The complications of whooping-cough may be accounted for mainly by the mechanism of the paroxysms and the lesions that may be caused by it directly. These include subconjunctival haemorrhages, epistaxis, vascular enlargement of the thyroid gland, ulcer of the frenum, and pulmonary emphysema due to increased expiratory pressure. Some times increased abdominal pressure leads to prolapse of the rectum and, in case the inguinal canal remains open, to inguinal hernia. Umbilical hernias, too, usually in small children, may occur during the process of whooping-cough. Rupture of the recti abdominalis muscle is a complication of rare occurrence.
Memorrhages of the mucous membranes of the nose, mouth and bronchi and multiple haemorrhages of the skin may be regarded as effects, partly of the greatly increased intravenous pressure and partly of causes affecting and altering the vascular walls. But it is questionable whether increased pressure alone is able to produce haemorrhages. 'hemorrhage also may occur from suppurating foci, from the sublingual ulcer, from moist eczema, from catarrhal areas in the nose, and from the ruptured drum membrane when the middle ear is involved. In subconjunctival haemorrhages a preceding lesion of the vascular wall (conjunctivitis) can be assumed as a causative factor. In young children bleeding from the mouth is often due to biting of the tongue during a paroxysm.
On account of their frequency and importance in the prognosis of whooping - cough, complications of the respiratory tract deserve the greatest interest. They occur mostly in the convulsive stage. If in the intervals between the attacks the general condition of the patient is not good, if between the paroxysms there is dyspnaa, irritative cough, and riles audible at a distance, we may infer that there is some complica tion of the respiratory organs. If there is also fever, then there is a capillary bronchitis or a pulmonary consolidation, as will be revealed by physical examination, which will show characteristic signs. As the lightest complication we find a diffuse catarrh. From this may develop, slowly or rapidly, a catarrh of the finer bronchi or a lobular infiltration of the lung.
Infancy especially predisposes to such complicating pulmonary affections, so that infants a few months old rarely escape. Children of any age affected with whooping-cough, who are weak with lessened resistance, or who are weakened by preceding or present constitutional diseases, have their chances of recovery vastly diminished by broncho pneumonia. Still the prognosis is never totally hopeless, not even for
the youngest infants. The duration of bronchopneumonia is prolonged by the severity of the underlying disease and often by more or less frequent relapses.
During the course of whooping-cough, we meet quite frequently with symptoms that can be referred to tuberculosis of the pulmonary and bronchial lymph-nodes. These develop either primarily, betraying themselves by a certain debility of the organism; by emaciation; by a faded gray color of the skin; by febrile manifestations, and objectively by impaired pulmonary resonance in one or both intrascapular spaces (tuberculous infiltration of the bronchial lymph-nodes); or they pass on to a protracted and relapsing lobular pneumonia and thus become an early manifestation of latent tuberculosis. Tuberculous complications of the lungs are uncommonly frequent. These are almost never wanting in the post-mortem examinations of whooping-cough patients. Still they may reach a state of symptomatic quiescence and later on, after days and years, may terminate with an abrupt manifestation of miliary tuber culosis or tuberculous meningitis.
Chronic tuberculosis of the pulmonary or bronchial lymph-nodes is often encountered as a sequel when all the symptoms of pertussis have disappeared. A goodly number of tuberculous children date their affection back to whooping-cough.
Another typical complication of pertussis is bronchiectasis, a cylin drical dilatation of the bronchi, mostly multiple and accompanied by scar formation in the proximity. About the termination of bronchiec tasis in childhood, not much is known. The significance of its progress is that it is rarely unaccompanied by the diseases of the lungs. Influ enza may set in during the course of whooping-cough; bacteriological examinations by Jehle showing the presence of the influenza bacillus in twenty-four cases of pertussis always in the lungs and twelve times in blood. Mediastinal or subpleural emphysema, apt to spread in the subcutaneous tissue over the upper half of the body, is frequently observed, disappearing after a shorter or longer time. In such cases the skin produces a sensation somewhat like an air cushion and crackles on palpation. Pleuritis of a serous or purulent nature occurs very rarely as a complication of pertussis.