blood pressure.



Very low blood pressure after exertion, after severe physical

exercise, or after competitive athletic tests shows that the heart

cannot sustain such strains and should not be again subjected to

them. In severe mental and physical strains the suprarenals may be

inhibited in their activities, and a hypotension, more or less

prolonged, may result.



Sewall [Footnote: Sewall: Am. Jour. Med. Sc., April, 1916, p. 491]

believes that hypotension is frequently due to splanchnic stasis,

and that sluggish circulation in this region, especially when the

person is in the erect posture, is an important factor in general

physiologic disturbances or lack of general tone. When the

splanchnic vessels are dilated there is also a lack of proper tone

to the cerebral vessels, and this may be a cause of mental weariness

and neurasthenia. While ptosis of organs in the abdomen and a

flaccid condition of the musculature of the abdomen are frequent

causes of this splanchlnic stasis, and therefore hypotension,

especially in women, it is quite possible that suprarenal

insufficiency will allow this condition of the splanchnic vessels to

occur frequently.



Serious illness and infections will lower the blood pressure

sometimes to a dangerous point. Of course, hemorrhages lower the

blood pressure. Shock and collapse cause lowering of blood pressure,

frequently to a fatal point, and Cornwall [Footnote: Cornwall: New

York Med. Jour. March 7, 1914, p. 470.] finds that a patient may

live several hours with a systolic pressure below 60, and several

days when it is below 70; that he may walk around with a systolic

pressure of 90, provided the pressure pulse is sufficiently large,

that is, that the diastolic pressure is low enough to cause a

circulation of blood. Of course, if the difference between the

systolic and the diastolic pressure is diminished to the vanishing

point, the patient cannot stand it, and dies. It should be

remembered that just before death venous pressure is likely to rise,

and this may raise the diastolic pressure.



With the progressive toxemia of typhoid fever the blood pressure

will become lowered from the myocardial degeneration. Of course, the

blood pressure will drop suddenly from a hemorrhage, but Piersol

[Footnote: Piersol: Pennsylvania Med. Jour., May, 1914, p. 625]

finds that with perforation the peritoneal irritation may cause a

rise of blood pressure, and he thinks that this sign may precede for

several hours more positive signs of the accident.



As in other infections, the blood pressure will fall in scarlet

fever; but if it suddenly rises, a kidney complication is to be

looked for. The blood pressure always falls in diphtheria, and

always falls in acute rheumatism; consequently, strenuous sweating

measures in the treatment of rheumatism should not be used as soon

as the blood pressure has become low.



Failing circulation in pneumonia, if accompanied by low blood

pressure, requires different treatment from the failure of

circulation in these cases when the blood pressure is high. Hence

the relationship of the systolic to the diastolic pressure in

pneumonia is of very great importance in deciding on the proper

treatment. In one instance the blood pressure must be lowered; in

the other, the heart must be stimulated.



While tobacco, in ordinary conditions, raises the blood pressure,

after the heart has been seriously injured by the nicotin, the blood

pressure is likely to be found lower, and such patients are quickly

benefited by the withdrawal of the tobacco and the administration of

digitalis.



Anemia almost invariably causes low blood pressure. Also in a

patient who has hypotension without any distinct evidence of

disease, especially if there has been any possible exposure to

tuberculosis, that disease should be suspected and every test made

to eliminate such a cause.



Serious cachexia, such as that caused by carcinoma or other growths,

gives low blood pressure. Diabetes causes low blood pressure,

provided there are no nephritis and no marked suprarenal

stimulation.



Excessive use of alcohol, while tending to promote hypertension by

the disturbances that it causes, may give, by causing a weak heart

muscle, a permanent low blood pressure. A single large dose of

alcohol always lowers the blood pressure.



Arteriosclerosis frequently reaches a stage when the blood pressure

is low, and with atheroma of the arteries of the arms a true blood

pressure is difficult to obtain. Addison's disease, or any other

organic lesion of the suprarenals, will lower the pressure, while

stimulation of the suprarenals increases the pressure. Any great

drain on the system, whether from diabetes without nephritis, or

from profuse diarrhea of any type, will cause hypotension.

Occasionally a girl with chlorosis who is not menstruating may have

an increased blood pressure. Many of the hemorrhagic or purpuric

conditions will show a hypotension.



Meningitis in various forms may show a hypertension from cerebral

and nervous irritation. Neurasthenic patients quite generally have

hypotension, although occasionally with suprarenal disturbance they

may have an increased tension.



In the hypotension of surgical shock and in shock during anesthesia,

Henderson's findings [Footnote: Henderson: Am. Jour. Physiol., 1910,

xxvii, 158.] that hyperoxygenation and insufficient carbon dioxid

may be partially responsible for the condition should be remembered,

and it has long been known that carbon dioxid congestion, as caused

by laughing gas anesthesia, for instance, increases the blood

pressure.



A systolic pressure of 110 mm. or lower in an adult should be

considered hypotension, anything below 105 mm. calls for treatment,

and a systolic pressure of 100 or lower in an adult calls for rest

from all active duties.



These patients are weary, they have mental and physical tire, may

get short breathed, may have palpitation of the heart, and often

have headaches and dizziness from imperfect circulation in the head.

There may be edemas of the legs and ankles toward night. If such

patients have the systolic blood pressure raised even a small

amount, or if the diastolic pressure, which is very low, is raised

even a small amount, they immediately feel better.



If the kidneys are normal, they should have meat as part of their

diet. If they are not nervous and irritable, coffee and tea should

be allowed, except at the evening meal. While sleep may tend to

lower pressure somewhat, these patients' hearts require a long bed

rest; in other words, they should go to bed at an early hour. They

should rise early, however, in the morning, and, as recommended by

Goodman, [Footnote: Goodman: Am. Jour. Med. Sc., April, 1914, p.

503.] they should perform mild calisthenic exercises before

dressing.



The increased muscle tone thus caused raises the blood pressure

somewhat, and the great depression before breakfast is not

experienced. These patients rely oil their morning coffee for

bracing. If they have much indigestion at night which keeps them

awake so that they do not get good comfortable rest, their largest

meals should be the morning and noon meals, and the evening meal

should be very light.



Pendent abdomens or ptosed abdominal organs should be held up by

proper abdominal bandages or corsets.



If the bowels are constipated, only the vegetable laxatives should

be used, if it drug is needed at all. Salines should not be allowed,

or other cathartics which cause profuse watery discharges. If a

brisk purge is required, castor oil is the best.



Plenty of fresh air, and mild exercises in the open air all tend to

increase the pressure. Graded walking, climbing, or other more

interesting exercises are advisable, as all tending to raise the

pressure, provided that at no time are they carried to the point of

exhaustion.



Forced feeding may be useful. Cool sponging in the morning, if there

is proper reaction, is often of benefit. Iron may be indicated;

bitter tonics may be indicated. Digitalis and strychnin are often of

advantage. Caffein may be used as a drug as well as given in coffee

and tea. Atropin may be of value in some forms of hypotension.



At times with a low systolic pressure, but a relatively high

diastolic pressure, nitroglycerin is valuable.



More or less actite hypotension may occur in hot weather or with

overheating, often termed heat exhaustion. Such patients should, if

possible, go to a cooler region, whether to the seashore or to the

mountains is unimportant. The treatment of dangerous sudden low

blood pressure, as shock, will be discussed elsewhere.





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