Determination of specific airway conductance by a simplified plethysmographic procedure.

Attention is drawn to the fact, obvious for simple mathematical reasons, that in patients that airway obstruction the values for specific airway conductance (SGaw) calculated directly from the flow-pressure loop registered during quiet breathing with a constant-volume body plethysmography closely approximate the values obtained by the conventional plethysmographic method which includes temporary interruption of the airflow. The simplified procedure may be useful e.g. in serial determinations of SGaw in situations where simultaneous measurement of the lung volume is not considered essential.