IT HAS been previously shown1 that the elasticity of the lungs and chest wall is decreased in patients in whom there has been respiratory impairment due to poliomyelitis. This change is of considerable practical importance in the management of such patients, because it increases the work of breathing and decreases the efficiency of mechanical respiratory aids. It further affects the rapidity with which such patients can be weaned from mechanical aids and influences the length of unassisted breathing time, since the latter is dependent upon the work of breathing as well as the respiratory reserve. These changes can explain why similarly involved patients may require vastly different tank pressures for adequate ventilation when frank obstructive factors are absent.
We are reporting an evaluation of a simple clinical technique for estimating the combined elasticity of the lungs and thorax which can be used wherever a tank respirator and a continuously