In some cases the decline in the symptoms is gradual and the disease terminates by lysis and not by crisis. In unfavorable cases signs of heart-failure appear within the first few days, and the patient sinks rapidly into collapse and dies.
With this brief outline of the disease I will pass to an analysis of its prominent symptoms.
Respiration.—The respirations are more constantly increased in frequency in croupous pneumonia than in any other acute disease. In most febrile diseases the respirations increase in frequency with the pulse-rate. In pneumonia there is no uniform ratio between pulse and respiration; this is regarded by some as an important diagnostic sign.28 In some cases the respirations will be 80, and the pulse only 90, per minute. The acceleration in the respiration is not in proportion to the amount of lung-tissue involved, but seems to be due to a peculiar condition of the nervous system which existed prior to the pneumonic seizure or is caused by a poison acting upon the nerve-centres. Traube29 thinks that it is due to the pain and to the high temperature. This theory would not explain its occurrence in those cases where the pleura is not involved—i.e. when no pain is present—and yet the shallow, panting, rapid breathing is well marked.
28 Dis. of Lungs, Walshe, 1860, p. 366.
29 Annal. de Charité
In other pulmonary diseases, when there is high temperature, as in acute phthisis, the respirations are not so much accelerated as in pneumonia. The character of the respiratory acts is also peculiar: they resemble the panting of a dog. Accelerated breathing may or may not be accompanied by dyspnoea; in many cases the dyspnoea seems to be independent of it, for extreme dyspnoea is often present where the respirations are but slightly increased in frequency.
In children the acceleration of respiration is more marked than in adults, and the ascent of the chest occurs during expiration, and not, as normally, with the inspiration. The diaphragm is markedly contracted with each expiratory act, and the diagnosis will as often be made by the character of the respiration as by the physical exploration of the chest, for in children the early physical signs of pneumonia are often unsatisfactory.
The hurried breathing prevents a young child from nursing; it takes the mother's nipple for an instant, nurses greedily, and then drops back, gasping for breath.
It is to be remembered that in pneumonia in children the pulse and respiration discrepancy will not be so well marked as in adults: the pulse may be 150 to 160 per minute, while the respirations are 80 or 90. In children there will early be noticed the peculiar expansion of the nostrils which comes on late in adults. In senile pneumonia the chest enlarges vertically during inspiration. The whole act has a panting character, and the expiration is prolonged.
In perfectly healthy old people the inspiratory movements are jerky in character. The lungs become fully expanded only after a succession of interrupted efforts. An exaggeration of what is physiological in old age—i.e. catchy breathing—is the most frequent form of abnormal respiration in senile pneumonia.