As stated above, the demonstrable pathology was in the lower lobe, and more frequently in the left than in the right, only occasionally in the middle lobe, and never, we might say, in the upper lobes. The very earliest definite signs were found at the apex of the left lower lobe.
This observation seems to be entirely contradictory to that of the pathologist, who found in 65 per cent. of all cases coming to autopsy a lesion in all the lobes of the lungs (Klotz). The only explanation we can give which seems at all satisfactory to us is that the pathology in the upper and middle lobes must not have been sufficient, or must have been of such a nature that it did not yield the physical signs, i. e., definite impaired percussion resonance, increased vocal fremitus and tubular breathing, with varying shades of moist râles—signs upon which we insisted before we were willing to state definitely that there is a demonstrable pneumonia present.
In this description it has been attempted to follow the order of invasion in a lung which seemed to go through the entire course of the disease. There were, necessarily, all degrees of the process, some cases showing few signs and yet being remarkably ill, and others all of the signs with very little other evidence of serious illness.
We were continually impressed with the notion that the pathology in the lung, at least the pathology demonstrable physically, did not tell the whole story of the case, and that the outcome depended as much or possibly more upon a general infection or toxæmia of which the recognized condition in the respiratory system was only a small part. We were particularly impressed with this in the success or failure following the application of any therapeutic measures. It was quite a common remark, therefore, in the wards of the hospital among those associated in the work that “the patient died too quickly to permit of the succession of the various stages of pneumonia”; or, in the autopsy room, that if the patient had lived long enough he would have had demonstrable, well-recognized pathology of the lung, instead of the cyanotic, wet, spongy lung which was found.
The temperature course in the pulmonary cases was characterized by its irregularities, and by its being entirely out of harmony with the extent and severity of the lung invasion in so far as it could be interpreted by the physical signs. The temperature as described in a simple influenza might not come to the normal in the time of three to seven days, and might even go higher, with no demonstrable chest signs, but with every other evidence of lung involvement. Later the temperature might come down by lysis, which was the usual way, and the chest signs gradually or suddenly become evident. The temperature might remain normal throughout the rest of the course, and a lobe or even both lower lobes of the lungs be as solid as in a true lobar pneumonia. Occasionally the temperature fell by crisis, but there was no associated change in the physical signs of the chest. In short, the temperature seemed to run a course entirely independent of the physical signs in the chest. In two remarkable cases seen in consultation on two consecutive days the physicians in charge declared that no signs of consolidation could be found, though all other evidences of pneumonia were present. In the 12 hours which had elapsed from the time the last examination was made the temperature fell by crisis. At the consultation, to the surprise of the family physicians, we found both lower lobes consolidated, it having occurred apparently with the crisis. Both patients were healthy-looking, robust, young men, and both recovered with delayed resolution. In the convalescence of such cases, if the patient got up too soon or if any other indiscretion took place, a relighting of the lung occurred. From the above description it can be readily seen that a diagnosis of the conditions in the chest in influenzal pneumonia was frequently impossible, because one had to abandon all his previous ideas of pneumonia, in so far as onset, crisis, blood picture, sputum, temperature, respiratory and circulatory phenomena, physical signs and prognosis were concerned.
Assistance from the laboratory was meager, especially in the early days of the epidemic. This was due largely to the inability to get laboratory workers in sufficient numbers to follow the work through, but more largely to the fact that we were unable to interpret the unusual laboratory results which were available. When we were once fully aware of the difficulties in diagnosis which confronted us, we utilized every practical means at our disposal. Among these was an examination of the chest with the X-ray. On account of lack of facilities and of help, it was impossible to make routine X-ray examinations of the chest in all cases. Besides, it was difficult to interpret the X-ray findings, on account of the unusual character of the lesions. Also, many of the patients were so desperately ill one hesitated to disturb them. We hear that other clinics had similar experiences, and that very little substantial help came from the X-ray, except in cases with complications. Several attempts were made to determine the kind of shadow, if any, the “cyanotic, œdematous, wet” lung would make, but no satisfactory observations have been forthcoming. From our own observations and from the discussions of other observers, it would seem to us that the stereoscopic examination of these chests is the only possible way of getting satisfactory plate readings in these cases where the pathology seems so lawless in its extent and peculiar in its distribution. This method of examination, however, demands facilities convenient at the bedside and perfect co-operation of the patient—difficult conditions to meet under the circumstances. In the acute cases, when the desire to make a diagnosis not only of the presence but of the extent of the disease was keen, X-ray examination was largely impractical. In cases of delayed resolution, or in cases with complications with prolonged convalescence, X-ray examinations were extremely helpful.
Diagnosis of Influenzal Pneumonia
In the consideration of any disease the well-trodden path of a painstaking history, a thorough physical examination, and reliable laboratory investigation, together with an intelligent interpretation, will usually lead to a definite diagnosis. In certain diseases, as is well known, the stress must be placed about equally on all of these factors, while in others one or other factor predominates. In influenzal pneumonia, until more is known of the etiology (bacteriology) and of the pathological changes and of the physiological disturbances, the controlling factor in the diagnosis (we feel embarrassed to admit) must be the history. This is true not only of the diagnosis of influenza with or without pulmonary involvement, but is also true of the diagnosis of the various complications, and will be found to be particularly true in the recognition of the bizarre sequelæ, which no doubt in the succeeding months or years will be attributed to or will follow in the train of influenza.