FIG. 71.-Male. Aged forty-two. Hemorrhage from gastric ulcer. Exmination prior to hemorrhage (A) shows a slightly elevated systolic pressure in one of rather active physical and mental habits. Pressure recorded

at (B) was made a few hours after a copious hemorrhage from gastric ulcer, at which time the patient was almost totally blind, showed extreme pallor and apathy, with a rapid-running pulse, and hurried gasping respiration. By actual measurement the amount of blood lost within an hour or two was not less than a quart. This is the characteristic curve of massive hemorrhage in which the greatest reduction first occurs in the systolic pressure resulting in an extremely small pulse pressure immediately following. Circulatory balance is rapidly established by a reduction in diastolic pressure with or without much change in systolic pressure, resulting in a rapid return to a safe pulse pressure usually several days before the systolic pressure again approaches normal.

ous injection of pituitrin or adrenalin during spinal anesthesia give only a small and very transitory rise.

10. Adrenalin alone injected into the spinal canal was found to have no effect on blood-pressure.

Hemorrhage. The amount of reduction in systolic pressure caused by hemorrhage as a rule bears a direct relation to the amount of blood lost and to the rapidity with which the loss of blood occurs. An exception to this is seen in cerebral hemorrhage where increased intracranial pressure occasions great elevation.

John B. Briggs1 has reported intracranial hemorrhage with a systolic pressure of 400 mm. Hg. In the usual acute hemorrhage, as from external wounds, from gastric ulcer or during typhoid fever, in tuberculosis and in epistaxis, the systolic pressure may fall so low as to endanger life. This complication becomes more serious when the hemorrhage is engrafted upon a weakened state caused by previous hemorrhage, or during collapse when the vasomotor system is greatly weakened or paralyzed. It is noteworthy that the fall, even when marked, is transient unless the hemorrhage continues, so that the value of this sign diminishes in proportion as the time between the hemorrhage and the observation is prolonged (Fig. 71). It is fortunate that all hemorrhages, except those coming from very large vessels, tend to become arrested long before great danger due directly to loss of blood occurs. The fall of pressure from hemorrhage is not as great as the actual amount of blood lost would indicate; this is due to the reflex augmentation of cardiac output and also to a rapid drawing upon the fluid in the lymphatic system. If arrest

1Johns Hopkins Hosp. Bulletin, Aug. 10, 1910.

of hemorrhage fails to occur before these reserves are exhausted, then the circulation fails, because the mechanical function of the heart cannot be carried out (see also shock). In other words the amplitude of cardiac contraction decreases chiefly because of the lack of sufficient fluid in the actual system upon which to operate. Henderson and Barringer1 ascribe this result to the evident fact that the venous pressure is greatly lowered, and conclude that the so-called "critical factor" in hemorrhage is dependent largely upon a failure of venous supply to the right heart, which results in failure of the circulation as a whole. On the other hand, it may be that lowered venous pressure decreases the heart output indirectly by lessening pulsepressure on the arterial side, thereby reducing the rate and volume of actual flow, which, being inadequate to maintain the nutrition of the important centers, contributes to the fatal termination.

Diagnosis of Concealed Hemorrhage.-Carl J. Wiggers2 recommends a frequent determination of the pulse-pressures in cases of suspected internal hemorrhage, believing that frequent estimation of the blood-pressure in suspected hemorrhage is of great value in differentiating this complication from others also accompanied by a falling pressure. He has found that almost invariably a progressive decrease in pulse-pressure accompanied by an acceleration in pulse-rate, occurring after surgical procedures, is indicative of continued bleeding and that the converse, if persistent after several observations, indicates a cessation of the bleeding. He recommends that the following series of

1 Loc. cit.

2 Arch. Int. Med., September, 1910 and Arch. Int. Med., July, 1914

diagnostic features be considered in cases of suspected or evident internal hemorrhage.

In arrested hemorrhage the pulse pressure tends to be abnormally large. If the respiration undergoes little or no change, the following deductions may be drawn: (a) A progressive decrease in pulse pressure with a decrease in the product of the pulse pressure and the pulse rate, indicates a continuance of the bleeding. (b) An increase in both, if permanent, after several determinations, indicates a cessation of hemorrhage. (c) A temporary increase of both followed by a marked decrease as shown by subsequent examinations, indicates an exacerbation. These points have been experimentally proven by animal research.

In all operations control of hemorrhage is an important factor in maintaining blood-pressure. When hemorrhage is slight and well controlled the effect on pressure is usually unimportant and does not call for special treatment. On the other hand, operations accompanied by considerable bleeding may result in severe and dangerous hypotension. The tendency to shock is greatly increased by hypotension from any cause during anesthesia, but if shock is successfully combated, pressure soon returns to a safe level.

INFLUENCE OF ANESTHETICS ON BLOOD-PRESSURE

Discussing the mechanism of the action of anesthetics on blood-pressure Guy, Goodall and Reid1 remark that blood-pressure may be lowered by (1) depression of the heart; (a) by vagus inhibition, either by direct stimulation of center by the drug, or by reflex stimulation through the nervous system; (b) by weakening of the heart muscle. 1 Edinburgh Med. Jour., August, 1911.

(2) Dilatation of the vessel wall or paralysis of vasomotor tone. Blood-pressure may be elevated by (1) stimulation of the heart; (a) by excitement; (b) by stimulation of the heart by the drug. (2) Stimulation of the vasomotor centers; (a) by the action of the drug; (b) by asphyxia.

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(B) Anesthesia complete.

FIG. 72.-Ether anesthesia-laparotomy. Aged twenty-three. (A) Anesthetic begun. (C) Skin incision. (D) Peritoneal cavity opened. (E) Peritoneum closed. (F) Anesthesia discontinued.

Experiment and clinical study show that the different anesthetics in general use affect the circulation and bloodpressure in different ways, and that the extent of the depressing effect of the anesthetic on blood-pressure de