THE PULSATORY VARIATIONS IN BLOOD PRESSURE 387 



detail, because they are identical with those exhibited by the systolic 

 and diastolic pressures individually. It naay therefore be said that 

 it is subject to alterations in (a) the energy of the heart, (6) the 

 peripheral resistance, (c) the elasticity of the blood-vessels, and (d) 

 the quantity of the circulating blood. 



The Clinical Significance of the Sphygmo^am. — The information 

 to be derived from a study of the sphygmogram is of slight clinical 

 value. No doubt, if properly adjusted, the sphygmograph may serve 

 as an accurate means for determining the frequency and rhythm of the 

 heart, although it does not permit us to draw definite conclusions re- 

 garding the dynamical conditions prevailing in the vascular system. 

 In the first place, the length of the individual pulse-waves, as well as 

 their general character, may be varied considerably by technical errors 

 committed in adjusting the instrument. Thus, it is often difficult to 

 apply it with that degree of pressure which is required to counter- 

 balance the systolic pressure. In the second place, it must be granted 

 that the excursions of the instrument depend in a large measure upon 

 the thickness of the tissues overlying the artery and upon the degree 

 of injection of the neighboring veins. It is best, therefore^ to regard 

 the sphygmograph merely as an aid to diagnosis and to draw no rigid 

 conclusions from its records. It is much easier, and also much safer, 

 to base your deductions upon the methods of inspection and palpation, 

 because by these means the frequency and regularity of the heart are 

 made evident in a much more direct manner. In addition, these 

 simple methods enable us to estimate the general character of the 

 pulse-wave, and hence, also the tension prevailing in the arterial sys- 

 tem and the efficiency of the entire circulatory mechanism. The fol- 

 lowing quaUtative differences are generally ascribed to the pulse: 



(a) Frequens or Rams. — A pulse is characterized as quick if it surpasses the 

 normal maximum and as slow if it falls below the normal minimum. For men, 

 these limits lie respectively at 75 and 68 beats in a minute. 



(6) Celer or Tardus. — Attention should first be called to the fact that these 

 terms do not refer to the frequency of the pulse, but solely to the speed with which 

 the individual waves are developed. Their rise and fall may be quicker or slower 

 than normal. Pulses of the first type indicate either a relaxed condition of the 

 vascular system, a quick escape of the arterial blood, or an undue brevity and slight 

 force of the ventricular contraction. An especially pronounced pulse of this kind 

 is present in aortic regurgitation, because the incompetency of this valve permits 

 of a quick escape of arterial blood into the heart. A tardy pulse is obtained 

 whenever the ventricular discharges encounter a high peripheral resistance. 



(c) Magnus or Parvus. — These terms are used to describe the amplitude or 

 volume of the different pulse-waves. A third term, namely, pulsus inequalis, is 

 employed to show that the successive waves are unequal in their volume. 



(d) Durus or Mollis. — These qualities of the pulse are independent of the 

 condition of the arterial wall and are indicative of the tension prevailing in the 

 arterial channels. If an undue force must be employed to compress the artery 

 sufficiently to cause the disappearance of the pulse, it is characterized as hard. 

 If it is readily obliterated, it is said to be soft. 



(e) Intermittens or Deficiens. — Disturbances in the rhythm of the pulse 

 result either in consequence of weak contractions of the heart or in consequence of 



