J.Jpn. Surg. Soc.. 56(11): 1475-1486, 1956

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BRONCHOSPIROMETRIC STUDIES ON THE COMPENSATORY FUNCTION OF A HUMAN LUNG.
PART Ⅰ. EXCLUSION OF AN UNILATERAL LUNG FROM RESPIRATORY SYSTEM BY OCCLUSION OF A BRONCHUS DURING BRONCHOSPIROMETRY
PART Ⅱ. EXCLUSION OF AN UNILATERAL LUNG FROM RESPIRATORY SYSTEM BY RESPIRING PURE NITROGEN.

The present methods of preoperative evaluation of patients who are candidates for pneumonectomy are not entirely satisfactory. In usual cases, present pulmonary function tests are sufficient to determine the condition of the patients. If, however, there is a suspection of functional impairment in remaining lung, or if some degree of cardiopulmonary insufficiency is already present, it would be advantageous to have a more accurate method to evaluate these cases than the present ones.
In these cases, it would therefore be desirable to rule out one of the lungs from the respiratory system, in order to detect some incapacity of the other lung to accomplish respiratory function.
The author used two methods of exclusion of a lung. The first consists of clamping a tube leading to one of the lumina of the double lumen catherter (Carlens), and the other of breathing pure nitorogen in unilateral lung. Following the exclusion of a lung, the relative arterial oxygen saturation were followed with a Milican's ear peace oximeter to investigate the ability of a lung to compensate.
PART I. EXCLUSION OF AN UNILATERAL LUNG FROM RESPIRATORY SYSTEM BY OCCLUSION OF A BRONCHUS DURING BRONCHOSPIROMETRY
This paper deals with the effect on respiration of occlusion of a bronchus.
1) Twelve patients, all suffering from bilateral pulmonary tuberculosis and being evaluated for chest surgery were used. Four of these patients could not tolerate the procedure.
2) Immediately after occlusion of a bronchus, the other lung always showed hyper-ventilation, but the response differed in some respects dependent on whether a lung was blocked at the peak of inspiration or at the end of expiration.
3) In spirometric investigation during occlusion, the occlusion at the peak of normal inspiration causes an increase in inspiratory capacity and decrease in expiratory reserve volume. Occlusion at the end of expiration showed quite the reverse.
4) The intrapulmonary pressure of the blocked lung recorded manometrically, showed a great increase. Average in three cases : from 12 to 13 mmHg. during occlusion at inspiration and from 18 to 19 mmHg. at expiration.
5) It would seem that occlusion experiments provide so extremely unphysiological factors that they would be an inadequate methods to investigate individual lung function.
PART II. EXCLUSION OF AN UNILATERAL LUNG FROM RESPIRATORY SYSTEM BY RESPIRING PURE NITROGEN.
This paper deals principally with a method of evaluating the function of an unilateral lung by studying the changes of arterial oxygen saturation after the other lung has been excluded from the respiratory system. The lung to be operated on was excluded by taking pure nitrogen, while the other was taking oxygen. The changes of relative oxygen saturation was measured continuously by Milikan's ear peace oximeter. These changes were plotted in form of a curve.
1) Twenty-one patients, suffering from bilateral pulmonary tuberculosis and evaluating for chest surgery were used. None of these patients complained of greater discomfort than ordinary bronchospirometry.
2) Following exclusion of the unilateral lung, the other lung always showed compensatory increase of oxygen intake and ventilation.
3) When a more severly damaged lung takes oxygen and the other pure nitrogen, striking fall of arterial oxygen saturation ensues. While a more severly damaged lung takes nitrogen and the other oxygen, such fall of arterial oxygen saturation does not occur. Thus, there has been a definite relationship between the degree of functional impairment of a lung and lowering of arterial oxygen saturation.
4) In the patients who showed the favorable results, there has been no one suffering from respiratory insufficiency after extensive pulmonary resection.
5) The percentage ratio of oxygen intake of a lung showed a closer relationship with the compensatory power of individual lung than those of vital capacity and minute ventilation. Percentage ratio of oxygen intake should be considered as a final determinant of evaluating individual lung function.
6) It would appear that this method can provide practical information when the extensive pulmonary resection is under consideration, particularly in poor risk patients.
(author's abstract)

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