Conditions for occurrence of pendulum airflow under spontaneous ventilation were studied in adult dogs with flail chest experimentally constructed by removing three ribs and the chest wall. Pendulum air flow was recorded pneumotachometrically from outside the body by intubation to the bronchi. Despite objections to the occurrence of pendulum air by many investigators, we found that pendulum airflow occurs under various conditions. The main factors facilitating the occurrence included 1) Significant differences in airway pressure and ventilatory volume between the lungs on the injured and the opposite side. 2) A high frequency of respiration. 3) Increased resistance in the upper airway. The pendulum airflow occurred not only at the area of tracheal bifurcation but also in the peripheral bronchial airway in the ipsi-lateral thorax of the flail chest. However, pendulum airflow was observed only transiently coinciding with the time of change from one phase of respiration to the other, and volume of pendulum airflow was considered to be so minimal that it had no significant deleterious influence on the alveolar ventilation. In cases of marked dysfunction of the chest wall or with increasing upper airway resistance, pendulum airflow may disturb alveolar ventilation to a considerable extent.

Recovery of the lungs after the reinflation of chronic atelectasis was studied experimentally using adult dogs. Obstructive absorption atelectasis was induced by banding the left main bronchus with a thin metallic plate. Tests were conducted 1 month after reinflation of the lungs. In the group of dogs which had suffered atelectasis for 3 months, static compliance and pulmonary blood flow were decreased by half at 1 month after reinflation; the conditions of reduced Po₂, increased A-aDo₂, and increased shunt flow rate in the affected lung persistently continued, and histological findings also showed collapse of the majority of alveoli and dilatation of the peripheral bronchioli, while macroscopically the lungs appeared to be aerated. It was therefore assumed that further aeration of the alveolar areas was impossible. The pulmonary function of the dogs within 1 month of atelectasis was restored to the same degree as that of the control group

Mass screening for breast cancer using physical examination alone has been carried out since 1983 in Zentsuji, Kagawa Prefecture, Japan. Over a 7-year period, breast cancer was detected in 11 of a total 8,271 examinees, the detection rate being high at 0.13%. The detected cases included a few early-staged breast cancers, suggesting that mass screenings are of slight efficacy. Seven cases of interval cancer were found by breast self-examination after the mass screenings, supporting the value of breast self-examination. A relatively large number of interval breast cancers was detected in 1985 and 1986, when the rates of required further examination remained under 1%. The sensitivity and specificity of this screening were 61.1% and 94.5%, respectively, indicating a low sensitivity. These results suggest that the qualitative diagnoses made from the first screening by physical examination alone were often revealed to be false negatives. Therefore, the existing diagnosis should be employed in the first screenings. It is recommended that mammography be introduced to detect breast tumors which are nonpalpable or undetectable by physical examination alone.

No abstract

After a pneumonectomy in patients of advanced age with lung cancer, over-inflation of the contralateral lung causes a further emphysematous change. This aggravation of emphysematous disturbances occasionally leads to serious cardiopulmonary dysfunctions. Therefore, we have devised a new therapeutic method which consists in injecting sulfur hexafluoride, SF₆, an inert gas, into the postpneumonectomy pleural space so as to maintain the chest cavity. As SFó gas is slowly absorbed through the pleura, gas injection at intervals of 6 months can maintain a clear pleural space with neither retention of pleural effusion nor deformity of the thorax. As a result, in 23 patients who were treated by this method, overinflation of the contralateral lung after unilateral pneumonectomy could be prevented, and respiratory functions could be improved, i.e., the vital capacity increased about 20% and the residual volume decreased over 20% after SF₆ gas injection. All patients have been in good condition of their performance status, and it was not disadvantageous to continue the SF₆ gas injection for a long term such as several years