A modified conception of phrenic nerve crush and pneumoperitoneum therapy.

The object of this paper is to present a modified view of the mode of action of phrenic nerve crush and pneumoperitoneum therapy in pulmonary tuberculosis. In a study of mediastinal shift in a series of 80 cases of phrenic nerve crush and pneumoperitoneum therapy (Fox, 1950) it was found that the average mediastinal shift to the left in the cases with right phrenic paralysis was 1.6 cm., and to the right in those with left phrenic paralysis was 1.5 cm. Furthermore, of these 80 cases, only 10 had no demonstrable mediastinal shift. It is therefore apparent that mediastinal shift is present in the large majority of cases following phrenic nerve crush and pneumoperitoneum therapy, and the figures quoted demonstrate that the generally accepted view of the form of the collapse produced by phrenic nerve crush and pneumoperitoneum therapy is fallacious. The literature on phrenic nerve crush and pneumoperitoneum therapy in pulmonary tuberculosis gives the impression that the sole spatial effect of the treatment is to reduce the apico-basal diameters of the lungs. The two hemidiaphragms are regarded as plungers situated at the thoracic outlet. These plungers become elevated as a result of the therapy, and so there is a diminution in the apico-basal diameters, the greater reduction occurring on the side of the paralysed hemidiaphragm. In this view each hemithorax can be represented as a right-angled triangle the base of which moves upwards as a result of the therapy, thus producing a smaller rightangled triangle (Fig. 1). This, however, is inaccurate, for not only are the bases moving, but in addition the perpendicular sides move too, so that an acute angle is produced on the paralysed side and an obtuse angle on the unparalysed side in any case where the mediastinum is not markedly rigid (Fig. 2). It is important to appreciate this point because it materially alters the mechanism of the therapy on both sides. Each side will now be considered in turn.