EXSUFFLATION WITH NEGATIVE PRESSURE (E.W.N.P.)

Abstract

THE ELIMINATION of radiopaque material from the tracheobronchial tree of anesthetized dogs was reported in a previous paper.¹ This was accomplished by two devices which produced high-volume expiratory-flow rates simulating the natural cough.* Studies of bronchial dynamics by serial bronchography revealed a twofold dilatation of the medium-sized bronchi in animals subjected to an inflationary pressure of + 40 mm. Hg. The restoration to normal of the blood gas values found in obstructive dyspnea, reported by Cherniack, Gordon, and Drimmer,⁵ may be explained in part by the marked dilatation of the bronchi. The development of a more effective technique, whereby there is slow inflation of the lungs, followed by an "explosive expiration," resulted in a total pressure-drop of approximately 100 mm. Hg, with expiratory-flow rates that surpassed those attainable by the most vigorous cough of normal human subjects.⁶ A positive pressure blower served to inflate the lungs to a