After the symptoms of pulmonary catarrh have continued for some time they suddenly change their character. The temperature rises ; the cough becomes short and hacking ; the pulse and respirations are hurried ; the face is more or less livid ; the flares act ; and in the infant a well marked labial line becomes developed, passing from the angle of the mouth down wards and outwards to the ramus of the lower jaw.
The pyrexia varies in degree. In children in whom an ordinary bron chitis gives rise to fever, the temperature, when inflammation of the lung is superadded, may reach a high level. Thus, the thermometer may mark 104° or 105°, but undergoes more decided variations during the twenty four hours than is the case in croupous pneumonia. In most instances there is a decided remission between 6 A.?. and noon ; the chief elevation occur ring between 10 P.M. and 3 or 4 A.m. Sometimes, however, for twenty-four or forty-eight hours the temperature may remain at about the same level, varying only by half a degree. In spite of the pyrexia the skin is often moist, and in some cases perspiration is profuse.
In catarrhal as in croupous pneumonia the pulse-respiration ratio is perverted ; but the disproportionate rapidity of the breathing is variable according to the acuteness of the case In the severe acute variety the ratio may be 1 to 2 or even 1 to 1.5 ; while in the subacute form the ratio may be only 1 to 2.5 or 3. The pulse is very rapid (120 to 150, or even higher), but is small and feeble, for the impediment to the passage of blood through the lungs obstructs the whole circulation. Consequently the ar teries are comparatively empty, while the venous system, as is shown by the fulness of all the superficial veins, is congested.
The breathing besides being hurried is laborious, and there is evident dyspncea. The child often cannot lie down in bed and has to be supported by pillows. At each inspiration the Bares dilate widely, and the shoulders rise with the laboured action of the accessory muscles. Often the child endeavours to aid the expansion of his chest by grasping tightly the bars of his cot. Still, with all his endeavours the patient is unable to fill his lungs with air, for at each movement of the chest the intercostal spaces and supra-clavicular hollows become depressed, the epigastrium sinks in, and the lower ribs are retracted.
The cough, when the air-cells become attacked, changes its character and seems painful. This change in the cough is a very valuable sign. In stead of the prolonged, rather paroxysmal cough of bronchitis, we hear the short hard back of pneumonia ; and this may be repeated with each expiration for many minutes together, causing great distress and exhaus tion.
Looseness of the bowels is a common symptom, the stools being slimy and thick, or thin and watery. Vomiting, induced by the cough, is also often present ; and much mucus is discharged both from the stomach and lungs. Nervous symptoms are sometimes noticed. In an uncomplicated case convulsions do not occur in the course of the illness, although they may be present shortly before death when asphyxia is imminent; but twitch ings and spasmodic movements of the muscles of the eyeball are often seen during sleep.
At this time a physical examination of the chest discovers merely the signs of bronchitis ; for the consolidation being limited to small scattered nodules and surrounded by emphysematous air-cells, can rarely be detected by percussion. Sometimes, however, by employing broad percussion, i.e., by striking with three fingers on three fingers applied to the chest-wail as pleximeters, we notice some diminution of healthy pulmonary tone ; and in some cases a careful exploration distinguishes certain spots where there is more evident diminution in resonance, and perhaps bronchial breathing over the same limited area. If the pneu monia occurs in collapsed portions of lung we can often find at each base a pyramidal strip of dulness reaching upwards for a certain distance, when percussion is made very lightly. With the stethoscope general fine bub bling rhonchus is heard, and in certain spots this will be noticed to be finer, dryer, and more crepitating in character. This crepitating quality is especially noticeable over an area where the breathing is bronchial ; for unlike croupous pneumonia, the crepitus is not lost when consolidation oc curs.