Amidst the uncertainties that still surround the subject of pneumonia one fact seems to be generally accepted, namely, that the chief danger is death from cardiac failure. In considering the question of the value of alcohol in this disease one is met at the outset by two difficulties, first, that there is no agreement as to the cause of the cardiac failure, which is the reason for giving alcohol, and secondly, that there is no agreement as to the action of alcohol on the circulatory and nervous systems. For instance, it has been held by different writers that the cardiac failure is due to some form of inflammation of the heart, to obstruction of the pulmonary circulation, to poisoning of the medullary centre, and to the general toxaemia.
Now if alcohol in any form and in any amount is a poison to the system, as some maintain, and if the patient is already suffering from a toxaemia which is depressing the heart, it is plain that the combination of two poisons will not prove beneficial, unless one is the direct antidote of the other. Such a view is not commonly held, but Dr. A. H. Smith, writing in the Twentieth Century Practice of Medicine on the excessive amount of alcohol which may be given in pneumonia without producing toxic effects says : "It seems scarcely possible that the benefit in these cases comes from the stimulant effect alone. It is more likely that the alcohol acts directly upon the microbe by mingling with the medium in which it grows, or that it has an antidotal effect upon the poison already in the circulation." This suggestion appears to be altogether too speculative to call for further notice.
It may be urged that plenty of time and opportunity has now been afforded to settle the question as to the use of alcohol in pneumonia, but the question is not so simple as it appears.
It is not a case of treating pneumonia, it is a case of treating a patient suffering from pneumonia, and patients vary in their susceptibility to alcohol just as they do to other drugs. One class of patient may respond well to alcohol as a stimulant, in another it may act as a depressant, in a third it may provoke gastro-intestinal disturbance, and so on. Each observer will tend to be influenced in his judgment by the results which occur most frequently under his own observation, and as the experiences of various observers may differ very considerably, their conclusions may appear to be diametrically opposed. Again, the cardiac weakness may be due in one case to pre-existing heart disease, in another to pneumococcal carditis, in another to pulmonary obstruction, and so on. These are complications and not the ordinary conditions of pneumonia, which we are now discussing.
Regarding the use of alcohol in the treatment of pneumonia we are not justified in laying down any dogmatic rules which will apply in all cases. We must, however, have certain views as to the nature of the cardiac failure, and as to the action of alcohol, if our treatment is to be anything but empirical. For the sake of clearness two assumptions will be made in the following remarks, first, that the commonest cause of cardiac failure in pneumonia is poisoning and paralysis of the medullary centre, and secondly, that alcohol is in the majority of cases a stimulant of that centre. These are assumptions, and space will not allow of my going fully into the reasons for adopting them, but the following points may be briefly alluded to.
As regards the first it may be pointed out that pneumonia differs from most other acute fevers in the tendency to fatal cardiac failure within a brief period. Even in the case of rheumatic fever, which is the disease in which the heart tends to be affected early and in an indisputable form, we find no such liability to rapid failure. As a rule no post-mortem changes are found in the heart in pneumonia other than those common to pyrexial and toxic conditions. A condition of pericarditis, endocarditis, or myocarditis, of pneumococcal origin, must be regarded as exceptional, and as previously stated rather as a complication. The pyrexia is not in itself a sufficient cause, for in other affections pyrexia of equal degree does not rapidly induce fatal cardiac failure. The embarrassment of the pulmonary circulation is not sufficient to produce the conditions seen in pneumonia. Dilatation of the right heart may occur, but it is by no means the characteristic feature of cardiac failure in this disease. There is no apparent obstruction in the circulation which would account for death in most cases. Both on clinical and post-mortem evidence we are unable to trace the fatal result to the heart or to the circulation.