PULSE-KATE. 77 



to what extent maximum pulse may develop during paroxysms of 

 crying and with such activity as a child may exhibit when lying in 

 bed, but for all normal purposes such records have but little, if any, 

 scientific value. 



The younger the infant the greater is the difficulty of obtaining the 

 pulse-rate. With older children the element of apprehension should 

 not be entirely disregarded. If this apprehension is not present to 

 any great degree, the special precautions necessary for small children 

 will not be required for the older individuals. Our measurements 

 were all made while the child was inside a hermetically sealed chamber, 

 and the routine was invariable for all children studied. 



METHODS OF OBTAINING PULSE-RATE. 



The pulse-rate can be obtained either by palpation at the wrist 

 or by direct auscultation from the heart. During infancy it is difficult 

 to obtain an accurate pulse-rate from the wrist, because infants rarely 

 remain quiet for more than a few seconds. Infants dislike to be forced 

 to stay in one position, and when made to do so they usually straggle 

 and cry. It is often impossible to get the pulse-rate from the wrist 

 while the infant is asleep, for the slightest touch of the observer's 

 hand wakens the child. The difficulties present during the waking 

 hours are then accentuated by the fright which may result from the 

 sudden awakening. Obtaining the pulse-rate by means of a stetho- 

 scope held over the heart is also attended by many difficulties. Unless 

 an infant is phlegmatic or becomes used to this procedure, he may 

 squirm and cry and sometimes violently resist the application of the 

 stethoscope. When a child or an infant resists, it is obviously im- 

 possible for the observer both to hold the stethoscope on the chest- 

 wall and to make an accurate record of the pulse-rate unless someone 

 holds the infant. 



The most successful method of obtaining an accurate pulse-rate is 

 by means of a small Bowles stethoscope fastened with adhesive plaster 

 to the body-surface of the infant over the heart. A long rubber tube 

 is run from the stethoscope under the clothing and out to the earpieces. 

 The child can then take any position he desires without feeling that 

 he is restricted and without realizing that the stethoscope has been 

 applied. All of our own pulse-counts were obtained by this method. 



In full recognition of the difficulties attending a study of the pulse- 

 rate, we have tabulated the results of our observations, taking into 

 consideration only the minimum pulse-rate. Our studies contribute 

 towards the solution of two main physiological problems: First, how 

 does the pulse-rate vary with age; secondly, what is the average 

 pulse-rate for children of various ages? Since the number of observa- 

 tions made was considerable, the results offer a fair basis for answering 

 these questions. 



