CRITICAL DISCUSSION OF RESPIRATION APPARATUS. 233 



the oxygen determinations being affected by changes in the volume of 

 the lungs. This disturbance, which does not play a noticeable part 

 in the oxygen determination by the open-circuit methods, gradually 

 disappears with most subjects as they become accustomed to the 

 apparatus, so that practice plays a significant role. 



When the motor is running and the air circulating, there is a slight 

 mechanical vibration due to the movement of the blower and motor 

 which varies with the apparatus used. This is at times noticeable, 

 being referred to occasionally by subjects. It is an objectionable 

 feature and constant attempts are being made to eliminate it. 



The respiration is, as a rule, fairly normal with the Benedict respira- 

 tion apparatus. The average subject breathes so regularly in quantity 

 that the variations are not marked. Many subjects have stated that 

 they were unable to tell whether they were breathing into the appa- 

 ratus or into the open air. In fact, in one instance, a new subject was 

 told that he would know when the valve was turned, as the air in the 

 apparatus had a very slight odor. A few minutes after the valve 

 had been turned he opened his mouth several times and, when asked 

 why he did this, stated that he did not know that he was breathing 

 into the apparatus. 



The fact that subjects often fall asleep in experiments with this 

 apparatus much more frequently than in experiments with apparatus 

 like the Zuntz-Geppert or the Douglas gives evidence that the appa- 

 ratus is certainly not unpleasant to breathe into and that the respira- 

 tion is fairly normal. Coleman and Dubois 1 have used the apparatus 

 with a number of typhoid patients in Bellevue Hospital, New York. 

 They state that, as a rule, patients are somewhat nervous the first 

 time the apparatus is used, but soon become accustomed to the 

 routine and seem to enjoy it, since they suffer no discomfort. They 

 report difficulty in obtaining normal results with two individuals 

 because of abnormal breathing, as they breathed too deeply or too 

 rapidly. Roily has also used his modification of this apparatus with 

 many fever patients. The apparatus has likewise been employed with 

 success by Professor H. M. Smith in his studies with athletes at Syra- 

 cuse University. Dr. Paul Roth, of the Battle Creek Sanitarium, has, 

 with this apparatus, studied the respiratory exchange of a large number 

 of individuals, both normal and pathological, with very satisfactory 

 results. More recently Dr. J. H. Means, of the Massachusetts General 

 Hospital, and Dr. W. H. Boothby, of the Peter Bent Brigham Hospital, 

 have used it for studies with patients in the hospitals mentioned. 



Considerable time is necessary to acquire the technique of the appa- 

 ratus, as it includes attention to many details outside of the usual 

 routine in any series of respiration experiments, such as weighing the 

 absorbers, making tests for leaks, adjusting properly the signal magnets, 



'Coleman and Dubois, Archives of Internal Medicine, 1914, 14, p. 168. 



