The Laryngoscope V C 2013 The American Laryngological, Rhinological and Otological Society, Inc. Assessment of Aspiration Risk From Dynamic Modulation of Endotracheal Tube Cuff Pressure Sohit P. Kanotra, MD; Evan J. Propst, MD; Igor Luginbuehl, MD; Paolo Campisi, MD; Joseph A. Fisher, MD; Vito Forte, MD Objectives/Hypothesis: To assess the risk of aspiration using a novel valve circuit that dynamically modulates endotra- cheal tube cuff pressure during the ventilatory cycle using bench and live animal models. Study Design: Animal model. Methods: The bench model consisted of a cuffed endotracheal tube inserted into an artificial trachea. Leakage of liquid around the cuff was measured after 4 hours of constant or dynamic modulation of cuff pressure at variable peak end expira- tory pressures. In the porcine model, eight animals were ventilated with the modulating valve circuit and compared to eight controls ventilated with a constant cuff pressure (25 cm of water). Aspiration was monitored quantitatively using a pH probe (measured as voltage) and visually using fluoroscopy. Results: There was no difference in the amount of fluid leakage around the endotracheal tube cuff in the constant or dynamically modulated pressure-cuff groups in the bench or animal models. Conclusion: Dynamically modulating endotracheal tube-cuff pressures to minimize tracheal mucosal damage does not increase the tendency to leak around the cuff compared to endotracheal tube cuffs inflated to a constant pressure. Key Words: Mechanical ventilation, endotracheal tube, modulation of cuff pressure, aspiration, bench top model, animal model, PEEP, intubation, injury, airway, larynx. Level of Evidence: N/A. Laryngoscope, 124:1415–1419, 2014 INTRODUCTION Despite advances in the design of endotracheal tubes and techniques of endotracheal intubation, pro- longed intubation and ventilation continues to result in laryngotracheal trauma. The most significant factor in laryngotracheal trauma is pressure exerted by the endo- tracheal tube (ETT) cuff on the laryngotracheal mucosa. 1 Cuff pressure that exceeds the capillary perfusion pres- sure of 20- to 25-cm H 2 O results in mucosal ischemia, which can lead to epithelial erosion and ulceration with subsequent exposure, infection, and necrosis of the cartilage. 2 Advancements in the design of the ETT, along with the use of uncuffed and smaller endotracheal tubes, have been proposed to reduce airway injury. Two methods of reducing cuff-related airway injury are: 1) altering ETT cuff material and 2) altering the pressure exerted by the ETT cuff. We previously demonstrated in an animal model that a polyvinyl acetate (Merocel; Medtronic, Min- neapolis, MN) “cuff” that conforms to the contour of the larynx could significantly reduce the amount of subglottic injury when compared to a standard inflatable polyvinyl chloride cuff. 3 We also demonstrated previously that syn- chronization of cuff pressure with the ventilatory cycle, using dynamic mechanical cuff inflation with an electro- mechanical device, could reduce mucosal injury. 4 Most recently, we demonstrated that similar cuff pressure syn- chronization performed passively using the strategic placement of a commercial positive end-expiratory pres- sure (PEEP) valve in the inspiratory limb of a ventilator circuit also reduces tracheal mucosal injury in a hypoxic porcine model of accelerated airway injury. 5 In order to be useful clinically, however, these novel methods of modulating ETT cuff pressure must not com- promise the amount of protection from the aspiration of pharyngeal contents afforded by constantly inflated ETT cuffs. Aspiration of oropharyngeal secretions is a major cause of ventilator associated pneumonia in the inten- sive care unit (ICU) setting. 6 High-volume low-pressure cuffs used in the ICU do not fully protect the lower air- way from contamination by subglottic secretions, even when the cuff pressure is maintained at an acceptable Additional Supporting Information may be found in the online version of this article. From the Department of Otolaryngology–Head and Neck Surgery (S.P .K., E.J.P ., P .C., V .F .); and Department of Anesthesiology (I.L.), University of Toronto, The Hospital for Sick Children; and Department of Anesthe- siology (J.A.F .), University Health Network, University of Toronto, Toronto, Canada Editor’s Note: This Manuscript was accepted for publication October 21, 2013. Presented at the American Society of Pediatric Otolaryngology, Arlington, Virginia. April 25–28, 2013. Drs. Forte and Fisher have registered for a patent for the pressure modulating in-line valve under the auspices of the Commercialization Offices of the Hospital for Sick Children and the University Health Net- work, respectively. The authors have no other funding, financial relation- ships, or conflicts of interest to disclose. Send correspondence to Sohit P. Kanotra, Department of Otolaryn- gology–Head and Neck Surgery, The Hospital for Sick Children, 555 Uni- versity Ave, Toronto, Canada, M5G 1X8. E-mail: dr.sohitpaul@gmail.com DOI: 10.1002/lary.24481 Laryngoscope 124: June 2014 Kanotra et al.: Aspiration Risk and Cuff Pressure Modulation 1415