An (average) typical temperature-curve is shown on the preceding page (Fig. 33).
If after the fourth day of a pneumonia an unusual remission is followed by a high temperature-range, either an extension of the pneumonia or the occurrence of some active complication is indicated. If in an otherwise mild pneumonia the temperature suddenly rises to a high point, a grave complication is indicated. The sudden fall of temperature on the fifth or sixth day indicates a crisis and the beginning of convalescence; it may occur in the morning or after the evening exacerbation.
In a typical case it is usual to find the temperature on the morning of the fifth, sixth, or seventh day two or more degrees lower than on the preceding night, and subsequently it falls until a normal, or not infrequently a subnormal, temperature is reached. The crisis may occur by successive and increasing remissions, while the exacerbating temperature remains constant (Fig. 34); and indeed it is common for the remissions to be excessive immediately preceding the crisis.
| FIG. 34. |
| Lobar Pneumonia, where the Crisis was marked with Evening Exacerbations, reaching nearly the highest pyrexia of the second stage: Recovery. |
Just before the final fall the fever may be greater than at any time preceding.34 When the decline in temperature is gradual (lysis), the normal temperature is usually reached by the ninth day, but it may be delayed until the twelfth or fourteenth day. A very slow or protracted lowering of the temperature is attended by a coincident slow disappearance of the physical signs of consolidation. There is no explanation for this, except that it is met with oftenest in the weak, debilitated, and dissipated where venesection has been practised or a depressing plan of treatment has been resorted to.
34 See [Fig. 33], where a temperature of nearly 105° F. is followed on the evening of the fifth day by the final fall.
A high temperature persisting after the tenth day indicates purulent infiltration (see [Fig. 38]).
Pneumonia involving the apex of the lung is usually marked by a higher average range of temperature than when it is confined to the lower lobes. Statistics show that the fifth and seventh days are the days of crisis in the majority of uncomplicated pneumonias. Of 867 cases terminating by crisis, in 677 the crisis occurred before the eighth day. Neither the height of the temperature-range nor the amount of lung involved affects the critical day.
In the form of pneumonia sometimes called bilious—a form that prevails in miasmatic regions—the temperature is markedly paroxysmal.