152 RESPIRATION 



a machine, but with a living organism; and a living organism 

 always tends to return to the normal if the opportunity is given. 



Oxygen is still often given by methods which are either quite 

 ineffective or extremely wasteful. One method is to place a funnel 

 over the patient's face, and allow some quite indefinite amount of 

 oxygen to pass into the funnel. By this method the patient re- 

 breathes a good deal of expired air, but may hardly get any of 

 the oxygen, as the latter, being heavier, runs out below. A far 

 better method is to insert a rubber catheter or other soft tube into 

 the patient's mouth or nose, and pass a stream of oxygen through 

 the tube. Another good method, when pure oxygen has to be given, 

 is to allow the oxygen to pass at a sufficient rate into a rubber bag 

 connected with the inspiratory valve of an anaesthetic mask placed 

 over the patient's mouth and nose. The patient inhales from the 

 bag, and exhales to the outside through the expiratory valve in 

 the mask. 



In ordinary cases the patient does not require pure oxygen, but 

 only a sufficient addition to the air of oxygen to prevent the an- 

 oxaemia. In any case it would be very undesirable to continue the 

 administration of pure oxygen for more than a limited time, as 

 pure, or nearly pure, oxygen has a slow irritant action on the 

 lungs, as will be shown in Chapter XII. If the mask is left open 

 to the air, so that the patient can breathe as much air as he likes, 

 and a stream of oxygen is allowed to pass into the mask directly, 

 the oxygen which passes in during expiration is of course wasted. 



It became evident during the war that an efficient apparatus 

 for the continuous administration of oxygen with maximum econo- 

 my in oxygen was greatly needed, particularly in the treatment 

 of acute cases of poisoning by lung-irritant gas. I therefore de- 

 vised an apparatus so arranged that by a simple device the patient 

 inspired through a face piece the whole of the added oxygen, 

 without waste during expiration, while the proportion of oxygen 

 could easily be cut down or increased, according as was needful. 

 The original form of this apparatus was described in the British 

 Medical Journal, February lo, 191 7, page 181, after it had already 

 been supplied extensively to the army in France. Its use there for 

 gas cases was initiated, and the managment of it carefully investi- 

 gated, by Lieutenant Colonel C. G. Douglas of Oxford. Other 

 well-known medical officers also made very valuable observations 

 on the effects of oxygen inhalation. The results, particularly in 

 gas cases, were strikingly successful; and practically continuous 

 administration could easily be carried out over the two or three 



