486 EMIL GOETSCH 



calculate the heat production. This unit apparatus has, however, some 

 disadvantages for clinical work. It is rather cumbersome. Constant 

 checking is required to see that it is absolutely air tight, for a leak of 

 20 to 30 c.c. during a fifteen-minute determination will appreciably affect 

 the results, because such a leak in this type of apparatus will be equivalent 

 to the loss of so much oxygen and not equivalent to the loss of so much 

 air as is the case in the gasometer method. Furthermore, the accumula- 

 tion errors of the apparatus fall on the oxygen and not on the carbon 

 dioxid determination, thus causing an error in the calculation of the 

 respiratory quotient and heat production. The absorbing chemicals must 

 be changed frequently and with the repairing and constant checking of 

 the apparatus it is on the whole difficult to use in clinical work. 



The portable respiration apparatus 4 recently devised by Benedict (&) 

 for clinical work is a modification of his unit apparatus described above. 

 It is designed primarily to give a rapid and at the same time a com- 

 paratively accurate measurement of the oxygen consumption without in- 

 volving analysis or weighing. The difficulties inherent in the closed circuit 

 type of apparatus are still present in the portable apparatus. Sandiford 

 at the Mayo Clinic has not adopted this method, as she prefers to de- 

 termine not only the oxygen consumption, but also the carbon dioxid elimi- 

 nation since the heat production can thereby be more accurately cal- 

 culated. 



For clinical work Sandiford used the gasometer method introduced 

 by Tissot in 1004 and considers it the most satisfactory. "Briefly, the 

 determinations are made in the following manner : A mask is adjusted 

 over the patient's mouth and nose and by means of expiratory and in- 

 spiratory valves the total volume of the patient's expired air is collected 

 in a gasometer for a known period of approximately ten minutes. Du- 

 plicate determinations are made of carbon dioxid and oxygen content of 

 the expired air, the analysis being done in the Haldane gas analysis 

 apparatus. Since the ventilation rate for each minute is known, as well 

 as the amount of carbon dioxid produced and the oxygen absorbed, it 

 is possible to calculate by means of calorie tables the total number of 

 calories produced each hour." The method of routine determinations of 

 the basal metabolic rate is then more fully discussed, to which reference 

 should be made (Sandiford, 11)20, p. 74). r> 



One of the chief advantages of the gasometer method is that, should a 

 leak ot a tew cubic centimeters occur around the mask the end result is not 

 appreciably affected, while a leak of a similar volume in the closed circuit 



'Tin- I'.enedict portable respiration apparatus is manufactured and sold by the 

 Sanborn Company, 7!> Sudbury Street, Boston, Mass. 



I be details of the teelmic are described in a laboratory manual by Boothby and 

 Sandiford. Tin- apparatus may be obtained from H. N. Elmer, 1136 Monadnock 

 Hldg., Chicago. 



