64 GASEOUS METABOLISM OF INFANTS. 



to zero, the spirometer read, and the valves turned, thus deflecting 

 the air through the original set of absorbers, which in the interim had 

 been weighed and again connected. In the middle of the period, a 

 test for possible unabsorbed carbon dioxide was made by deflecting 

 a small part of the air-current for a few moments through a solution 

 of barium hydroxide in a small flask, returning the air to the system 

 again to insure no loss of air from the chamber. 



Throughout the entire period of observation, the pulse-rate was 

 recorded every two minutes by a nurse, who made this her sole duty. 

 Likewise other body movements distinguishable by means of the stetho- 

 scope, such as coughing, crying, or a deep breath, were noted and an 

 occasional record made of the respiration-rate, which was counted 

 directly from the stethoscope. 



Occasionally the observations had to be interrupted because a change 

 in position of the baby displaced the stethoscope and the pulse-rate 

 could no longer be counted. Under such conditions, it was necessary 

 to remove the cover of the chamber and reapply the adhesive plaster. 

 The stethoscope caused the baby no discomfort at any time. The 

 ward records were consulted to determine the normal or minimum 

 normal pulse-rate and when the record reached this point and the 

 kymograph showed that the infant was quiet, a period was started. 

 At first the infant was observed through the window in the cover of 

 the apparatus to see whether or not he was quiet, but in many instances 

 it was found that infants which appeared absolutely quiet to the eye 

 showed slight movements on the kymograph and the pulse-rate remained 

 high. The visual estimation was therefore discontinued as being too 

 inaccurate and unreliable a record of the degree of quiet. 



The conduct of such an observation as has been outlined is not unlike 

 the actual technique involved in a short-period alcohol check test, 

 although the results of the short experimental periods with an infant are 

 by no means as satisfactory. The temperature distribution throughout 

 the chamber is more uneven in observations with infants ; furthermore, 

 the slightest movement of the infant may so disturb the temperature 

 equilibrium that at the end of the period the temperature will be some- 

 what different from that at the beginning. Such changes, of course, 

 affect the determination of the oxygen; as a result, the respiratory 

 quotients for successive periods do not often agree. It is perfectly 

 feasible, however, to determine the respiratory quotient during the 

 entire period that the infant is inside the respiration chamber, inde- 

 pendent of whether the subject is quiet or restless; as so determined, 

 the respiratory quotient is an accurate indication of the character of 

 the combustion. On the other hand, the determinations of the carbon 

 dioxide for each individual period are extremely exact. It is possible, 

 therefore, to utilize the carbon-dioxide measurements as an index of 

 the total katabolism for each individual period and the respiratory 



