Hypotension

HYPOTENSION, or hypotension, is reduced blood pressure below normal (for reduction in venous and capillary pressure - see Blood Pressure). By arterial hypotension is meant reduction in mean arterial pressure, unless specifically speaking of systolic or diastolic hypotension. The lower limit of normal for maximum (systolic) arterial pressure is conventionally considered to be 105 mm Hg for men, 100 for women; of minimum (diastolic) pressure, 65 mm for men, 60 for women. Reduction of maximum arterial pressure below the indicated limit by more than 20-30 mm is rarely encountered. With pressure reduction, the minimum is usually reduced to a lesser degree than the maximum, so that pulse pressure decreases. Hypotension occurs also in completely healthy, fully capable people (in 2¹/₂-3¹/₂%). Based on the experience of American life insurance companies, hypotension after 40-50 years of age (of course, in the absence of the pathological conditions accompanied by hypotension mentioned below) rather gives the right to expect a longer life span; according to these societies, mortality among persons of this age with hypotension amounts to only 35%, compared to 80% mortality on average for this age. Among Chinese, Negroes, inhabitants of the Philippine Islands and Bengal, pressure is on average 10-20-30 mm Hg lower than among Europeans. But with longer residence of the latter in the respective countries, their pressure in most cases also tends to decrease and is established on average 10 mm Hg lower than previously (Tung). Whether the nature of nutrition or the warmer climate plays a role here has not yet been clarified. It creates the impression that in northern and temperate climates arterial pressure is on average lower in summer than in winter. Remarkably, in persons who engage intensively and systematically in sports, absolutely healthy and resistant, arterial pressure at rest is almost invariably lowered. Under pathological conditions - hypotension is above all a symptom of numerous disease states, acute and chronic. Of acute conditions - hypotension is observed in the most pronounced degree in traumatic and anaphylactic shock, general anesthesia and in all acute infectious diseases. The degree of hypotension is approximately proportional to the height of temperature, but to a greater extent is determined by the severity of the general condition. Of chronic diseases, hypotension is characteristic of tuberculosis, mainly pulmonary; the degree of hypotension here is also proportional primarily to the severity of the general phenomena of intoxication. In severe insufficiency of cardiac activity, sometimes a sharp drop in arterial pressure is observed, although conversely, moderate elevation is often encountered. All diseases causing exhaustion, cachexia, anemia, are also accompanied by a drop in arterial pressure. Particular interest is presented by hypotension in certain diseases of the endocrine glands, namely - in Addison's disease, in myxedema and in the so-called pluriglandular insufficiency. Prolonged starvation or undernutrition, especially deficiency of proteins and fats in the diet, causes marked hypotension. In all these conditions, hypotension is only a symptom. Besides this, among ambulatory and hospitalized patients, 2.5-5% can be found who have hypotension with conditions that cannot be classified as one or another specific form of disease. These are usually persons with asthenic constitution, thin, pale (but not anemic). Lymph glands are sometimes enlarged, the heart is rather small, there are no signs of its insufficiency, but with heavy physical work it shows signs of weakness. The pulse is more often slowed (sinus bradycardia), and extrasystole is also observed. Hypotension, in contrast to hypertension, shows increased stability of the arterial pressure level, venous pressure is slightly above normal, extremities are sometimes cyanotic, cold. Often there is ptosis of abdominal organs. The main complaints of such persons are dizziness, fainting, weakness, rapid physical fatigue, less often mental, shortness of breath with movement, less often headaches, tendency to diarrhea and constipation, periodic polyuria. Often in such persons weakly expressed symptoms of decreased function of the adrenal glands and thyroid gland are encountered. Sometimes infantilism and an undeveloped picture of pluriglandular insufficiency are found. Martini and Pierach draw attention to the frequently observed in such hypotension decrease in the sella turcica on skull radiographs, suggesting the presence of an abnormally small pituitary gland. From the side of the autonomic nervous system, symptoms of vagotonia, resp. sympathicohypotonia can often be noted: besides the mentioned bradycardia - also hypothermia, lymphocytosis, etc. The hypotension itself represents 18 rather a vagotonic, resp. sympathicohypotonic symptom. But often (as is generally almost the rule in pathological functional states of the autonomic nervous system), along with vagotonic symptoms, sympathicotonic symptoms are also encountered. - In the cases briefly characterized here, accompanied by hypotension, it is difficult to make a definite diagnosis. In any case, it is hardly possible to attribute to the lowered arterial pressure the same significance that is attached to elevated pressure in essential hypertension. Hypotension is only one of the symptoms of this symptom complex, causing no severe consequences, whereas in most cases of hypertension the elevated arterial pressure itself entails a series of severe consequences. Therefore, one can speak only of a hypotonic symptom complex, calling it so after the most distinct, measurable symptom. That this hypotonic symptom complex is usually observed in asthenic constitution, is often accompanied by one or another disturbances of function of the endocrine glands and autonomic nervous system; that in it no anamnestic indications of the cause of the disease are encountered - all this speaks for the constitutional origin of the pathological condition that underlies this symptom complex. - The pathogenesis of hypotension itself in these cases has not yet been sufficiently studied. One can assume that endocrine-vegetative-nervous peculiarities determine the lowered tone of the entire vasomotor system, mainly its centers. Generally, the lowering of arterial pressure observed as a symptom in the above-mentioned pathological conditions is most likely in most cases the result of lowered tone of arterial musculature due to nerve-reflex, toxic, endocrine, etc. effects on various parts of the nerve-muscle apparatus maintaining arterial pressure. - The prognosis in the hypotonic symptom complex is unquestionably favorable. If with hypotension the above-mentioned symptom complex is observed, then treatment is necessary, which should consist of rest, enhanced nutrition and all climatic-therapeutic, balneotherapeutic and physical therapy methods having a general strengthening, tonic effect. Of medications, preparations of arsenic, strychnine and caffeine are appropriate. Organotherapy is appropriate only with clearly expressed insufficiency of a specific endocrine gland. Hypotonia of muscles, see Tonus.