CHEST Original Research CRITICAL CARE MEDICINE www.chestpubs.org CHEST / 138 / 4 / OCTOBER, 2010 863 E ndotracheal tube (ETT) intubation impairs cough and mucociliary transport, and mucus stasis can lead to atelectasis, airway infection, and respiratory compromise. ETTs eliminate the normal protection against aspiration so that secretions from the orophar- ynx can pool above the ETT cuff and be aspirated into the lungs, potentially leading to ventilator- associated pneumonia (VAP). One case of VAP can result in more than $40,000 in additional hospital costs. 1,2 The Hi-Lo Evac (Mallinckrodt Medical; St. Louis, MO) ETT can aspirate secretions above the ETT cuff through a separate lumen that supports continuous or intermittent aspiration of subglottic secretions. In a study of 140 intubated patients who had a conven- tional ETT and 140 treated with the Evac ETT, Cox regression analysis showed that the risk of VAP was Background: Endotracheal tube (ETT) intubation impairs mucus clearance, which can lead to respiratory compromise. We compared three ETTs that have intrinsic capacity to aspirate secre- tions pooling above the cuff. Methods: We evaluated the ability of three ETTs with suction, Hi-Lo Evac, Teleflex ISIS, and Por- tex Blue Line SACETT, to aspirate saliva and mucus simulants at continuous or intermittent vacuum pressures. We also evaluated the potential for a flexible tracheal membrane to obstruct the ETT suction port with applied vacuum. We measured the dimensions of the suction tubing at critical points to calculate differences in flow. Results: In a rigid tracheal model, the ISIS aspirated saliva simulant more quickly with continu- ous low pressure suction than Evac ( P 5 .0006) and SACETT ( P , .0001) as well as with intermit- tent high pressure suction ( P , .0001). For mucus simulant, the ISIS aspirated stimulant better than the other ETTs at high intermittent suction ( P , .0001); the Evac was more effective than the SACETT ( P 5 .0019). For low and continuous suction, suction ports in all ETTs occluded with mucus, except for ISIS, at the highest continuous suction tested. In a trachea model with a flexible posterior membrane, this membrane either partially or completely occluded the suction port of all tubes at high continuous or intermittent suction. The ISIS was more prone to obstruction by the flexible membrane than the Evac. We found large differences in suction tubing cross-sectional area between the ISIS and the other tubes, and flow calculations using the Hagen-Poiseuille equation can explain the observed differences in volumes aspirated and tendency toward lumen obstruction. Conclusions: The ISIS transmits suction pressure to the tube orifice more powerfully than the Evac and SACETT. This feature makes the ISIS less prone to obstruction by mucus but more likely to obstruct by tissue suction. CHEST 2010; 138(4):863–869 Abbreviations: ETT 5 endotracheal tube; VAP 5 ventilator-associated pneumonia In Vitro Evaluation of Endotracheal Tubes With Intrinsic Suction Karla I. Mujica-Lopez, MD; Melissa A. Pearce, BS; Kyle A. Narron; Jorge Perez, BS; and Bruce K. Rubin, MD, FCCP Manuscript received December 29, 2009; revision accepted March 15, 2010. Affiliations: From the Department of Pediatrics (Drs Mujica- Lopez and Rubin, Ms Pearce, and Mr Narron), Virginia Com- monwealth University, Richmond, VA; and Teleflex Medical (Mr Perez), Research Triangle Park, NC. Funding/Support: This study was supported by research grants from Teleflex Medical and from CONACYT, University of Guada- lajara (to Dr Mujica-Lopez). Correspondence to: Bruce K. Rubin, MD, FCCP, Virginia Com- monwealth University School of Medicine, 1001 E Marshall St, PO Box 980646, Richmond, VA 23298; e-mail: brubin@vcu.edu © 2010 American College of Chest Physicians. Reproduction of this article is prohibited without written permission from the American College of Chest Physicians (http://www.chestpubs.org/ site/misc/reprints.xhtml). DOI: 10.1378/chest.09-3117 Downloaded From: http://journal.publications.chestnet.org/ on 06/25/2014