When the laryngeal disease begins the breath-sounds lose their ordinary character and become harsh and. stridulous. At the same time the cough is hard and harsh and the voice and cry are hoarse. The change in the char acter of the breathing may be the earliest of the new symptoms, or may be preceded by the change in the voice and cough.
This stage of the disease may continue for several days ; but often after a few hours the breathing becomes greatly oppressed, and attacks of violent dyspncea throw the patient into the greatest distress. In these attacks, however violent they may be, there is no orthopncea, for the breathing is not more oppressed when the head is low. As a rule, the child lies back in his cot or in his mother's arms. His face is livid ; his mouth is open ; his eyes stare wildly, and he looks dreadfully anxious and frightened. The dyspncea affects both respiratory movements. Each inspiration is pro longed, high-pitched, and metallic ; the expirations shorter and harsh ; the cough hoarse and whispering. If the chest is uncovered at this time it will be noticed that at each inspiration the lower half of the breast-bone bends inwards so as to leave a deep pit in the epigastrium. At the same time the intercostal spaces deepen and the supra-sternal notch is depressed. The attack of dyspncea lasts from a few minutes to a quarter of an hour or longer. When it subsides the child's terror disappears ; his breathing be comes less noisy and stridulous ; his respiratory movements less laborious, and he passes into a state of comparative ease. Still, the breathing is rapid and audible ; the nares work violently ; some lividity remains in the face, and there is considerable recession of the soft parts of the chest in inspiration. On examination of the chest, the breath-sounds are accom panied by a stridor conducted from the larynx, and this may completely conceal all natural vesicular murmur.
The attacks of dyspncea return at short intervals, and are easily excited by movement or by anything which irritates or agitates the patient. The cough occurs frequently and is hoarse and whispering. Sometimes the patient expectorates patches or shreds of false membrane ; but unless the trachea be opened the child rarely expels enough of the obstructing sub stance to produce appreciable relief to his symptoms. At each recurrence of the dyspncea the attack is more severe than before, so that gradually the child passes into a semi-asphyxiated state. He lies back with purple lips
and livid face ; his pulse is feeble, frequent, and very irregular ; his breath ing rapid and shallow, although his nares still work ; his forehead clammy, and his extremities cold. He often moves his arms restlessly, and his heart's action may become very intermittent, a curious pause taking place between every two or three pulsations. On examination of the chest there is usually good resonance, except perhaps at the extreme base. The breath sounds are obscured by conducted stridor and may be accompanied by dry rhonchus. If no operative procedure be attempted the drowsiness deepens into stupor, and the child sinks quietly or dies in a last struggle for breath.
If this stage the trachea be opened, the immediate effect of the operation is most striking. In a favourable case, where the trachea below the opening is not obstructed, the child is at once relieved from almost all his distress. Air again penetrates deeply into the lungs ; the lividity dis appears ; the restlessness subsides ; the breathing becomes natural ; the nares cease to act, and the look of terror and suffering passes off and may even be succeeded by a smile.
When the disease thus attacks the larynx the duration is usually very short. From the time when the first signs of stridulous breathing are noticed to the end only a few hours may elapse. In other cases the child may live two or three days ; but this longer duration is due to slower progress in the earlier part of the illness. serious dyspncea super venes the child, if not relieved by operation, seldom survives the next twenty-four hours. Sometimes, however, if the false membrane is very limited in extent, recovery may take place. In these cases the symptoms are seldom very severe, and in particular the attacks of dyspncea, if pres ent at all, are mild and infrequent. The favourable change is marked by a less laboured character of breathing, a brighter look in the face, increased looseness and more natural quality of the cough, and a return of tran quillity to the manner. Still, there is little doubt that many cases of supposed recovery from membranous croup are really cases of stridulous laryngitis, which is a much milder complaint and rarely ends fatally.