Exceptionally, a patient not overdosed with anæsthetic, and not suffering from any mechanical obstruction to respiration, has a sudden attack of syncope during the progress of the operation. We here exclude patients who are suffering from surgical shock; the condition arises too rapidly for such an explanation to be accepted. Much speculation has been expended upon these cases. One view is that some procedure of the surgeon has set up a reflex inhibition of the heart through the vagus; another, that the reflex has taken the form of sudden vasomotor paresis. Levy would ascribe the condition to cardiac fibrillation. It may well be that all cases cannot be met by one explanation. The older surgeons stoutly maintained that reflex syncope could not arise if the patient were properly under, and that it was in the practice of those anæsthetists who were afraid of pushing the anæsthetic sufficiently, that such accidents occurred. The author’s own belief is that a _very_ light chloroform anæsthesia does pre-dispose to this accident, but that it may occur also at a deep, the very deepest possible level. With an anæsthetic other than chloroform, it is extremely rare--perhaps unknown. Treatment of Syncope. This must be speedy to be of any avail. The following are the points upon which to concentrate:-- (1) _Withdraw the anæsthetic._ (2) Make sure that the _air way is free_. (3) Begin _artificial respiration_ by Sylvester’s method, the movement of _expiration_ being first performed (_see_ Fig. 48). (4) _Lowering of the head and shoulders_ is usually to be recommended. It is best done by tilting the whole table as if for the Trendelenberg position. The lowering of the head attracts more blood to the carotid artery and raises the blood pressure of the main vessel and its cerebral branches (_see_ Fig. 35). It must, however, be remembered that it will also tend to empty the blood in the veins of the lower extremities and abdomen into the right side of the heart, and cases in which marked cyanosis has preceded pallor, are probably suffering already from engorgement and dilatation of the right heart. The tilting of the table should in such cases be very moderate in degree, and should not be persisted in if it seems to do no good. In no case, indeed, should the tilting be extreme. An angle of more than 15 or 20 degrees is as likely to do harm as good. [Illustration: FIG. 48A.--Artificial respiration by Sylvester’s method. Expiration.] (5) Hot cloths may be placed over the precordial region, care being taken not to burn the skin.