• M S Hannallah and J L Benumof.
• Department of Anesthesia, Georgetown University Medical Center, Washington, D.C. 20007.
• Anesth. Analg. 1992 Nov 1;75(5):784-7.

AbstractThe Univent tube is an endotracheal tube with a movable bronchial blocker. The blocker cuff reportedly exhibits high-pressure characteristics when inflated to seal any adult bronchus. This study was aimed at measuring the cuff volume that would seal the bronchus when two different techniques of cuff inflation were used. One technique is based on creating negative pressure and the other is based on creating positive pressure within the breathing system. In addition, we directly measured the compliance characteristics of the cuff. The study was performed in eight adult patients undergoing thoracotomy. The negative pressure technique of cuff inflation (NPT) was tested by applying -150 mm Hg of pressure to the blocker lumen, causing loss of volume in the breathing system as evidenced by deflation of the reservoir bag. The blocker cuff was then inflated until the bag ceased to deflate. In the positive pressure technique of cuff inflation (PPT), the blocker lumen was connected to a beaker of water while maintaining pressure of +30 mm Hg within the breathing system. The bronchial cuff was then inflated until air bubbles ceased to appear in the beaker. Direct measurement of compliance of the blocker cuff confirmed its high-pressure characteristics. Bronchial sealing volume ranged from 3 to 5 mL when measured with the NPT and from 4 to 6 mL when measured with the PPT.(ABSTRACT TRUNCATED AT 250 WORDS)

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