Ting et al studied isolated bullae after resection and found that bullae were very compliant with a sharp elastic limit and that the inflation pressures for bullae are less than they are for surrounding lungs. Morgan et al measured pressures in bullae just before excision and found that the pressure was never positive during inspiration and never more positive than pleural pressure at end-expiration. Accordingly, bullae appear to be formed by emphysematous destruction of pulmonary tissue and enlarge by the retractive forces of surrounding lung parenchyma. Improved recoil after LVRS could act to exaggerate this process.
The serial PV curves of the patient mentioned above are consistent with the latter theory. Before bullectomy (3-year curve), there was a right shift on the normalized PV curve. This could be consistent with the presence of the large bulla. Natural asthma inhaler read more The lung would be essentially divided into two compartments: a nondeflating bulla and a normally deflating compartment. The serial static recoil and maximum expiratory flow curves initially showed improved expiratory flows at any specific elastic recoil after LVRS. This may have been due to decreased airway resistance engendered by increased recoil tethering open airways.