Hooker [Footnote: Hooker: Am. Jour. Physiol., March, 1916.] says there is a progressive rise of venous pressure from youth to old age. He has described an apparatus [Footnote: Hooker: Am. Jour.
Physiol., 1914, x.x.xv, 73.] which allows of the reading of the blood pressure in a vein of the hand when the arm is at absolute rest, and best with the patient in bed and reclining at an angle of 45 degrees. He finds that just before death there is a rapid rise in venous pressure, or a continuously high pressure above the 20 cm. of water level, and he believes that a venous pressure continuously above this 20 cm. of water limit which is not lowered by digitalis or other means is serious; and that the heart cannot long stand such a condition. These dangerous rises in venous pressure are generally coincident with a fall of systolic arterial pressure, although there may be no constant relation between the two. He also finds that with an increase of venous pressure the urinary output decreases. This, of course, shows venous stasis in the kidneys as well as a probable lowering of arterial pressure.
Clark [Footnote: Clark, A. D.: A Study of the Diagnostic and Prognostic Significance of Venous Pressure Observations in Cardiac Disease, Arch. Int. Med., October, 1915, p. 587.] did not find that venesection prevented a subsequent rapid rise in venous pressure in dire cases. From his investigations he concludes that a venous pressure of 20 cm. of water is a danger limit between compensation and decompensation of the heart, and a rise above this point will precede the clinical signs of decompensation.
Hooker also found that there are daily variations of venous pressure from 10 to 20 cm. of water, with an average of 15 cm., while in sleep it falls 7 or 8 cm.
It seems probable that there may be a special nervous mechanism of the veins which may increase the blood pressure in them as epinephrin solution may cause some constriction.
Wiggers [Footnote: Wiggers C. J.: The Supravascular Venous Pulse in Man, THE JOURNAL. A.M.A., May 1, 1915, p. 1485.] describes a method of taking and interpreting the supraclavicular venous pulse. He also [Footnote: Wiggers C. J.: The Contour of the Normal Arterial Pulse, THE JOURNAL. A.M.A., April 24, 1915, p. 1380.] carefully describes the readings and the different phases of normal arterial pulse, and urges that it should be remembered that "the pulse as palpated or recorded from any artery is the variation in the arterial volume produced by the intra-arterial pressure change at that point."
A quick method of estimating the venous pressure by lowering and raising the arm has long been utilized. The dilatation of the veins of the back of the hand when the hand is raised should disappear, and they should practically collapse, in normal conditions, when the hand is at the level of the apex of the heart. When the venous pressure is increased, this collapse will not occur until the hand is above the level of the heart. Oliver [Footnote: Oliver: Quart.
Med Jour., 1907, i, 59.] found that the venous pressure denoted by the collapse of the veins may be shown approximately in millimeters of mercury by multiplying by 2 each inch above the level of the heart in which the veins collapse. When a normal person reclines after standing there is a fall in venous pressure, and when he again stands erect there is an increase in venous pressure.
Bailey [Footnote: Bailey: Am. Jour Med. Sc., May, 1911, p. 709.]
states that in interpreting pulsation in the peripheral veins, it should not be forgotten that they may overlie pulsating arteries.
Pulsation in veins may be due also to an aneurysmal dilatation, or to direct connection with an artery. As the etiology in many instances of varicose veins is uncertain, he thinks that they may be caused by incompetence of the right heart, more or less temporary perhaps, from muscular exertion. This incompetence being frequently repeated, peripheral veins may dilate. Moreover, the contraction of the right heart may cause a wave in the veins of the extremities, and he believes that incompetency of the tricuspid valve may be the cause of varicosities in the veins of the extremities.
NORMAL BLOOD PRESSURE FOR ADULTS
Woley [Footnote: Woley, II. P.: The Normal Variation of the Systolic Blood Pressure, THE JOURNAL A. M. A., July 9, 1910, p. 121.] after studying, the blood pressure in a thousand persons, found that the systolic average for males at all ages was 127.5 mm., while that for females at all ages was 120 mm. He found the average in persons from 15 to 30 years to be 122 systolic; from 30 to 40, 127 mm., and from the ages of 40 to 50, to be 130 mm.
Lee [Footnote: Lee: Boston Med. and Surg. Jour., Oct. 7, 1915.]
examined 662 young men at the average age of 18, and found that the average systolic blood pressure was 120 mm., and the average diastolic 80 mm. Eighty-five of these young men, however, had a systolic pressure of over 140. It is not unusual to find that a young man who is very athletic has an abnormally high systolic pressure.
Barach and Marks [Footnote: Barach, J. H., and Marks, W. L.: Blood Pressures: Their Relation to Each Other and to Physical Efficiency, Arch. Int. Med., April, 1914, p 648.] in a series of 656 healthy young men, found that the systolic pressure was above 150 in only 10 percent, and that in 338 cases the diastolic pressure, read at the fifth phase, did not exceed 100 mm. in 96 percent
Nicholson [Footnote: Nicholson: Am. Jour. Med. Sc., April, 1914, p.
514.] believes that with a low systolic pressure and a large pressure pulse there is probably a strong heart and dilated blood vessels, while with a low systolic pressure and a small pressure pulse the heart itself is weak, with also, perhaps, dilated blood vessels. If there is a high systolic pressure and a correspondingly high diastolic pressure, the balance between the vessels and the heart is compensated as long as the heart muscle is sufficient. He believes the velocity of the blood in the blood stream may be roughly estimated as being equal to the pressure pulse multiplied by the pulse rate.
Faber 44 [Footnote: Faber: Ugeskrifta f. Laeger, June 10, 1915.]
examined 211 obese patients, and in 182 of these there was no kidney or vascular disturbance. In 52 percent of these 211 persons the systolic pressure was under 140, while in the remaining 48 percent it ranged from 145 to 200 mm.
BLOOD PRESSURE IN CHILDREN
May Michael, [Footnote: Michael, May: A Study of Blood Pressure in Normal Children, Am. Jour. Dis. Child., April, 1911, p. 272.] after a study of the blood pressure in 350 children, came to the conclusion that the blood pressure in children increases with age princ.i.p.ally because of the increase in height and weight, as she found that children of the same age but of different weights and heights had different blood pressures. s.e.x in children makes no difference in the blood pressure, it being determined by the height and weight.
Judson and Nicholson [Footnote: Judson, C. F., and Nicholson, Percival: Blood Pressure in Normal Children, Am. Jour. Dis. Child., October, 1914, p. 257.] made 2,300 observations in children of from 3 to 15 years of age, and found there was a gradual increase in the systolic blood pressure from 3 to 10 years, and a more rapid rise from 10 to 14, with a rapid elevation during the fourteenth year, or the age of p.u.b.erty. The systolic pressure varied from 91 mm. in the fourth year to 105.5 in the fourteenth year, while the diastolic pressure remained almost at a uniform level. The pressure pulse, therefore, increased progressively with the increase of the systolic pressure.
BLOOD PRESSURE AND INSURANCE
An epitome of the consensus of opinion of the risk of accepting persons for insurance as modified by the blood pressure is presented by Quackenbos. [Footnote: Quackenbos: New York Med. Jour., May 15, 1915, p. 999.] Some companies have ruled that at the age of 20 they will take a person with a systolic pressure up to 137; at the age of 30 up to 140; at the age of 40 up to 144; at 50 up to 148, and at 60 up to 153, although some companies will not accept a person who shows a persistent systolic pressure of 150. Quackenbos says that when persons with higher blood pressures than the foregoing have been kept under observation for some time, they sooner or later show alb.u.min and casts in the urine. In other words, this stage of higher blood pressure is too frequently followed by cardiovascular-renal disease for insurance companies to accept the risk.
On the other hand, too low a systolic pressure in an adult, 105 mm.
or below, should cause suspicion of some serious condition, the most frequent being a latent or quiescent tuberculosis. Such low pressure certainly shows decreased power of resistance to any acute disease.
Statistics prove that there are more deaths between the ages of 40 and 50 from cardiovascular-renal disease, that is from heart, arterial and kidney degenerations, than formerly. Whether this is due to the high tension at which we all live, or to the fact that more children are saved and live to middle life, or whether the prevention of many infectious diseases saves deficient individuals for this middle life period, has not been determined. Probably all are factors in bringing about these statistics.
While the continued use of alcohol may not cause arteriosclerosis directly, it can cause such impaired digestion of foods in the stomach and intestine, and such impaired activity of the glands, especially the liver, that toxins from imperfect digestion and from waste products are more readily produced and absorbed, and these are believed by some directly or indirectly to cause cardiovascular- renal disease. Hence alcohol is an important factor in causing the death of persons from 40 to 50 years of age.
The question of whether or not a person smokes too much, and what const.i.tutes oversmoking, will soon be asked on all insurance blanks.
As tobacco almost invariably raises the blood pressure, and when the blood pressure again falls there is again a craving in the man for the narcotic, it must be a factor in producing, later in life, cardiovascular-renal disease. Hence an increased systolic blood pressure must be in part interpreted by the amount of tobacco that the person uses. BLOOD PRESSURE AND PREGNANCY Evans [Footnote: Evans: Month. Cyc. and Med. Bull., November, 1912, p. 649.] of Montreal studied thirty-eight pregnant women who had eclampsia, alb.u.minuria and toxic vomiting, and found the systolic pressures to vary from 200 to 140 mm. He did not find that the highest pressures necessarily showed the greatest insufficiency of the kidneys, but that the blood pressure must be considered in conjunction with other toxic symptoms. In thirty-two cases he was compelled to induce labor when the blood pressure was 150 mm. or under, while in four cases with a blood pressure over 150 mm., the toxic symptoms were so slight that the patients were allowed to go to term and had natural deliveries.
A rising blood pressure in pregnancy, when a.s.sociated with other toxic symptoms, is indicative of danger, and Evans believes that a systolic pressure of 160 mm, is ordinarily the danger limit.
Newell [Footnote: Newell, h. S.: The Blood Pressure During Pregnancy, THE JOURNAL A. M. A., Jan. 30, 1915, p. 393.] has studied the blood pressure during normal pregnancy, and finds that when the systolic pressure is persistently below 100, the patient is far below par, and that the condition should be improved in order for her to withstand the strain of parturition. When the systolic pressure is above 130, the patient should be carefully watched, and he thinks that 150 is the danger line. Some pregnant women have an increasing rise in blood pressure throughout the pregnancy, without alb.u.minuria. In other cases this rise is followed by the appearance of alb.u.min in the urine. Thirty-nine of the patients studied by Newell had alb.u.min in the urine without increase in blood pressure; hence he believes that a slight amount of alb.u.min may not be accompanied by other symptoms. Five patients had a blood pressure of 140 or over throughout their pregnancy, and in only one of these patients was alb.u.min found. All pa.s.sed through labor normally, showing that a blood pressure below 150 may not necessarily be indicative of a serious condition; but a patient who has a systolic pressure over 135 must certainly be carefully watched. A fact brought out by Newell"s investigations is very important, namely, that a continuously increased blood pressure is not as indicative of trouble as when a blood pressure has been low and later suddenly rises.
Hirst [Footnote: Hirst: Pennsylvania Med. Jour., May, 1915, p. 615.]
also urges that a high blood pressure in pregnancy does not necessarily represent a toxemia, and also that a serious toxemia can occur with a blood pressure of 130 or lower, although such instances are rare. Hirst believes that when a toxemia is in evidence in pregnancy while the blood pressure is low, the cause of the toxemia is liver disturbance rather than kidney disturbance, and he thinks this form of toxemia is more serious and has a higher mortality than the nephritic type. Therefore in a patient with eclamptic symptoms and a low blood pressure, the prognosis is more unfavorable than when the blood pressure is high. He believes that if high blood pressure occurs early in the months of pregnancy, there is preexisting, although perhaps latent, nephritis. In these conditions the diastolic pressure is also likely to be high.
With the patient eclamptic and stupid, whatever the date of the pregnancy, Hirst would do venesection immediately in amount from 16 to 24 ounces, depending on what amount seems advisable. If venesection is done before actual convulsions have occurred, the blood pressure falls temporarily but rapidly rises again. He finds that if a patient is past the eighth month, rupture of the membranes will usually bring a rapid fall of from 50 to 90 points in systolic pressure. Usually, of course, such rupture of the membranes will induce labor. He finds that the fluidextract of veratrum viride is valuable when eclampsia is in evidence or imminent. He gives it hypodermically, 15 minims at the first dose and 5 minims subsequently, until the systolic pressure is reduced to 140 or less.
He admits that this is rather strenuous treatment. He does not speak of treatment by thyroid extracts, which has been regarded as valuable by some other workers.
In these patients who show eclamptic symptoms, he maintains a milk diet, and purging and sweating. It should be remembered that venesection or profuse bleeding during induced parturition is more valuable than sweating in all eclamptic cases and in all nephritic convulsions. Profuse sweating does little more than take the water out of the blood, and even concentrates the poisons in the blood.
Hirst causes purging by 2 ounces of castor oil and a few minims of croton oil. He also advises large doses of magnesium sulphate. In such serious disturbances as eclampsia, it is not necessary to give a magnesium salt, which, it has been shown, can have unpleasant action on the nervous system. Sodium sulphate is as valuable and is not open to this danger.
Hirst urges that whatever the blood pressure, with alb.u.minuria, as soon as persistent headache occurs, and especially if there are disturbances of vision, the pregnancy must be terminated at once. On this there can be no other opinion. Temporizing with such a case is inexcusable.
After labor has been induced there is an immediate fall of blood pressure, which lasts some hours. The pressure will again rise, and usually is the last sign of toxemia to disappear, and he finds that this increased pressure may last from two to three weeks when there is not much nephritis, and several months when there is nephritis.
Although he says he has found no bad action from ergot, either by the mouth or hypodermically in these eclamptic cases, it would seem inadvisable to use ergot, which may raise the blood pressure. He finds that pituitary extract "can cause dangerous rise of blood pressure."
Pelissier [Footnote: Pelissier: Archiv. mens., d"obst. et de gynec., Paris, 1915, iv, No. 5.] believes that when there is prolonged vomiting in early pregnancy, with an increase in systolic blood pressure, and with an increased viscosity of the blood, the outlook is serious, and active treatment should be inaugurated.
Irving [Footnote: Irving, F. C.: The Systolic Blood Pressure in Pregnancy, THE JOURNAL A. M. A., March 25, 1916, p. 935.] reports, after a study of 5,000 pregnant women, that in 80 percent the systolic blood pressure varied from 100 to 130; in 9 percent it was below 100, at least at times, but a pressure below 90 does not mean that the woman will suffer shock; in 11 percent the pressure was above 130, and high pressure in young pregnant women more frequently indicates toxemia than when it occurs in older women; high pressure is more indicative of toxemia than is alb.u.minuria; a progressively increasing blood pressure is of bad omen, and most cases of eclampsia occur with a pressure of 160 or more, but eclampsia may occur with a moderate blood pressure. Irving believes that with proper preliminary preventive treatment most eclampsia is preventable.
ALt.i.tUDE
It has long been known that alt.i.tude increases the heart rate and tends to lower the systolic and diastolic blood pressures; that these conditions, though actively present at first, gradually return to normal, and that after a prolonged stay at the alt.i.tude may become nearly normal for the individual. Burker [Footnote: Burker, K.; Jooss, E.; Moll, E., and Neumann, E.: Ztschr. f. Biol., 1913, lxi, 379. The Influence of Alt.i.tude on the Blood, editorial, THE JOURNAL A. M. A., Nov. 1, 1913, p. 1634.] showed that alt.i.tude increases the red blood cells from 4 to 11.5 percent, and the hemoglobin from 7 to 10 percent The greatest increase in these readings is in the first few days. It has also been shown that with every 100 mm. of fall of atmospheric pressure there is an increased hemoglobin percentage of 10 percent over that at the sea level.
[Footnote: Blood and Respiration at Moderate Alt.i.tudes, editorial, THE JOURNAL A. M. A., Feb. 20, 1915, p. 670.]
Schneider and Havens [Footnote: Schneider and Havens: Am. Jour.
Physiol., March, 1915.] find that in low alt.i.tudes abdominal ma.s.sage increases the red corpuscles, and the percentage of hemoglobin in the peripheral vessels. While there is thus apparently a reserve of red corpuscles while the individual is in a low alt.i.tude, in a high alt.i.tude they find such reserve to be absent; in other words, abdominal ma.s.sage did not cause this increase in red corpuscles in the peripheral vessels. This absence of reserve is easily accounted for by the fact that after one reaches the high alt.i.tude there is an increase in red corpuscles and hemoblogin in the peripheral blood.
Schneider and Hedblom [Footnote: Schneider and Hedblom: Am. Jour., Physiol., November, 1908.] showed that the fall in systolic pressure at alt.i.tudes is greater and more certain than the fall in diastolic, some individuals even having a rise in diastolic pressure. This rise in diastolic pressure is probably caused by dyspnea.
Schrumpf, [Footnote: Schrumpf: Deutsch. Arch. f. klin. Med., 1914, cxiii, 466] on the other hand, finds that normal blood pressure is not much affected by an ascent of about 6,500 feet, while patients with arteriosclerosis and hypertension, without kidney disease, have a fall in pressure. A patient with coronary disease should certainly not go to any great alt.i.tude, while patients with compensated valvular lesions, he found, were not injured by ordinary heights. He found that alt.i.tude seemed to decrease high systolic and diastolic pressures, while it even elevated those which were below normal, and caused these patients to feel better.
Any person who has a circulatory disturbance, and who must or does go to a higher alt.i.tude, should rest for a series of days, until his blood pressure and blood have reached an equilibrium.
Smith [Footnote: Smith, F. C.: The Effect of Alt.i.tude on Blood Pressure, THE JOURNAL A. M. A., May 29, 1915, p. 1812.] made a series of observations on blood pressures at Fort Stanton which has an alt.i.tude of 6,230 feet. He took the blood pressure readings in fifty-four young adults, seventeen of whom were women, and found that the average systolic reading in the men was 129 mm., and in the women 121, while the average diastolic in the men was 84, and in the women 82. Therefore he agrees with Schrumpf that the effect of alt.i.tude on normal blood pressure has been overestimated. In tuberculosis he found that the effect of alt.i.tude was not great. He does not believe that this amount of alt.i.tude, namely, a little more than 6,000 feet, makes much difference in an ordinary tuberculous patient. He did not find that artificial pneumothorax made any important change in the blood pressure. His findings do not quite agree with Peters and Bullock, [Footnote: Peters, L. S.r and Bullock, E. S.: Blood Pressure Studies in Tuberculosis at a High Alt.i.tude, Arch. Int. Med., October, 1913, p. 456.] who studied 600 cases of tuberculosis at an alt.i.tude of 6,000 feet, and found the blood pressure was increased, both in normal and in consumptive individuals. They also found that the increase in blood pressure, which kept gradually rising up to a certain limit, was indicative that the tuberculous patient was not much toxic; therefore the increase in blood pressure was of good prognosis.
CONDITIONS CAUSING CHANGE IN BLOOD PRESSURE