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
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
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
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
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
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
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
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.