Modern surgery has rendered the occurrence of serious infections of operation wounds a rarity, but it has not succeeded so well in abolishing postoperative infection of the lungs. The development of pneumonia after an operation, even though the greatest care be taken in both anesthesia and operation, is always a dreaded possibility, and one which no amount of precaution can positively eliminate. In well-conducted surgical clinics the mortality from postoperative lung infections undoubtedly exceeds the mortality from infections arising in the operation wounds; the latter are reduced by careful technic to practically zero, while the lung complications, although much reduced by improved methods of anesthesia and better care of the patient during and after the operation, still remain a serious menace.
The reasons for these lung infections are obvious enough. Direct irritation of the respiratory passages by the anesthetic vapors, chilling of the tissues by the ether-cooled air, to say