110 mm. Hg., during the first week, dropping about five points per week during the next three, and then begins to return to normal as convalescence is established.

The Diastolic Pressure.-As in any case of pressure variation, the diastolic pressure tends to follow the systolic, though the movement is usually less. This results in a reduction in pulse pressure, which is present during the active stages of the disease and which becomes gradually lost as the case recovers, to return temporarily if the heart is overstrained.

The blood-pressure changes in typhoid fever are so characteristic that in obscure cases of continued fever, a carefully prepared blood-pressure chart may aid in clearing up the diagnosis. Blood-pressure readings should be made as regularly and frequently as are the pulse and temperature observations, because here, as in any other conditions when comparatively rapid alterations are to be expected, an occasional reading is valueless. This fact is demonstrated by the evidence afforded by systematic bloodpressure records which may call attention to the occurrence of such complications as perforation or hemorrhage. They may also assist in an early diagnosis, or in demonstrating the effect of therapeutic measures, particularly baths, upon the cardiovascular apparatus.

Complications.-Perforation.-Crile1 and Cook and also Briggs2 note that in typhoid fever with perforation and peritonitis, there is an early and decided rise, which is followed by a fall as toxemia increases. This was found to be the invariable rule by Crile in twenty surgical patients.

1 Jour. A. M. A., May 9, 1905.

Johns Hopkins Hos. Rep., Vol. xi, 1903.

A sudden rise in pressure in the course of a case of typhoid is almost positive evidence of a perforation, though we should remember that a stationary pressure is no indication that the catastrophe has not occurred.1

Hemorrhage. There is a rapid fall in blood-pressure without the initial rise, by which fact it may be separated from the preceding. The degree and rapidity of the fall in some measure indicates the extent of the hemorrhage. The pressure tends, upon the arrest of hemorrhage, to return rapidly to almost the level noted before the hemorrhage occurred.

Value in Treatment.-In the treatment of the disease, a study of blood-pressure will be found to be of great value. It shows the best mode of combating the circulatory failure and indicates whether our efforts should be directed toward improving peripheral resistance, or toward heart stimulation, and gives a clear indication whether the case is receiving too little or too much fluid for the capacity of the circulation.

Nowhere is the effect of stimulatory measures shown to greater advantage than by the changes in blood-pressure relations shown by the sphygmomanometer through records taken before and after a bath.

Secondary and Late Effects of Typhoid Infection upon Blood-pressure.-Acute infections are now recognized as among the most frequent as well as the most insidious causes of arteriosclerosis and it has been shown that typhoid fever is particularly involved in the early production of arteriosclerosis (see page 257).

1 A. L. Sheppard, Lancet, May 11, 1907.

DIPHTHERIA

The effect of the diphtheria toxin upon muscular tissue throughout the body, and upon the heart muscle in particular, has long been a grave concern of the practising physician, heart death after diphtheria being an all too frequent sequela. The routine estimation of blood-pressure therefore becomes an important prognostic measure, particularly in this disease.

As in other infections, the blood-pressure tends toward subnormal during invasion, with a gradual return toward normal during convalescence.

From a clinical study of 179 cases of diphtheria Rolleston1 found a subnormal pressure in sixty-three cases or 35 per cent., the extent and duration bearing a direct relation to the severity of the faucial attack. The highest readings were found during the first and the lowest during the second week. The normal tension was usually reëstablished by the seventh week. Evidence of dyspnea (partial asphyxia) in laryngeal cases caused an elevation in pressure. Tracheotomy in these cases was followed by an immediate fall of 20 to 40 mm. The effect of serum administration was a rise in pressure in 40 per cent. of cases. Albuminuria did not cause a rise in pressure, except in one case with uremia.

In studying the relation of blood-pressure in diphtheria to myocardial alterations Bruchner2 examined critically 200 cases of this disease. He found that mild cardiac involvement did not affect the normal blood-pressure curve, and that cases with irregular blood-pressure showed

1 J. D. Rolleston, Brit. Jour. of Children's Diseases, October, 1911.
• Deutsche med. Wochen., Oct. 28, 1909.

various clinical pictures. Every case of marked fall in pressure was associated with definite signs of myocarditis. Falls amounting to as much as 50 mm. (Gärtner's tonometer) appeared only with severe myocarditis. This was the greatest drop in which recovery occurred. A steady progressive fall in pressure was present in the fatal cases. In every case, with one exception, marked falls in pressure were accompanied simultaneously by signs of cardiac involoement; in one case only did the fall precede the clinical signs.

Anaphylactic Shock.-This fortunately rare, although usually fatal, condition is believed to be due to a toxic constriction of the bronchial tree which results in a condition of strangulation. As far as known we believe that this process is primarily accompanied by a rise in pressure.1 This rise however, is, so transient that it is rarely observed; so that in the average case, if pressure readings are made, there will usually be found a marked hypotension, which is the usual accompaniment of acute cerebral anemia (see page 379).

SCARLET FEVER

In the study of the systolic pressure in a series of cases of scarlet fever, Rolleston2 noted that the extent and duration of the depression was usually in direct relation to the severity of the initial attack, and that while the greatest number of normal readings occurred during the first week, there was nevertheless a predominance of lowest readings in the same week. The great majority of low readings

1 Auer and Lewis, Jour. A. M. A., 1909, Vol. liii.

2 J. D. Rolleston, Brit. Med. Jour. of Children's Diseases, October, 1912 lx, p. 444, 106.

occurred in the second week, while normal tension was usually reëstablished some time during the fourth week. In the majority of cases the blood-pressure was lower during convalescence than in the active stage, although nothing of a characteristic nature regarding the relative height of the pressure during the acute stage as compared with the nature of the convalescence has been found.

With the exception of nephritis, the ordinary complications have little if any effect on blood-pressure. The chief value of the sphygmomanometer in scarlet fever is in detecting the occurrence of marked renal irritation as, with the development of an acute nephritis, there is always a sudden and marked rise in arterial pressure. Buttermann1 has observed a rise of more than 50 mm. within twenty-four hours after such an occurrence.

The presence of marked hypotension, especially if accompanied by other signs of vasomotor insufficiency, calls for appropriate measures directed toward circulatory support.

Rolleston's Table Showing the Number of Cases in Each Week
in which the Highest Readings were Recorded

An unusual range of systolic blood-pressure readings may be met in scarlet fever in children; thus Rolleston

1 Arch. f. klin. Med., lxxiv, p. 11.