surgical treatment of pulmonary tuberculosis whereby the lung is totally or partially, temporarily or permanently, immobilised. The procedure was based on the popular concept that collapsing the affected portion of a tuberculous lung allowed the infected area to rest and thereby recover. at the beginning of the 20th century artificially induced pneumothorax (pneumothorax, artificial) was popular. Later a variety of other techniques was used to encourage collapse of the infected portion of the lung: unilateral phrenic nerve division, pneumonolysis, pneumoperitoneum (pneumoperitoneum, artificial), and thoracoplasty. Collapse therapy has declined since the advent of antitubercular chemotherapy.