Cigarette smoking and pressure-volume characteristics of the lung

This study was done to identify the immediate changes induced by cigarette smoking on the mechanical properties of the lung. Static compliance (C stat), static pressure-volume (Stat P-V) hysteresis, vital capacity (VC), frequency dependence of dynamic compliance (C dyn) and collateral ventilation (Coll V) of the lung were studied in six mongrel dogs. The smoking of one cigarette induced a fall in VC and static P-V hysteresis of the lungs. These changes indicate an increase in elastic recoil of the lung probably caused by inactivation of pulmonary surfactant. Frequency dependence of C dyn did not develop after smoking. Extensive collateral ventilation was seen in the lungs of all the experimental animals and in those of five other normal dogs, who had not been exposed to cigarette smoke. The significance of these findings are discussed.